The weakest link: back to the drawing board when building in the bush

Alexandra Spring
The weakest link: back to the drawing board when building in the bush. Experts say more Australians must consider their home’s bushfire resilience and some communities should rethink their town plan

As the initial devastating shock of this summer’s bushfires recedes, homeowners and authorities have begun to grapple with urgent questions about how or whether to rebuild more than 2,000 properties destroyed across south-eastern Australia.

But it’s not just those who lost their homes who will need to rethink. With extreme weather likely to extend bushfire seasons, experts say more Australians must consider the bushfire resilience of their homes, and those living in at-risk areas should consider retrofitting or rebuilding. And for some communities it could be time to come up with an entirely new town plan.

There has been much discussion about whether to rebuild. Three planning experts recently told Guardian Australia that destroyed homes in the riskiest areas should not be rebuilt, recommending that the state government buy the land.

Related: Bushfire-proof houses are affordable and look good – so why aren't we building more?

That’s valid in the most dangerous areas, says Kate Cotter, chief executive of the Bushfire Building Council of Australia, but it won’t work for all properties. She estimates there are 2m properties within 100m of bushland, putting them at extreme risk. As the risk of fires increases, there will be fewer areas that can confidently be declared safe.

“Our view is that we have to manage the risk, and if we don’t do it then we’re going to keep losing,” Cotter says.

In the past few weeks, the council has been swamped by calls from those considering rebuilding. Usually it takes those affected a few months to get in touch, Cotter says, surprised at the flurry. And they aren’t just asking about how to meet the minimum bushfire standards, but also about affordability and sustainability. Cotter welcomes this development because houses that are built to high bushfire-proof standards are also energy efficient.

“[Perhaps] people who are still without power are thinking: is there a way around that in the future?” she says.

Rebuilding has to be much more holistic or we are just doomed to repeat previous failures

Kate Cotter, Bushfire Building Council of Australia

For research architect Ian Weir, the first step for homeowners thinking about building or rebuilding in bushfire-prone areas is to get an independent attack level assessment of their property. He stresses this should be independent, rather than relying on council assessors, and says the peak body Fire Protection Association of Australia can provide referrals. It’s something he hopes governments will subsidise.

The national bushfire attack level ratings (BAL) range from low to dangerously high and are based on the severity of potential exposure to ember attack, radiant heat and direct flame contact. Homes compliant with high BAL ratings can survive even the worst blazes, such as the beach house in Rosedale, on the NSW south coast, that remained intact while neighbouring homes burnt to the ground. Lower BAL ratings are just a baseline and should not be considered fireproofing.

Ron Weir’s bushfire resilient beach house, designed by architect Thomas Caddaye, in Rosedale, NSW, before and after the fires.

Weir also recommends homeowners get hold of a copy of the Australian standards AS3959 to educate themselves about building in these areas. “[With these two things] they would be getting themselves out of the dark as far as understanding what their level of risk, what management requirements they would have for land, and what they would have to do to build a new home.”

Strengths and weaknesses

CSIRO’s bushfire expert Dr Justin Leonard says the most important thing is that the owner understands the strengths and weaknesses of the planned home. “You could have a fantastic architect-designed house with plenty of cool features but if, in the first year of ownership, they build a garden shed off the side of it, all of a sudden the whole house is as weak as its weakest link,” he says.


Homes that are built in a bushfire-prone area are governed by the Australian Standard 3959 or the NASH standard for steel-framed homes, both of which are referenced in the National Construction Code. The code says that homes built in bushfire-prone areas need to “reduce the risk” of ignition from a bushfire. The risk is categorised across six levels, known as the “bushfire attack level” (BAL).

“If you’re going to build on a site that has been inspected, and then is being categorised as a BAL-FZ (the highest rating), then that’s about the toughest set of requirements you’ll need to comply with,” said Raymond Loveridge, an adjunct professor at the University of Technology, Sydney. “And they’re mandatory.”

The BAL rating covers building materials such as floors, walls, roofs, doors, windows, vents, drainage, verandahs, and water and gas pipes.

