Levels of Bushfire Attack
A Bushfire Assessment of your new house will put it in one of the following 6 levels:
|
Bushfire Attack Level (BAL) |
Description of Predicted Bushfire Attack and Levels of Exposure |
|
BAL – Low |
There is insufficient risk to warrant specific construction requirements |
|
Ember attack (Burning twigs, branches or leaves airborne and carried on the wind ) with heat flux* up to 12.5kW/ m2 (Heat flux = Amount of heat transferred per unit area per unit time to a surface) |
|
|
BAL – 19 |
Increasing levels of ember attack and burning debris ignited by windborne embers together with increasing heat flux between 12.5 and 19 kW /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 of ember attack and burning debris ignited by wind borne embers together with increasing heat flux (29 – 40 kW/m2) with the increased likelihood of exposure to flames |
|
Direct exposure to flames from fire front in addition to heat flux and ember attack |
*As a comparison the Heat flux from the Sun is around 400 W/m2.
Remember these levels are based on the BAL when the house is being planned. If you build and then fill the garden with shrubs and trees a few years later the Level, and the Risk, will be higher!
Don’t think that because you are in a suburb that you will be automatically be in a ‘BAL Low’ Area. Some suburban areas can still be at risk!
What Is The Bushfire Attack Level explains what factors are used in the Assessment