What Wye River can teach us about building for bushfires
On Christmas Day 2015, the weather conditions around southern coastal Victoria weren’t particularly notable. There had been a long dry spell, and a total fire ban had been forecast, but otherwise there was little to forewarn of what was to come.
That day, a bushfire swept through the small coastal township of Wye River and destroyed more than 100 houses – 80 per cent of the town. Thanks to early warnings and a fast-acting community, no lives were lost. But the devastating event has revealed some significant flaws in our interpretation and implementation of bushfire regulations, as well as highlighting opportunities for improvement.
Some of the houses that burned in the Wye River fire had been built to bushfire regulations. There is a misconception that this makes them bushfire-proof, and this reveals a basic flaw in our understanding of the aims of these regulations.
The goal of bushfire building regulations is ultimately to prevent loss of life, by making a house that can withstand bushfire long enough that its occupants can escape safely after the fire front has passed.
But no house is an island. It is surrounded by other houses, by landscaping, by add-ons, by natural debris, by the everyday bits and pieces of life, and by an environment whose aesthetic appeals to its owners. None of these elements are covered by bushfire building regulations, and each one of these can significantly amplify the impact of a bushfire on a house and a community.
One of the key contributors to the high number of houses burnt in Wye River was that while many were built to bushfire standards they had flammable wooden outdoor stairs and decks, wooden retaining walls, and in one case wooden cladding over fire resistance regulation cladding.
Many houses built into steep slopes had large open storage areas underneath them that contained flammable items such as firewood, retaining walls, building materials, plastic kayaks, and plastic water tanks. As the town did not have access to mains gas, many houses had LPG cylinders stored close to the house.
When the fire came through at ground level, fuelled by, grass, dry leaf litter and twigs that had built up throughout the township, it fed straight into these vulnerabilities.
Even houses built to the highest bushfire regulatory standards were not designed to withstand the radiant heat and flame contact from these stored materials and retaining walls, and that is one of the main reasons why so many houses were lost.
The impact of proximity
Another issue that emerged from the Wye River was house-to-house ignition. This is expected in bushfires, but what was unusual about Wye River was that the houses were in many cases well-spaced.
However low wind conditions on the day meant that as one house burned, the neighbouring houses reached a higher temperature, causing many to ignite.
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The building regulations focus on the house itself; its design, construction and materials. The regulations do not account for the typical fuel loads underneath houses, let alone the many-layered envelope of potential combustible features that surrounds it and extends out to include the entire community.
With that in mind, we and Emergency Management Victoria have developed new guidelines that address some of the unique bushfire vulnerabilities and challenges faced by, steep coastal towns under tree canopy like Wye River. These bushfire protection measures take into account not just building design and construction, but also water supply, gas supply, landscaping, defendable space, and building location and separation.
For example, to reduce the chance of one burning house igniting those around it, we recommend that houses with BAL 29-rated walls and eaves be separated by at least 12 metres, while those rate for flame zone can be 4 metres apart.
The guidelines also emphasise the importance of building houses to bushfire regulations, which includes using non-combustible materials for window and door frames, cladding, decks, gutters, insulation and sub-floor supports. This includes water tanks, as the failure of a water tank during a bushfire not only deprives fire fighters of a water source, it can break open the side of a house and allow the fire to enter, and burning tank materials can set fire to houses and materials nearby.
The same applies to potentially flammable items and materials stored around and under houses, including boats, cars and caravans. The guidelines recommend that unless these are fully enclosed within or under the house, they should be stored at least 6 metres away from the house and from any access routes to the house.
Gas tanks pose a huge risk during a fire as they can vent or explode, so the guidelines now recommend no portable gas cylinders be used or stored anywhere. Similarly, electricity services to individual houses should be underground, to reduce the likelihood of people encountering fallen live wires as they try to escape.
Landscaping is another important issue that affects not only the home-owner, but also their neighbours and firefighters. While part of Wye River’s unique charm is the fact that it is so embedded in the coastal bush, it is possible to landscape to reduce bushfire risk while still maintaining this character. This includes using non-combustible fences and retaining walls, and planting low-flammability plants around houses.
Wye River has the opportunity, as do we all, to learn from these exposed vulnerabilities in our bushfire adaptation. While Wye River has many unique aspects – steep coastal terrain, houses under the tree canopy, difficult routes throughout and leaving the town – these are also found in many other coastal settings around Australia. Similarly, the vulnerabilities that contributed to the destruction of Wye River, such as wooden retaining walls and stored flammable items, are likely to be common across the country.
The other important thing to remember is that while bushfire guidelines may be aimed at the individual home-owner, a community is only as resilient as its weakest link. For our guidelines to truly achieve their goal, we need not just a few home-owners, but everyone to step up and embrace them.
The end result will be a much more resilient community, and one that is able to weather bushfire challenges for many decades to come.
January 2, 2017 at 7:43 am
Why don’t they at least partly build underground, with the correct materials to protect the exposed bits? The slope would suggest ease of building into the hill. Double glazing, external sprinkler systems and exterior window shutters would then go on the exposed areas. Surely the cost is now comparable to totalreplacement?
March 1, 2021 at 4:00 pm
I agree with Mal. Underground, or part underground, is the way to go. I have successfully owner built twice now(but pay for the experts to come in).I would now like to build a small, simple underground granny flat. However I am finding it difficult to locate real life experiences of water proofing plus high insulation rating – my current cottage is strawbale and I now expect R8 or higher!