New house near Kinglake West, 6 December 2009

With November bringing record temperatures across much of southern and inland Australia, bushfires are well and truly back in the headlines. And after last summer’s catastrophic Victorian bushfires, awareness of building design and safety in bushfire-risk areas has never been greater.

While there have been changes to building requirements since last January, some bushfire safety and urban design experts believe building standards in bushfire-prone areas need to be much tougher.

The release of a report on building recommendations by the 2009 Victorian Bushfires Royal Commission last month, with a particular focus on bushfire bunkers, was another timely reminder that the bushfire season is upon us. (www.royalcommission.vic.gov.au/documents/IR2/VBRC/_IR2_HR.pdf )

The interim report is the second from the Royal Commission since it was established on February 16 to investigate the causes and responses to the Victorian bushfires. The report makes seven recommendations regarding the need for a national standard for bushfire bunkers and urgent changes to construction requirements in bushfire-prone areas.

As a result of the Victorian fires, the Australian Building Codes Board began working on a national standard for bunkers and the Victorian Government has introduced interim regulations. The regulations mean those intending to build a bushfire bunker need a building permit and must undergo an accreditation process.

Announcing the regulations on November 11, Victorian Planning Minister Justin Madden, said it was absolutely vital that people considering building a bunker or private bushfire shelter were aware of the risks.

Near Kinglake west, December 2009

“Bunkers or shelters cannot be relied upon to save lives”, Mr Madden said. “Victorians living in bushfire-prone areas should have a bushfire survival plan and be practising it.

“We understand that there are some people who are considering installing bunkers or private bushfire shelters. That’s why we are putting in place interim regulations to provide Victorians who do decide to build a bunker or private bushfire shelter with a clear set of guidelines they need to adhere to.

“This is about ensuring people in bushfire-prone areas have all of the information and are aware of conditions they need to meet,” Mr Madden said.

After last February’s Victorian bushfires, new residential building standards were introduced throughout the state. A new system for assessing the type of construction and materials required for buildings in specific geographic areas is now in place, with six categories of bushfire attack levels (BALs), each with different building requirements. (More information on this is available at www.buildingcommission.com.au/resources/documents/guide_to_building_after_bushfires_March10pdf )

The BAL takes into account a number of factors including the fire danger index; the slope of the land; the types of surrounding vegetation, and proximity to other buildings. The fire danger index is a measure of the associated fire weather and the probability of a bushfire starting. It also includes its rate of spread, intensity and difficulty of suppression.

The fire danger index for Victoria is 100, one of the highest in Australia. In Victoria’s alpine areas it is 50 and in the Northern Territory and Queensland it is only 40.

Regulations need to aim higher

But just how prepared are we for another searingly hot summer and extreme fire risk? Justin Leonard, CSIRO research scientist and expert consultant on urban planning for bushfires, told The Fifth Estate that while people had learned from last summer’s bushfires, building codes had not yet been upgraded to cope for extreme bushfires. This was urgently needed.

“The building standards were long overdue for an overhaul, so the current updating of them is certainly a step in the right direction,” Mr Leonard said.

“One of the fundamental questions is how high will the ‘design fire’ [the fire danger index] be in the new building standards? The Victorian fires demonstrated that we need to aim high.

“People who are thinking about urban design are aiming significantly higher than the prescribed building standard.”

Mr Leonard said new building codes were in draft form when the Victorian bushfires happened and they were then rushed into regulation. However, there were a number of flaws that needed to be addressed, he said.

“There were a number of deficiencies that should have been fixed relating to the size of gaps allowed and, from a materials’ perspective, some fairly obvious issues of combustibility.”

Mr Leonard said that most ember related ignitions in houses happen in the roof cavity and under the floor. Using non-combustible materials in these areas, such as steel roof construction with rock wool or fibreglass insulation, significantly increased the chance of saving a building.

“Sustainable housing objectives are also very compatible with fire resistant construction,” he added. “Features such as rainwater capture, insulation and other approaches that reduce a building’s impact also improve ember resistance.”

The Victorian Bushfire Reconstruction and Recovery Authority

Christine Nixon

The Victorian Bushfire Reconstruction and Recovery Authority has been overseeing construction in the bushfire affected areas. Its commissioner, Christine Nixon, said that more than 1085 building permits have been approved for houses, sheds and commercial buildings since the fires.

