Australia’s wildfire season is one of the most devastating to date. There are more blazes to contend with, and every state and territory has been affected. In the state hit the worst, New South Wales (NSW), the fire destroyed more than 2,000 houses. The big question now is how do we ensure our homes are better prepared for next time?
Rebuilding Bushfire Resistant Homes
The Bushfire Building Council of Australia is receiving an “enormous number” of inquiries from people wanting advice for rebuilding, says Kate Cotter, CEO of the BBCA. This is a change from earlier fires when there has been a time lag between the disaster and the focus on recovery.
People are seeking guidance on what they can do and how to attain an affordable, sustainable and bushfire resistant home. It is not only those who lost homes seeking advice as many communities now have a heightened sense of their risk level. Even those unaffected want to know how to improve their existing homes through retrofitting.
Where new homes are being built, using the National Construction Code Deemed-To-Satisfy pathway to meet AS3959 requirements may not be sufficient, Cotter says, particularly when it comes to ember proofing for lower BALs and house to house ignition.
“Regulation is a minimum safety standard and doesn’t provide a holistic or best-practice approach to bushfire resilience, such as building performance, landscaping, life safety contingency, maintenance and emergency planning.”
Big Fires Not Limited to Bushland
Fire has impacted areas most planners, builders and homeowners would usually consider lower risk, as explains Kate Cotter, CEO of the Bushfire Building Council of Australia.
According to Cotter, many Australians think of bushfire as something that affects regional and rural communities. But these fires show not just remote bushland can be impacted—tropical regions and housing estates can be similarly affected.
Generally, regulatory requirements around bushfire protection and safety have been based on the site, proximity to vegetation, historical fire record and other landscape-related factors. Homes designed and built in at-risk areas have to address the requirements of AS 3959, the bushfire building standard.
The requirements regarding materials, methods and design are defined by the Bushfire Attack Level rating [BAL] assigned to a specific site. The aim is to reduce the likelihood of ignition to under 10 per cent.
New Star Rating System
The BBCA is addressing this head-on, through the development of a star rating system for bushfire resilience. The basic principles the BBCA recommends start with the footprint of the building on the site.
Many Australian subdivisions have a very small distance between homes. For bushfire safety, a house-to-house gap of at least 10m is regarded as better practice.
Fencing should be non-combustible. Where the 10m distance cannot be achieved, design and materials that incorporate radiative heat shielding and non-combustible external elements are a sound idea.
Timber decking and timber access stairs should be avoided, even though AS3959 currently allows them. Combustible cladding, such as vinyl weatherboards, also shouldn’t be used.
The home layout design should aim for what Cotter described as “slow loss of tenability.” Such as rooms with multiple exits and good external views that allow an occupant to exit to cleared or safer areas in case of a fire.
Little Changes, Huge Impact
Cotter says many design, construction and detailing features that improve a home’s fire resistance can be achieved at little or no additional cost compared to a standard build.
You just have to do things differently.
For example, paying attention to building sealing, avoiding flammable external window treatments, and ensuring gap-free architraves are easily achievable. Cotter says builders should use non-combustible external materials including cladding, window and door frames, decking, stairs, pipes, vents, light fittings and roofing.
Much of this advice also applies to retrofitting a home for improved protection as the Victorian Country Fire Authority explains in its guide to retrofits.
Another potential weakness is the location of a home’s garage. Whenever possible, iit should be at least 10m away from the home. In cases where this is not possible, non-combustible materials and fire separation strategies need to be implemented.
Seeking out the advice of a bushfire building expert is also a good idea before you start building. The BBRC has teamed up with CSIRO to develop and deliver training and professional development in improving bushfire resilience for the construction industry. There is also a need for more demonstration projects that showcase best practices, Cotter says.
Many trades and construction professionals are keen to help out with the rebuilding effort, particularly with so many community buildings and uninsured homes lost to the fire.
Two trade-focused organisations are currently calling for volunteers and donations of expertise, labour and materials: Blaze Aid, which assists farmers and others in repairing fencing and other rural infrastructure, and Tradies for the Bushfire Rebuild, which is assisting with homes, community and public buildings and other assets. The Australian Institute of Architects is also supporting the provision of pro bono design advice for rebuilds through Architects Assist.
“Any design style you can think of can be made bushfire resilient,” says Carter. “With innovative materials and innovative designs, we can do a lot better than just a concrete box. Homes have to be liveable, comfortable and look good, too.”