At the higher end, Loveridge said, there may be requirements for fire-resistant timber, but generally you can build the home as you’d like provided you can “satisfy the building certifier that what you’re proposing to build will comply with the mandatory performance requirement”.

“The main concern of the government is how the building will perform, not how individuals will put the Lego together to achieve that outcome.”


The cost of building bushfire-resilient homes need not be prohibitive. An expensive architect is not essential. A local draftsman or building designer can help – as long as they have experience in working with the risk of bushfires in mind.

There are also plenty of free resources available. Joost Bakker, the eco designer behind BuildByJoost buildings, has made the plans and specifications for a fireproof house that he built in Kinglake, Victoria, freely available via the Bushfire Building Council of Australia. Architects Assist also helps those affected by bushfires by referring them to architects or builders who will provide free design and planning approval services.

Before construction of Bakker’s Kinglake house began, its building system was successfully burn-tested by the CSIRO under extreme conditions. The roof is covered in soil, making it highly fire resistant. The off-grid house is built entirely with recycled or recyclable materials, including a 100% recycled concrete slab and a steel frame made with crushed recycled brick and insulated with straw bales. Completed in 2015, the construction cost about $600,000,

“A lot of people say they can’t afford to build sustainable houses”, Bakker says. “But maybe we should build slightly smaller houses and spend more money making them resilient. When you make a house bushfire-resilient, you are also making it a better house and it uses less energy when you live in it.”

Building bushfire-resilient houses obviously demands a move away from traditional aesthetics, such as timber decks, but they don’t have to be concrete bunkers.

“You only really need to robust design if your house is perched right up against the bush and it’s going to receive direct flame contact,” says Leonard. “And [the compliance standards] will give you the specs on how you build a non-concrete box type house that actually can withstand flames.”

A bushfire-resilient house can be a simple design, says Cotter. It’s the detailing and the materials that matter. Bushfire-proof windows, doors and roofs, steel walkways and non-combustible cladding can make the difference between survival and not. The cost of some of these has come down recently, although things like fireproof windows systems are still expensive, something Cotter hopes the industry will address.

“A lot of places where people are losing houses are in our most beautiful regions, the coastal areas or mountains, so you want to be able to have some larger sized windows,” she says.

It’s important to think of the property as a whole, rather than separating architecture and landscaping, says Cotter. Fencing, access and the proximity of combustible habitat should all be considered.

House gaps should be sealed up or filled with metal meshes to avoid any embers, and sprinklers can also be helpful. Bunkers are another way to manage risk, says Cotter: “Obviously we don’t want people’s houses to burn down, that’s what matters, but we have to have back up for life safety.”

While the current focus is on rebuilding devastated homes, there is an even larger problem on the horizon: retrofitting existing properties. The building council says 90% of homes in dangerous regions in Australia are not bushfire-resilient, and the cost of retrofitting can be considerable.

“It’s always more expensive to get a poorly designed house and start changing bits out until it works really well rather than start from scratch,” Leonard says.

Cotter thinks it’s critical that the government subsidises retrofitting on a large scale: “If we don’t do it, we then just have to accept the losses.”

Building smarter towns

To make communities safer, rebuilding or retrofitting individual buildings is only part of the answer. The experts say the scale of the recent fires could be an impetus to reconsider plans for developments, or to reimagine existing ones. Leonard would like communities to come up with masterplans for their towns in case of bushfire, to consider whether the property boundaries are right, reconfigure how the houses are laid out, and get critical services laid in.

Cotter agrees: “If we could invest in building in a smarter way, everybody benefits [and] we’ll reduce the risk for the next bushfire that is likely to come … If you’ve got an old house next to a new house [and it] catches fire, it will burn the next house and the next house, like a domino effect. Rebuilding has to be much more holistic or we are just doomed to repeat previous failures.”

It comes down to political will, she says: “Do we want to put the money into community measures, do we want to look at retrofitting or do we want to just shut these places down? [Ultimately] we’d have to move millions of people every decade, away from bushfire, and eventually we just won’t have anywhere else to go.”