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Essentials of Essentials of Specifying Specifying Wood Wood FlooringFlooring

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Wood Floor Resource Group 2007

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Learning Objectives

Understand the fundamental characteristics of wood as a material: sources, types, hardness, stability, etc.

Understand the essentials of wood flooring: species, formats, performance issues, common pitfalls, etc.

Understand the pros and cons of solid vs. engineered wood flooring

Where Wood Comes From – Recycled/Salvaged/ReclaimedWhere Wood Comes From – Recycled/Salvaged/Reclaimed

< Salvaged

Logs

Examples: Urban Forest, Agriculture, Waterways, Deadwood

< Reclaimed

Previously manufactured wood products

Example: Building deconstruction

< Recycled(Pre-Consumer/Post-Industrial)

Wood pieces or fiber that are manufacturing by-products

Example: Sawdust

Some well-managed, some not

Teak plantation Natural forest

Where Wood Comes From – Forests & PlantationsWhere Wood Comes From – Forests & Plantations

Want to know more?

“Wood Flooring for Green Building”

Hardwoods vs. SoftwoodsHardwoods vs. Softwoods

Hardwoods come from broad-leaf trees

deciduous

Softwoods come from needle-bearing trees

coniferous

Most hardwoods are harder than most softwoods, but there are soft hardwoods and hard softwoods.

the Janka hardness of balsa (a hardwood) is 75

the Janka hardness of red oak (a hardwood) is 1290

the Janka hardness of Australian Cypress (a softwood) is 1375 !

How Trees GrowHow Trees Grow

Medullary rays

Growth RingsGrowth Rings

Early Wood

Late Wood Fast Growth

Slower Growth

Heartwood vs. SapwoodHeartwood vs. Sapwood

HeartwoodHardened and stiffened dead cells – no longer conducting sap

Species where heartwood is desirable:Cherry, Mahogany, Teak

SapwoodSap conduction

Species where sapwood is desirable:Maple, Birch

Lumber & Veneer – Plain Sawing/SlicingLumber & Veneer – Plain Sawing/Slicing

Plain sawing = the most efficient way to convert a round log into rectangular pieces of lumber

Plain slicing

Lumber & Veneer – Quarter Sawing/SlicingLumber & Veneer – Quarter Sawing/Slicing

Quarter sawing

Quarter slicing

Lumber and Veneer – Rift Sawing/SlicingLumber and Veneer – Rift Sawing/Slicing

Rift sawing

Rift slicing

Quarter- vs Rift-Sawn - AppearanceQuarter- vs Rift-Sawn - Appearance

Quarter-sawn

Rift-sawn

Only species with pronounced medullary rays (oaks, maples, sycamores, lacewood) present this difference.

Plain vs. Quarter-Sawn/Sliced -- Plain vs. Quarter-Sawn/Sliced -- AppearanceAppearance

Plain sawnQuarter sawn

Quarter sawn synonyms:

• Vertical grain/VG• Straight grain• Comb grain

Plain sawn synonyms:• Flat sawn• Flat grain

Only species with pronounced growth rings will present this appearance

Rotary Peeling – Process & AppearanceRotary Peeling – Process & Appearance

The log is peeled by a blade and is worked around the log toward the center, creating a wood veneer.

A sample of veneer produced by rotary peeling.

Wood HardnessWood Hardness

All wood will dent if sufficient force is applied

High heels will dent even the hardest woods

115 lb woman exerts about 2500 lbs of force via a high heel

Hardness TestingHardness Testing

Wood hardness is measured by the Janka hardness test

Comparative Hardness GraphComparative Hardness Graph

Industry Standard

The Structure of WoodThe Structure of Wood

The cellular structure of wood: a big bundle of “straws”

Notice how it looks very much like a sponge

Why Wood MovesWhy Wood Moves

• All wood gains and loses moisture

• The MC of wood will always equalize w/ ambient humidity

• When it does, all wood expands and contracts

Dry Sponge

Wet Sponge

Differential ShrinkageDifferential Shrinkage

Two main dimensions on which wood moves:

1. Radially

2. Tangentially (twice as much)

R = Radial

T = Tangential

L = Longitudinal

A

B

lumber

A = bark face, or sap faceB = heart face

Large shrinkage in the tangential direction

Small shrinkage in the radial direction

Shrinkage: Different Amounts & DirectionsShrinkage: Different Amounts & Directions

