December 05, 2019
It’s hard to not think about bushfires at the moment, regardless of where you live in Australia. Given our typically hot and dry climate, bushfire concerns are a very real part of the conversation during Spring and Summer.
Just like wind classification and soil classification, there are building guidelines and standards that govern the construction of residential homes in bushfire prone areas that need to be met when building your new home.
Referred to as “bush fire prone land” in NSW and “bushfire prone areas” in Victoria, the NSW Rural Fire Service classifies this as, “land that has been identified by local council which can support a bush fire or is subject to bush fire attack”. Bush fire prone land maps are prepared by local councils and certified by the relevant state or territory fire authority.
Understanding Bushfire Attack Level categories
There is no one size fits all designation for determining what is and isn’t classified as bush fire prone land. But if your building site is surrounded by bush, or located close to grassland, paddocks or the coastline, then you may be on bushfire prone land.
If your site is determined to be on bush fire prone land, it will be assessed as falling into one of six categories of Bushfire Attack Level (BAL). Each level measures (in kilowatts/m2) the severity of a building’s potential exposure to ember attack, radiant heat and direct flame contact. Which BAL your site will be classified in will be determined by:
- the region where you site is located;
- the type of vegetation surrounding your property;
- the distance from your home to individual vegetation types; and
- the slope on your property.
The six BAL categories, as covered in Australian Standard AS 3959 – 2009, Construction of buildings in bushfire-prone areas, are:
- BAL – Low: Insufficient risk to warrant specific construction requirements.
- BAL – 12.5: Ember attack with heat flux of up to 12.5kW/m2.
- BAL – 19: Increasing levels of ember attack and ignition of debris with a heat flux of up to 19kW/m2.
- BAL – 29: Increasing levels of ember attack and ignition of debris with a heat flux of up to 29kW/m2.
- BAL – 40: Increasing levels of ember attack and ignition of debris with a heat flux of up to 40kW/m2 and increased likelihood of exposure to flames.
- BAL – FZ: Direct exposure to flames from the fire front, in addition to heat flux and ember attack greater than 40kW/m2.
Critical requirements for building on bush fire prone land
If you’re building in a bushfire prone area, there are additional requirements that you and your builder need to consider regarding the building materials that you use on your project. This includes critical structural aspects of your home, such as piers, decks, floors and roofs. These requirements are outlined in two Australian building industry standards:
- Australian Standard AS 3959 – 2009, Construction of buildings in bushfire-prone areas; and
- NASH STANDARD Steel Framed Construction in Bushfire Areas – 2014.
The onus is on both the property owner and their builder to ensure that these standards are met. In order to build the home that you want to in a bushfire prone area, you may need to modify the style, plans and construction material used in your build.
Spantec building supplies for bushfire prone sites
At Spantec, our proprietary range of steel piers, decks, suspended floors and roofs can be incorporated into designs to meet the requirements for all six
BAL categories. Spantec steel building components comply with the above-mentioned Australian building industry standards and, with few limitations, are equally suitable for inclusion in designs prepared using either AS 3959 or the NASH Bushfire Standard.
For more information on how Spantec’s steel building materials can enable you to build the home that you want on your bushfire prone site, visit our building in bushfire prone areas page now.
Need help with building on a bushfire prone site?
For nearly 30 years Spantec Systems has been pioneering the use of light steel flooring systems, including structural steel beams and adjustable steel piers under sub-floors, for building professionals, owner-builders and DIY-ers. To find out how we can help with your next build, contact us on (02) 4860 1000 or by firstname.lastname@example.org. Already have plans and engineers drawings? Then get a quote now.ß