A Bushfire Attack Level (BAL) Assessment is a statement of your Bushfire Attack Level (BAL) rating in the form of a certificate and report. The report gives detail about why you are that rating by the classification of vegetation in a 100 m radius around your development and measuring the separation distance from classified vegetation.
The heat flux that a structure would be exposed to in case of a bushfire is what denoted your Bushfire Attack Level (BAL) rating and is measured in kW/m2. The third level in the Bushfire Attack Level (BAL) rating is BAL-19. This level is a moderate bushfire threat rating with a sufficient risk of an ember attack along with some risk of burning debris ignited by windborne embers and also an increasing heat flux.
For a Bushfire Attack Level (BAL) rating of BAL 19, there is a reasonable amount of construction requirements listed within the AS3959 which prevent burning debris and an ember attack. In order to ensure that the building is able to withstand a heat flux of about 19 kW/m2 in the case of a bushfire, these construction requirements must be adhered to. AS3959 lists bushfire construction requirements for Bushfire Attack Level (BAL) as following:
- Walls of a structure to achieve compliance with a Bushfire Attack Level (BAL) rating of BAL 19 are to be of non-combustible material, or cladded with non-combustible materials or a combination of the materials specified by the AS3959.
- Roof covering shall be made of non-combustible or materials specified by the AS3959 and the underside of roofs are to be sealed to avoid any gaps and threat of ignition through ember attack.
- For attached structures such as garage/carport, enclosed verandas, decks, ramps the roof and decks covering and stair treads (and all trafficable surface) are to be made of non-combustible materials or materials specified by the AS3959.
- All doors and windows must be fully covered by bushfire shutters or screens
- Door and window frames and all assemblies are to be non-combustible.
- Glazing within a certain height from the ground shall be safety glass, the rest can be annealed glass.
- Ember guards and mesh screens are to protect all openings vents, weep holes etc.
- Joint openings in all joinery to be kept at a minimum size as specified by the AS3959
- All water and gas supply pipelines to be made from metal
A Bushfire Attack Level of BAL-19 warrants significant requirements for bushfire construction but most of the requirements are something a solid construction will already follow. If your development has a Bushfire Attack Level (BAL) rating of BAL-19 and you need advice on bushfire construction requirements for your Bushfire Attack Level (BAL) rating, then contact us your BPAD accredited Bushfire Attack Level (BAL) Assessor today for a compliance report.