Alternative Wall Systems for Low-rise Housing

esearch ReportR

HOUSING

TECHNOLOGY

SERIES

a lt e r n at i v e wa l l s y s t e m s

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ALTERNATIVE WALL SYSTEMSFor Low-Rise Housing

June 2002

Prepared by:

Sun Ridge Group

for:

Canada Mortgage and Housing Corporation

CMHC offers a wide range of housing-related information, For details, call 1 800 668-2642 or visit our Web site at www.cmhc.ca

Cette publication est aussi disponible en français sous le titre : Variantes de murs : habitations de faible hauteur, 63010

Alternative Wall Systems

This research project was (partially) funded by Canada Mortgage and Housing Corporation (CMHC). The contents,views and editorial quality of this report are the responsibility of the author(s) and CMHC accepts no responsibility forthem or any consequences arising from the reader's use of the information, materials and techniques described herein.

National Library of Canada cataloguing in publication data

Main entry under title : Alternative wall systems for low-rise housing

Issued also in French under title : Variantes de murs : habitations de faible hauteur.

ISBN 0-662-32562-1 Cat. no. NH15-391/2002E

1. Walls -- Design and construction.2. Apartment houses -- Design and construction.I. Sun Ridge Group.II. Canada Mortgage and Housing Corporation.

TH2235.A44 2002 690'.12 C2002-980198-2

© 2002 Canada Mortgage and Housing Corporation. All rights reserved. No portion of this book may be reproduced, stored in a retrieval system or transmitted in any formor by any means, mechanical, electronic, photocopying, recording or otherwise without the prior written permission ofCanada Mortgage and Housing Corporation. Without limiting the generality of the foregoing no portion of this bookmay be translated from English into any other language without the prior written permission of Canada Mortgage andHousing Corporation.

Printed in CanadaProduced by CMHC

i

ACKNOWLEDGEMENTS

The authors would like to thank the following individuals and organizations who contributed to this project:

Tony Mammone, P. Eng., Plasti-Fab

Richard McGrath, P. Eng., Cement Association of Canada

Eric Jones, Canadian Wood Council

Peggy Lepper, Canadian Wood Council

David Stubbs, Ontario Masonry Contractors’ Association

Robert Savignac, International Log Builders’ Association Intl.

Dr. Kris J. Dick, P. Eng., University of Manitoba, Department of Biosystems Engineering

Jack Shields, Tembec Forest Products Group

John Law, TrusJoist a Weyerhauser Business

Ginette Dupuy, B.Arch, M.Sc.A. en aménagement

Bill Semple, Canadian Home Builders' Association

iii

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Section 1 - Moving From the Mainstream . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Section 2 - Alternative Wall Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Lightweight Steel Framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Structural Insulated Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Insulated Concrete Forms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Post and Beam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Concrete Block Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Log Homes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Stackwall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68Straw Bale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78Manufactured Wood Wall Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88Earth Construction Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Section 3 - List of References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

!""#$%&'(!) !**+,&-.&+$*(-$%(/+$.-,.*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

!""#$%&'(0) 1#2&#3(/+44&..## . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Table of Contents

The purpose of this publication is to raise the awareness of Canadian builders andconsumers regarding some of the alternativewall systems being applied in the constructionof low-rise housing, and to provide them withthe ability to determine the applicability ofthese new systems to their home buildingprojects.

The movement toward alternative buildingsystems has come about as the result of anumber of factors, including the depletion of forest resources, and concerns about energyefficiency and construction costs.

Some research needs to be conducted prior to making the decision to use alternative wallsystems. The first step is to review this andother publications in order to get a betterunderstanding about a system and some of the options. Another step is to visit siteswhere an alternative system is being installed,and talk to one or more builders orhomeowners.

There are several factors that can be used toanalyze the different wall systems including:cost, impact on services, energy efficiency,durability, fire, sound, environmental issues,indoor air quality, construction sequencing,trade training, market acceptance and resalevalue, regulatory approvals, warranty programapprovals, and insurance.

Ten alternative wall systems are presented,including: lightweight steel framing, structuralinsulated panels (SIPs), insulated concreteforms, post and beam, concrete block, log,stackwall, straw bale, manufactured woodwall, and earth wall construction systems.

Information was gathered using the Internet,by conducting research in libraries and from

publications received from industryassociations. In addition, builders andhomeowners were interviewed, and theirfeedback was used in analyzing the systems.Contacts and information sources are listed.

The appendices contain a list of associationsand organizations that can provide furtherinformation on each of the alternative wallsystems. The appendices also contain a list ofindividuals that have considerable experiencein one or more of the alternative wall systemsand have reviewed this document.

Lightweight steel framing consists of cold-formed galvanized steel “C” sections forjoists, studs and rafters. The steel sectionscome in various depths and gauges, so thatextra structural capacity can be achieved bychanging the gauge while keeping the depththe same. Insulation is generally placed in the wall cavity, with at least some insulationplaced on the outside of the studs to reducethermal bridging. The primary target marketfor lightweight steel frame houses isprofessional builders.

Lightweight steel framing is strong,dimensionally stable and is easy to work with.This framing system won't warp or twist andthis results in straight walls and square corners.The materials used in this wall system are notsusceptible to termite damage. The steel studscan be precut which results in less waste beinggenerated and the waste that is generated canbe recycled. A large percentage of steel studsare made with recycled material.

Structural insulated panels (SIPs) are panelswith a core of rigid foam insulation betweenan exterior and interior skin. The mostcommon materials used for the skins arestructural Oriented Strand Board (OSB) or

1

Executive Summary

plywood. The foam cores are composed ofexpanded polystyrene, extruded polystyreneor polyurethanes. The two skins, incombination with the integral insulation core, carry all of the loads of the structure.The foam insulation keeps the two skinsaligned, acting as a web and provides theinsulation value. Professional builders are the primary target market for SIPs.

The advantages of SIPs are that they are energyefficient, installation is fast, and the walls arestraight and smooth for the interior finishesand exterior cladding. There may be somelimitations under high loading conditionsand/or concentrated loads. Extra moistureprotection may be required. Also, sometraining is needed to install the system.

Insulated concrete forms (ICFs) are hollowblocks or panels made of expanded orextruded polystyrene, that are stacked intothe shape of the exterior walls. There areconnection ties between the inner and outer forms, which are usually steel or plastic.Reinforcing steel is then installed in the cavitybetween the inner and outer forms, andconcrete is poured into the cavity. The foamform becomes part of the wall and remains in place, thus providing the insulation valueto the wall system. Both the owner/builderand the builder have shown interest in thistype of wall system.

The ICF wall system is easy to install, quiteenergy efficient, has good sound and fire ratingcharacteristics, and is very durable. However,the cost of a house with ICF exterior walls istypically a few per cent higher than a standardwood-frame house. Also, the increased weightof the exterior walls may require largerfootings to accommodate the increased loads.

Post and beam construction consists of aseries of vertical posts or columns supportinghorizontal beams to form a structuralframework. Posts are located at each corner of the building, and are usually spaced evenlybetween the corner posts to support the loadsfrom the roof. The post and beam frame is usually left fully visible to the inside. Post and beam framing is typically installedby professional builders.

Post and beam construction provides thestructural components of the building, and atthe same time provides an interior finish thatmany homeowners find attractive-the entireinterior of the house does not require load-bearing walls, allowing for a very open design.The major drawback of this system involvesthe drying of the wood. Shrinkage can resultin cracking and movement due to the dryingprocess. The design of the members, includingconsideration of wind loading, may requirethe services of a design professional.

Concrete block wall construction is typicallyused in commercial buildings, but has beenused sporadically in residential construction.It has been used residentially primarily as afoundation system, but is equally applicableto above-grade walls. Concrete blocks areinstalled in courses, with each course set in a bed of mortar. Reinforcing can be installedboth horizontally and vertically to carryimposed loads. Special blocks are installedover openings so that additional reinforcementcan be placed to carry vertical loads over theopenings. This system is best installed bytrades experienced in masonry work.

The key advantages of concrete block wallconstruction are excellent fire and soundratings, and durability. The main drawback


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is that it is more expensive than the traditionalwood-frame system. A more specialized tradeis usually involved in the installation. Inaddition, strapping and insulation, or the use of rigid insulation will likely be requiredto provide adequate insulation.

In recent years, log homes have made thetransition from seasonal to year-roundresidence, and today, the majority of loghomes are being built for year-roundoccupancy. This has resulted in larger and more sophisticated structures, plus the recognition that building a log home is far more complex than building a weekendcabin. Hand-crafted log homes are best suitedto owner/builders that are skilled in the use of tools, are physically fit, and have time andpatience.

A log house is one of the most aestheticallysatisfying homes in which to live. With agood foundation to protect the wood, and a wide overhang to shelter against moisture, a log home is very durable and can last forgenerations. However, building a log homerequires skill, is very time consuming, and isnot low-cost. In addition, log homes requiremore maintenance than brick, vinyl- oraluminum-sided houses.

The stackwall system, also known as cordwood masonry, round wood, and log-endconstruction, is a building technique in which short logs are stacked side by side likefirewood, with the spaces between them filledwith a cement mortar. The log-ends themselvesestablish the width of the wall and are exposedon both the interior and exterior surfaces.Stackwall homes are more likely to beconstructed by owner/builders, and theeconomically and environmentally conscious.

The key advantages of stackwall constructionare economics, ease of construction, resourceefficiency, and ecological harmony. The costof building can be considerably less than astandard wood-frame house, depending onhow much labour is provided by the owner/builder and what materials are used. The maindrawback to this system is that it is very labourintensive and takes more time to build than a conventional house.

Straw bale construction uses baled straw fromwheat, oats, barley, rye, rice, and other grainsto build walls, which are then covered byplaster. This technique has been recentlyrevived as a low cost, environmentally friendlyalternative for building highly insulated walls.There are two commonly applied buildingtechniques using straw bales: post and beamand load-bearing. Straw bale homes aresuitable for most markets, but tend to bebuilt by owner/builders.

Environmentally, economically, and in termsof efficiency, straw bale houses offer manyadvantages. Straw is a natural, affordable, and annually renewable building material.However, careful attention to details duringand after construction is crucial in order toavoid moisture problems. High moisturecontent in bales can provide habitat for fungi,and can lead to decomposition within thewall assembly. The recent adoption of strawbale construction may not be readily acceptedby building code officials, warranty programs,and the home insurance industry.

Manufactured wood wall systems are similar totraditional wood framing, with the substitutionof manufactured studs for traditionaldimensional lumber studs. The manufacturedstuds include I-Joist, finger jointed studs,Laminated Strand Lumber (LSL) and Parallel

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Strand Lumber (PSL). LSL and PSL membersare typically used for beams, columns andlintels. I-Joists are mostly used in floorsystems, and finger jointed studs have similarstructural characteristics to dimensionallumber.

LSL and PSL members can be cut to virtually any dimension and to any length.The manufactured product has a significantincrease in strength over dimensional lumber. LSL members can be substituted for traditional studs; PSL members are nottypically stud material. Finger jointed studsare made from short lengths of dimensionalmaterial that are joined with adhesives.

The primary advantage of wall systems usingmanufactured wood studs is the uniformity of the material, which results in walls that arevery straight and will not warp and twist inthe future. Also, LSL can be used in tall wallswith the same size and spacing as dimensionallumber, but with the capability of handlingaxial loads in combination with wind loads.The main drawback to manufactured woodwall systems is the cost. The studs can be upto double the cost of traditional wood studs.

Earth wall construction is an ancient form of building, and includes techniques such as rammed earth, compressed earth block,adobe, cob and earth-sheltered. In therammed earth method, damp soil mixed withcement is compacted in enclosed formwork,similar to that of cast-in-place concrete, and cured. Compressed earth blocks can bemanufactured on-site using a variety of block-making machines. The same soil is then usedin the mortar for binding the blocks togetherinto walls. The primary target market forearth construction is owner/builders whowant the satisfaction of building a home using

indigenous, recyclable, low-cost materials thatare less damaging to the environment.

The main advantages of earth constructionare thermal mass and hygroscopicity. The thick walls of a rammed earth homemake it less susceptible to the effect ofextreme outdoor air temperatures. Earth wallsabsorb the extra moisture in the air and releaseit when there is not enough. Other advantagesinclude durability, reduced exterior maintenancerequirements, excellent fire and soundresistance, and resistance to wood predators,fungus and rot. However, earth wallconstruction is not suitable for all climatesand locations. In addition, the initial costfor a rammed earth home is higher than for a standard wood-frame house.


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The purpose of this publication is to raise theawareness of Canadian builders and consumersregarding some of the more common non-proprietary alternative wall systems that couldbe applied in the construction of low-risehousing. It will also provide them with someability to determine the applicability of thesealternative systems to their home buildingprojects, upon further study.

Canadian consumers and builders may not beaware of the wide range of possible alternativewall systems. Many builders are reluctant to experiment with new concepts andtechniques because of the potential risksinvolved. They would rather wait for othersto prove that new techniques work, are costeffective, and are marketable.

Many of these systems offer potentialadvantages, such as reduced constructioncosts and the use of locally available materials.However, there are also disadvantages, such asincreased construction time and high labourrequirements. The information provided herewill assist consumers and builders incomparing these systems.

This publication will assist builders to assessthe pros and cons of alternative wall systemsso they can determine the potentialimplications for their businesses. It will assist Canadian consumers to acquire enoughknowledge to make informed decisions onthe type of wall system they want to use.

The first section discusses some of the factorsthat can be used to analyze the different wallsystems. These range from environmentalissues to regulatory approvals, and from tradesequencing to warranty coverage. All of thesefactors should be considered prior to makingthe decision to use an alternate system, as

some can have a significant impact on theconstruction cost or construction process.

The second section deals with 10 alternativewall systems including: lightweight steelframing, structural insulated panels, insulatedconcrete forms, post and beam, concrete block,log, stackwall, straw bale, manufactured woodwall, and earth wall construction systems. It should be noted that there are many otheralternative wall systems not included in thispublication, including hybrid systems of both standard and alternative wall systems.

Each system is discussed in terms of thefollowing: primary target market, key benefits,key drawbacks, structural considerations,material considerations, sequencing ofconstruction, labour and equipmentrequirements, impact on services, designflexibility, key construction notes, constructioncosts, energy efficiency, durability, fire andsound considerations, impact on indoor air quality, environmental issues, regulatoryimpediments, warranty and insuranceimplications, market acceptance and resalevalue, export potential, and geographiclimitations.

In order to make the comparison of systemsmore consistent, the sections and the analysisof the various building systems deal with wallsonly. Although some of the systems haveother applications, such as for foundations,floors, and roofs, the discussion and analysisis limited to above grade exterior walls.

The third section of this document is a list of references. Research was conducted at the library, and the Internet was used forcollection of information on each of thesystems. In addition, builders and homeownerswere interviewed, and their feedback was used

5

Introduction

in analyzing the systems. Contacts andinformation sources are listed.

The appendices contain a list of associationsand organizations that can provide furtherinformation on each of the alternative wallsystems. The appendices also contain a list ofindividuals that have considerable experiencein one or more of the alternative wall systemsand have reviewed this document.


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Moving from the Mainstream

Prior to the turn of the century, there was anawareness of the necessity for safe, affordablehousing. At that time, there were few codesto govern the construction of the buildingspeople lived and worked in, but mostbuildings proved to be safe and usable. People constructed buildings from thematerials that were usually readily available.

Rough sawn lumber produced in randomlengths and with no grading was graduallyreplaced with mass produced, smallerdimensioned, planed and graded material.Local industry grading rules gradually evolvedto national grading rules that were harmonizedwith similar American industry standards toserve a North American market. The efficiencyin scale and the move to panel materials,which influenced ceiling heights, led to thespecialization of lumber lengths to minimizecutting on-site.

In recent years, there has been renewedinterest in materials of the past, as well as the development of new building products.The time has come to recognize some ofthese alternatives as acceptable, even if on a limited basis.

Anytime someone proposes to use a buildingmaterial that does not fit into the typicalmould, some people attack or ridicule theidea. In some cases, there exists onlyanecdotal knowledge about alternative framingtechniques, backed by some experience. Thisgives some basis for understanding how thesebuildings work, but does not always provideenough information to make a decision.

Research should be undertaken prior tomaking the decision to use alternate wallsystems. The first step is to review this andother publications in order to get a betterunderstanding about a particular system, and some of the alternatives. Another step is to visit some construction sites where analternative system is being installed, and talkto builders. Feedback from homeowners isalso valuable. The Internet offers the meansto access valuable sources of information. In addition to Web sites maintained byvarious industry groupings, some Web sitesoffer feedback from users that describe bothpositive and negative experiences.

There are several factors that should beconsidered when researching alternative wallsystems. The following is an overview of thesefactors.

Cost

Material, labour and equipment costs must beassessed before undertaking any constructionproject. Material costs can vary greatlybetween and within alternative buildingsystems. For example, straw bales will beconsiderably less expensive in a high straw-producing region at the end of the harvestseason. In a low straw-producing region, it maybe more economical to consider other methods.

Labour costs can be difficult to determinebecause, in some of the alternative wallsystems, much or all of the labour can bedone by the owner/builder. This is also truefor conventional lumber framing. Since itmay be considered self-gratifying to participatein building your own home, this cost may

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Section 1: Moving From The Mainstream

not be included. Some of the systems are verylabour intensive; therefore, labour costs couldbe quite high if sub-contractors are hired.

Another aspect of the labour component isthe learning curve associated with some of the systems. Traditional trades may be askedto perform tasks they have never tried before. If trades are working with new materials orsystems, they typically overestimate costs inorder to account for unknown factors.

Framers may be asked to frame a steel house,but may have never worked with the materialor the needed tools or fasteners. Thus, thefirst house or two built could have significantlyhigher labour costs than subsequent houses.

Impact on Services

The installation of services such as plumbingand electrical systems may be more complicatedwhen alternative wall systems are used. Thecavities in which services are typically installedmay not be available, alternative locationsmay need to be used, or modifications to the new system may be required.

There may also be implications for interfaceswith other components in the house. Forexample, kitchen cabinets are hung on thewalls in a standard wood-frame house; forstraw-walled houses, there is no backing orsolid materials on which to hang the cabinets.These details must be anticipated andaccounted for early in the construction processin order to reduce complications later. Similararguments are true for both interior andexterior finishes and how much extra it maycost for their installation, and even whetheror not some finishes are appropriate for somewall systems.

Energy Efficiency

Most of the building systems can be designedto be as energy efficient as a conventionally-built, wood-frame system; however, some ofthe alternatives may require new details ormaterials to make them perform well. Forothers, energy efficiency is one of their strongfeatures. Thermal bridging, air tightness, andoverall insulation value should be consideredfor each option. It is important to rely on validtest data and information from independentsources. Inflated values for energy efficiencyas it relates to insulation value or air leakagemay be valid under controlled conditions, butmay be difficult to achieve on a constructionsite.

Energy efficiency is important not only forreduced operational costs to the occupant,but also for the house’s impact on theenvironment. Less energy used to heat and/orcool the house means that less carbon dioxideis produced, and this reduces the impact onglobal warming.

Durability

Durability refers to the long-term performanceof a structure with only regular maintenance.Houses should last for many decades withoutmajor repairs or upgrades. If constructedproperly, most of the alternative buildingsystems can be as durable or more durablethan conventionally-built houses. Theselection of materials, and their installationand care on-site, may affect both short-termand long-term performance. For example,some building systems may be more affectedby high humidity or other environmentalfactors.


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Fire

Fire testing has not been conducted on all of the alternative wall systems; therefore, insome cases, anecdotal evidence must be reliedupon. Single-family construction typically is not required to be fire rated, but theflammability of the materials and their abilityto withstand, or be structurally capable in afire, may be deemed to be important. This maybe particularly critical in remote areas orwhere fire fighting services are not close by.

Sound

Sound transmission is a function of thevibration of the wall, air leakage through thewall system and flanking noise. Testing hasbeen conducted on a number of systems such as wood frame, steel frame, and concreteblock, but is not available for many of theother systems. Comments from homeownersand/or builders may need to be relied upon if sound is an important factor in deciding on a type of wall system.

Environmental Issues

Concern for the environment is one of thereasons why some homebuilders are consideringalternative construction methods. All buildingmaterials are derived, to some extent, fromnatural resources. For some products andsystems, the major environmental impactarises from the energy consumed for heatingand/or cooling the living space. Theenvironmental impact of some other productsand systems lies in both these energy needs as well as the energy needed to produce them.

Resource efficiency is a factor that may beconsidered when deciding on a buildingsystem. This refers to the energy and resourcesused in the extraction, refinement, andtransportation of building materials to thesite, and the total resources used duringconstruction. It includes everything from the use of renewable resources, to themanufacturing process, to the amount ofwasted materials on-site. One must work backseveral steps in the process, since wastage ofmaterials may be low on the construction site,but may be relatively high at themanufacturing plant.

The environmental impact resulting from the use of alternative wall systems rangesconsiderably from system to system. Theenvironmental factors should consider thedepletion of resources, renewability, theamount of waste generated on-site, the energyefficiency of the system, the resulting amountof fuel needed to heat and cool the house and longevity. In addition, the disposal of the structure after its useful life is over mustbe considered, including the reusability andrecyclability of the materials into a productthat is as useful as its preceding application.

These factors may be difficult to assess inabsolute numbers, since other systems in thehouse also affect them. For instance, the typeand efficiency of the heating and coolingsystems has as much or more of an effect on the amount of greenhouse gases producedas the thermal resistance of the wall system.Also, the materials used in the wall systemmay not currently be biodegradable orrecyclable, but the recycling options maychange in the future.

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Indoor Air Quality

Concern about indoor air quality has becomea high priority for homeowners in recentyears. Increased exposure to chemicals andtoxins, as a result of manufactured buildingproducts, has led to a trend towards the useof natural or inert materials. However, evensome natural materials may affect air qualityor trigger allergies.

The trend towards energy efficiency and low air leakage has resulted in improved air barriers in most new housing. This hasisolated the interior environment from thematerials in the wall system, and for the mostpart, has resulted in better indoor air qualitywhen combined with an appropriateventilation system. Alternative wall systemsshould be analyzed for their air tightness andcapacity to control the interior environment,as well as for their potential impact on theinterior environment, for example, if they haveproducts that off-gas, promote the growth ofmold, or otherwise affect occupant health.

Indoor air quality is dependent on a numberof factors besides the structural elements.Other materials used in the exterior wallassembly such as insulation, caulking,sheathing, paints, wood preservatives, etc.,may have an impact on the indoor air quality.Contaminants can also enter the living space through window and door openings,ventilation air intakes, or through penetrations.

Moisture that gets into the wall assembly canresult in degradation of materials and moldgrowth. Wall assemblies that attract pestsinvite mitigation methods such as pesticideapplications, which contribute to poor indoorair quality.

A continuous and well-sealed air barrierinstalled to the interior side of the wallassembly reduces entry of contaminantsthrough the wall to the living space.

Most wall systems can affect occupant healthif they do not properly manage moisture inthe form of liquid or vapour, from whateversource. In addition, the choice and use ofmaterials that can off-gas to the interiorshould be accounted for. These are choicesthat the builder must make in conjunctionwith the particular building system that isused. While having a well-sealed air barriernear the interior face of the wall can provide a good environmental isolator, hybrid designs can also achieve this goal. For theenvironmentally hypersensitive, special caremust be taken in the choice of all materialsinvolved and their location in the wall system.

Construction Sequencing

The orderly arrival and departure of trades on a construction site has been fine-tuned bymany builders, and is well known by the tradesthemselves. The drywallers know that theinsulation must be installed before they canbegin, and the insulators know that theelectrical must be completed before theybegin, etc.

Other types of wall systems may requireadditional trips to the site by some trades and may change the order in which the tradesarrive. For example, the plumber may need to locate and/or install some pipes prior tothe completion of an insulated concrete formwall, or the interior finishers may need toinstall some backing early in construction.