Plain-Sawn Lumber More Prone to CuppingPlain-Sawn Lumber More Prone to Cupping

Quarter sawn cross-section

Plain sawn cross-section

Quarter-Sawn Lumber is More StableQuarter-Sawn Lumber is More Stable

Plain-sawn lumberQuarter-sawn lumber

Arrow thickness denotes movement amount

Some Species are More Stable than OthersSome Species are More Stable than Others

Species TangentialShrinkage

RadialShrinkage

Hard Maple 9.9% 4.8%

Red Oak 8.6% 4.0%

Brazilian Cherry

8.5% 4.5%

Teak 5.8% 2.5%

Values are percentage of shrinkage from green to oven dry

Tangential Shrinkage

This 6” wide piece of Maple will shrink 10% (3/4”) in width.

What does all this mean for wood flooring?What does all this mean for wood flooring?

Water & wood do not mix well• Wet concrete slabs or other subfloors• Wet mopping• Flooding

What does all this mean for wood flooring?What does all this mean for wood flooring?

Big changes in relative humidity also a problem

Wood flooring performs best in RH ranges of 35% - 65% (typical of house interiors)

What does all this mean for wood flooring?What does all this mean for wood flooring?

Solid Wood Flooring: Wood properties = performance

What does all this mean for wood flooring?What does all this mean for wood flooring?

In conditions of fluctuating moisture, care must be taken when using wood flooring in the following:

• Solid formats• Plain sawn• Wide widths• Less stable species

What does all this mean for wood flooring?What does all this mean for wood flooring?

• In conditions of fluctuating moisture, generally best to specify wood flooring in…

Engineered format – more stable in width than solid (about 50%)

But engineered format is generally less stable than solid lengthwise

Veneer face very stable because of fracturesWhen sawn face, cross plies help control movement

Solid wood doesn’t move longitudinallyCross plies move sideways and can affect lengths

Engineered FlooringEngineered Flooring

Engineered flooring is more complicated than solidMany formats that perform differently in different situations

Two main components

wear layer

substrate

Engineered Flooring: Wear LayersEngineered Flooring: Wear Layers

Sawn• 2 to 3.5 mm (6 - 8 mm possible)• Less efficient (sawdust)• Properties same as solid wood• Entire face moves

Veneer (sliced or peeled)

• Sliced 0.6 to 1 mm• Peeled 1.5 to 2.5 mm• Efficient (almost no waste)

• Knife checking/fracturing

Engineered Flooring: AppearanceEngineered Flooring: Appearance

Sawn wear layersSame as solid

Sliced veneerSame but slightly more repeating pattern

Peeled veneerRotary – whacky plywood look

Engineered Flooring Formats: 3-LayerEngineered Flooring Formats: 3-Layer

3 layer (must utilize thicker wear layer or “telegraphing” may occur)1. Wear layer2. Cross-slat core3. Veneer back

Pros – least susceptible to cuppingCons – telegraphs in super-dry and wet conditions

Engineered Flooring Formats: 2-LayerEngineered Flooring Formats: 2-Layer

2 layer1. 2 mm or thicker sawn face2. Plywood substrate

Pros – Not susceptible to telegraphingCons – More susceptible to cupping, end peaking

Engineered Flooring Formats: Multi-Engineered Flooring Formats: Multi-LayerLayer

Multi-layer1. Wear layer < 2 mm2. Plywood substrate

Pros – Not susceptible to telegraphingCons – More susceptible to cupping, end peaking

Engineered Flooring Formats: HDF CoreEngineered Flooring Formats: HDF Core

HDF core1. 2 mm or less sawn face on HDF substrate

Pros – InexpensiveCons – Quality of HDF = how it holds up to moisture

absorption

Engineered Flooring – Edge/End Engineered Flooring – Edge/End TreatmentsTreatments

Edge and end treatments• Beveled• Micro-beveled• Micro-eased• Square edge• True square

Square edge

Engineered Flooring – Flooring TreatmentsEngineered Flooring – Flooring Treatments

Surface treatments and finishesTreatments• Smooth• Handscraped

Finishes• Glossy• Matte• Cashmere/Low-Gloss

Hand scraped wood flooring

Engineered Flooring – T&G SystemsEngineered Flooring – T&G Systems

Regular T&G

Click T&G

Installation MethodsInstallation Methods

Nail/StaplePros - Cheap, fast (where substrate exists), more integrity

than floatCons - No substrate, need to install one, no particle board

substrate

GluePros - quiet, solid, any sound, dry, flat substrate, more

integrity than floatCons - relatively costly & labor-intensive, messy, curing time