“It is important that people rebuild at their own pace, and they have all the necessary support in place to make rebuilding as simple possible,” Ms Nixon told The Fifth Estate.

“To ensure this happens, the Victorian Bushfire Reconstruction and Recovery Authority has established a mobile building advisory service.

“This includes free, face-to-face rebuilding advice and information, which is available across all bushfire-affected communities, from qualified building advisers.”

Ms Nixon said construction was taking place right across affected areas including Gippsland, the Kinglake Ranges and Marysville.

New planning scheme provisions had been introduced and the red tape slashed so landowners rebuilding after the fires did not have to satisfy normal planning scheme requirements to re-establish their properties.

Ms Nixon acknowledged there had been significant challenges for those needing to build to the highest bushfire attack level – called FZ or flame zone.

“While there has been a lag in the availability of some approved building materials for the BAL FZ, the building industry has responded to the need for these new materials, which are continuing to come on to the market. There are now a range of FZ-compliant materials on the market, including five new roofing systems which have recently been added,” Ms Nixon said.

The state’s Building Commission and the Victorian Bushfire Reconstruction and Recovery Authority’s (VBRRA) rebuilding advisors had been working with residents to help them understand the construction requirements of FZ, complementing VBRRA’s mobile building advisory service.

John Collins was one of Archicentre architects who after last summer’s fires, came up with 110 home design concepts, with the sponsorship of James Hardie and Forest Wood Products. Above is a design that Collins did for a property at Pheasants Creek: a two storey, lightweight construction, BAL FZ, clad in cement sheet and corrugated steel sheet roof, external walls and floor are 30 min fire rated

Melbourne’s Archicentre, the building advisory service of the Australian Institute of Architects, is one organisation that has been assisting in designing houses for reconstruction. After last summer’s fires some of the group architects came up with 110 home design concepts, with the sponsorship of James Hardie and Forest Wood Products.

John Collins’design for a bushfire rebuild at Kinglake: two-storey, lightweight construction, BAL 29, clad in brickwork and timber cladding

Archicentre’s chief executive David Hallet says the bar has definitely been raised for anyone designing in a bushfire-prone area.

“The first big change is that for every domestic building, whether a renovation or a new building, a BAL assessment has to be done,” he said.

“The likelihood is that if you are in Hawthorn there will be no change to building requirements, whereas if you live in Horsham [which was at the centre of February’s fires] there will be.”

In the lower four BAL categories, the emphasis of building requirements is on ember resistance. At the higher levels it is on radiant heat.

Mr Hallet said bushfire bunkers, or private bushfire shelters as they are officially referred to, have presented a challenge as they weren’t officially identified as a building.

“In the last fortnight this has changed as they are now a Class 10 building but as there is no Australian standard for them they still present a challenge.”

And while most specified building materials in the new BAL assessment regime are readily available, when it comes to windows there are still none suitable for the highest-risk areas.

“This leaves people in these areas in a quandary. A solution is to put in shutters, as they act like a shield. The issue with windows is that they shatter and then embers can get in,” Mr Hallet said.

Despite the streamlining of planning requirements by the Victorian Government for people affected by last February’s bushfires, at this stage not much rebuilding has occurred in the worst affected areas.

“Building takes a long time at the best of times,” Mr Hallet said. “There wouldn’t be many of the 2000-plus houses that have been rebuilt or even started at this stage.”

lblundell@thefifthestate.com.au

The Victorian Bushfires Royal Commission second interim report’s recommendations include:

The Australian Building Codes Board (ABCB) develop a national standard for bushfire bunkers and make it publicly available by 30 April 2010.
The ABCB amend the Building Code of Australia (BCA) to include bunkers.
The ABCB reference the national standard for bushfire bunkers in the BCA as soon as possible, ideally in the 2010 edition.
The Commonwealth, through the Building Ministers’ Forum, encourage all jurisdictions to adopt the standard for bushfire bunkers as soon as possible.
The Victorian Government prescribe the national standard as a minimum standard in Victoria by amending the building regulations no later than May 2010.
Standards Australia, no later than 31 March 2010, publish amendments to AS3959-2009 to include unmanaged grassland in vegetation types and classifications, and use of sarking as a secondary ember protection measure. Also report to the Commission on progress of amendments increasing ember protection measures at lower bushfire attack levels, in particular subfloor requirements and materials for doors, windows and wall barriers.
Standards Australia publish a fully revised handbook on building in bushfire prone areas no later than 31 December 2009.