Rethink Roofing: A Specifier’S Guide to roof tilinG

INTRoDUCTIoN

RooF TILE MATERIALS

In most cases, the roof represents 30% of the external façade of a home and significantly contributes to the aesthetics of a project. The material for the roof has a massive impact on the look of the finished product, as well as its durability and long-term performance.

Terracotta tiles have been used in Australian homes since the late 1800s, with Federation Queen Anne style homes characterised by steeply pitched roofs made of terracotta tiles or slate with extensive decorative embellishments. Having been used in Europe from the late 1800s, concrete roof tiles entered the Australian

market in the 1950s due to the financial limitations, material shortages and building restrictions in the years following World War II1, and recently lightweight composite panel systems have also become available.

Roof tiles have maintained their popularity through to the present due to their versatility and design flexibility. When deciding which roof tile is suitable for a project it’s important to consider the design potential of the materials, the location of a project and its thermal and acoustic needs.

The three main roof tiling options are terracotta, concrete and lightweight composite panel systems. Each type is unique and will bring different properties to a project.

terracotta tiles: are made from clay ground from the earth and baked at approximately 1100°C. Terracotta is extremely durable and offers a richness and depth of colour that doesn’t fade, ensuring the beauty and value of a design is preserved. Terracotta tiles are available in a range of colours and finishes such as satin or more recently, a more contemporary metallic finish, and are either glazed, unglazed, semi-glazed. They are easy to install and can be used in roof and wall installations.2 concrete tiles: are the most economical, durable roofing material on the market. They are made of water and aggregate and the raw materials are extruded under high pressure. They offer high

colour performance and become stronger with age, providing long-term protection against harsh elements. Most concrete tiles will require more structural support than lightweight materials, but do not need to be tied down to the slab like metal roofing does.3 lightweight composite panel systems: can be manufactured slimmer than concrete and terracotta tiles, and up to five times lighter. Their properties also allow them to be made significantly larger than practical for alternative tile options, creating the opportunity for a unique design aesthetic. originally developed for the aerospace and automotive industries, lightweight composite panels have been adopted by the industry for their innovative qualities, from dent resistance in a hailstorm to corrosion resistance in marine and coastal environments.4 They use an advanced fibre reinforced engineered composite material and can withstand the harshest conditions.

MATERIAL BENEFITS

Roof tiles have an array of benefits over their alternatives, including their thermal and acoustic properties. Rust and corrosion resistance, easy installation and ability to withstand harsh weather conditions are properties that all roof tiles and panel systems have, making them ideal for the Australian climate. They are low-maintenance and offer breathability, resulting in less mould and a healthier home. Runoff from tiled roofs can additionally be used as potable drinking water with proper consideration of atmospheric fallout.

thermal insulation: The climate in most parts of Australia requires the roof to limit heat gain for optimal thermal comfort. Clay and concrete roof tiles have natural thermal mass insulation properties, making the roof space less susceptible to changes of temperature on the outside than other commonly used roofing materials. Simultaneously, this thermal mass helps reduce the load on artificial cooling devices. Further thermal benefits can be achieved by selecting certain colour and tile profiles. While research shows that light coloured roofs keep cooler and reflect more heat, dark tiles may still be used in conjunction with other thermal solutions such as sarking, ceiling insulation and powered ventilation in order to achieve a high performance roof.

Sarking is considered best practice in building whatever material you put on your roof. Sarking can reflect up to 97 per cent of radiant heat when installed correctly in a suitable climate.5 It will also help protect your roof cavity from storm driven rain and dust, improve its thermal performance, help resist bushfire ember attack as well as mitigate the risk of harmful condensation. By reducing condensation and eliminating the harmful effects of mould, you create a healthier environment for your family. Acoustic insulation: Roof tiles are also effective sound insulators due to their density and thickness. Terracotta and concrete roof tiles achieve levels of sound insulation performance far greater than the minimum required by the BCA. They are particularly effective for low to medium frequencies and can reduce noise by up to 30dB, compared with a reduction of 12dB by sheet metal.6 designed for Australian Weather conditions: Designing for climate is of utmost importance for any project and roof tiles are no exception. The location of a project will determine how resistant to the elements a roof tile must be. Roof tiles manufactured in accordance with AS 2049-2002 are suitable for use in all exposure environments, including severe marine environments. Many tile manufacturers will promote products ideal for use in coastal areas as “salt safe”. Unlike alternative materials, roof tiles are impervious to rust and corrosion, and are low maintenance generally.7 Concrete, terracotta and advanced composite roof tiles are suitable for use in bushfire prone areas as they are non-combustible, providing optimal protection against radiant heat from bushfires.8 Tiles can be used in areas rated BAL-LoW without any additional provisions, and from BAL-12.5 to BAL-40 with approved-grade sarking and the recommendation of an anti-ponding board.9 Approved-grade sarking has a flammability index of no greater than 5; must be located directly below

