James Hardie RAB™ Board is a solid fibre cement pre-cladding. It acts a a ‘Rigid Air Barrier’ – hence the name RAB. This means it’s a layer that is sandwiched between the external cladding of the building and the wall framing, generally replacing building paper. For residential builds it is most commonly used for new homes that will be exposed to extra high (EH) wind zones, or in our case, for a home of a higher quality that is looking to achieve above “standard” specifications that benefit the home structurally. RAB Board has several key advantages over alternative products.
Why have we chosen to use RAB Board for our Mackit Habitat house?
- A stronger building: RAB Board is made from solid fibre cement, adding strength to the home. We’ve used RAB for Habitat to help us achieve our design goal of much higher seismic resistance and reparability than standard building code requirements – it will sustain a 1 in 1000 year event. Using RAB for bracing is good for the longevity and earthquake performance of the home – which ties in with the high performance foundations Habitat has.
- A more weather-tight building: RAB Board provides superior weather-tightness because its water-repellant sealant stops moisture getting in, and the board’s breathability properties allow moisture vapour to get out.
- Made for extra high wind zones: RAB Board’s rigid air barrier equalises the air pressure inside the outer wall cavity, allowing your new building to stand up to extra high wind zones.
- Better soundproofing: RAB Board makes your building quieter because its rigid air barrier helps absorb and deflect unwanted noise, more so than thin flexible underlay.
- Fire resistant: up to 60-minute fire resistance rating.
- Peace of mind: RAB Board is BRANZ appraised with a 15-year warranty.
There are also benefits of using RAB Board in terms of construction and project management;
- Ability to close in the building envelope faster: Because RAB Board is solid and more weather-proof, we are able to enclose the building envelope faster, giving a protected and dry environment to continue with work on the inside.
- Easy to install: RAB Board is easy to install with a three step installation process – score, snap and nail.
The many attributes and benefits listed above translate to James Hardie RAB being a superior high quality, high performing product. With New Zealand being a hotbed of seismic activity, bracing design and the products specified in these bracing systems are vital considerations.
On site, we’ve spent a huge amount of hours working through the set out and construction of our complex roof and wall shapes. The James Hardie RAB install on all these angular walls is very nearly complete, closing in the building, and giving it most of its bracing value already. We’re looking forward to receiving delivery of roofing and window joinery in the coming days. So now it’s time to put down the calculator, forget about the pages of trigonometry, and start seeing this building’s materiality come to life.