It may seem unthinkably soon, but last weekend’s heat wave ushered in the start of Australia’s next bushfire season. It’s time to ask if we are keeping our homes, businesses and loved ones safe. Did existing construction regulations prove tough enough? What can we do for the one million homes built before bushfire regulations? What did we learn about designing for bushfire resilience, and are people building back in super dangerous spots at all?
The 2019-20 Black Summer bushfires destroyed around 3000 homes and they’re likely to change forever some of the more at risk communities, with homes along inaccessible ridgelines likely to become prohibitively expensive to construct and insure according to
Nigel Bell, principal of Blue Mountains architectural practice ECOdesign Architects + Consultants has seen his insurance premiums go up by about 28 per cent since the summer bushfires.
His house is in a high-risk area, above a tree-filled gully, that was built before modern bushfire regulations came into force.
“I would not be allowed to build it now,” he says.
Around 3000 homes were destroyed by last summer’s bushfires. According to Bell they’re likely to change forever some of the more at risk communities, with homes along inaccessible ridgelines becoming prohibitively expensive to construct and insure.
Bell, who gave evidence to the Bushfires Royal Commission (released earlier this month) on behalf of the Australian Institute of Architects, says that he’s worked on at least two NSW projects in high-risk areas that have fallen over due to budget constraints.
This included the expansion of a classic 1950s fibro house in NSW with “a lovely view” in a high-risk area (Bushfire Attack Level 40) to make way for a growing family. Bell says the whole budget was swallowed up by high insurance premiums and the necessity of retrofitting the existing house to the required standards.
“What’s happening is it is slowly but surely effecting people’s ability to build, based on budget.”
Typically he says, projects are abandoned and the home or site sold to an unsuspecting person who “hasn’t done their homework”.
Sadly, the failure to recognise a property at risk is not unusual, according to UTS academic Raymond Loveridge.
“The public think that the government has got their back, and I don’t necessarily think that’s the case from a building regulatory perspective,” Loveridge says.
Modern bushfire standards that came in after Victoria’s Black Saturday bushfires – the AS 3959 – are solely concerned with protecting life.
“It will treat a person’s house as protection mechanism that can be used in the short term.”
He says the government doesn’t require the house to be bullet proof. “That’s a decision between insurers and homeowner”.
This may not be the case for much longer, with the inclusion of protection of property as well as life, one of few building-related recommendations in the Bushfires Royal Commission.
Some spots likely to become too dangerous – and expensive – to live
Bell suspects the ballooning cost of dealing with bushfire will be enough to slowly change the composition of development, with some homes at risk of becoming “stranded assets”.
“You will find these brick veneer houses along lone ridges that are hard to access too expensive to retrofit.
“We are at the start of significant reconciliation with our native woodland vegetation and bushland, and this raises questions about where and how we should be building.”
Principal architect at Light House Architecture and Science Sarah Lebner says that the cost of rebuilding is a “complex multilayered issue”. At Rosedale, on the south coast of NSW, an assessment was made for the BAL (bushfire attack level) that was subsequently dropped because some people could not afford the rebuilding costs.
“This would potentially result in a mass exodus of locals and an influx of a different group of people, causing the erosion of community.”
Strength of existing regulations and where they need work
Bell, who has been involved with property bushfire resilience for over 20 years, says that most buildings constructed to modern bushfire standards survived pretty well.
That’s not to say there aren’t issues. One thing that’s problematic, for instance, is the “remarkable dog’s dinner” of rules across states and territories.
Partly this comes down to variations in the National Construction Code in each jurisdiction.
The inconsistency results in a dangerous level of confusion. For example, the fire danger index, which underpins the BAL ratings that people are more familiar with, has been kept more up-to-date in some states and territories than others.
This index is designed to identify the level of forest fire risk based on climatic conditions such as rainfall patterns and average temperatures. But Bell says few jurisdictions have kept up with the effects of climate change, meaning that homes are often at greater risk than their assigned BAL might indicate.
“This is a backward-looking index of historically what was at risk,” he says.
