A key factor in designing sustainable spaces is specifying materials that last, add to the durability of the structure and minimise energy requirements of the project. To this end, weather barriers are an essential part of any sustainable building envelope’s cladding - but they do more than protect against wind.

Weather barriers create a seal that stops moisture forming through the transfer of warm air to a cool surface, meaning the structure can dry, minimising rot. By providing protection from the elements air barriers can also increase the energy efficiency of the envelope overall. They can be so effective that a study from the US National Institute of Standards and Technology estimated the potential energy savings at up to 36% in commercial buildings.

RAB™ Board by James Hardie is a specialised fibre cement rigid air barrier for use beneath cladding. It uses CoreShield™ penetrating sealer technology to keep air, water and wind out, while letting moisture vapour escape from within. RAB™ Board is comprised of low-toxicity, locally sourced materials with minimal volatile organic compounds to reduce environmental impact. It is ideal for use behind ventilated rainscreen cladding where it acts as a pressure equaliser between the interior and exterior of the cladding. RAB™ Board’s fibre cement is deemed non-combustible, as well as being resistant to termites and rot, making it one of the most durable weather barriers in the market.

Being fibre cement, They are suitable for use in high-wind zones and in wind pressures of up to 7kPa. They come in variable standardised sheet sizes and - with a mass of 8.69kg/m² - are lightweight to allow easy transport and installation.

RAB™ Board is built for easy installation, streamlining the construction process and minimising wastage onsite. Using the purpose-built Villaboard Knife the installation process is as easy as score - snap - screw, and tape meaning lengths do not need to be pre-ordered to size and adjustments can be made as needed during fitout. The quick installation and strength of RAB™ Board allows for early close-in, avoiding potential weather delays and allowing sub-trades to start quickly.

Specifying durable, long-lasting materials is key to any sustainable design, and RAB Board is created with longevity in mind. Whereas flexible underlays may deteriorate from positive/negative pressurising actions created by gusting winds within the cavity and on building façade, the fibre cement composite of RAB Board remains rigid even under extreme gusts, providing greater long-term durability. The panels can be exposed to the weather for up to 180 days without cladding over them which can alleviate time pressures and make for a more economical, energy and resource efficient build.

RAB™ Board proved its prowess in the construction of the $790M Newmarket Westfield redevelopment in New Zealand. Spanning multiple sites over 4.5 hectares and with interior floor space of 186,766m², the project is the largest undertaken by Scentre Group (who operate the Westfield brand) in Australasia. With 7,100 tonnes of structural steel used in the buildings and a constrained build site in the middle of a busy retail area, the project had numerous challenges. RAB™ Board was selected as an ideal air barrier due to its structural rigidity, weather resistance and ease of installation. As a non-combustible material it passed stringent local Council fire standards and allowed the time-sensitive build to continue quickly and without issue.

Thinking long term and designing sustainably is at the very core of modern architecture and construction. It is essential that designers and specifiers opt for materials that last, are environmentally friendly, and contribute to greater energy efficiency throughout the project’s lifespan. James Hardie’s cement fibre RAB Board air barriers are weather resistant, durable and reduce energy requirements in commercial or residential settings.

James Hardie is a proud sponsor of the 2019 Sustainability Awards, to be held at The Star in Sydney on 7 November 2019. Learn more about RAB™ Board and James Hardie’s other high-performing, sustainable products here.

Architecture & Design Team

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