the roof battens; must cover the entire roof area including the ridge; and must be installed without any gaps that would allow the entry of embers.10 In areas rated BAL-FZ, “tile roofs are permitted provided it is part of a system tested according to the method described in AS 1530.8.”11 When extreme weather hits, the safety of a home depends on the roof’s ability to withstand strong winds. Tiled roofs can be designed to withstand high winds, right up to a cyclonic event. Unfortunately, not all roofing materials have these characteristics, demonstrated in a study conducted by James Cook University, which investigated the damage caused by tornados in Shoalwater, Rockingham areas and another in Roleystone, WA in 2008. Researchers observed a shift in the materials used in housing construction over the past 10-15 years, noting, “Some construction practices may not always have been modified to deliver satisfactory performance”. The report highlighted an

increase in the number of sheet roofs used - which suffer from significantly higher wind uplift forces than tiled roofs.12 Terracotta and concrete roof tiles offer greater resistance to wind suction than lighter weight materials; with research showing concrete roof tiles can sustain winds over 200 kilometres per hour.13

DESIGN PoTENTIAL

Roof tiles offer many design possibilities and are made in a wide range of colours, architectural styles and specifications. The main design options are:

roof pitches: The material and profile of a tile will determine the pitch it can achieve. Generally concrete tiles have a minimum pitch of 15° and composite panels have a minimum pitch of 10°. Terracotta tiles range between a minimum of 12° and 25° depending on profile.ridging: Conventional lapped ridging overlaps one tile over the other, providing a stepped finish14 and is suitable for a more traditional look or heritage designs. An A-line contemporary streamline ridge system seamlessly aligns the ridge capping in one straight line.15 It is a geometric-looking design popular for contemporary or industrial styles. Bonding: Bonding refers to the pattern in which the tile is laid. Cross bond is when tiles are laid using an alternating pattern; straight

bonding involves vertically aligning tiles and quarter bond is where tiles are staggered at a quarter of the tile width, creating a new design dimension. Gutters: Box gutters are internal concealed gutters between the slopes of a roof or a roof and a wall, and discharge water internally through a sump. Concealed gutters are formed at a valley or against an abutment and are concealed by the tiles and flashing.16 These options create a concealed effect, providing the roofline with a sleek, modern look.17 The alternative is classic gutters, which come in a range of profiles to support a variety of different architectural styles. flashing: Flashing refers to components used to weatherproof or seal the roof system edges by diverting the water elsewhere.18 Roof design should consider the requirement for special flashings at parapet walls, chimneys and other details. Generally, flashings should overlap the upstand of at least one tile or provide concealed gutters. The potential for water to pond in sarking should be considered, particularly at eaves and around large penetrations, where anti-ponding boards should be installed.colour range and profiles: Ranging from flat or curved profiles to the quite ornamental, the profile of a tile refers to the shape of its exposed side, which will be an important design consideration for any project. Flat profiles can offer a cleaner, more contemporary look, while more ornamental profiles may embody an established design aesthetic. The design potential for tiled roofs also encompasses their colour, which can range from whites to earthy browns, greens and greys up to black.

MoNIER RooFING

ACCESSoRIES

Accessories that can be used to finish a roof include ridge and hip tiles, along with ventilation and sarking. Ridge tiles are placed at the peak of a tiled roof, while hip tiles will hide the edge formed by the meeting of two pitched roof surfaces. They can be used to create a smooth join. There is also the option of using roof crests or finials to create an accent. Many manufacturers also offer range of natural and powered ventilation solutions. Roof ventilation is an easy and cost-effective way to reduce temperature build up and the impact of moisture in a roof space, resulting in improved comfort and potentially reduced cooling energy costs, dependent on the construction of the roof system as a whole. Reflective sarking is another effective way of minimising solar heat gain, capable of reflecting up to 97 per cent of radiant heat.19

SMART RooFS

Far from just an aesthetic consideration, and on top of being a passive environmental solution, roofs can now be put to work for additional energy cost reductions. While solar panels have been around for some time, solar tiles are a relatively recent development that have proven themselves as viable options for roofs. Solar tiles can provide the same benefits of solar panels, without the additional weight, installation costs, or reduced aesthetic value.

