What are the requirements for a Bushfire Attack Level (BAL) of 19?

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:

  1. 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.
  2. 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.
  3. 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.
  4. All doors and windows must be fully covered by bushfire shutters or screens
  5. Door and window frames and all assemblies are to be non-combustible.
  6. Glazing within a certain height from the ground shall be safety glass, the rest can be annealed glass.
  7. Ember guards and mesh screens are to protect all openings vents, weep holes etc.
  8. Joint openings in all joinery to be kept at a minimum size as specified by the AS3959
  9. 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.

 

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