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Trade Training

Most builders are not familiar with many of the alternative wall systems. Some other“expert” will likely be needed to providetraining to the builder and to the trades. This could be a supplier’s or manufacturer’srepresentative, or it could involve a designprofessional such as an engineer or anarchitect.

Training prior to construction will usuallyresult in significant savings in labour andreduced mistakes on-site. There is usually a learning curve involved, resulting in a highlabour component for the first house or two,and then dropping quickly for subsequentunits. Trade training should involve not onlythose installing the new system, but alsoother trades that will be affected, as well as building officials.

Market Acceptance and ResaleValue

Some alternative wall systems are more readilyaccepted than others. This often depends on how familiar people are with the system.For example, building with logs is part ofCanadian history. In recent years, log homeshave made the shift from seasonal to year-round residence. This has resulted in largerand more sophisticated log homes beingbuilt. This recognition has resulted inacceptance in the Canadian market.

On the other hand, stackwall, earth wall, and straw bale homes are not common, andin fact, most people probably don’t knowwhat they are. These materials may not beperceived as sturdy enough to build a houseor to be energy efficient. Other systems, such

as block wall, have traditionally been usedcommercially, and may be seen as beingoverdesigned and costly in a residentialapplication.

In many cases, alternative construction systemsare used by the owner/builder, who has nointention of selling, at least in the shorterterm. Eventually however, the property willchange hands, either to the next generation or by sale to the general public.

Lack of knowledge by the general public canresult in a lack of interest in purchasing sucha property, or in a significant reduction in themarket value. Since many people considertheir residence to be a retirement nest egg,market value should be carefully considered.Another consideration is the future marketacceptance of alternate wall systems. If a newsystem gains market acceptance over time, itsvalue may increase dramatically in the future.

Having homes professionally inspected priorto purchase may also alleviate purchasers’concerns about alternative systems. It shouldbe noted that professional inspectors may notbe familiar with certain systems and may avoidgiving an evaluation of a particular system.

Regulatory Approvals

Building codes exist throughout Canada, andare typically enforced by local municipalities.Permits are issued based on plans and oncompliance with the building code. TheCanadian Construction Materials Centre(CCMC) evaluates many innovative productsand systems used in housing. CCMCevaluations are useful in seeking approvalfrom building authorities. Some of thealternative wall systems are not covered under

11


the scope of Part 9 of the National BuildingCode. Many municipalities may require theinvolvement of a design professional(architect or engineer) to approve thebuilding even if CCMC evaluation numbersare available. Design professionals will likely be required for all innovative systems.

The inspection of the building may alsocreate some roadblocks. Inspections areconducted based on the building code; inmany instances, new wall systems deviatefrom the norm. This may be perceived as adeficiency, when in fact the system may besatisfactory. One typical example is whetheror not the new wall systems require an airand/or vapour barrier that is commonly usedin conventional systems. Any variances fromstandard construction should be analyzed,and approvals for acceptance should beacquired prior to construction.

New sequencing on the construction site may also create some problems forinspections. Extra inspections or new timingfor inspections may be needed depending onthe type of wall system being constructed.

Warranty Program Approvals

Warranty coverage in Canada varies fromprovince to province. In some provinces,independent third party warranty coverage is mandatory for builders, while in otherprovinces it is optional. Owner/builders arenot typically included under conventionalwarranty programs.

If warranty coverage is desired for a houseusing alternate wall systems, advanceconfirmation should be obtained from thewarranty provider. One of their main criteria

is whether or the not the house meets thebuilding code. In most instances, acceptanceis likely since it is the builder primarily whobacks up the product; the warranty provideris simply a backup for the builder and buyershould the builder fail and not be able tocorrect a major deficiency.

Insurance

Property insurance is usually thought of as primarily fire insurance, but many otherthings are also considered, such as earthquakes,flooding and other weather-related disasters.In addition to this, liability insurance is oftenpart of the insurance package. If there is amortgage involved, some type of insurance is usually needed to protect the investment. If there is no financing, insurance may beoptional, but it is highly recommended.

The primary considerations with insuranceare the premiums and whether or not thestructure is even insurable. With somealternative wall systems, insurance companiesprobably do not have a good history on claims,and this could result in higher premiums. In some instances, coverage may be denied.

Premiums may not vary from the standardframe dwelling premiums, except for strawbale, earth wall, and stackwall, which couldbe uninsurable in some areas. If a bona fidecontractor builds stackwall homes, earth wall,or even straw bale homes, there is a possibilitythat both could be insured without asurcharge over wood-frame home premiums.


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Lightweight Steel Framing

Introduction

Lightweight Steel Framing (LSF) consists ofgalvanized and galvalumeTM cold-formed steel“C” sections for joists, studs and rafters,although this publication deals only with walls.The steel sections come in various depths andgauges, so that extra structural capacity canbe achieved by changing the gauge whilekeeping the depth the same.

Structural items such as bridging, lintels andbracing must be considered. Lintels are createdby placing joist sections back to back. Cross-bracing consists of flat straps on the exteriorof the walls and connections to the foundation.Insulation is generally placed in the wallcavity as well as on the outside of the studs,appropriate for a particular climate, to reducethermal bridging.

Primary Target Market

The primary target market for lightweight steelframe houses is builders. This is due to thelearning curve required, and the efficienciesachieved by building a number of steel houses.The builders can invest in the training programsavailable to them through their suppliers andthe Canadian Sheet Steel Building Institute(CSSBI). An owner/builder would not realizethe future savings invested in learning thetechnology, but may still find the knowledgevaluable.

The market share of this type of wall systemis still relatively small, but the number of unitsconstructed each year keeps growing. In 1999,according to the Canadian Sheet Steel BuildingInstitute, approximately 850 homes wereconstructed in Canada using lightweight steel framing, with about 750 of them in the Greater Toronto area.

13

Section 2: Alternative Wall Systems

Photo Courtesy of Ken Sexton

Key Benefits

Steel wall sections of equivalent strength will be lighter than solid wood sections. This makes the assembled wall sections easier to handle.

Steel is produced straight and once the wall isproperly constructed it won’t shrink, crack orwarp resulting in fewer cracks and nail pops.This results in fewer callbacks. In addition,steel framing is not vulnerable to termites or other organisms.

The Canadian Construction Materials Centre(CCMC) has recently completed its technicalevaluation of Light Steel Framing forresidential construction. With the aid ofindustry-developed span and height tablesand an installation guide, a builder orowner/builder can select member sizes for the assembly they are building withoutthe aid of a design professional.

Recently developed Canadian ConstructionMaterials Centre (CCMC) guidelines allow a builder to build a house within theparameters of the guidelines without theinvolvement of an engineer.

Key Drawbacks

Some training of the trades is needed iftraditional carpenters are involved in thefabrication of lightweight steel houses. Inaddition to requiring some new tools, theywill need to learn the techniques of workingwith steel. Training programs created by theCanadian Sheet Steel Building Institute arenow available.

Thermal bridging and condensation must beaccounted for in the design and fabrication of the wall. This will require the use of anexterior insulating sheathing. In addition to insulation, careful attention must be paidto control air and vapour infiltration bothfrom the outside and the inside to controlcondensation during heating or coolingseasons. Similar to conventional wood-frameconstruction, proper construction practice is required to manage moisture.

Structural Considerations

The connection between the floors and thewalls, and between the walls and roof, areimportant for the lateral stability of thestructure and for the transfer of loads. The size and type of connectors must be detailed on the plans.

Large openings in exterior and load-bearingwalls are handled in a similar manner towood framing, but using steel members.Lintels are typically designed with doublemembers, and jack studs are located aroundthe opening. The gauge and depth of themembers is important as this affects theirstrength. Again, the connections are veryimportant.

To account for lateral loading, usually fromwind, cross-strapping is typically installedon the exterior face of the exterior wall studs.This provides the racking strength that thesheathing provides in conventional woodframing. Rigid insulation should always be installed over the cross-strapping.


14

The floor and roof assemblies can be fabricatedfrom steel or they can be wood. If steelframing is used, wood sheathing is oftencombined with the steel structural members.The use of wood sheathing allows for theattachment of traditional materials, such as asphalt and wood shingles.

Material Considerations

Lightweight steel is readily available in mostmajor markets, and even if construction is to take place in rural or remote areas,transportation costs should not be a factor.There are a number of suppliers in majorcentres, which keeps prices competitive.

While the price of lumber has fluctuatedconsiderably over the last few years, the price of lightweight steel has remained fairlyconstant. This makes a direct cost comparisonbetween wood framing and steel constructiondifficult. It is generally accepted that the priceof the two systems is quite comparable whenall things including the cladding areconsidered. The cost of the total wall systemmust be considered including the longerfasteners needed to attach cladding when an adequate insulation buffer is used.

Standard practices are used for cutting steelframing to length for stick-framed assemblies.These provide lasting performance of the

15


Figure 1: Steel Framing System

Wall framing610 mm (24 )o.c. maximum

4 m (14 ) maximumunbraced length of wall

Wall cut away to showsecond floor joists

Diagonal flatstrap brace

Horizontal studbridging and

blocking

King stud

Cripple stud

Lintel

Head

Sill

Jack stud

60 maximumbracing angle

Insulatingsheathing

covering entirewall area

Closurechannel

Cornerframing

metallic coating on steel framing members.However, analogous to wood rot frommoisture in wood-framed construction,anomalies that result in excessive moisture in the steel-framed wall cavity can lead to premature consumption of the metalliccoating and corrosion of the framingmember. Construction moisture, particularlyin the bottom channels, must be removedbefore the cavities are enclosed.

Thermal expansion of steel studs is not an issue. As the studs are insulated on theexterior to reduce thermal bridging, and asthe whole wall is made of similar materials,any movement should be uniform.

The installation of wood finishing andmaterials into a steel frame can beaccomplished by placing wood blockingaround openings. This adds to the time andcost of installation. Jambs and windows arenow often screwed into their openings whiletrim work can be stapled using a power nailer.


The scheduling of trades remains the same aswood-frame construction. CCMC evaluationsmay remove the need to have a designprofessional involved, provided the designfalls within the scope of the CCMC evaluation.Additional preplanning is required if a designprofessional is involved. Once the cut list ofmaterials is prepared, the manufacturer canprecut all the sections and bundle the sectionsinto groups that can be delivered to the site as required.

A lightweight steel house is constructed usingthe same steps as in wood framing. Subsequenttrades follow once the structure is in place.

Labour and EquipmentRequirements

The labour cost for the first steel house erectedby a builder is usually considerably higherthan for a wood-framed house. This reflectsthe learning that is required by the tradesinvolved. Most builders find that subsequenthouses see a considerable reduction in thelabour component.

In most cases, a framing crew erects the steelframed house. Their hammers are replacedwith a screw gun. Other equipment neededincludes aviation snips and a chop saw. Some builders use prefabricated steel-framedassemblies, which can reduce site framing time.

Training is an important part of the labourcost for the first house. The Canadian SheetSteel Building Institute has created a trainingcurriculum for steel framing. The program,which builds on a framer’s existing knowledgeof framing a home, is available in both textbook form and on CD. This training couldsignificantly reduce the learning curve thatmost builders and framers go through whengetting involved with this wall system.

Impact on Services

Services include plumbing, heating andelectrical. The requirements for the electricalmay vary slightly from region to region, but readily available materials can be used.Grommets are placed in the stud knock-outswhere wires pass through. Electrical outletboxes are fastened to the steel studs in anormal fashion.

Copper plumbing pipes must be isolated fromthe steel studs, or plastic piping can be used.


16

Other implications for plumbing areminimal. If fixtures are hung or fastened to a steel wall, the connection will need tobe considered. There are minimal, if any,implications for the heating ducts.

Design Flexibility

Any residential plan can be constructedusing lightweight steel framing. The member sizes are selected andassembled using information from theindustry design manuals. This includesconstruction of lintels, columns, bracingand blocking. Steel framing members canbe manufactured to any specific length. Future alterations or renovations arestraightforward and can be easily done.

Key Construction Notes

Commercial steel erection crews are usuallynot well oriented to residential framing toreduce labour costs or time, while traditionalcarpenters need training and some new toolsto carry out the work. There is a learningcurve on the first few houses.

Proper planning is important for schedulingthe delivery of materials. A good design andgood plans are important for minimalmodifications on-site.

The Canadian Construction Materials Centre(CCMC) evaluate construction products withrespect to their conformance to applicablecodes and standards and suitability forintended use. At the discretion of themunicipality responsible for building codes,the use of CCMC evaluated products maynot require the involvement of a designprofessional.

Construction Costs

The cost of lightweight steel framing isinfluenced by the labour component, whichwill be quite high during the learning curve,for example, the first few houses. Comparingsteel framing to wood framing will vary widelybecause of the fluctuating cost of wood andby the variable labour costs. There are severalfactors to consider when comparing costs,with some of the variables being quitesubjective. Most independent articles oncomparing the cost of steel framing to woodframing have priced them similarly when allaspects are considered.

Energy Efficiency

Steel wall systems can be quite energy efficient.Thermal bridging must be addressed becausea standard steel stud conducts more heat thana wood stud. The heat loss averaged over thewall can be greater than for a wood-framed

17


Figure 2:Wall/floor connection

wall unless the appropriate insulating practiceis used. A common solution to this is toinstall rigid insulation to the outside of thesteel studs. A thermal break can also beprovided on the inside.

Additionally, the insulation of stud cavities is required to achieve the necessary thermalperformance. Since the steel studs are thinrelative to wood, standard insulation batts forwood-frame don’t fit properly in the cavitybetween the studs. Wider batt insulation isavailable to accommodate steel stud walls and is common in commercial construction.Another technique is to use a blown insulationin the stud cavity as this will accommodate anystud spacing and will fill all gaps. An 89-mm(3-1/2-inch) steel stud wall, with 25 to 75 mm(1 to 3 inches) of rigid insulation on theexterior, and blown or batt insulation in thecavity, can have as much or more insulationvalue as a 38 x 140-mm (2 x 6) wood-framewall. The cost of the rigid insulation is often

more than blown or batt insulation and mayincrease the overall cost of the insulation.Although the exterior cladding usually doesnot affect the insulation value, the cost ofinstalling the cladding over rigid insulationwill affect the overall cost for any wall system.

Durability

Steel studs stand up well during on-site storageprior to installation. This wall system is quitedurable and should be comparable to woodframing if properly constructed. Testing todate indicates that the metallic coating willoffer long-term protection to the base steel in a properly designed and constructed wallassembly.

As for most wall systems, sheathing materials,in particular rigid exterior insulation, willneed to be protected as they can sustainmechanical damage and can be affected by prolonged exposure to ultraviolet light.

Fire and Sound Considerations

The fire resistance ratings for lightweight steel framed walls, with the same finishes, is comparable to wood-framed walls ifmineral fibre is processed from rock or slag(see table below). Fire resistance ratings aremost applicable for party walls that are usedin multi-family construction. There does not appear to be fire resistance testing ofresidential exterior wall systems.

Sound ratings for steel-framed walls areconsiderably better than for wood-framedwalls as indicated in the table below. As forfire resistance ratings, the sound ratings applyprimarily to party wall applications.


18

Figure 3: Header wrap/poly barrier

Impact on Indoor Air Quality

Steel itself will not support mold growth,however, insulating materials in a steel-studwall can support mold. Cold-rolled steelsections are reported to have some residuallubricant from the rolling process and thiswill off-gas. It is likely that much of that oilwill leave during the construction periodexcept in unusual cases. This is not expectedto have a noticeable impact on air quality,particularly if an effective interior air barrieris employed.


Comparisons of the environmental impact ofsteel versus wood-frame construction is complexand not definitive at this time. While theproduction of steel studs can be more energyintensive than wood, much of the steelmanufactured into studs is recycled.2 In addition,there is less job-site waste produced, which canalso be recycled. This contributes to a lowerlifecycle energy embodied in this product,

compared with its wood counterpart. Also toconsider is that forests, as a renewable resource,which capture CO2 (a greenhouse gas), play adirect role in reducing climate change. Similaroffsetting factors can be cited for the processingor harvesting and transportation of the twomaterials.

The debate comparing the environmentalbenefits of wood versus steel continues.

Regulatory Impediments

At present, there are no prescriptive standardsfor steel framing in Part 9 of the NationalBuilding Code. The CCMC has issuedevaluations for steel framing products asproduced by the Canadian Sheet Steel BuildingInstitute and industry design manuals havehad some oversight by the CCMC. Theseresources give building inspectors confidencein the residential steel construction system. As a result, design professionals may not berequired for construction within the parametersof evaluated designs.

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Note: Fire and sound ratings will be higher or lower depending on the combintion of materials used.Note:This table compares two similar assemblies; however they may not meet Fire or STC requirements.

Wall DescriptionTypical Sound

Transmission Class

36

4845 minutes

• 38 mm x 89 mm (2” x4”) wood studsspaced 400 mm (16”) or 600 mm (24”) o.c.

• 89 mm (3-1/2”) thick absorptive material• 15.9 mm (5/8”) Type X drywall board each side

• 31mm x 92 mm (1-1/4” x 3-5/8”) steel studsspaced 600 mm (24”) o.c.

• 89 mm (3-1/2”) thick absorptive material• 15.9 mm (5/8”) Type X drywall board each side

Fire Resistance RatingNon-Load Bearing

60 minutes

Table 1. Fire and Sound Ratings1

Warranty Approval

Only registered builders can enroll houses inthe provincial warranty programs. The basiccriteria for enrollment of a house are that the builder be certified or registered with the warranty program, and that the home be built in compliance with the applicableBuilding Code. As this type of wall system is very common in commercial constructionand is well known in the industry, regulatoryagencies should have few problems acceptingsteel framing. There should not be impedimentsfor a house using this type of wall system tobe enrolled in a warranty program.

Insurance Approval

Home insurers contacted, indicated thatinsurance coverage is provided for steel-framedhouses. As for all construction types, homesare to be constructed in accordance with theapplicable Building Code. It was furtherindicated that the premium would not vary considerably from that of wood-frameddwelling units. These policies may vary from insurer to insurer. The insurability andpremiums should be checked in advance, asthere is a limited insurance history for thistype of wall system. As home insurancepremiums typically include various insurancerisks (fire, flooding, liability, etc), the type ofwall system may not significantly affect theoverall premiums.


While this wall system is still not common in many communities, knowledge andacceptance of steel framing is growing inmany regions of Canada. As for wood-frame,

resale value for steel framed homes followmarket trends and thus will vary fromcommunity to community.

Export Potential

There is a market for export of lightweightsteel framed houses. The steel wall system canbe marketed as part of a manufactured housepackage, or as steel framing components. The market acceptance of steel constructionvaries from country to country, but efforts areunderway internationally to market this system.

Geographic Limitations

From a structural point of view, there shouldbe no geographical limitation to the use ofthe steel stud framing system provided designprofessionals are involved for constructionwhere the limitations to the applicability ofthe Canadian Sheet Steel Building Institutedesign manuals are exceeded. Similarrequirements apply when any construction is not prescribed by the building code. As for wood-frame, durability is affected bythe manner that the cladding and the air andvapour barriers are designed and installed,both on the wall, and at penetrations and at windows. Properly dealt with, there shouldbe no geographic limitation of this system.

Footnotes

1. National Building Code of Canada, 1995,Table A-9.10.3.1.A, Fire and soundresistance of walls.

2. Environmental Building News, Steel orWood Framing: Which Way Should WeGo? BuildingGreen, Inc., EBN Volume 3,No. 4, July/August 1994.


20

Additional Reading

Adair, Jim. 1995. Frame alternatives. Today’s Builder Magazine. January/February.

Adair, Jim. 1995. Steel frame insulation.Today’s Builder Magazine. January/February.

Andrews, Steve. 1996. Cold facts about steelframing. Builder Magazine. February.

Canadian Sheet Steel Building Institute.Residential Steel Framing: InstallationManual. Canadian Sheet Steel BuildingInstitute. August, 1999. 652 Bishop StreetN., Unit 2A, Cambridge, ON, N3H 4V6.www.cssbi.ca

Canadian Sheet Steel Building Institute.Residential Steel Framing: Member SelectionTables: Wall Studs and Floor Joists. CanadianSheet Steel Building Institute. August, 1999.652 Bishop Street N., Unit 2A, Cambridge,ON, N3H 4V6. www.cssbi.ca

Canadian Sheet Steel Building Institute.Lightweight Steel Framing. TechnicalBulletin. Report on: Life cycle assessment ofsteel framed homes. Vol. 3, Number 2. July1999. 652 Bishop Street N., Unit 2A,Cambridge, ON, N3H 4V6. www.cssbi.ca

Canadian Sheet Steel Building Institute.Lightweight Steel Framing. TechnicalBulletin. Report on: Thermal performance of lightweight steel framed homes. Vol. 5,Number 1. July 1999. 652 Bishop Street N.,Unit 2A, Cambridge, ON, N3H 4V6.www.cssbi.ca

Canadian Sheet Steel Building Institute.Lightweight Steel Framing. TechnicalBulletin. Report on: Life cycle assessment of steel framed homes. Vol. 3, Number 1.March 1999. 652 Bishop Street N., Unit 2A,Cambridge, ON, N3H 4V6. www.cssbi.ca

Canadian Sheet Steel Building Institute.Lightweight Steel Framing. TechnicalBulletin. Report on: Durability. Vol. 2,Number 1. March 1999. 652 Bishop StreetN., Unit 2A, Cambridge, ON, N3H 4V6.www.cssbi.ca

Canadian Sheet Steel Building Institute.Member selection tables, wall studs and floorjoists. March 1997. 652 Bishop Street N.,Unit 2A, Cambridge, ON, N3H 4V6.www.cssbi.ca

Canadian Sheet Steel Building Institute. An introduction to residential steel framing.December 1994. 652 Bishop Street N., Unit 2A, Cambridge, ON, N3H 4V6.www.cssbi.ca

Canadian Sheet Steel Building Institute. Steelframed houses across the country and around the world. 652 Bishop Street N., Unit 2A,Cambridge, ON, N3H 4V6. www.cssbi.ca

Chini, Abdol and Kavita Gupta. A comparison between steel and woodresidential framing systems. Journal ofConstruction Education. (available at http://ascweb.org/jce/ underArchive, 1997 Vol. 2, Summer, pp. 79-147, pp. 133-145).

Environmental Building News. 1994. Steel or wood framing: which way should we go? July/August.

21


Mills, Chris. 1999. Wood vs. Steel: The battlefor the hearts (and wallets) of Ontario’sbuilders. Ontario Home Builder. Summer.

O’Brien, Frank. 1995. Steel vs. wood: theshowdown. Home Builder Magazine.January/February.

Schwolsky, Rick. 1994. Steel crazy after all these years. Builder Magazine. December.

Solplan Review. 1996.Wood and steelframing: the environmental cost. January.


22

Structural Insulated Panels

Introduction

Structural insulated panels (SIPs) are panelswith a core of rigid foam insulation betweenan exterior and interior skin. The mostcommon materials used for the skins arestructural Oriented Strand Board (OSB) orplywood. The foam cores are composed ofexpanded polystyrene, extruded polystyreneor polyurethanes. The two skins incombination with the integral insulation core carry all of the loads of the structure.The foam insulation keeps the two skinsaligned, acting as a web, and provides theinsulation value. There are some panels systemsthat have ribs, which are structural membersthat carry some or most of the load. Whilethese are not true SIPs, they are often discussedin the same category of wall system.

The panels are available in various sizes and thicknesses depending on location and application requirements. The layout of the house can be preplanned for themanufacturer, with openings provided forwindows and doors, or blank panels can besupplied in standard sizes, with alterationsmade on-site for openings. There are variousoptions offered by different manufacturers forconnection of the panels. Structural insulatedpanels can also be used for floor and roofassemblies, although those applications arenot being dealt with here.