Monier is an experienced roofing company manufacturing quality concrete, terracotta, Elemental™ and solar roof tiles. Monier has a rich and proud history in the Australian and New Zealand building industries and has been a trusted roofing solution for over 100 years. The company’s enduring success is underpinned by its commitment to quality Australian made roofing products, superior customer service and continued innovation. Monier’s innovation has led to the Monier SoLARtile, Australia’s first integrated, modular flat solar tile system and the introduction of the Monier Elemental™ Composite Lightweight roofing system.Monier tiles are made from raw materials derived from the Australian landscape. Its terracotta tiles have a depth of colour that last a lifetime and its concrete tiles feature 8x better gloss retention than metal roofing. Monier’s SoLARtiles are sleek tile-integrated solar tiles, which blend in and have all the benefits of a regular solar panel. The Monier Elemental™ panel system is a streamlined range of lightweight low pitch roofing products, which will withstand all the elements. Elemental™ panels are also available in sizes up to 1500x750mm – significantly larger than standard tile sizes. Monier also provide a range of accessories, including sarking, natural and powered ventilation options and insulation.To find out more about Monier’s extensive range of quality roofing solutions, visit www.monier.com.au.

REFERENCES

1 Monier Roofing. (2014). Monier Roofing’s guide to the perfect roofing tile. Architecture & Design. http://www.architectureanddesign.com.au/suppliers/monier-roofing/monier-roofing-s-guide-to-the-perfect-roofing-tile

2 Monier. What’s the difference between materials? Monier. http://monier.com.au/Roofing-Information/Whats-the-difference-between-concrete-terracotta-and-elemental

3 Reardon, C & Downton, P. (2013). Construction Systems. YourHome. http://www.yourhome.gov.au/materials/construction-systems

4 Monier. What’s the difference between materials? Monier. http://monier.com.au/Roofing-Information/Whats-the-difference-between-concrete-terracotta-and-elemental

5 “Reflective Foil Insulation”. (2017). BUILD. Accessed July 4. http://www.build.com.au/reflective-foil-insulation..

6 Ganger, Max. (2017). Roof Acoustic Performance Noise Attenuation. RTAA. Accessed July 4. https://rtaa.blob.core.windows.net/media/1418/roof-acoustic-performance-noise-attenuation.pdf

7 Monier Collections - SA. (2013). Monier. http://monier.com.au/-/media/Feature/Professionals/Brochures/Monier-Brochure-SA-2013_final.pdf.

8 RTAA. The Properties of Roof Tiles. Roofing Tile Association of Australia. https://rtaa.blob.core.windows.net/media/1419/the-properties-of-roof-tiles.pdf.

9 RTAA. Building with tile roofs in bushfire prone areas. Roofing Tile Association of Australia. https://rtaa.blob.core.windows.net/media/1420/building-with-tile-roofs-in-bushfire-prone-areas.pdf

10 Ibid.11 Ibid.12 Boughton, G & Falck, D. (2008). Shoalwater and Roleystone WA tornadoes Wind damage to buildings. Cyclone

Testing Station, School of Engineering. James Cook University. https://www.jcu.edu.au/__data/assets/pdf_file/0006/321990/Technical-Report-54-Shoalwater-and-Roleystone-WA-tornadoes-Wind-damage-to-buildings.pdf.

13 RTAA. The Properties of Roof Tiles. Roofing Tile Association of Australia. https://rtaa.blob.core.windows.net/media/1419/the-properties-of-roof-tiles.pdf.

14 Ajax Gregson Tiles. (2014). Roofing System: Difference between lapped ridge and A-line ridge. Ajax Gregson Tiles. http://ajaxgregsontiles.com.au/difference-between-lapped-ridge-and-a-line-ridge.php

15 Ibid.16 Hindmarsh Roofing. (2014). Roofing terminology explained.

http://www.hindmarshroofing.com.au/app/webroot/blog/roofing-terminology-explained/.17 Robbins, D. (2014). What are box gutters? Alcoil.

http://alcoil.com.au/inspiration/resource-centre/what-are-box-gutters18 Hindmarsh Roofing. (2014). Roofing terminology explained.

http://www.hindmarshroofing.com.au/app/webroot/blog/roofing-terminology-explained/.19 “Reflective Foil Insulation”. (2017). BUILD. Accessed July 4.

http://www.build.com.au/reflective-foil-insulation.