FloatPros - very fast, inexpensiveCons - “Springy” feel, clicking or tapping sound

Installation Really MattersInstallation Really Matters

The performance of wood flooring is only as good as the installation

You need to choose the correct installation method for your conditions and other requirements

Consult with Bob Goldstein, WFRG Director of Technical Services

Phone: 856-705-1118 Email: bgoldstein@wflooring.com

Job site conditions really matterJob site conditions really matter

Biggest pitfalls• Wet slab• No heating/ventilation

Common Pitfalls – Color ChangeCommon Pitfalls – Color Change

Some species dramatically change color (esp. exotics)• With exposure to air and/or• With exposure to light

Brazilian Cherry expected color change

Fresh>

Aged>

Common Pitfalls - MoistureCommon Pitfalls - Moisture

• Too wet:• Swelling (and subsequent compression set) • Lifting off the floor • Telegraphing • Tips up

•Too dry:

•Shrinking•Cupping•Cracking•Telegraphing

Cupped floor usually caused by a wet subfloor

Engineered vs. Solid Wood FlooringEngineered vs. Solid Wood Flooring

¾” Solid Wood Flooring

9/16” Engineered Wood Flooring

Engineered vs. Solid Wood FlooringEngineered vs. Solid Wood Flooring

Comparing the sandable wear surface

Engineered wear layer; 1.5 mm – 2.5 mm once, 3 mm+ twice

Solid wear surface; 3 - 4 re-sandings total

Engineered vs. Solid Wood FlooringEngineered vs. Solid Wood Flooring

High-quality wood efficiency usage

Engineered vs. Solid Wood FlooringEngineered vs. Solid Wood Flooring

Solid wood flooring has to acclimate

Engineered wood flooring does not. Result…

T&G can be milled to tight fit, plywood “built in”

Glue-down or floating installation Eliminate plywood subfloor

Save $$$ and resources!Save $$$ and resources!

Comparison of Cost BreakdownComparison of Cost Breakdown

Unfinished vs. Prefinished Unfinished vs. Prefinished

Solid flooring – usually unfinished, must be site-finished Engineered flooring – factory finish

Quality of FinishQuality of Finish

Factory finish

• 9 coats urethane, aluminum-oxide sub-coats• UV-cured (no off-gassing)

Site-applied finish• 2 or 3 coats max. • solvent- or water-based (may off-gas VOCs)

Site-applied finishes less durable but scratches can be more apparent in factory finishes

Benefits of Screening/Top-CoatingBenefits of Screening/Top-Coating

• Relatively quick/inexpensive - $.75 - $1.75/sq. ft.

• Repairs most signs of wear

• Creates uniform look• Seals surface of floor • Chemical system doesn’t require mechanical sanding

Bona Prep Recoating Adhesion SystemBasic Coatings “TyKote” Sandless Recoating System• Can be repeated indefinitely

Bob Goldstein: “Remember, you walk on the finish, not the wood!”

Phone: 856-705-1118 Email: bgoldstein@wflooring.com

Wood Flooring in Commercial ApplicationsWood Flooring in Commercial Applications

Factors affecting how well wood flooring performs in demanding commercial applications:

Care and maintenance over the life of the floor

Pick the right installer and installation method

Pick the right product for the application and site conditions in terms of:

Format Species Finish Hardness

Wood HardnessWood Hardness

High traffic = harder woods

Industry Standard

Care & MaintenanceCare & Maintenance

• Humidity/moisture issues Operate a humidity control system Clean up spills quickly—DON’T wet mop

•Use recommended cleaners Bona Swedish Formula Hardwood Floor Cleaner Basic Coatings Cleaner

• To remove scratchesBonaKemi fill stick and marker touch-up kit

Wood Flooring Care and Maintenance GuidelinesWood Flooring Care and Maintenance Guidelines

Other ConsiderationsOther Considerations

Budget• Least expensive installed product is generally multi-ply or

HDF-backed engineered flooringOn- or above-grade or below-grade

• Engineered only below-gradeSubfloor material and condition

• Engineered often used over concrete, almost always over radiant heat

$

Environmental IssuesEnvironmental Issues

• LEED compliance• Forest certification• Plantations vs. Natural Forests• Recycled/Reclaimed/Salvaged• Rapidly Renewable• Regional Sourcing• Offgassing/IAQ

Wood Flooring for Green Building

Thank you!Thank you!

Questions??Questions??

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