Some builders find this wall system attractivebecause it can provide them with benefitsduring construction; as well it is a product thathas benefits for their customers. The energyefficiency of structural insulated panel systems,and the speed of construction, along with

23


Photo Courtesy of Plasti-Fab

reduced labour on-site, can be attractive tosome builders. Thus, professional buildershave been the primary target market.

Owner/builders can also benefit from this typeof wall system. The reduced labour on-sitespeeds up construction during the framingstage. Depending on the panel sizes, twopeople can erect the exterior walls in a matterof hours for simple structures.

Key Benefits

The panels have good insulation value sincethe various types of foam insulation used fillthe wall cavity providing uniform insulationcoverage and which has a relatively highereffective insulation value. SIP systems arequite energy efficient since there is very little thermal bridging and there is a goodopportunity to produce a low air leakagestructure. Both of these factors contribute to the energy efficiency of SIP wall systems.

The panels are quite light-weight (dependingon panel size) and the smaller sizes can becarried and placed using manual labour. This allows for installation where heavyequipment is not available or accessible, and can easily be done by framers orsomeone with carpentry skills. Installation is quick, which is helpful with tight schedules or during inclement weather.

The walls are straight and smooth for theinterior finishes and exterior cladding. Theapplication of these finishes is easy since it ispossible to nail anywhere on the wall surface.

Key Drawbacks

The panels require some care if they arestored on-site prior to installation. If they getwet, the edges can swell and cause problemswhen fitting the panels together. Protection of the panels is required during storage.

There may be some limitations on highloading conditions and/or concentrated loads.Both the interior and exterior panels carryload, thus both require full and continuousbearing at the base of the panel.

The exterior cladding system must be carefullyconsidered. The concern relates to possibledeterioration of the skins due to penetrationof moisture and whether or not extra moistureprotection, such as using the rain screen


24

Photo Courtesy of Plasti-Fab

Installing structural insulated wall panels.

principle, is needed. Most manufacturersrequire that rain screen protection is usedwith their product.

While some builders assume that you canconstruct SIPs like a wood-framed house,there is some training needed. There are some critical details to be dealt with, many of which are provided by the manufacturer.

Inspectors and regulators may want design professionals and third-party qualityinspections involved, depending on thecomplexity of the design. This ensuresproducts are manufactured and installedaccording to engineered load tables. Mostmanufacturers of these systems have basicdesigns to follow, but large openings, angled walls, and large point loads may need special design. Clients should use in-house or knowledgeable design services.There is currently one Canadian ConstructionMaterials Centre evaluated SIP producthaving ribs. Other SIP panel systemscurrently under review incorporate structuralribs.


Structural insulated panels are considered partof a design-build system where specific loadcarrying requirements are determined inadvance of construction to meet BuildingCode requirements. For most residential uses,typical loads used in wood-frame constructioncan be assumed, but concentrated loads needto be considered separately as additionalsupports may need to be added. Some type of column may be needed to handle this typeof loading just as with typical wood framing.Panels will need to be altered to accommodatethe installation of a column at the concentrated

load. The involvement of an experienced andknowledgeable engineer to review assemblyplans is important.

Structural insulated panels use dimensionallumber to meet special height, span and loadrequirements. The design professional detailsthe use of dimensional lumber in buildingsfor things such as columns for concentratedloads and lintels over windows.

Creep is a long-term consideration for thistype of wall system. Creep is the deformation,usually permanent, of a component subjectedto continuous and long-term loading. It is a concern for floors and roofs and to someextent for walls subjected to eccentric loading.Creep is dealt with for those products withCCMC evaluations. Load span tablesprepared for CCMC evaluated SIP panelsincorporate creep. Creep tests are requiredunder the CCMC evaluation program.


The options to consider will depend on the manufacturer and the availability ofcompeting products. The panels come with a structural sheathing on both sides of thepanel, and usually a specific manufacturerwill use only one type of structural sheathingmaterial. The panel sizes available may varyand may be customized for each project. The option of having openings preplannedand cut into the panels is also possible.

There is usually some choice of panel thickness,ranging from about 50 mm (2 inches) up toabout 250 mm (10 inches). The thickness ofthe panel will be determined by the amountof insulation value required and the structuraldesign loading. As the thickness increases, the

25


load-carrying capacity of the panels increases.Due to limitations of the core, the capacityincrease is not proportional to the thicknesssquared. It is nonlinearly related.

The panels are connected using varioustechniques and this will vary from manufacturerto manufacturer. In many instances, dimensionallumber is used to connect the panels. Thebeams over openings must be properly designed,and typically standard lintels are used at theselocations. These lintels must be incorporatedorattached to the wall panels along with thesupports at each end of the lintels.


The sequencing of construction should not besignificantly altered with this type of wall system,although some of the tasks will change. Inmany instances, conventional floor and roofsystems can be used, with the conventionalexterior walls simply converted to structuralinsulated panels. This will not require changingthe order in which trades are involved. Insulationof exterior walls obviously is eliminated, whiledealing with the installation of wiring mayrequire an extra step.

As with other components, such as trusses andwindows, the structural insulated panels mustbe ordered well in advance so they can bedelivered on time to the site in order to fit intothe framing schedule. Other accessories, suchas lintels and splines, also need to be accounted for.

Labour and Equipment Requirements

There is some special knowledge needed forthe installation of structural insulated panels.Check with suppliers about the availability of specialized training courses and materials

as there are some critical details that must bedealt with. Traditional framers would typicallyinstall the wall sections using conventionaltools and a few additional tools. The amountof labour on-site is actually reduced, since a manufactured product is being used. The exterior walls for a house can literally be erected in a few hours.

Panel sizes can be selected to match thenumber of workers on-site for moving anderection of the panels. Large panels mayrequire the use of lifting equipment such ascranes or forklifts. The interface, or connectionof the panels, is caulked, both inside andoutside, to provide a wall with low air leakage.

Impact on Services

The primary service that will be affected iselectrical. Some manufacturers provide channels(vertically and/or horizontally) to allow forthe installation of the wires. If this is not done,other options must be considered, such asaltering the way that the wiring is done, oreven strapping the inside to accommodate the


26

Figure 4: Cross section of wall panel.

electrical. Any cutting into the faces of thepanels weakens the panels and should not bedone without consulting the manufacturer ordesign professional who is qualified in thisfield.

Other services are typically not installed in the exterior walls. Plumbing pipes andheating ducts can be run through the walls by drilling holes the same size as the ducts or pipes. There may be limits on the size of holes allowed.

Design Flexibility

Very high walls and high loading conditions must be properly designed by a knowledgeable SIP design professional.Concentrated loads can be handled in a similar manner to conventional woodframing. A good and level base must beprovided, since both the inside and outsidestructural panels must have full bearing.

Flexibility for future modifications should notbe overly difficult. Additions to the structurecan be tied to the existing walls with eitherconventional framing or with more structural

insulated panels. Modifying or addingopenings in the walls is possible but must bedone with full knowledge of the limitationsto altering the structural skins. As with anywall system, care must be taken to distributeloads over openings.


The following are some suggestions for thedesign, handling and use of structuralinsulated panels:

• Use panels specifically designed for theproject with precut openings to minimizewaste

• Store panels under cover and off theground to protect them until installation

• Ensure a good connection and a good sealbetween panels

• Ensure good bearing of panels at the basefor transfer of loads

• Preplan the wiring and work with theelectrician in advance

27


Figure 5: Panel section options.1

Construction Costs

The cost of structural insulated panel wallsystems is higher in most installations than forwood-framed walls. The material cost will behigher, while the installation or labour costswill likely be lower. Some of the softer benefits,such as tighter schedules, a reduced work force,and less volatile material, may be additionalbenefits. The overall cost will also be affectedby how the electrical distribution is handled,the type of cladding system, and whether ornot the rain screen principle is used. Manymanufacturers mandate the use of the rainscreen principle with their product.

Energy Efficiency

This wall system will provide a higher effectiveinsulation value than a conventional wood-frame wall of the same thickness because the foam insulation has better insulatingcharacteristics than batt insulation. In addition,thermal bridging is reduced considerably.

The air tightness of structural insulatedpanels is typically better than conventionalwood-frame construction.2 This improvescomfort and reduces heat loss due to naturalinfiltration. However, any house with low airleakage requires adequate levels of controlledventilation to provide fresh air and tomaintain good air quality within the house.

Durability

The panels will need to be protected on-siteprior to installation like most constructionmaterials. Mechanical damage and damagefrom the weather should always be taken intoconsideration. Durability can be affected bythe quality of the joint assembly. Proper sealing

and assembly site installation as per manufacturerprocedures is critical to maintain performanceand durability.

The durability of this wall system can beaffected by three issues: creep of the panels,burrowing of insects, and degradation due tomoisture. Deformation of the panels due toloading (creep) is more important for roofand floor panels than for wall panels, butshould still be addressed by the supplier ormanufacturer. CCMC evaluated productsalready address the issue of creep.

Where burrowing insects are known to be a problem, insect protection and preventionstrategies should be employed.3 Finally, theissue of damage due to moisture penetration,largely from the exterior, needs to beaddressed with the possible use of the rainscreen principle. Many manufacturers requirethis when using their product.


Building Codes do not typically requireindependent testing of any wall system for fireor sound ratings for single family-detached


28

Figure 6: Corner detail.

residential applications. Attempting to assessthe fire rating relative to a wood-framed wallis difficult since the structural elements andinsulation types vary. Sound ratings for a SIPwall system are likely to be at least as good as a conventional wood-frame wall. This isbased on the provision of tightly sealed jointsin the SIP wall system, resulting in reductionof airborne sound transmission.


The structural insulated panels should notnegatively affect the air quality in the houseprovided the wall panels are separated fromthe interior by a continuous and well-sealedair barrier. The structural panels, whether of plywood or oriented strand board, do not emit formaldehyde, which previously was a concern; however, they can emit otherVolatile Organic Compounds (VOCs). Thefoam insulation is sealed between the structuralpanels and thus should not affect the interiorenvironment. These houses are typically quiteair-tight; therefore, proper ventilation isimportant to control contaminants generatedwithin the house. The building code requiresminimum levels of ventilation capacity.


Structural insulated panels use wood moreefficiently; several hundred board feet of wallstuds and plates can be eliminated with thissystem. If the panels are made using OSB,additional savings are achieved since OSB is made from scraps and fast-growing trees.There should also be less waste generated on-site as the panels are often manufacturedto fit the house. There should be little cuttingand waste generated, unless the openings arecut on-site.


If a CCMC evaluation is provided, thereshould be limited difficulty in getting thiswall system approved by the local authorities.As with other manufactured products,specification sheets and design literature maybe required. Most manufacturers will alreadyhave this information produced and available.Unless the Canadian Construction MaterialsCentre (CCMC) has evaluated the system,the involvement of a design professional is likely required. It is recommended thatbuilding inspectors be contacted and askedabout the local regulatory needs prior topermit application.

29


Figure 7: Panel connection detail.

Figure 8: Floor connection.

Warranty Approval

Only registered builders can enroll houses in theprovincial warranty programs. The basic criteriafor enrollment are that the builder must becertified or registered with the warranty program,and that the home be built in compliance withthe Building Code. In most instances, thistype of wall system will include a designprovided by a manufacturer or designprofessional, which would have it comply with Part 4 of the National Building Code.The warranty provider should thus be able to enroll a house using structural insulatedpanels. Many manufacturers have their ownlimited warranty on the product they supply.

Insurance Approval

Of the home insurers contacted, the majoritywould offer coverage for structural insulatedpanel houses. This is based on homesconstructed in accordance with either Part 4 orPart 9 of the National Building Code. It wasfurther indicated that the premium wouldnot vary considerably from standard dwellingunits; however, policies may vary from insurerto insurer. The insurability and premiumsshould be checked in advance, as there is a limited insurance history for this type of wall system. It should be noted that homeinsurance premiums typically includeeverything from fire to flooding to liability, andthus the type of wall system, if it is insurable,may not affect the overall premiums significantly.

Market Acceptance and Resale Value

There may be minor concerns by consumersabout this new system regarding structuraladequacy and future alterations. If properlydesigned and constructed, there should be

minimal, if any, difference in resale valuebetween this system and a standard wood-frame home. Some benchmark programs, such as R2000 and EnerGuide for Houses,can rate houses with this and other wallsystems to give the purchaser an indication of energy efficiency.

Export Potential

Structural insulated panels are well suited to manufactured housing and for exporting,and there are already companies doing this.Structural insulated panel packages have beenshipped to Europe, Asia, the Caribbean and the United States.


Structural insulated panels are manufacturedand distributed across the country. Withproper care, they are appropriate for allclimatic conditions and may even have somebenefits in remote or rural regions because of their reduced labour requirements on-site.In very cold weather, they also allow forquicker enclosing of the space and a reductionin the operating costs of remote structures.


30

Figure 9: Base of structural insulated panel.

Footnotes

1. Natural Resources Defense Council,Efficient Wood Use in ResidentialConstruction.

2. Ibid.

3. Griffith, D., Termite Control: MultipleSolutions Bring Results, Wood Design and Building.

Additional Reading

Andrews, Steve. 1999. Foam-Core Panels &Building Systems: Principles, Practice, andProduct Directory. Third Edition. CutterInformation Corp.

Binsacca, Rich. 1998. Straight Talk AboutSIPs. Builder Magazine. June.(available at www.builderonline.com).

LeRoy, Jim. 1997. Building with Foam-CorePanels. Journal of Light Construction. July.

Natural Resources Defense Council. EfficientWood Use in Residential Construction.

epsmolders.org/eps/panels/htm(EPS Molders Association).

www.plastifab.com/sips/index.html (PlastiFab - Calgary).

www.sipweb.com

31


Insulated Concrete Forms

Introduction

Insulated concrete forms (ICFs) are hollowblocks or panels, made of expanded orextruded polystyrene, that are stacked intothe shape of the exterior walls. There is aconnection between the inner and outerforms, which is usually steel or plastic.

Reinforcing steel is then installed in the cavity between the inner and outer forms,and concrete is poured into the cavity. The foam form becomes part of the wall andremains in place, providing the insulationvalue to the wall system.

Interior and exterior finishes are then appliedto the forms. The mechanisms for connectionof interior and exterior finishes varies frommanufacturer to manufacturer.


Both owner/builders and builders have shown interest in this type of wall system.Homeowners may find this system attractivein areas where fire-fighting capabilities arelimited. The builder market has acceptedinsulated concrete forms, but in many casesmore as a substitute for cast in place concretefoundations than as a replacement for abovegrade wood-frame exterior walls. Builders canbenefit from this system once the installationtechnique is learned and refined.

There is a short learning curve and manymanufacturers recommend or insist ontraining prior to installation. For theowner/builder, this up-front training mayoffset some of the potential cost benefits of the system. The demand for this systemmay vary with the availability of materials,primarily concrete.


32

Photo Courtesy of Western Concrete Supply

Key Benefits

The insulated concrete form wall system iseasy to understand and install. There are fewspecialized tools required and no investmentin forms is necessary. The insulation in theforms allows concrete to be poured in coldweather conditions without extra protection.The cavity in which the concrete is poured isan ideal location for good curing of the concrete.

This system is quite energy efficient and hasgood sound and fire rating characteristics. It is very durable and quite sensitive to theenvironment, since waste generated on-siteshould be minimal.

Key Drawbacks

The construction costs will vary somewhat andwill depend on the availability and cost of theconcrete. The cost of a house with insulatedconcrete form exterior walls is typically a fewper cent higher than a standard wood-framehouse. The increased weight of the exteriorwalls may require larger footings toaccommodate the increased loads.

The foam insulation will or can have animpact on some of the subsequent trades.The installation of wiring in the outside walls will require the electricians to use new techniques. Pipes and ducts through theexterior walls need to be planned in advance.Depending on the type of insulating formsused, interior and exterior finishes may needspecial fasteners or mechanisms for attachment.

Inspectors and regulators may want designprofessionals involved, depending on thecomplexity of the design. Most manufacturersof these systems have basic designs to follow,

but large openings, angled walls, and largepoint loads may need special design.


Insulated concrete form (ICF) wall constructionhas plenty of capacity to handle loads, bothvertical and horizontal. Typically, conventionalroof trusses and dimensional lumber or trussesfor the floors are used. The high strength ofICF walls allows the use of long span concretefloors in place of wood-frame flooring.

The extra weight of the exterior walls willrequire that the foundation (footings, piles,etc.) be sized to adequately handle it.

33


Concrete is usually pumped into the forms.

Figure 10: Cross section.


Insulated concrete forms are available invarious configurations as there are dozens of manufacturers of this product. Some havebuilt-in attachments for reinforcing bars and some have integrated mechanisms forattachment of interior and exterior finishes.These various options can influence the typeof system selected.

Another consideration is the type of interiorand exterior finish that will be applied.Certain types of finishes may not work well directly over foam insulation, and othermaterials may require special attachment. In the case of exterior masonry, special ledgesmust be used so that the loads are carriedback to the main structure, which is theconcrete inside the insulating forms.


The sequencing of construction and thescheduling of trades will change little, if at all,from conventional wood-frame construction.In most cases, the foundation and the abovegrade walls are formed and poured independently

so that the floor can be used when workingon the above grade walls. This also reducesform blowouts that can occur if excessiveheights are done at once.


The erection of the forms can be carried outeither by traditional foundation trades or bythe framing trade. The learning curve isrelatively short, and within one or two units


34

Figure 11: Reinforcing needed aroundwindow and door openings.

Wood bucksaroundopeningskeepsconcrete in forms andprovides forattachmentof windowsand doors.


the site people can become quite comfortablewith the installation. Many ICF manufacturersoffer training programs, which should be takenby any trades undertaking the construction ofan ICF wall system.

The basic tools required to erect the forms are quite minimal, but bracing and jacks areneeded to support and level the forms. Sometype of scaffolding will also be needed whenpouring the concrete. Since the tops of theforms are several feet above grade, the concretewill have to be pumped into the forms.

Impact on Services

The impact on services is relatively small, and in most cases, it is primarily theuncertainty of dealing with the unknown that causes trades to be cautious. Electricalwiring is run in grooves that are cut orroutered into the foam.

Penetrations through the wall for plumbing pipes, heating ducts, or ventsmust be accommodated by installingsleeves at the time the forms areinstalled. Proper planning is all that is required since very little plumbingor heating is actually installed in anoutside wall.

If blocking or backing is needed atspecial locations, such as for cabinets,drapery rods, grab bars, etc., the innerform can be cut out and the blockingcan be fastened to the concrete directly.This must be planned in advance, priorto the drywall being installed.

Design Flexibility

This type of exterior wall can handle bothhorizontal and vertical loads, but the wallitself can be quite heavy. Soil pressures mayneed to be verified and/or footing sizes mayneed to be increased to accommodate theincreased loading. Various connections arepossible for support of floors, which must be decided upon in advance.

There are few limitations on the length ofwalls installed; however, the height that canbe installed at one time is limited to thecapacity of the forms. Wall heights of morethan 3,050 to 3,650 mm (10 to 12 feet)would normally be done in two or more pours.

Future alterations to the wall are possible, but significant work is involved if openingsare to be installed. If loads from above arebeing supported, the installation of openingswill require reinforcement of the area abovethe opening.

35


Figure 12: Connection of wood floor to insulatedconcrete form wall.

If an addition with a different wall system is added, the interface between the two wallsystems needs to be considered. Specialpinning or attachment of one wall system to another along with finishing details mustbe considered.


Additional precautions or procedures may berequired, depending on the type of floor androof system, and the materials used for thesesystems. The following are some standardconsiderations:

• Make sure you start out on a level base

• Make sure the forms are plumb and arebraced well before placing concrete

• Prepare for blowouts during the pour

• Use the right concrete with a slump thatflows well

• Use “S” curve at the discharge end ofconcrete pump

• Educate the trades, both those installingthe system and those that will be affectedby the system

• Check for necessary approvals in advance,such as requirements to involve designprofessionals

Construction Costs

Construction costs, in particular the labourcomponent, will drop as the trades and thebuilder become more comfortable with thissystem. It appears that this system is similarin cost to a traditional wood-frame wall

system. Costs have been estimated to beanywhere from a few per cent less to a fewper cent more than a wood-frame wall housefor the structural part of the wall.

The type of interior and exterior finishes, the specific type of insulated concrete formsystem, and the availability and pricefluctuations of materials (wood and concrete)will have an impact on the cost comparison.Some insulated concrete form systems haveintegral fastening strips for interior and/orexterior finishes while others do not. Thisalong with the type of finish can significantlyaffect the price of this type of system.

Rural or remote regions may have addedfactors affecting the price of materials. Someof the intangibles such as comfort, sound andfire resistance are difficult to quantitativelyanalyze.

Energy Efficiency

Energy efficiency is a significant benefit ofthis wall system. The insulating forms providehigh-quality insulation that remains in place,and since there is complete coverage of thewall, there is no thermal bridging. This systemalso has very little air leakage, which can alsobe a significant area of heat loss. Both ofthese factors improve comfort and reduceheating bills.

The thermal mass of this wall system issandwiched between the two layers ofinsulation. The inner layer of insulation will reduce the benefits of the large thermalmass, which otherwise could be used to evenout temperature swings and reduce peakdemands, although there may still be somebenefits. The size of the heating and/or air


36

conditioning appliances may be able to bereduced, which will result in capital costsavings.

The R-value provided by the wall systemdepends on the type of foam insulation usedfor the forms, and on the thickness of theinside and outside forms. The total R-valuecan exceed R20 (RSI 3.5) if desired.

Meeting or exceeding applicable energy codes,where required, should be verified prior toselecting a particular system. The authoritiesmay not give credit for the thermal mass ofthe wall system, but may only consider thenominal insulation value.

Durability

Insulated concrete forms is a durable system-concrete is expected to last many decadeswithout problems. When the foam formmaterial is protected, as it usually is with

interior and exterior finishes, it should alsolast for many decades. This system is also very resistant to damage from moisture, andis desirable in areas where flying debris is aconcern, such as in tornado and hurricaneregions. Where termites are a problem, specialcare must be taken to prevent them fromgetting into the wall system.


The fire and sound ratings for insulatedconcrete form walls should be at least as good as or better than that of concrete alone.The fire resistance rating of concrete alone isusually a minimum of two hours, dependingon thickness and it usually maintains itsstructural integrity in a fire. The foaminsulation can give off toxic gases in fires, but by code requirements, it is protected by the interior and exterior finishes.

The sound transmission class of concretealone is over 50, again depending uponconcrete thickness. The foam insulationshould not affect the sound rating significantly.Since the wall is poured as one integral unitwithout breaks from inside to outside, soundtransmitted through air pathways should be minimal. The large mass of the wall willreduce the amount of sound transmitted byvibration. Both of these factors are reflectedin the relatively good sound rating ofconcrete walls.


Insulated concrete forms use foam insulationand should be sealed off from living spaces tocontain any low-level emissions. A commonconcern with all new housing is reduced airleakage and the need for ventilation. As with

37


Figure 13: Connection detail at top of wall.

most new houses, this type of wall system isquite air tight and will require appropriatelevels of ventilation.


Changing the exterior walls from wood toconcrete shifts the focus from forests to thecomponents of concrete, namely cement andaggregate. The sum of the embodied energyin the concrete and foam insulation is higherthan that in wood-frame construction.Transportation can also be a significantcomponent in the resource efficiency ofconcrete, both in accessing the aggregate and in delivery of the final product.

