Bushfire Attack Levels under the Australian Standard
To ensure new homes, alterations and additions are located and constructed with greater bushfire protection, the new Australian Standard AS 3959–2009 Construction of buildings in bushfire-prone areas now applies across Australia.
AS 3959–1999 has 4 levels of risk of bushfire attack, (Low, Medium, High and Extreme) while AS 3959–2009 has 6 levels described as Bushfire Attack Levels (BALs).
There is a need to assess the building site based on the vegetation type and effective slope of the ground under the classified vegetation and distance from the vegetation, to determine the Bushfire Attack Level (BAL).
Despite the changes to the Australian Standard, CHH’s broad range of timber, LVL and plywood products are still the preferred choice for your timber wall, floor, decking and roofing solutions for either high-set lightweight homes or brick veneer homes with enclosed subfloor spaces.
The following information is a guide to meeting the different construction requirements with CHH’s products. For further technical assistance call Carter Holt Harvey on 1800 808 131 or contact the Timber Development Association (NSW) on 02 8424 3700.
| Bushfire Attack Exposure under the Australian Standard 3959-20091 | Description of the predicted Bushfire Attack Levels |
|---|---|
| BAL – LOW | Insufficient risk to warrant specific construction requirements |
| BAL – 12.5 | Ember attack |
| BAL – 19 | Increasing levels of ember attack and burning debris ignited by windborne embers together with increasing heat flux between 12.5 and 19kW/m2 |
| BAL – 29 | Increasing levels of ember attack and burning debris ignited by windborne embers together with increasing heat flux between 19 and 29 kW/m2 |
| BAL – 40 | Increasing levels or ember attack and burning debris ignited by windborne embers together with increasing heat flux between 29 and 40 kW/m2 and increased exposure to flames |
| BAL – FZ2 | Direct exposure to flames from the fire front in addition to heat flux over 40 kW/m2 and ember attack |
1 Based on site assessment conducted by an experienced architect, building designer or builder.
2 NSW requirements do not allow solution from AS3959 to be used.
BAL–LOW: There is no limitation on the use of CHH wood products for any building element that is in BAL– LOW, except in South Australia. South Australia requirements are not covered in this guide.
For recommended solutions in the other BALs (12.5, 19, 29, 40 and FZ) refer to the following guides.
July 2010 (2)
