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Bushfire Attack Levels


In response to the devastating Black Saturday bushfires and subsequent Royal Commission, Australian Standards AS3959 were updated to include more stringent fire safety building regulations in both the residential and commercial spheres. AS3959 classifies different bushfire intensity levels that a building may experience during a bushfire. These intensity levels are referred to as Bushfire Attack Levels, or BAL’s for short.

A building’s BAL rating will determine a suite of requirements with which your structure must comply. These requirements are typically identified and enforced at the point of application for a building permit.

Included in the suite of requirements at each BAL rating are window and door specifications. An unexhaustive list of features regulated include: How windows and doors are to be screened, what materials are suitable for screening, the type of timber or metal suitable in windows and door frames and grade of glass and glazing required.

Often what is required for one window is different to the next window, therefore for homes that fall within BAL-19 to BAL-FZ a professional assessment by CDK Screens or an equivalent body is required.

There are six bushfire attack levels in total, these are:
  • BAL Flame Zone
  • BAL 40
  • BAL 29
  • BAL 19
  • BAL 12.5
  • BAL Low
The BAL rating is formulated according to:
  • The ‘type’ of building (i.e. single dwelling with attached garage)
  • The region where you live.
  • The vegetation type around your property.
  • The distance from your home to individual vegetation types.
  • Slope on the property.


The table below outlines the predicted bushfire intensity at each Bushfire Attack Level: 

BAL Ratings Table. Description of the expected heat flux exposure at each BAL, with a unique suite of building regulations pertinent at each rating.


How do I find my homes BAL rating?

Following amendments made to the Australian Standards AS3959 in March 2009, namely the insertion of BAL ratings, all structures built after March 2009 must undergo a BAL assessment as part of the building permit acquisition process. With this in mind, if your home was built after March 2009, your home’s BAL rating will be included in the building permit.

It is important to note that the amendments that created the BAL rating system are not retrospective, meaning if your home received building approval prior to March 2009, you are not bound to comply with BAL building regulations (however other AS3959 regulations in force prior to March 2009 still apply).

If you are still unsure as to the BAL rating of your home, please consult the following PDF which illustrates the assessment criteria used to identify a building’s BAL rating: BAL Assessment Report (PDF) or alternatively you can consult this easy six step guide: Quick Step Guide to BAL Ratings

For more information on the Australian Standards AS3959-2009 click here.

What type of screening is required at each Bushfire Attack Level?

Once we are clear of your homes BAL rating, CDK Screens can assess your property and compile a dossier which outlines what each window and door requires in terms of flyscreens, flydoors and security doors. We can also consult on what window and door specifications are required to match your properties BAL rating (see our sister company Stock Windows and Doors).

To read further on the specific screening requirements at each BAL rating Click Here

A summary of the requirements can be found in the table below:

Condensed table outlining the screening requirements at each Bushfire Attack Level. For a complete detailing on window and door regulations pertinent to each BAL, follow the click here link immediately above

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Bushfire Attack Levels

In the Australian Standards As 3959, they have classified different bushfire intensity levels that a home may experience during a bushfire.

These are referred to as Bushfire Attack Levels, or BAL’s for short.

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