Building energy studies indicate that up to 80 per cent of the energy expended on a building is expended in the operation andmaintenance of that structure over its servicelife. Additionally, waste material such as flyash is often used in concrete mixes to improvecertain characteristics of the concrete. Thisprovides an additional environmental benefitwhen using concrete.1

There is very little wastegenerated on-site; therefore,there should be little impacton the environment fromthis perspective. Anotherconsideration with this wall system is the type of insulation being used.Typically, batt insulation isused in exterior wood-framewalls as the primaryinsulation. With theinsulated concrete formsystem, foam insulation is used exclusively.

Chlorofluorocarbons (CFCs) havetraditionally been used in the production of foam insulations. The environmentalconcerns associated with foam insulation are less of an issue, as most manufacturers are now using alternate methods and/orproducts in production such ashydrochlorofluorocarbon (HCFC).


The insulated concrete form system isessentially a cast in place, reinforced concretewall. Local authorities may require a designprofessional to be involved regardingconnections and amount and type ofreinforcing to handle anticipated loads. Most of the manufacturers have standarddetails for common loading conditions.The Canadian Construction Materials Centre (CCMC) evaluates products andsystems used in housing and may help in the approval process.


38

Insulated concrete form under construction.


Warranty Approval

Only registered builders can enroll houses inthe provincial warranty programs. The basiccriteria for enrollment of a house are that the builder be certified or registered with the warranty program, and that the home bebuilt in compliance with the Building Code.In most instances, standard details are usuallyavailable from the supplier or manufacturer ofthe wall system, which can be made availableto the regulatory authority. If additional or special details are needed, a designprofessional may be required to verifycompliance with the Building Code. Thereshould be no other impediments for a houseusing this type of wall system to be enrolledin a warranty program.

Insurance Approval

Of the home insurers contacted, the majoritywould offer coverage for insulated concreteform houses. This is based on homesconstructed in accordance with the NationalBuilding Code. It was further indicated thatthe premium would not vary considerablyfrom standard dwelling units. These policiesmay vary from insurer to insurer. Theinsurability and premiums should be checkedin advance, as there is a limited insurancehistory for this type of wall system. It shouldbe noted that home insurance premiumstypically include everything from fire toflooding to liability, and thus the type of wallsystem, if it is insurable, may not affect theoverall premiums a lot.


This is a relatively new system in somemarkets, and some people may be hesitant in accepting it because of lack of knowledge.However, there should be minimal, if any,difference in resale value between this systemand a standard wood-frame home.

Export Potential

There is a potential for export of this wallsystem, although it is already being used inother parts of the world. The product is quitebulky and thus shipping costs may berelatively high.


There does not appear to be geographiclimitations for this wall system. Numerousmanufacturers supply variations of this product,and it seems to be readily available throughoutthe country. As with other alternative wallsystems, remote and rural areas may experienceincreased transportation costs, because theremay not be a local supplier of the forms.Availability and/or transportation of concretemust also be considered.

39


Footnotes

1. Suzuki, M. and T. Oka, Estimation of LifeCycle CO2 Emissions of Office Buildings in Japan, Conference Proceedings Vol. 1 - Green Building Challenge 98, An International Conference onPerformance Assessment of Buildings, Oct 26-28, 1998, Vancouver Canada.

Additional Reading

Canadian Portland Cement Association.1996. A Comparative Study of Low-RiseResidential Building Systems in Canada.

NAHB Research Centre, Inc. PrescriptionMethod for Insulating Concrete Forms inResidential Construction. Upper Marlboro,Maryland. EB118.

VanderWerf, Pieter. 1998. Foam Forms BringConcrete Results. Home Energy Magazine.July/August.

VanderWerff, Pieter, Stephen J. Feige, PaulaChammas, and Lionel A. Lemay. 1997.Insulating Concrete Forms for ResidentialDesign and Construction. McGraw-Hill Inc.

Woodard, Ralph. 1998. Building AboveGrade With ICFs. Journal of LightConstruction. June.

www.icfweb.com/FAQ.htm

www.forms.org (Insulating Concrete Forms Association)

www.plastifab.com/icf/index.html (PlastiFab - Calgary)


40

Post and Beam

Introduction

In the post and beam construction method, a series of vertical posts or columns supporthorizontal beams to form a structuralframework. Posts are located at each corner of the building and are usually spaced evenlybetween the corner posts to support the loadsfrom the roof. The roof can also includeheavy members (beams) that in turn supportsmaller members that carry the roof load.Post and beam framing can be done withmanufactured lumber products such aslaminated beams or with traditional heavytimbers.

The post and beam frame is usually left fullyvisible to the inside. The infill between theposts is not structural and can be made ofvarious materials, including high-tech rigidfoam panels, stud frame, or some of the other

alternative wall systems included in thispublication such as log, straw bale andstackwall.

The exterior of the structure can be finishedwith traditional materials. Some of thestructural members may be partially exposed,as in the case of beams that are extendedbeyond their supports. This adds to theappeal of the structure from the outside, but care must be taken to properly protectexposed materials from the outdoor elements.


The exposed heavy members provide an interior finish that many people findaesthetically pleasing. Post and beam homesare relatively easy to construct, but mayrequire extra labour due to the size andweight of the members. This system offraming is typically suited to professionalbuilders.

41


Photo Courtesy of Troy Scheer

Key Benefits

Post and beam construction provides thestructural components of the building, and atthe same time provides an interior finish thatmany homeowners find attractive. This typeof construction is often seen in upper endhouses, but with the new manufacturedproducts available, it is equally suited toalmost any type of home.

There is a good deal of flexibility in theexterior walls of the home since most of thewall area is not structural. This allows forlarge window openings without furtherstructural considerations, and plenty of

options for location of services. Futuremodifications to the exterior walls can usuallybe made easily, with minimal or no structuralconcerns.

Aside from the posts, the entire interior of the house does not require load-bearing walls.This results in a very open design, as theinterior partitions can be randomly located to suit the occupant. Future changes to theinterior partitions do not affect the structuralintegrity of the building.

Key Drawbacks

The major drawback of post and beamconstruction involves the drying of the

wood in service. Shrinkage can result in cracking and movement, due to thedrying process. This must be accountedfor in the construction of the building. The availability of, and the use of,engineered manufactured wood products eliminates most of this problem.These new products are shipped dry, andthus do not change much on-site if they are protected during construction.

Post and beam construction is not ascommon as it used to be; therefore, manyframers are not as familiar with it as theyare with conventional wood framing. The design of the members, includingconsideration for wind loading, must often involve a design professional, sincestandard tables for the members do notexist in Part 9 of the National BuildingCode. The connection of the members isalso very important and becomes part ofthe design.


42

Post and beam framework.

Photo Courtesy of Troy Scheer


Since the weight of the roof is transmittedthrough the posts to the foundation, thefoundation must be capable of supportingconcentrated loads, as compared to uniformloads in standard wood-frame construction.In the case of a two-storey house, theseconcentrated loads will be even larger.

The connections between structural membersis important for proper transfer of loads.Details showing these connections should be provided by the designer involved with the project.

Wind and/or seismic loading must also beconsidered in post and beam construction. In traditional framing, the sheathing on thewall provides the racking strength to resistlateral or wind loads. The connections in postand beam construction usually will not resistthe lateral loads on their own; therefore, cross strapping or shear walls may be needed.


The primary consideration when selectingmaterials is overall strength for bending,deflection, shear, and axial loads. Manufacturedlumber may be stronger than dimensionallumber. Another factor to consider whenselecting materials is shrinkage. Larger sizemembers usually shrink more than smallermembers, thus for heavy beams and columns,this movement must be considered.


The traditional sequencing of constructiontrades will not change significantly with post and beam framing. The framers will be scheduled as usual, and other trades willbe scheduled around the framing. The leadtime in ordering specialty materials, such asengineered wood products or heavy timbers,will need to be determined, and liftingequipment, such as fork lifts or cranes for the large structural members, will need to be assessed and scheduled.

43


Figure 14: Structural elements of post and beam construction.


Post and beam construction is typically doneby skilled framers. The total amount of labourmay also be higher than in wood framing forany particular size of house. Framers areaccustomed to platform wood framing, andany time there is a change, the added cost maynot be a direct reflection of the difficulty ortime involved, but includes a safety factor forthe change. The labour costs for this type ofconstruction are usually a bit higher than forwood framing.

The tools required by the trades is the same;however, due to the size of the members involved,additional equipment may be necessary. Cranesor forklifts may be needed to lift the heavybeams, and some bracing will be needed tokeep them in place until the entire structureis erected and all connections are made.

Impact on Services

The installation of services should not besignificantly impacted by post and beamconstruction. Since most of the exterior wallsare not structural, services can be locatedvirtually anywhere there is room for pipes orwires. Usually the pipes and wires are locatedaway from the structural members. Notchesand holes in the posts and beams will affecttheir load carrying capacity and must be eithereliminated or kept within design guidelines.

Since post and beam construction allows foran open design, there may be few interiorpartitions in which to locate services, such aselectrical outlets and plumbing lines. There ismore of a concern in a two-storey arrangementwhere services must be run from one level to thenext. Interior partitions or chases for serviceswill have to be considered in the design process.

Design Flexibility

The post and beam framing system can providea good deal of flexibility in design. Large openareas are easily accomplished, even in a two-storey arrangement. Alterations are also easybecause only the structural posts and beamsmust stay in place-everything else can bemodified. Changing window openings oreven adding openings is easily accomplished.


• Select or use dry material to reduce oreliminate shrinkage

• Ensure all structural members areadequately sized

• Ensure connections between structuralmembers properly transfer loads

• Ensure lateral loads are accounted for withbracing or shear walls

• Plan services in advance so they do notaffect the structure and so that the servicescan be incorporated into the building


44

Figure 15: Bracing needed to resist lateral loads.

Construction Costs

The cost of construction for a post and beamsystem will likely be somewhat more than for conventional wood framing. The largermembers used for the main structure aretypically more expensive than smallermembers that can also provide the loadbearing capacity. In post and beamconstruction, additional members are also needed to fill in the space between the structural members.

The additional equipment that may beneeded for lifting will also add to the price of this system. Framers often use liftingequipment in platform framing as well;however, the equipment is generally used foronly a short period of time, while in post andbeam construction, the equipment would beused over an extended period of time.

Energy Efficiency

The energy efficiency of a post and beamhouse will depend largely on infill walls usedbetween the columns. Since this can rangefrom foam insulation, to wood studding with fiberglass insulation, to straw bales, theinsulation levels of the exterior walls can rangefrom R12 (RSI 2) up to R30 (RSI 5) or more.

Air leakage will have to be addressed wherethe infill meets the posts. These will often betwo different systems; therefore, some type of seal will be required at the interface of thetwo materials. The bridging of the air and/orvapour barrier across the posts must beaddressed in order to control the movementof air and vapour, and to make the housemore comfortable and energy efficient.

Durability

The durability of post and beam constructionis similar to wood framing. The large size ofthe structural members should ensure theirdurability. Protection of the wood membersfrom moisture is important for long-termperformance.


There does not appear to be any recognizedfire and sound tests for post and beamframing. Intuition would lead one to believethat the heavier members would be affectedless in a fire than lighter members used inconventional wood framing. Post and beamsystems using lighter members, such asmanufactured lumber, would not perform aswell in a fire. Ratings would also depend onthe type of infill used between the beams andcolumns. The sound ratings will be affectedby the size of the members, the type of theinfill between the structural members and bythe air leakage of the wall system. The soundrating would likely vary considerably fromone design to another.

45


Figure 16: Area between posts is filled in and mustprovide thermal resistance.


The installation of a good interior air barrierwill separate the occupants from the materialsused to close in the structure. If moisture and humidity are controlled, as they shouldbe in all wall systems, the impact of mold and mildew will also be kept under control. There may be some difficulty installing andmaintaining a good air barrier since theinterior of the structural components istypically exposed. This requires sealing airbarriers to the structural elements and thusresults in maintenance of this seal.


Post and beam framing uses resources fairlyefficiently, because little manufacturing isneeded to produce the materials. The amountof waste produced on-site will be similar towood framing, and this waste can be recycledwhere practical.

The impact on the environment is affected by the selection of materials for the structure.The indiscriminant use of logs or heavy

timber contributes to the depletion of matureforests. If manufactured lumber is used theimpact will be less, since scrap materials andsmaller logs are used.


There should be minimal problems in obtainingregulatory approval. The regulatory authoritieswill require the design and inspection of a design professional, since the structuralmembers are not included in Part 9 of theNational Building Code.

Warranty Approval

Only registered builders can enroll houses inthe provincial warranty programs. The basiccriteria for enrollment of a house are that thebuilder be certified or registered with thewarranty program, and that the home bebuilt in compliance with the Building Code.The regulatory authority will determinecompliance with the code when the permit is issued. This wall system will not affectwhether or not the house can be covered by warranty.


46

Interior views of post and beam construction.

Photos courtesy of Troy Scheer

Insurance Approval

A post and beam home constructed inaccordance with the National Building Codeis usually insurable. The premium should not vary considerably from standard dwellingunits; however, policies may vary from insurerto insurer.


Post and beam construction is well-known andaccepted in most markets. This system shouldhave a good resale value, and some consumerswill even pay a premium, especially if thestructural members are exposed.

Export Potential

This wall system would not be used for exportin a manufactured state. The individualmaterials may be exportable, and the

knowledge on how the system works may be exportable, but a manufactured packagewould have limitations, as there is aconsiderable amount of site work needed.

47


Figure 18: Cross section of post and beam framing with roof rafter.

Figure 17: Base of columns must be attachedto foundation to resist lateral movement.


There should be no geographic limitations forpost and beam construction. The availability ofappropriate materials may be a limiting factor,especially in some regions if heavy timbers arebeing used for the structural members.

Additional Reading

Mitchell, James. 1984. The Craft of ModularPost and Beam: Building Log and TimberHomes Affordably. Hartley & MarksPublishers Inc.


48

Concrete Block Wall

Introduction

Concrete block construction is typically usedin commercial buildings and has been usedsporadically in residential construction. It has been used residentially primarily as afoundation system, but is equally applicableto above grade walls.

Concrete blocks are installed in courses, with the blocks typically being 200 mm (8 inches) high, 400 mm (16 inches) wide,and 200 or 250 mm (8 or 10 inches) deep.Each course is set in a bed of mortar and

there is reinforcing both horizontally andvertically to carry imposed loads. Specialblocks are installed over openings so thatadditional reinforcement can be placed tocarry vertical loads over the openings.

Interior and exterior finishes can be applieddirectly to the face of the block wall; however,insulation and control of air and moisturemust be considered. The cores of the blockscan be insulated, or the entire wall can beinsulated on the inside or the outside. Floorscan be either wood, concrete or steel, whilethe roof is typically either wood or steel.


Concrete block wall systems are best installedby trades experienced in masonry work. This may reduce or eliminate some of the potential labour savings for theowner/builder, unless they have somemasonry skills and experience. Most builderswill have masonry trades working for themthat can install this system.

Key Benefits

The key advantages of concrete block wall construction are excellent fire ratings,sound ratings and durability. This system is generally used for fire separations and fire walls, and thus is very desirable if fire is a concern. Even if a fire does occur, it usually does not seriously affect thestructural capability of the walls. Due to themass of the wall, sound transmission is alsoquite low. Outside noises are minimized andthis can be a benefit in high noise areas suchas around freeways, airports and rail lines.

49


Photo Courtesy of Halyna Tataryn, CMHC

Concrete block walls are very durable. Theyresist termites, dry rot and fungi associated withhigh moisture conditions. These walls are alsovery resistant to mechanical damage, and thusare highly rated in hurricane and tornado areas.

Key Drawbacks

The construction of a block wall system ismore expensive than a traditional wood-framesystem. The costs will vary depending oninterior and exterior finishes and howadequate levels of insulation are achieved. A more specialized trade is usually involved in the installation, and there may be problemswith scheduling and availability. In addition,installation in very cold weather requiresprotecting the walls from freezing duringinstallation, which can impact the timing of construction and the cost.

Insulating only within the cores of the blockswill not be adequate to satisfy most customers,and likely will not meet applicable energycodes. Strapping and insulation, or the use ofrigid insulation will be needed, and this willadd to the costs of the wall system.


Concrete block walls are very sturdy and verydurable, and can support significant verticalloads; however, some special conditions mustbe dealt with. If large concentrated loads areto be carried by the wall, special columnscalled pilasters are needed for support. Thisconcentrated load must then be carried downto the foundation.

Large openings need to have beams installedover them. These can either be steel beams or

they can be made from special concreteblocks with steel reinforcing. These beamsmust be designed to handle the loads over theopenings.

Very high walls may need additionalreinforcement and/or the installation ofcolumns (pilasters) to accommodate thehorizontal loads, which comes primarily fromwind loading. The connection at the top andbottom of the walls is important so thatlateral restraint is provided.

Finally, the extra weight of the concrete blockwall will require an increase in the foundationdesign. Larger footings (130 mm or 5 incheswider per storey of masonry) will be requiredto accommodate the increased weight of thewalls. The use of lightweight blocks willreduce the impact.


Concrete blocks are available in mostmarkets, but transportation to rural or remote


50

Figure 19: Wood connection to block wall.

areas may be costly. Shipping is usuallyincluded in the price of the blocks, as they aredelivered on trucks with lifting capability. Asdiscussed earlier, if installation is done undervery cold conditions, protection of the wallsduring installation and curing is necessary,thus adding to the costs.

New types of concrete block are being offered in some areas. Lightweight blocks are produced by using lightweight aggregates,and because they are easier to handle, canspeed up installation. Some of the newerblocks even have insulation integrated withthe block by using foam beads as aggregate.While these are interesting concepts,availability and acceptability by theenforcement agencies should be checked.

Control of heat, air and moisture is animportant consideration for all wall systems.In the case of concrete block walls, variousoptions exist regarding the location and type of insulation, and moisture barriers.

Insulation can be a combination of inside,outside, or within the wall cavity, and it canbe foam, batt or loose fill. The moisturebarrier is located on the outside of the wallbut its installation may affect the exteriorfinish. These options can affect price, tradesand scheduling.


The order in which trades are scheduled on-site may not change much from conventionalwood framing, but this is highly dependenton the type of floor and roof system, type of moisture barrier, and type of interior andexterior finish. Wood or steel framing wouldtypically be used for interior partitions, andoften wood or steel strapping would be doneon the inside of the concrete block walls.Once the exterior block walls are installed,the framers install the roof and complete theinterior partitions and strapping. Other serviceswould then be installed in the normalsequence, both inside and outside.

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Figure 20: Interior strapping provides cavity for insulation and services.

Figure 21:Typical exterior insulation.

If a wood floor is installed, it is placed on theinside of the block wall and is supported bythe block wall. This floor would be installedby the framers, either before or after theabove grade wall is erected. This could affectthe scheduling of the trades and the numberof times the framers are required to return tothe site.

If the cores of the block wall are beinginsulated, then an additional trade needs to be scheduled while the wall is accessible.The moisture barrier location and type mustbe decided upon, and depending on theoption selected, new trades and alternatescheduling may be involved.


The installation of concrete block walls is best done by an experienced mason. This will reduce the amount of labour that can be provided by the owner/builder. A crew of three or four people is typical,including two or three masons plus anindividual mixing the mortar as well asbringing blocks and mortar to the masons.Equipment such as a mixer, scaffolding,trowels, levels, plumb lines, and possiblehoarding for cold weather are all suppliedby the mason.

An owner/builder could gain the expertise for installation of concrete block walls, but may need the help of others. Equipmentwould need to be purchased or rented.Progress would be quite slow if only one or two people are available to carry out the numerous tasks.

Impact on Services

The impact on services will depend largely onwhether or not the interior of the block wallis strapped. If strapping is installed on theinterior, services such as electrical andplumbing are installed in the strapping; thus, the installation of these services isconventional. The installation of pipes andvents to the outside would be slightly alteredsince they would be run through the blockwall. This would require punching a holethrough the wall or installing sleeves in thewall at the time of erection.

If the interior of the walls are not strapped,the electrical and other services will requirealternate installations. Wiring and outlet boxescan be incorporated into the block wall, butthis is not conventional and requires additionalplanning and work. Some of the servicescould be relocated, moving them from theoutside walls to an interior location, but thereare limitations in order to comply with codes.


52

Figure 22:Wood cap at top of wall providesconnection for wood roof.

Design Flexibility

Concrete block walls are capable of carryinglarge loads, but the walls themselves can poseproblems due to their considerable mass.Cantilevers are quite common in housingtoday, but block walls cannot be supported by a cantilevered floor without considerablestructural reinforcement. Arches, angles andcurved walls can be achieved using concreteblocks but there likely will be additional coststo accomplish this.

Future alterations to the building may notbe as easily accomplished as with some otherwall systems. If a new opening is desired, for instance, cutting out the opening andproviding support across the opening must be properly designed and carried out.

Additions to the building will have to takeinto consideration the possible interface of different wall systems and the possibleintegration or removal of existing block walls.


Careful and thorough planning is importantso that changes are not required after the wallis constructed. Location of services, correctwindow and door opening sizes, and detailsof connections to other components need to be designed. Types of interior and exteriorfinishes must be selected in advance, as theycan affect the type and location of insulationand how the services are located and installed.

Block walls must be supported directly on thefoundation because of their weight. Althoughthe foundation walls and the main wallscould be erected at once, it may be morepractical to install the foundation along with

the floor and then backfill. This will reducethe amount of scaffolding and bracingrequired for the main floor walls.

Air and moisture flows must be prevented at the tops of the wall. This means that theinterface with the roof must be well designedand detailed.

Construction Costs

A concrete block wall system is more expensiveto construct than a wood-frame wall system.The costs will vary depending on interior andexterior finishes, and on the type and amountof insulation used. Costs will typically beanywhere from 25 per cent to 100 per centmore than for wood-frame walls. This willincrease the overall cost of the house by a smalleramount because the walls make up only apercentage of the total house cost. Costs canbe controlled by also using concrete blocksfor the foundation. This reduces set-up timefor two different trades. Cold weatherconditions will require hoarding and heat,which will further increase costs.

53


Figure 23: Dowels in top of foundation provideconnection for block walls.

Energy Efficiency

Concrete block wall systems can be as energyefficient as other systems. Uncracked blockwalls have very low infiltration rates, whichkeeps the air leakage component low.Insulation can be added to either theinterior or to the exterior of the walls.The type and amount of insulation can be varied to achieve almost any desired level of thermal resistance and to meet coderequirements. An uninsulated block wall witha thickness of 200 mm (8 inches) would havean insulation value of R1 (RSI 0.2).1 Thiswould not meet the code requirements forthermal resistance in many municipalities.

Insulation on the exterior, usually with foaminsulation, keeps the block wall warm andincreases the thermal mass within thebuilding. This tends to moderate temperatureswings in the house and increases comfort.This can result in energy savings and canreduce the size of the heating and/or airconditioning equipment. Insulation on theexterior will have significant implications for the type and cost of the exterior finish.

Insulating on the inside of the concrete blockwall, which is typically practiced in a coldclimate, is similar to strapping a concretefoundation. Various levels of insulation can be achieved and a good air and vapour barrier can be installed. This also allows forconventional installation of interior finishes.

Durability

The durability of a concrete block wall is very good, as long as proper moisture controlis undertaken. It is a very sturdy and massivematerial and thus will resist mechanical

damage better than most other systems. This can be particularly important inhurricane and tornado areas. Due to the massof the system, uplifting and displacement isnot as big a concern.

Concrete blocks will not rot and are notsusceptible to termites and other insects. This system is quite tolerant of moisture,provided salts and other chemicals that canweaken the bonds in the mortar are notpresent. Concrete block walls can last forliterally hundreds of years with only minimalmaintenance.


A concrete block wall has excellent fire andsound characteristics. It is often used inmulti-family construction where fire andsound separations are required. The table belowcompares fire rated and sound rated woodstud and concrete block walls. Extensive testinghas been done on this wall system and is welldocumented in the building code. Sound istransmitted by the vibration of the wall andby air leaks through the wall system. Since concrete block walls are quite massive,there is very little sound transmitted fromvibration. Concrete block walls are usuallyquite air tight as well, unless cracks develop.

