The difference between Method 1 and Method 2 assessments for Bushfire Attack Level (BAL) ratings under Australian Standard AS 3959-2018 lies in their level of detail and accuracy:
Method 1 – Basic Approach
Method 1 provides a simplified way to determine the BAL by using general assumptions and tabulated data. This approach:
Groups vegetation into broad categories within 150m of the site.
Uses standard tables to determine the BAL based on distance, vegetation type, and slope.
Is quicker but can sometimes lead to an overestimated BAL, requiring unnecessary fireproofing measures.
Method 2 – Detailed & Precise Approach
Method 2 is a more precise, site-specific approach using detailed bushfire behavior calculations. It:
Uses actual data (instead of assumptions) to calculate flame length, heat exposure, and site elevation.
Applies fire engineering equations for a tailored BAL assessment.
Typically results in a more accurate BAL, avoiding unnecessary building costs.
At Queensland Bushfire Planning, we specialize in Method 2 assessments to ensure the BAL is as precise as possible, helping clients reduce unnecessary fire protection costs while maintaining their design vision.