Bushfire areas and overlays
Bushfire Attack Level (BAL)
The residential building standard for bushfire protection aims to improve the ability of a building to withstand a bushfire attack. This provides greater protection for the occupants who may be sheltering inside while the fire front passes.
The following chart outlines how the baseline data, which is defined as a Bushfire Attack Level (BAL), determines the type of construction required for you to obtain a building permit.
The BAL takes into consideration a number of factors, including the Fire Danger Index, the slope of the land, types of surrounding vegetation and its proximity to any building.
Bushfire attack level
Radiant heat exposure (AS 3959)
Description of Predicted bushfire attack and levels of exposure
The risk is very low and radiant heat on the building is not significant enough to warrant specific construction requirements; however ember attack may still occur.
If you are in a designated BPA and your bushfire attack level is BAL - LOW, you must still construct to a minimum BAL 12.5.
BAL - 12.5
|0 to 12.5 kW/m2||Primarily risk of ember attack; risk of radiant heat is considered low.|
BAL - 19
|12.5 to 19 kW/m2||Risk is considered moderate with increasing levels of ember attack and burning debris ignited by wind borne embers; increasing likelihood of exposure to radiant heat.|
BAL - 29
|19 to 29 kW/m2||Risk is considered to be high with increasing levels of ember attack and burning debris ignited by wind borne embers; increasing likelihood of exposure to radiant heat.|
BAL - 40
|29 to 40 kW/m2||Risk is considered to be very high. Increasing levels of ember attack and burning debris ignited by wind borne embers; increasing likelihood of exposure to radiant heat and some direct exposure to flames possible.|
BAL - FZ
|40 kW/m2 + (flame contact)||Risk is considered to be extreme. Direct exposure to flames from fire front is likely in addition to high levels of radiant heat exposure and ember attack.|
Bushfire Prone Areas
Victoria’s bushfire prone areas (BPAs) have been determined using up-to-date scientific information and data, considering factors such as weather, topography and vegetation. If you are going to rebuild within a BPA, you will need a bushfire attack level (BAL) assessment under AS 3959 Construction of Buildings in Bushfire Prone Areas. All new homes constructed in a BPA must be built to a minimum BAL 12.5 to help withstand ember attack. This includes sealing roofs, sealing around doors and windows, and screening windows.
Higher construction levels may be required as determined by the site BAL assessment. The State Government is considering prescribing BAL levels for bushfire-affected areas. BAL levels should be assessed on the basis of the likely revegetated state following regrowth of burnt areas.
Bushfire Management Overlay
If you are in an area of extreme bushfire hazard, it is likely that your property will be in a Bushfire Management Overlay (BMO) and your council’s planning scheme will apply to its development and use. You will need to apply for a planning permit in addition to applying for a building permit. Referral to fire authorities may also be required to confirm particular site requirements for firefighting and property protection.
For more information about building under a BMO, contact your local council or visit the Department of Environment, Land, Water and Planning’s Bushfire Management Overlay page.