Concrete block homes are quite resistant to fires and even if a fire does occur, thestructure of the home is often not seriouslycompromised. This can make repairs lessexpensive if a fire does occur.


Concrete block walls do not affect theinterior environment. Indoor air quality


54

can be affected by pollutants entering fromoutside, from within the wall cavity, and bypollutants generated inside the house. Sincethese walls can be quite air tight, especiallywith a good interior air barrier, pollutantsfrom outside and from within the wall cavityshould be minimal. A good interior air barriershould also minimize moisture leakage and theresulting condensation and molds within thewall cavity. Any house with low air leakage willneed to be properly ventilated. A continuousventilation strategy will be needed to controlpollutants generated from inside.


The manufacture of concrete blocks is not veryenergy intensive; however, the manufacture of cement, which is used to make the concreteblocks, is energy intensive. Transportation canimpact the resource efficiency in remote or

rural areas; however, this product is readilyavailable in most communities.

The waste generated on-site from this wallsystem is usually quite small. There areusually not many damaged blocks or partiallyused blocks. Any damaged product can andshould be used for fill, and thus should notadversely affect the environment.


This wall system is widely known andaccepted commercially, and therefore should not experience significant barriersresidentially. There may be a requirement to have a professional involved in the designand/or inspection of the system if the limitswithin Part 9 of the National Building Codeare exceeded. There should be no difficulty in getting approvals and a permit.

55


Wall DescriptionTypical Sound

Transmission Class

43

51

• 38 mm x 89 mm (2” x 4”) wood studsspaced 400 mm (16”) or 600 mm (24”) o.c.

• 89 mm (3-1/2”) thick absorptive material• resilient metal channels on one side spaced

400 mm (16”) or 600 mm (24”) o.c.• 12.7 mm (1/2”) Type X gypsum board each side

• 140 mm (5-1/2”) concrete block• absorptive material filling, resilient metal

channel space• resilient metal channels on one side spaced

at 400 mm (16”) or 600 mm (24”) o.c.• 12.7 mm (1/2”) Type X gypsum board each side

Note: Fire sound ratings will be higher or lower depending on the combination of materials used.Note:This table compares two similar assemblies; however thay may not meet Fire or STC requirements.

Fire Resistance RatingNon-Load Bearing

45 minutes

2 hrs

Table 2. Fire and Sound Ratings2

Warranty Approval

Only registered builders can enroll houses inthe provincial warranty programs. The basiccriteria for enrollment are that the buildermust be certified or registered with thewarranty program, and that the home bebuilt in compliance with the Building Code.There should be no impediments for a concrete block house to be enrolled in a warranty program.

Insurance Approval

Of the home insurers contacted, there was no indication that coverage for concrete blockwall houses would be a problem. This isbased on homes constructed in accordancewith the National Building Code. It wasfurther indicated that the premium wouldnot vary considerably from standard dwellingunits. These policies may vary from insurer to insurer. The insurability and premiumsshould be checked in advance. It should be noted that home insurance premiumstypically include everything from fire toflooding to liability, and thus the type of wallsystem, if it is insurable, may not affect theoverall premiums significantly.

Export Potential

There is not much potential for export of theconventional concrete blocks. Many othercountries have their own manufacturingfacilities and the sheer weight and volume ofthe materials make shipping or transportationrelatively expensive. Some of the new concreteblock technologies may be exportable. Theseinclude the use of foam beads in the concrete,coloration of the concrete, and texturing ofthe finished surfaces.


Concrete block walls can be installed virtuallyanywhere that the product is available. In some climates, protection of the wallduring installation and curing may benecessary. The cost of transportation may bean impediment in a few locations; however,this wall system is well known and theproduct is generally available.

This system may not be appropriate inpermafrost conditions because of the types of foundations used in those regions.


56

Figure 24: Lintels over openings carry vertical loads.

Footnotes

1. Canadian Home Builders’ AssociationBuilders’ Manual.1989. Canadian HomeBuilders’ Association. Ottawa, ON.

2. National Building Code of Canada, 1995,Table A-9.10.3.1.A, Fire and soundresistance of walls.

Additional Reading


Hatzinikolas, Michael, Kuzik, Marc andKashuba, Scott. Masonry Walls That ResistBullet Penetration. Canadian MasonryResearch Institute. 10524 178th Street,Edmonton, AB T5S 2H1.

National Building Code of Canada. 1995. Fire and Sound Resistance of Walls. Table A-9.10.3.1.A.

http://www.masonrycanada.ca

http://www.cement.ca/cement.nsf (Cement Association of Canada)

http://www.canmasonry.com (Canadian Masonry Research Institute)

http://www.omca.org (Ontario Masonry Contractors Association)

http://scrpa.com/appeal.html

http://scrpa.com/benefits.html

57


Log Homes

Introduction

In Canada, both the English and Frenchsettlers built log walls by laying logshorizontally on top of each other to form a four-sided structure. This was replaced bymass produced, smaller-dimension lumber,which enabled people to buy an entire housepre-cut and delivered. Log home building wasreduced to the summer cabin.

In recent years, log homes have made thetransition from seasonal to year-roundresidence, and today, the majority of log homes are being built for full-timeoccupancy. This has resulted in larger andmore sophisticated structures, plus therecognition that building a log home is farmore complex than building a weekend cabin.


Today’s log home market can be divided into two broad categories: hand-crafters andmanufacturers. This section deals mainly withthe first category.

Hand-crafted log homes are best suited toowner/builders that are skilled in the use oftools, are physically fit, and have time andpatience. Because of their large size, loghomes are more appropriate in rural areas.

The International Log Builders’ Association(formerly Canadian Log Builders’Association, International) writes anddistributes educational material on logconstruction to individuals, institutions, and industry. The Log Building Standards,available from the Association, are theminimum standards for residential, hand-crafted, interlocking, scribe-fit construction.


58

Photo Courtesy of Moose Mountain Log Homes Inc.

Key Benefits

A log house is one of the most aestheticallysatisfying in which to live. With a goodfoundation to protect the wood, and a wideoverhang to shelter against moisture, a loghome is very durable and can last forgenerations. In style, the log house neverlooks outdated. Finally, building a log homecan be a pleasurable experience for theowner/builder.

Key Drawbacks

Building a log home requires skill, is very timeconsuming, and is not low-cost. The skillsand processes necessary to produce a loghome are more costly than frame or masonryconstruction. In addition, a log home requiresmore maintenance than a brick, vinyl- oraluminum-sided house.

A supply of suitable logs must be available for log home construction—long, straight,and large enough to provide adequateinsulation. As a result, conventional logconstruction is somewhat limited in scope,particularly in many areas of northern Canada.1


In scribe-fit log construction, naturally roundhorizontal logs are scribed along longitudinaljoints so that the top log fits tightly to the log below. In a chinked structure, chinkingmaterial is used to fill the gaps between roundor squared logs.

Log homes are structurally unlikeconventional homes; large timbers behavevery differently over time than stick-builtwalls. Small buildings generally requiresmaller logs and large buildings require largerones. Not only to allow for shrinkage, theadded size is beneficial in several differentways-thicker and therefore better-insulatedwalls, fewer notches to cut, a more solidappearance, and superior strength.

There are two major factors to consider in maintaining the structure and appearanceof a log home: shrinking and settlement.Shrinking involves the gradual release ofmoisture contained in the log, and this willcontinue until the wood is in equilibriumwith its environment.2

Problems with shrinkage can be reduced

59


Figure 25: Log shrinkage is estimated at 12 mm (½”) per 300 mm (12”) of log thickness.

300 mm (12”)

12 mm (½”)

288 mm(11½”)

300 mm (12”) 300 mm (12”)

by using 19 to 38 mm (3/4 to 1 1/2 inch)diameter wood dowels through the logs, or by using structural splines at all door andwindow openings. This allows the walls tosettle straight down. Another method isthrough-bolting (spring bolts that maintainconstant pressure on the log walls for evensettling). It is very important to leave amplespace above the windows and doors to allowfor shrinkage.3

Moisture gain and loss can also be affected byroof overhangs, proper elevation from grade,and treatment of the wood surfaces witheffective stains and preservatives.4


Almost any species of tree that grows to logsize can be used to build a house. Althoughhistorically hardwoods were used extensively,the majority of log homes today are built withsoftwoods. Different species of wood behavedifferently, and even logs from the same speciescan respond differently. The environment of the log home must also be considered.

A moisture and temperature regime that variesgreatly from the one where the logs originatedcan greatly affect how the logs respond.

Some species such as spruce or fir are bettersuited for structural loading applications,such as floor joists or roof rafters. Wood isstronger where loading is applied parallel tothe grain (as with vertical posts) than it is atright angles to the grain (as with horizontalbeams). Green or dry logs can be used forconstruction. Seasoning logs can createproblems. Uncontrolled checking (surfacecrack caused by drying) may affect thejoinery’s ability to seal, and if stacked, thelogs will take a set according to the log pile in which they were stored. If they are to bestored, they should be decked in tiers, welloff the ground, using two or more skids.5

Controlling the moisture content of the logsis important. A surface stain or preservativemust allow the logs to breathe and expelexcess moisture. In some very arid areas,humidity should be introduced.6


60

Figure 26: Plate log can be through-boltedat the top of windows and doors.

Figure 27: Seasoning logs.


Following completion of the foundation, thefirst-floor log walls are erected. The first logs(sill logs) may be either on the side walls oron the end walls, depending on the kind offloor joists used and how they are carried onthe foundation. Normally, the butt ends allface the same way on walls that run the samedirection, unless there are two or more logsend-to-end to form a wall. The next logs areplaced at right angles to the first ones, withthe butts again all one-way. The corners of thelogs must be notched together. There are severalstyles of corner joinery used in constructing loghomes, for example, saddle notch, lock notch,square notch, and dovetail. In order to providea greater choice of style in finishing, the logends should run well beyond the corners,except with dovetail notches. When thebuilding is two or three rounds high, itbecomes more difficult to get the logs up ontothe walls. Other than using a crane or forklift,a simple way to put logs onto the structure isthe method of rolling logs up on skids withone or two ropes.7

Header logs, which house the top of doorsand windows, have a level, sawn cut facingthe opening. Wall plate logs (top logs on eachwall) must be notched,drifted, pegged, lag-bolted,or through-bolted to thelog below to preventmovement caused bydrying stress and roofthrust.8 Log walls withopenings cut for doors,windows, and passagewaysmay require additionalbracing.9


Hand-crafted log homes are generally moreexpensive than milled log homes, becausethere is so much more labour involved. Ifeverything is done by a contractor, the projectcan be expected to cost more than standardwood-frame construction. However, costs willvary depending on how much of the work isdone by the owner.

The builder of a log home will require specialtools for measuring and marking, lifting,moving and placing, and cutting and shaping.

Impact on Services

The electrical wiring layout must be detailedcompletely in the plans, because unless thehouse is built off-site, the wires have to beinstalled very early in the log work. Heatingand plumbing systems should also be fullylaid out in the plans to ensure that ducts orpipes do not conflict with beams in any way.

It is common to pre-drill vertical holes in thelog wall so that the holes are completely hiddenfrom view and no electrical wiring is exposed

61


Log home under construction.

inside or out. Outlets and switch boxes areusually mortised into a log so that the coverplate is even with the surface of the log.

It is usually preferable to run plumbing in partition frame walls vertically withouthorizontal offsets, although offsets arepossible, if settling considerations are made.10

In a two-storey log home with a bathroomupstairs, slippage joints or looped piping is required to compensate for settling.11

Virtually any heating system used inconventional homes is acceptable for loghouses. However, compensation must bemade for settling if heating ducts are installedon the second floor.

Design Flexibility

Any design for a log home should be reviewedby an experienced log homebuilder beforebeing submitted for permit.

A square building is probably easiest to buildand can be the most efficient in the amountof space enclosed for the least availablematerials. However, a variety of wall lengthswill make better use of the available material,so it is more likely that even a modest planwill be made into a rectangle, not only forappearance but also for better interiorarrangements. The rooms in a log homeshould be spacious and the height should alsobe expanded. With settling, the ceiling will be at least 125 mm (5 inches) lower withinthe first two years, based on 274 to 305 cm(9 to 10 foot) high walls.

Only skilled carpentry and careful attentionto structural support can make floor-to-ceilingwindows possible. Corner windows, for these

same structural reasons, should be plannedwith experience and caution. A great deal ofthe inherent strength of a log house is in itsinterlocking corners.

Shrinking and settlement of logs are issuesthat must be considered in the design of loghomes. In general, the smaller and simpler thedesign, the less the house will be influencedby shrinking and settlement. Logs will shrinkapproximately 12 mm (1/2 inch) for every300 mm (12 inches) of log thickness, and the whole wall will settle down for at leasttwo years and normally longer. It’s essential to provide enough open header space above all of the doors, windows, partitions, stairs,fireplaces, etc. During the first few years, the amount of settling should be checkedperiodically.12

Attaching a new log structure to an older onemay cause problems, because the additionwill shrink and move relative to the existingstructure.13 Log walls taller than two storeysrequire engineering analysis.


• Depending on climactic requirements andlocal building regulations, a minimum logdiameter will be required. (see Log BuildingStandards, available from the InternationalLog Builders’ Association).

• Log walls with spans greater than 9.75 m(32 feet) should have reinforcement.

• Every log should be scrutinized-considerdirection of grain, presence of wind shake,decay, insect infestation, mechanicalhandling scars, etc.


62

• Shrinkage and settlement must be accountedfor in the design and construction methods.

• Heating and plumbing systems should belaid out in the plans to ensure that ductsor pipes do not conflict with beams.

• Log walls with openings cut for doors,windows and passageways may requireadditional bracing.

• To avoid decay, it is important thatrainwater is directed away from under thesill logs (first logs above the foundation).

• A surface stain or preservative must allowthe logs to breath and expel excess moisture.

Construction Costs

The cost of building a log house depends onthe cost of the materials, and how much ofthe labour the owner-builder is able to do. A straightforward log home will usually cost30 to 50 per cent more to build than aconventional frame house.14 Frequently, the cost for a log home is higher because of custom features.

In the case of hand-crafted log homes, the costof materials is generally the cost of the logs plusdelivery to the building site. Prices vary amongindividual logging operators, depending uponweather conditions, and how busy they are. It will also cost more if it is difficult for theoperator to sort out the required number ofgood house logs.

Energy Efficiency

The insulation value of a log wall will dependon factors such as species of wood and moisture

content. A reasonable estimate to begin withis R1(RSI 0.18) per 25 mm (1 inch) of logthickness. Thick logs can achieve goodinsulation values, and the larger the logs, the more insulating qualities they possess.15

The mass of the logs allows them to absorb,store, and release heat over a period of time,which can result in less temperature variationsand increased comfort.

Log homes with many corners, joints, androof angles can consume more energy thansimpler designs. The most energy efficientcorner is insulated and scribed, then sealedwith gaskets, foam, or chinking. Log homegasket or chinking compounds that stop mostcold air infiltration and heat loss has increasedthe energy efficiency of log homes. Gasketand chinking compounds last about 15 years

63


Interior view of log home.

Photo Courtesy of Moose Mountain Log Homes Inc.

or longer, are environmentally friendly, watersoluble, and very flexible.16

The Minnesota Department of Public Servicesand the National Association of Log BuildersNational Research Center measured airleakage in 23 log homes. It concluded thatthe worst leakages were not log related, butoccurred at Cathedral ceilings, windows anddoor frames, and the tops of the walls.17

Durability

Any wood currently used in a properlyconstructed and maintained log home will lastseveral generations. Log home maintenance ismostly preventative, aimed at protecting logsagainst water, insects and decay, similar tothat for a conventional wood-frame home.The two most important protections areadequate roof overhangs and eavestroughs. A variety of water repellents, preservatives, andstains will help logs shed water, resist insects,and maintain their colour. To be effective,treatments must be applied regularly.

Weather conditions determine how often theexterior will have to be refinished. Dependingon the type of sealant used, if chinking orcaulking is used, refinishing and sealingshould be considered every three to five years.In this respect, a chinked or caulked loghome requires more attention than a brick,vinyl- or aluminum-sided house.18 Usingscribe-fit and gasketed seals may require lessmaintenance than a chinked or caulked wall.

Much of the maintenance is completedduring the first part of the building process.Proper care of the logs starts when they arriveon the job site. Logs should be unloaded in a dry area and kept above ground. Plastic tarp can be used to keep logs dry during wetweather, but should be removed during goodweather in order to allow air to circulatefreely.


A study of the fire resistance of a handcrafted,full-scribe, chink-less log wall was conductedin the Czech Republic. The wall withstood180 minutes from its integrity viewpoint, and 172 minutes from the point of its load-bearing capacity.19

Sound insulation performance of a log housewas tested and compared to a reinforcedconcrete house in Japan. The ratings for the log house were similar to those of thereinforced concrete house.20

Further information can be obtained fromForintek Canada Corp., a non-profit woodproducts research and development company.


64

Figure 28:Types of Notches.

Saddle Notch

Blind Dovetail Notch

Lock Notch

Square NotchSource: Mackie, 1998.


Log wall homes do not have an interior air barrier. This results in the interiorenvironment being exposed to the materialsin the wall system, such as the wood, anypreservatives that may have been used,caulkings and other sealants. Moisture andmold are the main air quality concerns withlog construction. Other concerns include off-gassing from the wood and a potentialharbour for dust and insects. Off-gassingfrom logs is difficult to assess because it maybe true for certain species and not for others.Some individuals may find that emissionsfrom wood products and wood finishes are a problem.21


It requires at least 100 years to grow a maturetree and up to 500 years for it to reach itsmaximum growth. The best forest technologycan speed that process up to only a 50-yearperiod; however, this is heavily dependent ongrowth rates of the different species and onthe climate.

Although log homes use more timber resourcesto build than a conventional wood-framehouse, they can be dismantled and reused or recycled rather than demolished, and caneasily have a much longer service life span.


Log homes are not included in Part 9 of theNational Building Code; therefore, the designand supervision of an engineer may be requiredby the municipality.

Warranty Approval

Only registered builders can enroll houses in theprovincial warranty programs. The basic criteriafor enrollment are that the builder must becertified or registered with the warranty program,and that the home be built in compliance withthe National Building Code. The regulatoryauthority will determine compliance with theCode when the permit is issued.

Insurance Approval

Homes constructed in accordance with theNational Building Code are usually eligiblefor home insurance. The premium should not vary considerably from standard dwellingunits; however, policies may vary from insurerto insurer. If a bona fide contractor builds loghomes, there is a chance that they could beinsured without a surcharge over wood-frameconstructed home premiums.


Building with logs has long been accepted asa method of home construction, particularlyin rural areas and on acreages. Most marketsare familiar with this type of construction andmany find this type of construction attractive.Resale value is good.

Export Potential

Canada is a world leader in solid log homesand these products are in demand around theworld. These packages are being exported bylog home manufacturers.

65



Environmentally-friendly wood protectorsand fungicides make it possible to build a log home in any region or environment.However, shipping costs may be animpediment to log home construction inareas where logs are not a natural resource.

Log homes are typically built on acreages orin rural areas because of the need for largeareas for construction. These types of homesare not well suited to small urban lots.

Footnotes

1. Mackie, B. Allan, Building With Logs,Firefly Books Ltd, 1997, Willowdale, ON.

2. Ibid.

3. Canada Mortgage and HousingCorporation, “About your house: loghomes - frequently asked questions,” CMHC, 2000, Ottawa, ON.

4. International Log Builders’ Association,International, Log Homes - From Land toLockup, Guide to Handcrafted Log HomeConstruction, 1996, American LogBuilders’ Association, P.O. Box 28608,Bellingham, WA 98228-0608, USA.





9. Ibid.

10. Ibid.




14. Beckedorf, L. personal communication,2000.



17. Laidlaw, T., “Are log homes energyefficient?” www.loghomes.com/articles.


66


19. Houdek, D. and Bahyl, V. Fire resistance of handcrafted log walls. Journal of FireProtection Engineering, 2001, Vol. 11. pp. 1-

20. Huang, Y. F., Chen, T. Y., and C. H. Chuang. Sound insulationperformances of a log-house and areinforced concrete house (II). MokuzaiGakkaishi, 1994, Vol. 40, No. 12, pp.1389-1393.


Additional Reading

Canada Mortgage and Housing Corporation.2000. About Your House: log homes -frequently asked questions. CMHC. Ottawa, ON.

Cooper, Jim. 1993. Log Homes Made Easy:Contracting and building your own loghome. Stackpole Books. Harrisburg, PA.

Houdek, D. and Bahyl, V. 2001. Fire resistance of handcrafted log walls.Journal of Fire Protection Engineering, Vol. 11. pp. 1 - 20.

Huang, Y. F., Chen, T. Y., and C. H. Chuang.1994. Sound insulation performances of a log-house and a reinforced concrete house(II). Mokuzai Gakkaishi, Vol. 40, No. 12, pp. 1389 - 1393.

International Log Builders’ Association. 1996. Log Homes - From Land to Lockup. P. O. Box 775, Lumby, British Columbia,Canada V0E 2G0.

Mackie, B. Allan. 1997. Building With Logs.Firefly Books Ltd. Willowdale, ON.

Mackie, B. Allan. 1998. Notches of All Kinds:A book of timber joinery. Firefly Books Ltd.Willowdale, ON.

Mitchell, James. 1984. The Craft of ModularPost & Beam: Building Log & TimberHomes Affordably. Hartley & MarksPublishers Inc.

www.forintek.ca (Forintek Canada Corp., 2665 East Mall, Vancouver, B.C. V6T 1W5).

Source: Mackie, 1997.Source: Mackie, 1998.

67


Stackwall

Introduction

The stackwall system, also known as cordwoodmasonry, round wood building, and log-endconstruction, is a building technique inwhich short logs are stacked side by side likefirewood, with the spaces between them filledwith a cement mortar. The log-ends themselvesestablish the width of the wall and are exposedon both the interior and exterior surfaces.

Stackwall construction is an ancient methodof building. The origin of the technique isunknown; however, there are structures inSiberia and areas of northern Greece that areestimated to be more than 1,000 years old.There are a number of excellent examples

in both urban and rural areas of Canada,including the Ottawa area, the Victoriavillearea of Quebec, and Manitoba. The stackwallsystem is particularly attractive for building inisolated northern areas, where local materialscan be used.

Stackwall structures are unique in appearance,particularly when they are multi-sided orcurved in design, or when other materials, suchas glass bottles, are incorporated into the walls.


Stackwall homes are ideal for owner/builders,and for the economically and environmentallyconscious. They are probably best suited torural sites because of the wall thickness.


68

Photo Courtesy of Kris Dick

Key Benefits

The key advantages of stackwall constructionare economics, ease of construction, resourceefficiency, and ecological harmony. The cost ofbuilding a stackwall home can be considerablyless than a standard wood-frame house,depending on how much labour is provided bythe owner/builder and what materials are used.

Stackwall houses can be built with simpletools and techniques using local materials.Virtually any kind of tree, including fire-killedtrees, as well as recycled wood products, canbe used. Fire-killed trees have been used,however their affect on indoor air quality isunknown. The insulation value can be madeto equal or exceed that of conventional wood-frame walls. Finally, designing and building astackwall home can be a unique and satisfyingexperience.

Key Drawbacks

Constructing a stackwall home is very labourintensive and takes more time to build than a conventional house. Obtaining a buildingpermit in an urban area, and resale may be a problem.


Stackwall construction can be used within a post and beam framework, or can be load-supporting. In the post and beam method,the entire frame can be built and the roof puton before any wood is laid. This section dealsmainly with the load-supporting method.