“The key point is if you are looking at the spread and intensity of the megafires you’ve seen in the last summer, then it is total nonsense.”
For Lebner, a major problem with existing bushfire regulations is how compliance is enforced.
“Throughout Australia you can do your own BAL assessment – any layperson can attempt to follow the rules and self-assess.”
She expects this to become a “thing of the past” in the wake of last year’s fires, especially for complex blocks.
“It’s very possible that bushfire assessors will be involved a bit more as part of the design certification, and also for the finished buildings. That responsibility is currently on building certifiers or surveyors.”
Bell also says water spray systems are rarely used in Australia despite “plenty of precedent” that they work.
He says research on the effectiveness of these systems for homes has been limited despite proving to be 99.8 per cent effective inside commercial buildings (where they are mandatory). Where they can be particularly useful is for buildings built to the boundary, he explains.
He says existing regulations still fail to recognise the advantages of these systems.
Lebner, who is part of a small group working to update design guidelines for bushfire work, would also like to see design that facilitates the active defence of a home discussed more openly.
While there are great guidelines for how (and when) to actively defend as well as clear rules for increasing a home’s passive defence features, there is no overlapping advice that sits between the two.
At the moment, there’s no regulatory requirement to allow rapid access to ceilings to spray with a hose or other design features that assist in the active defence of a home.
Lebner says that this is largely because authorities don’t want to encourage people to stay and defend (in fact, this is now sternly discouraged).
But she says this is devoid of reality – the truth is, many people chose to stay and defend their property. Plus, certain design features could make it easier for professional fire fighters to defend a home.
What the last bushfire season taught us about designing for resilience
Lebner says that while most architects would have been familiar with the AS 3959-2018 regulations before last summer, what’s changed is the level of interest and engagement from clients.
“Before they were seen as a check-the-box activity, whereas now we are seeing our clients coming in asking to at least meet the requirements and sometimes exceed.”
Rules can only do so much to control fire risk and aren’t very sophisticated when it comes to holistic, whole-of-site design that improves defensiveness, Lebner explains.
People tend to be naturally aware of the proximity of their home to trees and scrub, but a cleverly sited home that takes advantage of landscaping can also shield from radiant heat and create windbreaks.
Less obvious design choices are a compact, simple floor plan, which tends to lend itself to a simple roof free of corners and crevices that collect leaves and litter that risk catching alight from embers.
The lack of fire-proof barriers between homes was a big problem in the 2019-20 fires.
“Non-combustible fencing can help a lot in house-to-house ignition.”
Buildings built before bushfire regs
Compared to the thousands of homes built before modern bushfire resilience standards came in, building new homes for bushfire resilience is the easy part.
Up to a million homes have little or no bushfire protection according to the Bushfire Building Council, with up to 90 per cent of homes built in bushfire-prone areas built before any bushfire regulations for property came in.
UTS academic Raymond Loveridge days it’s “only a matter of time” for much of the old stock.
“They will really need to be upgraded to what’s required to be built to this day.”
The AS 3959 is designed for new construction and “half suitable” for alterations or additions, Bell says, and in many cases demolishing and rebuilding buildings is the only feasible way to meet the standard.
He says the best solution is to incentivise households to retrofit, just like the Ku-ring-gai Council in Sydney’s bushy northern beaches has with a bushfire retrofit subsidy of up to $1500.
“The direction you should go in is clear.”
He says incentives for bushfire retrofits is an ideal economic stimulus post Covid that will reach struggling regions also hit by bushfire.
“Widely distributed subsidies or interest free loans could be perfect, that would get tradies in these fire-affected areas in work.”
As embers (burning strips of bark or other debris that can travel kilometres away from the fire front) account for 80-90 per cent of homes destroyed by bushfires, Bell says the focus of adaptation should be on protecting from ember attacks.
These can be simple, low cost adaptations such as metal gauze fly screen over all glass, or filling in a suspended timber deck or replacing timber steps at ground level with galvanized steel or masonry,
These sorts of inexpensive changes might not guarantee a structure’s survival but “it would likely make a significant improvement.”