A Homeowner’s Guide To Bushfire Attack Level (BAL)

If you live in a part of Australia that’s at risk of bushfires, you’re already well aware of the significant danger they pose. You may be curious about the new building regulations and terminology that have sprung up in recent years with regards to bushfire protection, though. The Bushfire Attack Level, or BAL, has become critically important to assessing a given property’s risks. Read on to find out exactly what BALs are and how they’re determined.

Historical Background

Bushfires have always been a pressing concern for Australian homeowners, but risks have escalated dramatically in the last few years. Following the “Black Saturday” fires in 2009, which were the most devastating in recent memory, the government took a number of steps to mitigate the amount of danger presented by future fires. Chief among these was the adoption of AS3959-2009, a new building code that applies to homes constructed in areas where bushfires are likely. This standard offers multiple special construction requirements that must be addressed based on a new building’s BAL – bushfire attack level.


AS3959-2009 sets out six different bushfire attack levels, from BAL-LOW to Flame Zone. The intermediate levels (BAL-12.5, BAL-19, BAL-29, and BAL-40) are each categorized according to the growing levels of radiant heat that a building could be subjected to in a bushfire. BAL-LOW requires no special construction measures to combat bushfires, while a Flame Zone level requires extraordinary protection measures. BAL is calculated (by professionals) based on a property’s location, slope, and nearby vegetation. Protection measures that could be required at higher BALs include different exterior materials, fire shutters, radiant heat barriers, and even drenching systems.

What Homeowners Need To Know

The regulations described above currently only apply to new construction or major renovations, but Bushfire Attack Levels are naturally of interest to homeowners who are already living in bushfire-prone areas. There are a number of online calculators that can help you determine your property’s current BAL. Remember that a solid assessment of your BAL requires professional skills, though. Building surveyors will make their own BAL assessment when they inspect new construction in order to confirm that all work has been carried out according to AS3959-2009. The good news is that BAL can be effectively lowered if you’re willing to invest a little effort in the process.

Protecting Your Property

As mentioned above, BAL is derived from the proximity and type of vegetation around your home. This means that you can reduce your BAL by clearing your land in many cases. Establishing a bush-free protection zone around your home can make a big difference. The general rule of thumb is to have at least a twenty-meter clear perimeter on all sides, although your needs may be greater if you live in a heavily forested area. You can also retrofit your home to protect it from bushfire damage. Possible changes include the installation of fire shutters and fitting specially-designed safety windows. The windows of your home are often the weakest points of its exterior envelope, especially in high-BAL areas.

Fortunately, most builders and architects who work in bushfire-prone areas are already quite familiar with the tenets of AS3959-2009 and the concept of BALs. As long as you have professional guidance during construction or major renovations, it won’t be hard to provide your home with the protection it needs. With a little effort, the risks posed by bushfires can definitely be minimized.