If the stackwall is to be load supporting, thecorners must be built first (this is called thebuilt-up corner method or “stackwall corner”).Mortar is filled in between laid-up corners

of longer log-ends, or 150 mm x 150 mm(6 x 6 in) timbers, instead of betweenposts and beams. The advantage of thissystem is that a rectilinear structurecan be built completely out ofcordwood without the need for a postand beam framework; therefore, it isfaster, easier and usually cheaper thanthe post and beam. Also, the thickwalls provide better insulation andthermal mass.

69



“Stackwall corner”

A rigid masonry or concrete foundation isneeded in order to support the heavy walls.The cordwood walls should not be thickerthan the foundation because of potentialproblems with wall instability. The thicknessof the wall is determined by the length of the wood. Typically, walls should be between455 to 610 mm (18 to 24 inches) thick,depending upon the need for energy efficiency.There are some structures in the Yukon andeastern Ontario with wall thicknesses of 760 mm (30 inches) or more.1


Almost any wood can be used in stackwallconstruction, even wood unsuitable for othertypes of construction, such as deadwood inthe form of fallen or leaning trees, loggingslash, fence posts, and firewood or pulpwood.Fire-killed trees have also been used.2

Split wood or rounds can be used, but taperedor irregular log-ends should be avoided. It is a good idea to strip any bark, as insects areattracted to the area between the bark and theouter wood layers. Also, stripped wood driesfaster. Logs should be seasoned, similar to logsthat are to be used for log construction.3

The mortar matrix is equal in importance tothe log-ends, both structurally and in termsof appearance. There can be a problem withshrinking and cracking as the mortar cures. Inaddition, the dry log-ends draw moisture outof the mortar. This can be reduced by mixingsawdust into the mortar mix. Also, wetting thelog-ends and misting the wall after the mortarbeds have been pointed will help the mortar to“cure”. It is important that the mortar not dryout before the hydration that gives mortar itsstrength has had a chance to occur.4


In the “stackwall corner” method ofconstruction, corners are built first. The corneris usually constructed using squared timbersof approximately 150 x 150 mm (6 x 6 in) or 200 x 200 mm (8 x 8 in) in dimension;however, smaller timbers can be used. For a610-mm (24-inch) wall, the squared cornertimbers should be a minimum of 760 mm(30 inches) in length. This is done to ensurethat the corner is tied into the wall on eitherside. As the corners are being constructed itis very important to keep the timbers plumb,parallel and square.5

No matter what material is used in the built-up corners, the technique for laying the wallsis the same. The corners are built up about610 or 910 mm (24 to 36 inches), then amason’s line is stretched between two corners,and the cordwood masonry walls are in-filled.With any style of stackwall construction,door frames must be erected before in-fillingcan proceed.

Prior to building the walls, it is necessary to start with a clean dust-free foundation tomaximize the bond with the mortar. Mortar


70

Figure 29: How the mortar should be applied.

is placed on the foundation and shaped intotwo beds, about 25-mm (1-inch) thick. Onemortar bed is the outside of the wall and theother bed is the inside wall. Insulation, suchas sawdust and lime, vermiculite or otherblock fill can be used between the mortar beds.6

It is important to establish a random patternof sizes in laying the first course (exceptionsto this are when all log-ends are identical, or if a certain configuration is planned). Bymaintaining a random pattern, mistakes areless obvious, the wall is strong, and differentdiameters and shapes of log-ends areincorporated. Succeeding courses follow thesame process: mortar, insulation (sawdust andlime mixture, vermiculite or other block fill),and wood. The mortar beds will take on thecontours formed by the log-ends of the firstcourse.7

If engineered trusses are to be used in theroof construction, it is important to informthe truss supplier of the wall thickness. To ensure structural stability, the roof loadsshould be brought through the wall as closeto the centre line as possible. In many cases,the uplift forces on a roof created by windcan be more than the gravity loads due tosnow and other material loads. These forcesmust be transferred through the walleffectively. Thus, it is important that any roofsystem be tied down to the wall to providerestraint against uplift.8


The construction of stackwall houses is very labour intensive; however, only basiccarpentry skills are required for building thewalls. The Northern Housing Committee

at the University of Manitoba supervised theconstruction of a stackwall structure in Albertain 1976. In total, the wall construction,including the preparation and subsequentclean-up of mortar from finished work, required1.24 person-hours per square foot of wall.9

Impact on Services

Electrical wiring and plumbing can be easilyand successfully incorporated with the stackwalltechnique. An effective means of providing forboth electrical and other services is to incorporatea chase into the first course of logs by using logends that are 38 to 50 mm (1 1/2 to 2 inches)shorter for the first course.10 Outlets can becreated by cutting notches out of the blocks.

Design Flexibility

Stackwall construction allows for very creativedesigns-the building can be multi-sided, oralmost any curved shape: oblong, oval, spiral,round, freestyle. In addition, the wall can beany height; it is not limited by standard sizesof plywood or drywall.

71


Figure 30:Weak vs. strong cordwood wall.


• The wood material must be seasoned

• If the stackwall is to be load supporting,the corners must be built first

• A properly designed foundation is needed,which can be masonry, concrete, or rubble

• Load-bearing walls should not be less than300 mm (12 inches) thick (thicker wallsmay be necessary for adequate thermalprotection)

• A random pattern should be established in the first course of logs

• One mortar joint should not be placeddirectly over another.

Construction Costs

Stackwall houses can be low in cost,particularly when using low-grade wood, orrecycled and indigenous materials. Labour costsdepend on how much of the construction iscompleted by the owner/builder. It must beremembered that when comparing wall system

costs, the impact on other components mustbe considered. Wider foundations, longer spantrusses or rafters, and impact (positive andnegative) on interior and exterior finishesmust be considered.

Energy Efficiency

Stackwall construction combines insulatingproperties with thermal mass (the ability of a material to store heat). The log-ends providethe majority of the insulation value and also a large percentage of the thermal mass of thebuilding. The thermal diffusivity of the woodis quite low, which suggests that although it may be slow to warm up, once it is warm,it gives up its stored heat slowly.11

A properly designed and constructedstackwall home, with wall thickness matchedto the climate, should be easy to heat in thewinter and stay cool naturally in the summer.Since the inside mortar joints are separatedfrom the outside wall, the mortar acts asthermal mass to keep the house at a moreconsistent temperature. Sawdust and lime, orother insulating materials, can be used to fillin the cavity between the mortar, and helpinsulate the walls. Tests performed by the


72

Figure 31: A chase is an effective means to provide electrical and other servicesinto the home.12

Figure 32: Installation of top plates. 13

University of Manitoba point to an R-valueof about R1 (RSI 0.18) per 25 mm (1 inch).14

If shrinkage or severe checking takes place,the air tightness will be poor. This will resultin more air leakage and increased heatingcosts. Flexible caulking can be used to reduceair leakage due to shrinkage.

To allow more light in, and also to increasethe solar gain over the course of a day, thewindows can be flared out towards the insideof the structure.15

Durability

The durability of a stackwall house isexcellent, both in terms of normal wear andweathering, and in terms of fire resistance.If properly built, a stackwall house will lastat least 100 years.

Moisture problemscan be avoided byusing sound dry wood,keeping the wood offthe ground, andprotecting the wallswith a good roof over-hang. As in any wallsystem, moisture mustbe prevented fromentering the buildingby provision of properflashing. Log-ends willget wet in a drivingrain, but they breatheeasily along their endgrain, and soon dryout. The outside of the

logs should not get an impermeable coatingso they can breathe and wick out any trappedmoisture.


A stackwall house is constructed using logsand concrete. This would suggest that thistype of structure should have better resistanceto fire than conventional wood framing.There is no certified testing of this type of wall structure. The main concern is thechoice of materials inside the home.

Anecdotal evidence suggests that stackwallstructures are superior to conventional frame homes in terms of sound transmission.The large mass of the wall and the potentialfor reasonably low air leakage should reducesound transmission across the wall structure.

73


Stackwall house built in 1937 near Gimli, Manitoba.



Stackwall homes are normally built without anair/vapour barrier on the inside; however, onemay be required to meet municipal regulations.When an effective interior air/vapour barrier isprovided, indoor air quality would be ratedsimilarly to conventional wood houses. The mainconcern is moisture, which promotes moldgrowth and therefore affects indoor air quality.Dr. Kris Dick of the University of Manitobarecommends applying a waterproof coating onthe inside of the logs to slow down moisturemovement from the end grain. In his experience,even unprotected walls are naturally drying anddo not pose a moisture management problem.16


Although a stackwall house uses naturalresources, it can be constructed of recycledwood, such as telephone poles (non-treated),fence posts, and fallen trees. The mortar(cement), however, is energy intensive tomanufacture.


Stackwall construction is not included in Part 9 of the National Building Code, andthere may be problems obtaining regulatoryapproval. It may be necessary to have anexperienced architect or engineer involved in the design.

Warranty Approval

Only registered builders can enroll houses inthe provincial warranty programs. The basiccriteria for enrollment are that the buildermust be certified or registered with the

warranty program, and that the house is built in compliance with the Building Code.

The regulatory authorities will likely require a design professional to be involved in orderto have a permit issued. If the regulatoryauthorities issue their approval and a permit,it is probable that the house could be enrolledin a warranty program. It would be prudentfor the builder to confirm this prior toplanning the construction of a stackwall home.

Insurance Approval

Homes constructed in accordance with theNational Building Code are usually eligiblefor home insurance. Also, if a bona fidecontractor builds a stackwall home, there is a chance that it can be insured without a surcharge over wood-frame constructedhome premiums.


Although this is an old method of wallconstruction, stackwall is still new in today’sbuilding market. It has not proven itself to be a viable alternative, is labour intensive, and may not be acceptable in urban areas.

The market in general is very reluctant toaccept alternative wall systems, particularlythose that differ too far from the traditionalwood-framed house. As a result, the marketmay react negatively to stackwallconstruction. However, there is a smallportion of the market that is attracted toalternative systems, and a stackwall house in an attractive rural setting may draw apremium. It is difficult to speculate on theresale value of stackwall homes; many areowner-built and not intended for resale.17


74

Export Potential

There is no potential for export of thematerials, but possibly for design andconstruction methods.


There are no known geographic limitations;however, in remote northern areas, there maybe a lack of suitable local materials. In poorsoil conditions, installation may be difficultand costly due to the large mass of thestructure that must be supported.

75


Footnotes

1. Dick, K.J. personal communication,University of Manitoba, Department ofBiosystems Engineering, Winnipeg, MB.

2. Ibid.

3. Ibid.

4. Ibid.

5. Dick, K. J. and A. M. Lansdown,Stackwall, How To Build It, 2ndEdition, Instruction Manual, BuildingAlternatives Inc. P.O. Box 22, Anola,MB. 1995.

6. Ibid.

7. Roy, Rob, Complete Book of CordwoodMasonry Housebuilding: TheEarthwood Method, 1992, SterlingPublishing Company, Inc., New York.

8. Dick, K. J. personal communication,University of Manitoba, Department ofBiosystems Engineering, Winnipeg, MB.

9. Patterson, R. and A. M. Landsdown,“Housing for the North - The StackwallSystem: Construction Report - MildredLake Tank and Pump House,” NorthernHousing Committee, University ofManitoba, Winnipeg, MB., December1976.


11. Ibid.

12. Ibid.

13. Dick, K. J. and A. M. Lansdown,Stackwall, How To Build It, 2ndEdition, Instruction Manual, BuildingAlternatives Inc. P.O. Box 22, Anola,MB. 1995.


15. Ibid.

16. Ibid.

17. Beatty, D.A. personal communication,Appraisal Institute of Canada, 1111Portage Avenue, Winnipeg, MB, 2000.


76

Additional Reading

Dick, K. J. 1999. Economic Analysis ofRecently-Constructed Stackwall Structures in Canada. Proceedings of the ContinentalCordwood Conference. Cambridge, NY.

Dick, K. J. and Lansdown, A. M. 1995.Stackwall, How To Build It, 2nd Edition.Instruction Manual. Building AlternativesInc. P. O. Box 22, Anola, MB.

Dick, K. J. and Lansdown, A. M. 1994.Stackwall and the Building Inspector.Proceedings of 1994 Continental CordwoodConference (CoCoCo). Plattsburgh, NY.

Lansdown, A. M. and Dick, K. J. 1996.Stackwall House Construction - VapourManagement, Fire Resistance, InsulationValues and the Building Code. Proceedings of Canadian Society for Civil Engineering(CSCE) 1996 Annual Conference.Edmonton, AB.

Lansdown, A. M., G. Watts, and A. B. Sparling. 1975. Housing for the North - The Stackwall System. Part 1: TheExperimental Stackwall House: Background,Design and Construction. Northern HousingCommittee. University of Manitoba.Winnipeg, MB. May 1975. Report R1/75.

Patterson, R. and A. M. Lansdown. Housingfor the North - The Stackwall System:Construction Report - Mildred Lake Tankand Pump House. Northern HousingCommittee. University of Manitoba.Winnipeg, MB. Dec 1976.

Roy, Rob. 1992. Complete Book ofCordwood Masonry Housebuilding: The Earthwood Method. Sterling PublishingCompany, Inc. NY.

Shockey, Cliff. Stackwall Construction:Double Stackwall Technique. HuertoPublishing Co. Vanscoy, SK.

77


Straw Bale

Introduction

Even though straw has been used to provideshelter for thousands of years, it has only beensince the turn of the century that mechanizedbaling machines have transformed a wasteproduct into a building material.

Straw bale construction uses baled straw fromwheat, oats, barley, rye, rice and other grainsto build walls, which are then covered byplaster. This technique has been recentlyrevived as a low cost, environmentally friendlyalternative for building highly insulated walls.

In Canada, straw bale structures beganappearing in Quebec in the 1980s, and sincethen homes have been built in other areas ofthe country including Nova Scotia, Alberta,Manitoba, Ontario and Saskatchewan.

Early straw bale structures were fairlyconventional; however the flexibility of thistechnique makes it easily adaptable to a widevariety of design configurations. Typicalconcerns such as structural integrity, fire, pests,and moisture have been largely allayed. Theplaster, which is applied to the inside andoutside face of the bales, seals them againstfire, rain, wind and insects. It also providesthe wall with considerable rigidity and strength.

Straw bale construction is still in its infancy.As more data is gathered, and more structuresare built, new methods and techniquesare being developed. Many techniques areborrowed from conventional building practices.


Straw bale homes are suitable for mostmarkets, but are ideal for owner/builders, theeconomically and environmentally conscious,and particularly for those residing in highstraw production areas.


78

Photo Courtesy of Lynn Oliphant

Key Benefits

Environmentally, economically, and in termsof efficiency, straw bale homes offer manyadvantages. Straw is a natural, affordable, and annually renewable building material. By using straw wastes as a building material,the impact of carbon monoxide and nitrousoxides produced by burning straw can bereduced. In addition, straw bales bypass muchof the energy and waste produced by othermanufactured building materials.

In high straw production regions, straw balesare easily acquired and relatively inexpensive.Straw bale homes are durable and easy tomaintain. In addition, building walls withstraw bales can be accomplished with relativelyunskilled labour. Finally, properly constructedstraw bale homes can offer excellent thermalprotection against the environment.

Key Drawbacks

Shipping bales can be costly if residing in low straw production regions, and dependingon the location, may be difficult to acquire.The relatively recent adoption of straw baleconstruction practices may not be readilyaccepted by building code officials, warrantyprograms and the home insurance industry.

Straw bale homes require careful considerationof structural loading, unless the structure issupported by a more conventional approach,such as post and beam. Water penetration is another potential problem and carefulattention to details during and afterconstruction is necessary to avoid moistureproblems. High moisture content in bales can provide habitat for fungi, and can lead to decomposition within the wall assembly.

In very cold climates, the possibility ofvapour migrating from inside the house and condensing within the walls increases.Straw bale walls must be properly constructedto prevent access to insects and rodents.

The walls of a straw bale house are muchthicker than a conventional house; therefore,there is a considerable difference betweenexterior and interior dimensions. This factormust be considered in urban areas, whereland is limited.


There are two commonly applied buildingtechniques using straw bales. Post and beamuses a more conventional framing structure,with straw bales used as infill panels. In thisapproach, the straw bales do not bear theweight of the roof or floors above ground.

The second technique, commonly referred to as load-bearing or Nebraska style, uses thestraw bales themselves to support the loads.The plaster coating on the interior and

79


Figure 33: Straw bales placed on foundation.

exterior of the bale walls creates a stressed skinpanel. Plaster provides strength for the wall,and the straw bales provide support for theplaster. This section deals primarily with thistechnique.1


Straw bales can be obtained from feed mills,farmer’s cooperatives, grain elevators, ordirectly from the farmer. Straw from wheat,oats, barley, rice, rye or flax can be used,preferably long-stemmed and mostly free of seed heads. Bale quality is primarilydetermined by moisture content, density, and history (bale storage and protection fromharvest to construction). Bales should be keptdry before, during and after construction, withthe moisture content kept below 14 per cent.

Bales should be uniform in size and density,with a minimum density of 120 kg/m3

(7.5 lb/ft3). Density varies depending on thetype of grain, moisture levels, and the degreeof compression provided by the baler.

Bales must be tightly tied with durablematerial, preferably polyethylene string orbaling wire. Three-string bales are better thantwo-string bales, providing higher insulationvalues and greater structural rigidity.2

Various types of plaster can be used in strawbale walls; cement, clay, lime, and gypsum arethe most common varieties. The correct kindof plaster can provide a durable layer ofprotection from the elements, and a widerange of textures, colours and surfaces can be achieved.

Plastering a straw bale wall is different thanplastering a wooden or concrete wall; theplaster bonds with the straw. A great dealmore plaster is required to cover bale wallsthan equally-sized wood or block walls, andthe consistency will likely be different as well.3


In a post and beam building, a wood, steel,concrete or masonry framework is erected,and bales are used as infill. In a load-bearingdesign, bales act as structural components,keeping the roof in place. The weight of theroof structure bears directly on the top of thewall, which in turn transfers the loads to thefoundation.4

Foundations for straw bale construction mustbe sized to accommodate the increased widthof the walls, and high enough to protect thebottom of the wall from moisture. A minimum


80

Figure 34: Connecting bale wall to post withexpanded metal lath.

Source: Steen, Steen andBainbridge, 1994

of 200 mm (8 inches) above grade should be provided. In the majority of cases, load-bearing walls are constructed on a slab-on-grade. The foundation must be wide enoughto support the full width of the bale plus theinterior and exterior plaster coatings.5

Rows of bales are stacked to the desiredheight, beginning each course at the cornersand frames and working towards the centre of the wall. Rebar pins were used in earlystraw bale buildings to impale the first courseof bales; however, it was found that this canprovide a place for migrating moisture. A bale wall built without pins will not differappreciably in stability or structural strength.Corner guides can be used to ensure straightwalls.6

Bales should fit comfortably together—pushingthem too tightly together, or jamming in thelast bale in a course will cause undue stress onwindow and door bucks. Plans should allow a minimum of 1 1/2 bale lengths betweencorners and windows anddoors.7

Once the walls are fullheight, the top plate is installed. Traditionally,bales were stomped intoplace as they were stacked.Today, load-bearing walls arepre-compressed and leveledusing various mechanicalmethods. In earlier buildings,this was accomplished withall-thread rods beside orthrough the bales, whichconnected the top plate to

the foundation and were tightened with nutsat the top. Other methods include usingelastic polyester package strapping or heavygage wire wrapped over the wall and downthrough the footing, in both cases cinchingdown the bale assembly to the foundation.An inflatable bladder has also been used,which pushes down on the top plate.8

The use of some form of metal reinforcementfor the plaster is often mandated by thebuilding code and is recommended for many kinds of plaster; however, plaster can be applied directly to the bales. Plastering a straw bale wall is different than plastering a wood or cement wall-the plaster bonds withthe straw rather than creating a separate andthin layer. It is standard practice to applythree coats to both the interior and exteriorwalls: a scratch coat, a brown coat, and afinish coat. This coating provides a finish, aweather barrier, an air barrier, fire protection,and rodent and insect control.9

81


Straw bale house under construction.


Although some building contractors haveexperience in straw bale construction, moststraw bale homes are built by the owner, withsub-contractors being hired to do specific jobssuch as electrical wiring and plumbing. Strawbale walls can be erected quickly by someonewithout extensive building experience andwith few power tools.

Impact on Services

Electrical and plumbing layouts are not anydifferent in a straw bale house than in aconventional building. Interior services canbe installed by notching the interior surfaceof the bales. When conduit or electrical wiremust be run in the wall, it can be laid in thejoints between the bales as the walls arestacked, or it can be tucked between the bales later.

Electrical boxes and recessed light fixtures can be mounted by attaching them towooden stakes driven into cavities cut in thebales. Designs should minimize the need torun wiring or plumbing vents up the exteriorwalls as this will reduce the capacity of thewall to carry loads.

Water supply pipes can be run in interiorpartition walls, under the floor, in furred-outwalls in front of the bales, or through plasticchases to minimize the potential forcondensation in the bales.10

Design Flexibility

Load-bearing straw bale buildings can createsome challenges for the builder. Somebuilding codes limit the length of a straightuninterrupted load-bearing wall. Support can come from buttresses, interior walls,directional changes, or from temporarybracing. Wide window and/or door openingsalso pose a challenge. Very stiff top plates onthe wall and/or lintels over these openingsmust be able to transfer roof loads to thestraw walls without bending or buckling.Two-storey buildings are challenging becauseof added structural complexity.11

Post and beam construction allows for greaterdesign flexibility, allowing multiple storeys,greater roof spans, higher design loads, moreand larger window and door openings, andthe ability to easily expand the building inthe future.


82

Figure 35: Comparison of two- and three-string bales.

Source: Steen, Steen andBainbridge, 1994

2-String 23 kg (50 lbs.)

3-String 34-45 kg (75-100 lbs.)

355-430 mm(14”- 17”)

890-1016 mm(35”- 40”) 457 mm

(18”)

584-610 mm

(23”-24”)

813-1194 mm(32”- 47”)

355-430 mm(14”- 17”)


• Measurements should be determined forthe interior, allowing 460 to 610 mm (18 to 24 inches) for the walls to beconstructed outward.

• Foundations must be sized toaccommodate the increased width of thewalls, and high enough to protect thebottom of the wall from ground moisture.

• Bales must be stacked flat and shouldoverlap at joints.

• Load-bearing walls must be pre-compressedand leveled.

• A three-coat stucco should be applied tointerior and exterior walls.

• The primary design consideration must beto protect the straw from exterior wettingby incorporating features such asverandahs, oversize gables and overhangs,and adequate back splash protection.

Construction Costs

The cost of a straw bale house depends onthe size of the building, the cost of materials(including transportation costs), the designof the house, and the amount of sweat equitydonated by the owner.

Straw bales are just a wall system. Wallsconstitute about 10 to 15 per cent of the totalcost of the structure; therefore, a contractor-built straw bale house could cost about thesame as standard construction.

There is no real cost advantage in buildingwith straw, apart from the fact that you canuse unskilled labor for a large part of thework.

Energy Efficiency

A well-built straw bale wall creates anunbroken surface of high insulation. Thethermal resistance of straw bales is dependenton straw type and density, straw orientation,and thickness. Values of R17 to R35 (RSI 3to RSI 6) have been reported, although forthe common 450-mm (18-inch) thick strawbale of 110 to 190 kg/m3 (7 to 12 pcf )density, a value of at least R23 (RSI 4) can be expected.12

Durability

Straw, like wood, degrades when exposed to a sufficient amount of moisture for asufficient amount of time at above-freezingtemperatures. Air leakage and rainpenetration are usually the two largest sourcesof moisture. CMHC moisture testing of balewalls in Alberta found that contact withrainwater, especially on northern exposureswhere the sun provides little or no drying,was a much greater concern than moisturemigrating through the walls from inside.13

Many simple building techniques can be usedto protect bales from exposure to moisture.Generous roof overhangs and propereavestroughs eliminate most direct rainfalland splash-back from reaching the walls.Plastic or tar paper placed along the top ofthe walls helps shed any water that may comethrough the roof.14

83


There are many load-bearing straw balehomes in Nebraska and Wyoming that haveendured almost a century of snowstorms,high winds, temperature extremes, andhuman occupancy.


