As we move into the cooler, wetter season—known as Djeran in the Noongar calendar—the immediate risk of bushfire reduces significantly. Djeran, which typically spans April and May, signals a change in weather patterns across much of Western Australia, bringing lower temperatures, increased rainfall, and calmer conditions.

While fire risk may not feel urgent, this period provides the perfect window to prepare for the next bushfire season.

Planning to build in a bushfire-prone area? One of the smartest moves you can make is booking your BAL (Bushfire Attack Level) assessment early—before design work is finalised.

A BAL rating reflects the expected level of radiant heat exposure, measured in kilowatts per square metre (kW/m²) to your building. BAL ratings range from BAL–Low (minimal risk) to BAL–Flame Zone (FZ) (highest risk).

When people think of bushfire damage, they often imagine flames engulfing a house directly. But the reality is more complex. In fact, many homes lost to bushfire are located over 700 metres from the fire front—and most are not destroyed by direct flame contact.

Building in a bushfire-prone area means complying with AS 3959—but what does that actually mean for your home?

Here’s a straightforward guide to help you understand what AS 3959 is, why it matters, and how it affects your building design.

Receiving your Bushfire Attack Level (BAL) rating is a critical milestone in the planning and development process—but it’s not the finish line. Understanding what comes next is key to staying compliant, on budget, and on schedule.

How is your BAL rating actually determined?

A Bushfire Attack Level (BAL) rating is calculated using procedures outlined in AS 3959 – Construction of buildings in bushfire-prone areas. There are two methods available: the Simplified Procedure (Method 1) and the Detailed Procedure (Method 2). In most cases, Method 1 is sufficient, and that’s the focus of this article.

A BAL rating reflects the expected level of radiant heat exposure, measured in kilowatts per square metre (kW/m²) to your building. BAL ratings range from BAL–Low (minimal risk) to BAL–Flame Zone (FZ) (highest risk).

Bushfire behaviour refers to how a bushfire responds to its surroundings—like the type of vegetation, weather, and land slope. Understanding how a fire is likely to behave helps us predict its intensity, speed, and direction.

What will it cost, and what changes will be needed to ensure your home is safe?

You only need a BAL assessment if your property is located within a Bushfire Prone Area as designated by the DFES Commissioner. These areas are shown on the Bushfire Prone Map, which identifies all land in Western Australia subject to additional planning and construction requirements aimed at improving bushfire resilience.