Grasping the BAL rating for owner builders in Victoria holds the utmost significance. In the wake of Australia’s most devastating natural disaster in 2009, where over 2,000 properties were destroyed, Victoria is on a resilient journey to recovery. Amidst this recovery process. Prospective owner builders in Victoria are tasked with understanding and navigating the Bushfire Attack Level (BAL) ratings. These ratings are implemented to enhance building safety in bushfire-prone areas. Therefore, they are pivotal in ensuring that new homes and rebuilding efforts are equipped with the necessary measures for heightened protection.

Victoria The Pioneers

Victoria was the first state to adopt the Australian Standard AS 3959-2009 through its Building Regulations in March 2009.  As a result, it has established a comprehensive framework for assessing and addressing bushfire risks in residential construction. The BAL system categorises sites into six levels. Subsequently, each dictates specific construction requirements based on factors such as vegetation types, distance from vegetation, slope of the land, and the Fire Danger Index (FDI). Understanding and accurately determining the BAL is crucial for owner builders. Accordingly, to implement the appropriate construction methods and ensure the safety of their homes.


Six Steps to a Successful BAL Assessment:

  1. Determine your Fire Danger Index (FDI). Assess the probability of a bushfire based on temperature, humidity, wind speed, and fuel state. Victoria generally falls under FDI 100, except for alpine areas, where it is FDI 50.
  2. Identify your site’s vegetation types. To be able to in classifying vegetation based on tables provided in the Standard, considering exclusions for specific types like non-vegetated areas and managed grasslands.
  3. Measure the distance from the site to vegetation. Horizontal measurement from the edge of vegetation to the external wall or supporting posts. Subsequently, excluding certain features like eaves and rainwater tanks.
  4. Determine the slope of the land under vegetation. In order to assess the slope’s impact on bushfire severity by considering the effective upslope or downslope to the building.
  5. Assign the BAL. Using tables corresponding to FDI 50 or 100, upslope or downslope, vegetation type, and distance, determine the BAL for your site.
  6. Apply construction requirements. Refer to the Australian Standard AS 3959-2009 to implement construction methods aligned with the determined BAL, ensuring increased protection against bushfire threats.

Understanding BAL Ratings:

  • BAL-Low. Insufficient risk to warrant specific construction requirements.
  • BAL-12.5. Ember attack with increasing heat flux.
  • BAL-19. Increased ember attack and burning debris, higher heat flux.
  • BAL-29. Further escalation in ember attack and heat flux, potential flame exposure.
  • BAL-40. Direct exposure to flames, high heat flux, and ember attack.
  • BAL-FZ. Extreme risk with direct exposure to flames.


To sum up, by diligently following these six steps and adhering to the construction requirements outlined in the Australian Standard. Owner builders in Victoria can navigate the BAL assessment process successfully. Therefore contributing to the creation of safer and more resilient homes in bushfire-prone areas. For additional information, individuals can contact an Owner Builder Coach or relevant authorities or refer to the Building Commission’s publication, A Guide to Assessing Your Property’s Bushfire Attack Level ( BAL).

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