Fire is not of great concern for the completedstructure. The tight packing of the straw bales keeps the available oxygen needed forcombustion very limited. The NationalResearch Council of Canada tested plasteredstraw bales for fire safety and found them toperform better than conventional buildingmaterials. Even when unplastered, the balestend to char on the outside, which in turninsulates the inner straw.15 On the otherhand, unbaled straw is extremelycombustible, and care must be taken during construction.

Anecdotal evidence indicates that straw balehouses appear to be quite soundproof. This is likely due to the mass of the walls and therelative air tightness, especially with plasteron the interior and exterior. One home wasrecently built near railway tracks; passingtrains could not be heard from inside thehome, and a loud stereo played next doorcould also not be heard.


If a full continuous air barrier is part of theassembly, the indoor air quality of a strawbale house should be rated similarly to aconventional wood-frame house. The mainconcern with straw bale walls is moisture.Clean dry straw sealed in a wall should havevery little mold or allergy potential. However,

this is based mainly on anecdotal evidence,and further study is needed.16


The energy expended in the extraction,refinement, and transportation of buildingmaterials to the site, and the total resourcesused during construction, should be includedin the calculation of a structure’s efficiency.According to one study, straw bale walls wereat least 30 times less energy intensive thana wood-frame wall with equivalent fibreglass

insulation.17 However, because baled straw is a low-density material, shipping costs are high, both in terms of dollars andenvironmental impact (primarily from fuel consumption).


84

Figure 36: Load-bearing straw bale wall.

Source: Johnston and Swearingen, 1996

Straw is available wherever grain crops aregrown, and can be grown annually in acompletely sustainable production system.Depending on the region, straw is stillburned as a waste material, thus contributingto air pollution. By using straw forconstruction, this environmental hazard can be greatly reduced.

One of the most beneficial results of usingstraw for home building is the reduction oftimber use. However, it is not known howmuch straw can be used without negativelyharming soils by the extraction of nutrients.


Municipal regulations may require theinvolvement of a design professional, such asan engineer or architect, especially if the wallsare load-bearing.

Warranty Approval

Only registered builders can enroll houses inthe provincial warranty programs. The basiccriteria for enrollment are that the buildermust be certified or registered with thewarranty program, and that the home be in compliance with the building code.

The regulatory authorities will likely require a design professional to be involved in orderto have a permit issued. If the regulatoryauthorities issue their approvals and permit, it is probable that the house will be enrolled.It would be prudent for the builder toconfirm this prior to planning theconstruction of a straw bale home.

Insurance Approval

Homes constructed in accordance with theNational Building Code are usually eligiblefor home insurance. Also, if a bona fidecontractor builds a straw bale home, there is a chance that it can be insured without asurcharge over wood-frame constructed homepremiums.


Modern straw bale home construction is still in its infancy; however, its popularity is growing. The market in general is veryreluctant to accept alternative framingtechniques, particularly those that differ toofar from the traditional wood-framed house.As a result, the market may react negativelyto straw bale construction. However, there isa small portion of the market that is attractedto alternative systems, and a straw bale housein an attractive setting may draw a premium.18

Export Potential

There is no potential for export of the actualbuilding materials, but possibly for designsand construction details.


Most of the existing straw bale houses arelocated in dry areas, and have performedsuccessfully. However, more research needs to be conducted to determine if thesestructures are suitable for wetter climates.

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Footnotes

1. Magwood, C. and P. Mack, Straw BaleBuilding: How to plan, design and buildwith straw, New Society Publishers, 2000,Gabriola Island, B.C.

2. Steen, A. S., B. Steen and D. Bainbridge,The Straw Bale House, Chelsea GreenPublishing Company, 1994, Vermont.


4. Ibid.

5. Dick, K. J., personal communication,2000.


7. Ibid.

8. King, B. 1998, “Straw-baleconstruction,” National Conference ofBuilding Officials, September-October1998.

9. Straube J., “Moisture properties of plasterand stucco for strawbale buildings,”CMHC, Ottawa.



12. Straube J., “Moisture properties of plasterand stucco for strawbale buildings,”CMHC, Ottawa.

13. Jolly, R., Moisture in straw bale housing,Nova Scotia, Canada Mortgage andHousing Corporation, 1998, Ottawa.




17. Hoffmeister, R. in Steen A. S., B. Steenand D. Bainbridge, The Straw BaleHouse, Chelsea Green PublishingCompany, 1994, Vermont.

18. Beatty, D. A. personal communication,Appraisal Institute of Canada, 1111Portage Avenue, Winnipeg, MB, 2000.


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Additional Reading

Canada Mortgage and Housing Corporation.2000. Straw bale house moisture research.CMHC. Ottawa, ON.

Canada Mortgage and Housing Corporation.An innovative straw/bale mortar wall system.Housing Technology Incentive Program.CMHC. Ottawa, ON. NHA 5799 84/08.

Canada Mortgage and Housing Corporation.Moisture properties of plaster and stucco forstrawbale buildings. CMHC. Ottawa, ON.

Gagne, Louis. 1986. A Straw-Bale/MortarHouse Demonstration Project. CanadaMortgage and Housing Corporation. Ottawa, ON.

Johnston, Jane and John Swearingen. Building a Straw-bale house. FineHomebuilding June/July 1996. pp 74 - 78.

Magwood, Chris and Peter Mack. 2000. Straw Bale Building, How to plan, design and build with straw. New Society Publishers.Gabriola Island, B.C.

Platts, Bob. 1997. Pilot Study of MoistureControl in Stuccoed Straw Bale Walls. Canada Mortgage and Housing Corporation.Ottawa, ON.

Steen, Athena S., B. Steen and D. Bainbridge.1994. The Straw Bale House. Chelsea GreenPublishing Company. Vermont.

Straube, J. Moisture properties of plaster andstucco for strawbale buildings. CanadaMortgage and Housing Corporation. Ottawa, ON.

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Manufactured Wood Wall Systems

Introduction

Manufactured wood wall systems are similarto traditional wood framing, with thesubstitution of manufactured studs fortraditional dimensional lumber studs. Themanufactured studs vary from I-Joist to fingerjointed studs to Laminated Veneer Lumber(LVL) and Laminated Strand Lumber (LSL).LVL and PSL members are most typicallyused for beams, columns and lintels becauseof their dimensional stability and higherstrength compared to dimensional lumber. I-Joists are mostly used in floor systems as they replace the traditional floor joist.Finger jointed studs have similar structuralcharacteristics to dimensional material andare relatively new on the market.

I-Joists are manufactured in the configurationof an I-beam, with the flanges being made of LSL, LVL, or finger jointed material, andthe web being a high strength plywood ororiented strand board. I-Joists have been used in walls in limited applications; they aremostly used in this type of wall system whenthick walls are needed, primarily for increasedinsulation levels. Since their use as wall studsis not prevalent, they will not be dealt with inthe remainder of this section.

LSL and LVL members can be cut to virtually any dimension and to any length.The manufactured product has a significantincrease in strength over dimensional lumber.LVL and LSL members can be substituted fortraditional studs as they can be purchased inthe same dimensions (38 x 89 mm (2 x 4) upto 38 x 235 mm (2 x 10)).


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Photo Courtesy of TrusJoist, A Weyerhaeuser Business

Finger jointed studs are made from shortlengths of dimensional material that arejoined with adhesives. They are more stablethan dimensional lumber and have similarstrength characteristics.


The primary target market for manufacturedwood wall systems would be the upper-endresidential housing market. This would applyequally to owner/builders or to newhomebuilders. LVL members are moreexpensive than traditional studs, and thushave been used more in commercialconstruction, or in higher end houses wheretall walls require additional strength or wherevery straight walls are requested. Thesemembers may be used in combination withdimensional lumber, with the manufacturedproduct being used only in certain areas, suchas the kitchen or bathroom walls. Fingerjointed studs are less expensive than LVLmembers, but are still somewhat moreexpensive than traditional 38 x 89-mm (2 x 4-in) and 38 x 140-mm (2 x 6-in) studs.

Key Benefits

The primary advantage of wall systems usingmanufactured wood studs is the uniformity ofthe material. The material will not be bowedand there will not be large knots or otherirregularities. This results in walls that arevery straight and in walls that will not warpand twist in the future.

A second advantage of this type of wallsystem (using LSL) is the increased strengthof the studs. This allows them to be used intall walls with the same size and spacing asdimensional lumber but with the capability

of handling axial loads in combination withwind loads. Other benefits of manufacturedstuds include properties similar todimensional wood studs and very littlewastage on site.

Key Drawbacks

The main drawback to manufactured woodwall systems is the cost. Manufactured woodstuds can be double the cost of traditionalwood studs and thus can significantly increasethe cost of this wall system. This drawbackcan be offset when high strength walls arerequired or where special requirements forperfectly straight walls or thicker walls mustbe met.


Manufactured wood wall systems using LSL members do not have special structuralconsiderations. The strength properties ofthese materials exceed those of traditionalwall studs.

Finger jointed studs have strength characteristicsalmost identical to dimensional wood.Equivalencies have been established so thatfinger jointed studs can be substituted fordimensional materials when used in a verticalstud application. Local authorities mayrequire documentation on the suitability of manufactured materials as a substitute for traditional studs.


Manufactured wood studs are readilyavailable and can be used in the same manneras traditional wood studs. They require nospecial detailing (except for I-Joists) and they

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should result in less wastage on site because of the controlled quality of the material. The material must be protected on-site (as with other products) from moisture and mechanical damage.


Construction sequencing will be identical tothat of traditional wood framing. Since thistype of product is still not mainstream,stocking of specific sizes and lengths ofmaterial in adequate quantities must beconfirmed in advance so that the materials are available when needed on-site.


All traditional equipment and labour is usedfor this wall system. Saws, hammers andnailing guns are standard equipment. Framerswill not be affected when constructing thiswall system as cutting and fastening of thecomponents of the system does not changefrom the conventional system. Small gains in efficiency may be achieved since framerswill not have to inspect material—it will allbe uniform.

Impact on Services

Services can be installed in this wallsystem exactly as with a wood wall system.Plumbing, heating and electrical installationsremain the same. LVL and finger jointedmembers can be drilled and bored forinstallation of wires and pipes in thetraditional manner.

Design Flexibility

The extra strength of the wall studs used inthis wall system provides improved designflexibility for new construction. Higher walls,straighter walls and increased load capacitycan be benefits that increase flexibility.

There is also the same flexibility in the future,if and when renovations or alterations aredesired. Modifications can be easilyperformed by carpenters if they are wellversed with traditional wood construction.


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Figure 37: I-Joist Figure 38: Finger Jointed


Manufactured wall studs can be quiteexpensive, and thus care must be taken whenmeasuring and cutting to minimize mistakes.

Bracing and blocking will have to beaccounted for as it is usually taken fromculled material. Less expensive dimensionallumber will likely be used for this purpose.

Construction Costs

A manufactured wood wall system will bemore expensive than a traditional wood wallsystem. The labour component should beidentical; however, the material cost for thestuds will likely be between 25 and 100 percent higher than that of a traditional woodwall, depending upon whether LVL or fingerjointed studs are used.

A manufactured wood wall system does not affect the insulation, air/vapour barrier,interior or exterior finish. Except for the extracost of the studs, this system is neutral whencompared to conventional wood studs walls.

Energy Efficiency

Since manufactured wood studs can beobtained in almost any width, the amount of insulation that can be incorporated intothe wall system is quite flexible. A standard 38 x 8 mm (2 x 4 in) wall thickness can beachieved, as can thicknesses well beyond 235 mm (10 inches) if desired.

Finger jointed studs come in standard 38 x 89 mm (2 x 4 in) and 38 x 140 mm (2 x 6 in) sizes, and this would allow fornominal R12 (RSI 2.1) or R20 (RSI 3.5)insulation levels. If even higher insulationlevels are desired, an I-joist wall system couldbe used to increase the depth of the cavityand allow for more insulation.

Since a traditional air/vapour barrier is used,good air tightness is achievable. This alsocontributes to an energy-efficient wall system.

Durability

This wall system will be as durable as a traditional wood wall system, assuming the same level of moisture protection. The installation of a good exterior moisturebarrier and a good interior air/vapour barrierprotects the structural and other componentsof the wall system. These wall systems shouldremain serviceable for 50 years and beyondwith proper maintenance.


All fire and sound ratings contained in the National Building Code are based ontraditional studs. It is anticipated that thistype of alternative wall system would performin a similar manner to a conventional wood wall. According to some of themanufacturer’s literature, some fire testing has been done by independent labs. If fireand sound is a consideration, ask the supplierand/or manufacturer for the test data thatthey have available.

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The impact on indoor air quality from aspecific type of wall system will be determinedby the amount of off-gassing from thematerials used and the quality of the interiorair barrier. A good and tight interior airbarrier will separate the materials of the wall system from the interior environment.The manufactured wood wall system employsa traditional air/vapour barrier. The techniquesfor achieving a good air seal are quite wellunderstood and used by most builders; thus,this wall system should not affect the indoorair quality.


The benefit of using manufactured woodstuds, from an environmental perspective, is that wood veneers and wood from newgrowth trees can be used for this product.This reduces the impact on our forests whileat the same time producing a high-qualityproduct.

The potential drawback is the adhesivecomponent used and the energy used inproducing the final product. While dimensionalstuds also require some energy for milling anddrying, the amount of energy used to producea manufactured wood product is higher.


Code and municipal regulations may varywhen using LVL or finger jointed members in a wall system. In some instances, theinvolvement of an engineer may be necessary,however technical data sheets from themanufacturer may be all that is needed toverify that the strength characteristics of theseproducts meets or exceeds those ofdimensional lumber.

Warranty Approval

This system is virtually identical to atraditional wood-frame wall system, and thusno difficulty in receiving warranty approvalsis anticipated for a certified builder.

Insurance Approval

Insurance companies should not have aproblem in providing home insurance for thiswall system. Fire and durability will be verysimilar to a traditional wood-framing system,for which they have a long track record.Liability and other components of theinsurance policy will not be affected by this type of wall system.


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Various sizes of manufactured lumber.1

Photo Courtesy of TrusJoist, A Weyerhaeuser Business


The market acceptance and resale value formanufactured wood wall systems should notbe affected. In fact, most homeowners or purchasers would likely not know thedifference between this type of system andthe traditional system.

Homeowner caution about new andunfamiliar materials can be offset by thebenefits of the new materials. Awareness andeducation may be needed as with many of thealternative wall systems.

Export Potential

The export potential for this wall system is the same as for traditional wall-frameconstruction. The weight and size of panelswould not be altered and the acceptance inforeign markets would be similar todimensional lumber.


There does not appear to be geographiclimitations for manufactured wood wallsystems. Moisture and temperature variationsfrom region to region should not affect theperformance of this system.

Transportation of the material is the same asfor dimensional lumber, but availability in awide variety of sizes and lengths is uncertain.

List of References

1. Specifier’s Guide to the Silent FloorSystem, Trus Joist, A WeyerhaeuserBusiness.

Additional Reading

http://www.weyerhaeuser.com/wbm/products/5.asp

http://www.successfulbuilder.com/material.html

http://www.osbguide.com/sba.osb.info/sba.osbinfo.1.html

http://www.cwc.ca/english/wood_design/wood_products/catalogue/psl.html

http://www.apawood.org/level_b.cfm?content=app_bas_wall

http://www.canadianhomebuilder.com/cata...previous_issues/summer_99/natl/wood.htm

http://www.tembec.ca/english/products/eforest_products_summary.htm

Specifier’s Guide to the Silent Floor System. TrusJoist, A Weyerhaeuser Business

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Earth Construction Systems

Introduction

Soil has been used as a building material all over the world for centuries, and today,approximately one-third of the world’spopulation is living in earth buildings. Soil can be compacted into forms to createmonolithic (one unit) walls, formed intoblocks, or used to shelter undergroundstructures.

In the rammed earth method, damp soilmixed with cement is compacted in enclosedformwork, similar to that of cast-in-placeconcrete. Once the compacting is complete,the forms are removed, leaving a complete wall.

Compressed earth blocks can be manufacturedon-site using a variety of block-makingmachines, including manual, mechanical, and hydraulic presses. Soil mixtures for

compressed earth blocks are similar to thosefor rammed earth. The same soil used to formthe blocks is used in the mortar for bindingblocks together into walls.

Adobe is a term often used to describe anarchitectural style; however, it is actually a construction method in which bricks oftightly compacted earth, clay, and sometimesstraw are moulded and cast small enough toshrink without cracking. Adobe differs fromcompressed earth block because the blocks are not highly compressed and are left to dryin the sun. Construction methods and thecomposition of the adobe vary according to climate and local customs.1

For cob construction, no blocks are madeprior to building, nor is any mortar used.Soil, sand/small stones, straw and water aremixed together and then hand or shovel-formedlumps of the mixture are placed onto thefoundation and moulded.2


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Photo Courtesy of Ginette Dupuy

Earth-sheltered houses are either banked on one or more sides with earth, or builtpartially or entirely underground (at least 50 per cent of the wall and roof areaunderground). The surrounding soil providesnatural insulation, making these homesinexpensive to heat and cool. Earth shelteredhomes are typically made of concrete.3

This section focuses on rammed earth andcompressed earth block.


The primary target market for earthconstruction is owner/builders who want the satisfaction of building a home usingindigenous, recyclable, low cost materials thatare less damaging to the environment, andthat blend into the landscape. Builders whowish to specialize in alternative methods ofbuilding may also be interested in this formof construction.

Key Benefits

The main advantages of earth constructionare thermal mass and hygroscopicity. Because of the thick walls, an earth house is less susceptible to the effect of extremeoutdoor air temperatures. Earth walls absorbthe extra moisture in the air and release itwhen there is not enough. Because of thesetwo qualities, an earth house is always coolerin the summer.4

Another attraction of earth construction isthat the site itself is usually the source of thebuilding material; therefore, earth houses canbe built almost anywhere if the soil on thesite is suitable. If not, earth can be delivered

from a site nearby. Also, soil as a buildingmaterial has no ecological side effectsassociated with its harvesting or use.

Other advantages of this wall system include:long life expectancy, reduced exteriormaintenance requirements, improved fire and sound resistance, and resistance to woodpredators, fungus and rot.5 Also, individualscan participate in the construction of theirhome.

Key Drawbacks

There are some disadvantages associated withearth construction.

Earth construction is not suitable for allclimates and locations. The level of carerequired to avoid moisture problems is higher with earth construction, both duringconstruction and during the life of the house.The type of soil at the building site, andlevels of radon gas are other importantconsiderations. Also, in locations with limitedbuilding areas, the thick walls of a rammedearth house reduces the available living space.

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Compressed earth blocks drying.

The regulatory authority may require anengineer’s involvement since an earthstructure does not fall within Part 9 of theNational Building Code.

And finally, the initial cost for a rammedearth home is higher than for a standardwood-framed house.


The minimum thickness of rammed earthwalls is 300 mm (12 inches). They can benon-load or load bearing and reinforced withsteel if necessary.6 For stability and thermalefficiency, exterior rammed earth walls areusually 610 mm (24 inches) thick. Interiorwalls can be as narrow as 150 mm (6 inches).7

Sufficient tamping (compacting each layer) in 150 to 200 mm (6 to 8 inch) lifts is veryimportant in order to avoid structuralproblems.8

The structural blocks for a compressed earth block house usually measure about (300 x 200 x 100 mm (12 x 8 x 4 inches) for exterior walls, and about 300 x 140 x 90 mm(12 x 5-1/2 / 3-1/2 inches) for the interiorwalls.9


Studies undertaken in the 1920s found that stabilized soil was an excellent buildingmaterial. The best results were obtained whena small amount of cement (under 10 per cent)was damp-mixed with the soil. It wasdetermined that the resulting strength camefrom the migration of cementitious fibres andfrom compression.10

For rammed earth construction, the type of soil used has an effect on the finalcompressive strength. The soil must be highin sand and low in clay, and topsoil is notsuitable. The mixture, known as “road base”,is found at most gravel pits. It consists of finesand, coarse sand and pebbles with not morethan 15 per cent clay. The mixture can alsoinclude 5 to 10 per cent cement and justenough water to make a stiff conglomerate.11

The more cement that is added, the more theearth loses its thermal mass, hygroscopicityand breathing capacity.12

For compressed earth blocks, the idealquantity of clay is about 20 per cent. About 5 per cent cement is added, depending on thetype of earth. The gravel, sand and silt formthe structure and the clay is the binding agent.

If the blocks contain cement, they must curefor at least one week. The blocks are coveredwith a plastic sheet. Once the plastic isremoved it takes about three weeks for theblocks to dry. The blocks need to be shelteredfrom the rain.13


Prior to construction of earth walls, the soilcomposition should be tested. This can bedone by taking a sample at excavation depth,screening through a 6 mm (1/4 inch) screen(13 mm (1/2 inch) screen for compressedearth block), and conducting a suspensionfield test or taking it to a lab for testing.14,15

For rammed earth walls, the soil and cementare dry-mixed; water is added sparingly untilthe mix forms a ball when squeezed. The soilmix is poured into the form in lifts no morethan 200 mm (8 inches) deep. Before more


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dirt can be added, the lift is compacted down(rammed) to approximately 75 to 100 mm (3 or 4 inches).16 Ramming can beaccomplished manually or mechanically.Once the compacting is complete, the formsare carefully removed, and the earth walls are wet-cured for two weeks (leaving themunloaded and protected from the weather). A burlap cover sprinkled down three timesper day or well-sealed plastic sheeting can be used.17

Cured rammed earth will hold galvanizednails, which allows virtually any framedwindow or door treatment. Weather jointsbetween a wood-frame and a rammed earthwall can be closed by forming a keyway in theend of the wall.18

The final step is to tie the walls together witha bond beam. Constructed of timber, steel orreinforced concrete, the bond beam sits ontop of the earth walls and is used to tie thesystem together as well as to anchor theroof.19

Earth walls have very high permeability;therefore, it is a breathable material. Painting,wallpaper, panelling or drywall will affect thisfeature and result in the structure losing itsthermal mass and hygroscopicity. An earthwall can be finished with an earth stucco(using the same earth as the wall). A naturalpigment can be added to give colour. The wallcan also be lime-washed.20

Like poured concrete, rammed-earth wallsreflect the quality of the forms. Forms linedwith hardboard produce consistently smoothrammed earth walls.21

The construction process for a compressedearth block house is similar to that of a brickhouse, using a well-known technique—masonry. Compressed earth blocks have to be mortared. A sand-cement mortar on the first two courses of block will increase waterresistance. The mortar for the rest of thebuilding consists of one part cement, twoparts lime, and nine parts of the same soilused to make the blocks. A compressed earthblock house will have to be insulated fromthe outside to comply with the CanadianBuilding Code. Thus, all the heat inside the wall will not go to the outside.22


Continuous or monolithic rammed earthwalls require forms. A variety of materials can be used for forms, including wood,aluminum, or steel. The forms must beextremely strong; they must not onlywithstand the stress of the soil stacked upinto a wall, but also the concentrated forces asthe soil mixture pours into the forms and thesoil is tamped. The forms are held togetherwith a cross-tie on top and a strong back shoepinned into the footings on the bottom.With this system, holes are not cut in theplywood, thus reducing waste.

Other than the forms, equipmentrequirements include tampers, bucket loadersand shovels. Tamping can be done using apneumatic tamper, but some prefer to do itby hand using simple weighted poles.23

A study of rammed earth by the U.S.Department of Agriculture in 1938 foundthat a three-person crew working with handtools (shovels, buckets and tampers) could

97


complete a wall, with an area of 6.5 squaremeters (70 square feet) and 360 mm (14 inches ) thick, in one day.24

Compressed earth blocks can be made using a manual press, a mechanical press, or ahydraulic press. According to Ginette Dupuy,a Quebec researcher currently studyingcompressed earth block construction, two to three blocks per minute can be producedusing a manual press.25

Impact on Services

For rammed earth walls, plastic conduits canbe integrated during ramming inside the walland wiring fed through these conduits later.26

It is preferable not to run electric wires andplumbing into compressed earth blocks so as not to affect their structural integrity andto be able to access the wires and plumbing if needed. Interior wood walls can beconstructed for this use.27 Therefore, servicesmust be planned for and incorporated duringconstruction of the walls.

Design Flexibility

Rammed earth walls can bedesigned to almost anyconfiguration, including curvedwalls, rounded archways, archtop windows and inset windowseats.28 A two-storey rammed earth house is possible.

In compressed earth blockconstruction, block size can bevaried to accommodate a varietyof designs. Walls can be

sculptured, rounded or formed into keystonearches.29

With prior thought and planning, it ispossible to build on to an existing rammedearth or compressed earth block house.


The following are some suggestions for thedesign and construction of earth wall houses:

• Soil composition must be tested prior toconstruction

• Rammed earth walls should be a minimumthickness of 305 mm (12 inches)

• For rammed earth walls, sufficientcompacting in 150 to 200 mm (6 to 8 inch)lifts is very important in order to avoidstructural problems

• Planning for the installation of servicesmust be done prior to construction of thewalls of an earth house


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Interior of a compressed earth block home.

Construction Costs

Cost is influenced by design, site conditionsand location. If the soil on the building sitecan be used, the majority of the materials forthe walls of an earth house will cost nothing.However, if the soil is not suitable, other soilwill have to be transported to the site.

The labour and the formwork are the more costly items of a rammed earth wall.According to one Canadian builder, becauseit is not widely used yet, the rammed-earthstyle of house construction is typically 15 per cent more than a wood-frame house.30

The homeowner can bring down the cost by providing some of the labour.

For compressed earth block construction, the cost of a press ranges from a few hundreddollars for a manual press to $100,000 for a hydraulic press.

Energy Efficiency

Earth walls are not particularly goodinsulators. Dense materials, such as adobe,concrete, stone, brick, rammed earth andcompressed earth block have R-values roughly equivalent to .04 RSI per 25 mm(.25 per inch).31

Despite the low R-value, one of the biggestbenefits of earth houses is the thermal massprovided by the thick walls. This results in a high thermal capacity, keeping the internalconditions uniform in climates with largevariations in temperature from day to night.On cold days, the walls soak up the heatproduced inside the house. This is thenradiated (some inside and some outside)during the night. The reverse works on hot

days-cool night-time temperatures are stored in the walls and keep the house from overheating during the day.32 One B.C. company has modified rammed earthconstruction for northerly climates byinstalling a core of foam insulation.33

A compressed earth block house would haveto be insulated from the outside to complywith the Canadian Building Code. This wayall the heat inside the wall would not go tothe outside, but would go back to theinside.34

Durability

With proper roof and structural design,rainfall or severe weather should not affectthe structural properties of earth walls.

The main reason for the durability of earth walls is the clay content of the soil. Soil comes from a rock base, which issubsequently transformed into gravel, sand,silt and finally clay. Consequently, the claycontained in the earth wall is at the last stageof the transformation process; therefore, it isvery stable.35

Terra Firma Builders Ltd. in BritishColumbia built an experimental rammed-earth wall on Salt Spring Island. This wall isentirely exposed to rain and cycles of freezingand thawing. Although it is unsealed anduncapped, it is expected to last for over 200 years.36

The U.S. government has documented over350,000 currently existing earth houses andcommercial buildings in the United States.Many of these have been in existence withminimal maintenance for 100 years.37

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Several options are available for finishing soil-based construction materials. Two basicapproaches exist-waterproof or breathablefinishes. Waterproof finishes such as cementstucco are more permanent and moreexpensive initially. Such finishes will containand trap moisture, which may be problematic.Permeable finishes such as mud plaster areless expensive, less durable and will allow thewall to absorb and give off airborne moisture.38

Maintenance of rammed earth walls requiresonly the periodic application of an invisible,non-toxic, anti-dusting sealer about every 20 years.39


Fire resistance tests have been conducted onrammed earth walls in Australia. A 300-mm(12-inch) thick rammed earth wall gave a testresult of four hours.40

Paying careful attention to reducing air leaksthrough all the components of a rammedearth building can control airborne soundtransmission. A heavy mass wall absorbsconsiderable sound energy. Terra FirmaBuilders Ltd. has measured the sound transferof their double rammed earth wall. It wasrated over STC 60.41


A stabilized, insulated rammed earth wallcontains only six ingredients: earth, iron,oxide colouring, 10 per cent cement, steel,sealer, and insulation. The surface can becoated with a non-toxic sealant to preventany dusting.42

Compressed earth blocks are composed ofsoil, water, cement and sometimes lime. Limewashes or earth stucco coloured with naturalpigment can cover the inside walls or theycan be left as is. Therefore, there is noemanation of volatile organic compounds or formaldehyde.43

A well designed home should include aventilation system so that stale air can beexhausted and fresh air introduced to theliving space. Some methods to provideventilation include air-to-air heat exchangers,forced air furnaces with a fresh air supply to the return air plenum, and kitchen andbathroom exhaust fans.


Five acres of land can only provide enoughlumber for 20 houses, whereas a 5-acre pitcan provide enough earth for the walls of5,000 homes.44

The low energy consumed in the constructionof earth buildings and the longevity of thestructures make this form of construction lessdamaging to the environment. Although thecement used in the soil mixture has highembodied energy, only a small amount is used.


Municipal regulations will likely require theinvolvement of a design professional, such asan engineer or architect, especially if the wallsare load-bearing.


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Warranty Approval

Only registered builders can enroll houses inthe provincial warranty programs. The basiccriteria for enrollment are that the buildermust be certified or registered with thewarranty program, and that the home be in compliance with the Building Code.

The regulatory authorities will likely require a design professional to be involved in orderto have a permit issued. If the regulatoryauthorities issue their approvals and permit, it is probable that the house will be enrolled.It would be prudent for the builder to confirmthis prior to planning the construction of anearth wall home.

Insurance Approval

Homes constructed in accordance with theNational Building Code are usually eligiblefor home insurance. Also, if a bona fidecontractor builds an earth wall home, there is a chance that it can be insured without asurcharge over wood-frame constructed homepremiums.


The market in general is very reluctant to accept alternative building techniques,particularly those that differ too far from thetraditional wood-framed house. As a result,the market may react negatively to earthconstruction. However, there is a smallportion of the market that is attracted to this type of structure, and a earth house in anattractive rural setting may draw a premium.

Export Potential

There is no opportunity to export thebuilding materials for earth construction;however, plans, techniques, and theequipment for constructing forms and blocks could have limited export potential.


Rammed earth and compressed earth blockhomes can be built wherever suitable soil isavailable. They are not suitable for permafrostsoils.

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Manual press used for compressing earth blocks.

Footnotes

1. About.com, Inc., Adobe house and earth construction.http://architecture.about.com

2. The Natural Builder, Monolithic adobe:cob, http://naturalbuilder.com

3. Canada Mortgage and HousingCorporation, Earth-sheltered houses,Technical Series 04-220.

4. Dupuy, G. personal communication,2001.

5. Terra Firma Builders Ltd.www.sirewall.com

6. Mah, L., Rammed earth definedhttp://www.ecodesign.bc.ca/Practitioners/it100002.htm

7. Down, S., Down to earth, TheStarPhoenix, Saturday, October 7, 2000.Saskatoon, SK. pp. F6 - F7.

8. Easton, D., The Rammed Earth House.Chelsea Green Publishing Company,1996, PO Box 428, White RiverJunction, VT, 05001.

9. Dupuy, G., personal communication,2001.

10. McClintock, M., AlternativeHousebuilding, Sterling Publishing Co.,Inc., 1989, New York.



13. Ibid.



16. http://caicosdream.com



19. Easton, D., The Rammed Earth House.Chelsea Green Publishing Company,1996, PO Box 428, White RiverJunction, VT, 05001.





24. Ibid.


102


26. Terra Firma Earth Homes Ltd. www.earthhomes.com/faq.htm


28. Krayenhoff, Meror, Constructionalternatives: rammed earth, solplanreview, No. 82, pp. 9 - 10.



31. Easton, D. The Rammed Earth House,Chelsea Green Publishing Company,1996, PO Box 428, White RiverJunction, VT, 05001.




35. Ibid.

36. Terra Firma Builders Ltd.www.sirewall.com


38. Sustainable Building Sourcebook, EarthMaterials Guidelines,www.greenbuilder.com/sourcebook/EarthGuidelines.html


40. Dobson, Stephen, Continuity oftradition: new earthbuilding, Terra 2000Conference, Torquay, England, May 2000.


42. Ibid.

43. Dupuy, G. personal communication, 2001.


103


Additional Reading

Amoruso, Dena.1999. Adobe construction:no longer the ‘poor man’s’ house of theSouthwest. Realty Times.http://realtytimes.com/rtnews/rtcpages/19991222_adobe.htm

Berlant, Steve. 1997. Creating a cob structurewith soil. 1997 Natural Building Colloquium- Southwest. www.inti-solutions.com/cob/articles.htm

Canada Mortgage and Housing Corporation.Earth-sheltered houses. Technical Series 94-220.

Dobson, S., Managing Director, Ramtec PtyLtd., P.O. Box 84, Cottesloe, Perth, WesternAustralia, 6911e-mail: [email protected]

Dupuy, Ginette. Rapport de recherche,construction en blocs de terre comprimée. Mai 1999. Canada Mortgage and HousingCorporation.(English Version: “Compressed Earth BlockConstruction”)

Easton, David. 1996. The Rammed EarthHouse. Chelsea Green Publishing Company. PO Box 428, White River Junction, VT, 05001.

Energy Efficiency and Renewable EnergyNetwork (EREN). 1997. Earth-shelteredhouses. U.S. Department of Energy.Consumer Energy Information: EREC FactSheets www.eren.doe.gov/erec/factsheets/earth.html

Mah, Lillian. Rammed earth defined.Mnemosyne Architecture. Vancouver, B.C. www.ecodesign.bc.ca/Practitioners/it100002.htm

McClintock, M. 1989. AlternativeHousebuilding. Sterling Publishing Co., Inc.New York.

Residential Environmental Design. Alternative construction methods.www.reddawn.com/constructfaq.html

Richardson, Carol. 1997. Cob houses:modern housing made of earth, sand andstraw. Context Institute.www.context.org/ICLIB/IC40/Richrdsn.htm

Terra Firma Builders Ltd. 212 Cusheon LakeRoad. Saltspring Island, B.C. V8K 2B9.www.sirewall.com

www.earthbuilding.com/EBF-FAQ.html


104

Lightweight Steel Framing

Adair, J. 1995. Frame Alternatives. Today’s Builder Magazine. January/February.

Adair, J. 1995. Steel Frame Insulation. Today’s Builder Magazine. January/February.

Andrews, S. 1996. Cold Facts About SteelFraming. Builder Magazine. February.

Canadian Sheet Steel Building Institute.1994. An Introduction to Residential SteelFraming. December.

Canadian Wood Council. 1995. The ThermalPerformance of Light-Frame Assemblies.

Chini, A., and K. Gupta. 1997. A ComparisonBetween Steel and Wood Residential FramingSystems. Journal of Construction Education.(http://ascweb.org/jce/97vol1/no4/Chini1/)

Environmental Building News. 1994. Steel orWood Framing: Which Way Should We Go?July/August.


O’Brien, F. 1995. Steel vs. Wood: The Showdown. Home Builder Magazine.January/February.

Schwolsky, R. 1994. Steel Crazy After AllThese Years. Builder Magazine. December.

Solplan Review. 1996. Wood and SteelFraming: The Environmental Cost. January.

Structural Insulated Panels

Andrews, Steve. 1999. Foam-Core Panels &Building Systems: Principles, Practice, andProduct Directory. Third Edition. Cutter Information Corp.

Binsacca, Rich. 1998. Straight Talk AboutSIPs. Builder Magazine. June. (available at www.builderonline.com).

LeRoy, Jim. 1997. Building with Foam-CorePanels. Journal of Light Construction. July.

Natural Resources Defense Council. EfficientWood Use in Residential Construction.

epsmolders.org/eps/panels/htm(EPS Molders Association).

www.plastifab.com/sips/index.html (PlastiFab - Calgary).

www.sipweb.com

Insulated Concrete Forms


NAHB Research Centre, Inc. PrescriptionMethod for Insulating Concrete Forms inResidential Construction. Upper Marlboro,Maryland. EB118.

VanderWerff, Pieter. 1998. Foam FormsBring Concrete Results. Home EnergyMagazine. July/August.

105

Section 3: List of References

VanderWerff, Pieter, Stephen J. Feige, PaulaChammas, and Lionel A. Lemay. 1997. Insulating Concrete Forms for ResidentialDesign and Construction. McGraw-Hill Inc.

Woodard, Ralph. 1998. Building AboveGrade With ICFs. Journal of LightConstruction. June.

www.forms.org/ (Insulating Concrete Forms Association)

www.plastifab.com/icf/index.html (PlastiFab - Calgary)

Post and Beam

Mitchell, J. 1984. The Craft of Modular Post& Beam: Building Log & Timber HomesAffordably. Hartley & Marks Publishers Inc.

Concrete Block

Canadian Portland Cement Association.1996. A Comparative Study of Low-riseResidential Building Systems in Canada.

Hatzinikolas, Michael, Kuzik, Marc andKashuba, Scott. Masonry Walls That ResistBullet Penetration. Canadian MasonryResearch Institute. 10524 178th Street,Edmonton, AB T5S 2H1.


http://www.masonrycanada.ca/

http://www.cement.ca/cement.nsf (Cement Association of Canada)

http://www.canmasonry.com (Canadian Masonry Research Institute)

http://www.omca.org (Ontario Masonry Contractors Association)

http://scrpa.com/appeal.html

http://scrpa.com/benefits.html

Log Homes

Canada Mortgage and Housing Corporation.2000. About Your House: log homes -frequently asked questions. CMHC. Ottawa, ON.

Cooper, Jim. 1993. Log Homes Made Easy:Contracting and building your own loghome. Stackpole Books. Harrisburg, PA.

Houdek, D. and Bahyl, V. 2001. Fire resistanceof handcrafted log walls. Journal of FireProtection Engineering, Vol. 11. pp. 1 - 20.

Huang, Y. F., Chen, T. Y., and C. H. Chuang.1994. Sound insulation performances of alog-house and a reinforced concrete house(II). Mokuzai Gakkaishi, Vol. 40, No. 12, pp. 1389 - 1393.

International Log Builders’ Association. 1996.Log Homes - From Land to Lockup. P.O. Box 775, Lumby, British Columbia,Canada, V0E 2G0.

Mackie, B. Allan. 1997. Building With Logs.Firefly Books Ltd. Willowdale, ON.

Mackie, B. Allan. 1998. Notches of AllKinds: A book of timber joinery. FireflyBooks Ltd. Willowdale, ON.


106

Mitchell, James. 1984. The Craft of ModularPost & Beam: Building Log & TimberHomes Affordably. Hartley & MarksPublishers Inc.

www.forintek.ca (Forintek Canada Corp., 2665 East Mall, Vancouver, B.C. V6T 1W5).

Stackwall

Dick, K. J. 1999. Economic Analysis ofRecently-Constructed Stackwall Structures in Canada. Proceedings of the ContinentalCordwood Conference. Cambridge, New York.

Dick, K. J. and Lansdown, A. M. 1995.Stackwall - How To Build It, 2nd Edition.Instruction Manual. Building AlternativesInc. P.O. Box 22, Anola, Manitoba, Canada R0E 0A0.

Dick, K. J. and Lansdown, A. M. 1994.Stackwall and the Building Inspector.Proceedings of 1994 Continental CordwoodConference (CoCoCo). Plattsburgh,New York.

Lansdown, A. M. and Dick, K. J. 1996.Stackwall House Construction - VapourManagement, Fire Resistance, InsulationValues and the Building Code. Proceedings of Canadian Society for Civil Engineering(CSCE) 1996 Annual Conference.Edmonton, Alberta.

Lansdown, A. M., G. Watts, and A. B.Sparling. 1975. Housing for the North - theStackwall System. Part 1: The ExperimentalStackwall House: Background, Design andConstruction. Northern Housing Committee.University of Manitoba. Winnipeg, Manitoba.

Patterson, R. and A. M. Lansdown. 1976.Housing for the North - the StackwallSystem: Construction Report - Mildred LakeTank and Pump House. Northern HousingCommittee. University of Manitoba.Winnipeg, Manitoba.

Roy, R. 1992. Complete Book of CordwoodMasonry Housebuilding: The EarthwoodMethod. Sterling Publishing Company, Inc.New York.

Shockey, C. Stackwall Construction: DoubleStackwall Technique. Huerto Publishing Co.Vanscoy, Saskatchewan.

Straw Bale

Canada Mortgage and Housing Corporation.2000. Straw bale house moisture research.CMHC. Ottawa, ON.

Canada Mortgage and Housing Corporation.An innovative straw/bale mortar wall system.Housing Technology Incentive Program.CMHC. Ottawa, ON. NHA 5799 84/08.

Canada Mortgage and Housing Corporation.Moisture properties of plaster and stucco forstraw bale buildings. CMHC. Ottawa, ON.

Gagne, Louis. 1986. A Straw-Bale/MortarHouse Demonstration Project. Canada Mortgage and Housing Corporation.Ottawa, ON.

Johnston, Jane & John Swearingen. Buildinga Straw-bale house. Fine HomebuildingJune/July 1996. pp 74 - 78.

107


Magwood, Chris and Peter Mack. 2000.Straw Bale Building, How to plan, design and build with straw. New Society Publishers.Gabriola Island, B.C.

Platts, Bob. 1997. Pilot Study of MoistureControl in Stuccoed Straw Bale Walls. Canada Mortgage and Housing Corporation.Ottawa, ON.

Steen, Athena S., B. Steen and D. Bainbridge.1994. The Straw Bale House. Chelsea GreenPublishing Company. Vermont.

Straube, J. Moisture properties of plaster and stucco for straw bale buildings. Canada Mortgage and Housing Corporation.Ottawa, ON.

Earth Wall Construction

Amoruso, Dena.1999. Adobe construction: no longer the ‘poor man’s’ house of theSouthwest. Realty Times.http://realtytimes.com/rtnews/rtcpages/19991222_adobe.htm

Berlant, Steve. 1997. Creating a cob structurewith soil. 1997 Natural Building Colloquium- Southwest. www.inti-solutions.com/cob/articles.htm

Canada Mortgage and Housing Corporation.Earth-sheltered houses. Technical Series 94-220.

Dobson, S., Managing Director, Ramtec PtyLtd., P.O. Box 84, Cottesloe, Perth, Western Australia, 6911e-mail: [email protected]

Dupuy, Ginette. Rapport de recherche,construction en blocs de terre comprimée. Mai 1999. Canada Mortgage and HousingCorporation.(English Version: “Compressed Earth BlockConstruction”)

Easton, David. 1996. The Rammed EarthHouse. Chelsea Green Publishing Company. PO Box 428, White River Junction, VT, 05001.

Energy Efficiency and Renewable EnergyNetwork (EREN). 1997. Earth-shelteredhouses. U.S. Department of Energy.Consumer Energy Information: EREC Fact Sheets www.eren.doe.gov/erec/factsheets/earth.html

Mah, Lillian. Rammed earth defined.Mnemosyne Architecture. Vancouver, B.C. www.ecodesign.bc.ca/Practitioners/it100002.htm

McClintock, M. 1989. AlternativeHousebuilding. Sterling Publishing Co., Inc.New York.

Residential Environmental Design. Alternative construction methods.www.reddawn.com/constructfaq.html

Richardson, Carol. 1997. Cob houses:modern housing made of earth, sand andstraw. Context Institute.www.context.org/ICLIB/IC40/Richrdsn.htm

Terra Firma Builders Ltd. 212 Cusheon LakeRoad. Saltspring Island, B.C. V8K 2B9.

www.earthbuilding.com/EBF-FAQ.html


108

Associations and Contacts

Ontario Masonry Contractors’ Association360 Superior BoulevardMississauga, ONL5T 2N7Contact: David StubbsTel: (905) 564-6622Fax: (905) 564-5744www.canadamasonrycentre.com/omca

Cement Association of Canada1500 - 60 Queen StreetOttawa, ONK1P 5Y7Contact: Richard McGrath, P. Eng.Tel: (613) 236-9471Fax: (613) 563-4498www.cement.ca

International Log Builders’ AssociationP.O. Box 775Lumby, BCV0E 2G0Contact: Robert SavignacTel: (800) 532-2900Tel: (250) 547-8776Fax: (250) 547-8775www.logassociation.org

Canadian Wood Council1400 Blair Place, Suite 210Ottawa, ONK1J 9B8Contact: Eric JonesTel: (613) 747-5544Fax: (613) 747-6264www.cwc.ca

Canadian Sheet Steel Building Institute652 Bishop St. N., Unit 2ACambridge, ONN3H 4V6Tel: (519) 650-1285Fax: (519) 650-8081www.cssbi.ca

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Appendix A

Review Committee

Tony Mammone, P. Eng.Manager, Structural Insulated PanelsPlasti-Fab#270, 3015 - 5th Avenue NECalgary, AB T2A 6T8Tel: (403) 569-4323Fax: (403) 248-9325

Richard McGrath, P. Eng.Director - Engineered StructuresCement Association of Canada1500 - 60 Queen StreetOttawa, ON K1P 5Y7Tel: (613) 236-9471Fax: (613) 563-4498www.cement.ca

Eric JonesPeggy LepperSylvain SabourinCanadian Wood Council1400 Blair Place, Suite 210Ottawa, ON K1J 9B8Tel: (613) 747-5544Fax: (613) 747-6264www.cwc.ca

David StubbsMasonry Design Co-ordinatorOntario Masonry Contractors’ Association360 Superior BoulevardMississauga, ON L5T 2N7Tel: (905) 564-6622Fax: (905) 564-5744

Robert SavignacInternational Log Builders’ AssociationP. O. Box 775Lumby, BC V0E 2G0Tel: (800) 532-2900Tel: (250) 547-8776Fax: (250) 547-8775www.logassociation.org

Dr. Kris J. Dick, P. Eng.University of Manitoba, Department of Biosystems EngineeringBuilding Alternatives Inc.P. O. Box 22Anola, MB R0E 0A0Tel: (204) 866-3262Fax: (204) 866-3287www.buildalt.com

Jack ShieldsTembec Forest Products Group155, avenue DallaireBureau 100Rouyn-Noranda, Quebec J9X 4T3Tel: (819) 797-4782Fax: (819) 797-4784

John LawTrusJoist, A Weyerhaeuser Business101, 253 - 62 Avenue SECalgary, AB T2H 0R5Tel: (403) 259-4900Fax: (403) 259-5945www.tj.com

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Appendix B

Ginette Dupuy, B.Arch, M.Sc.A. en aménagement5920 Louis-HemonMontréal, QC H2G 2K6Tel: (514) 729-1890Fax: (514) [email protected]

Bill SempleCanadian Home Builders’ Association150 Laurier Ave. W., Suite 500Ottawa, ON K1P 5J4Tel: (613) 230-3060Fax: (613) 232-8214www.chba.ca


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