AS 3959 – Construction of Buildings in Bushfire-Prone Areas: What You Need to Know

What exactly is AS 3959, and what does it cover? AS 3959 (issued in 2018) is titled “Construction of Buildings in Bushfire-Prone Areas” and was introduced due to the growing risk of bushfires in Australia. It provides a framework for all new building construction and major renovations to improve their resistance to heat, flames and burning embers.

The National Construction Code (NCC) references AS 3959:2018 as a Deemed-to-Satisfy (DTS) solution. This means that AS 3959 is an approved method of meeting NCC requirements, and therefore, this standard has regulatory significance.

In this article, we’ll examine how AS 3959 has evolved, the major updates in the 2018 edition, explain the different Bushfire Attack Levels (BALs), construction requirements for the various threat levels, and how to achieve compliance and certification under the standard.

AS 3959 is the national standard outlining construction requirements to minimise bushfire attack damage. Standards Australia develops and maintains this standard, which is often referenced by the NCC, meaning its application is mandatory in designated bushfire-prone zones.

According to the Foreword of AS 3959, the standard is primarily concerned with improving the ability of buildings in designated bushfire-prone areas to withstand bushfire attacks more effectively, thereby providing a measure of protection to building occupants (until the fire front passes), as well as to the building itself.

AS 3959 “Construction of Buildings in Bushfire-Prone Areas” was first introduced in 1999 as a response to the demand for better building regulations in areas of high risk for bushfires.

The 2009 edition (released after the disastrous Victorian Black Saturday bushfires) introduced the Bushfire Attack Level (BAL) system, which is explained in full in the next section.

In the current (2018) edition, some major changes are:

• The site assessment has been simplified regarding slope, low-threat vegetation and grasslands.
• Shielding concessions only relate to the wall (and not the roof or subfloor structure).
• Changes to some requirements for bearers, joists and flooring, depending on BAL level.
• Clarification on requirements for windows, doors and vehicle access doors.
• Roofs can now include translucent or transparent roof coverings under certain conditions.

The AS 3959:2018 standard recognises three forms of attack in bushfire-prone areas, which are burning embers, radiant heat (the heat you feel from a fire) and flame contact, or combinations of these sources.

The Bushfire Attack Levels (BALs) are:

• BAL-LOW: Insignificant risk, and radiant heat is not considered significant. There are no specific construction requirements. However, if your property is in a designated BPA (Bushfire Prone Area), you still must construct to BAL 12.5.
• BAL-12.5: Low risk, primarily from ember attack. Radiant heat up to 12.5 kW/m².
• BAL-19: Moderate risk, with increasing ember attack and burning debris. Radiant heat between 12.5 and 19 kW/m².
• BAL-29: High risk, with significant ember attack and burning debris ignited by embers. Radiant heat between 19 and 29 kW/m².
• BAL-40: Very high risk, with exposure to radiant heat between 29 and 40 kW/m² and potential flame contact.
• BAL-FZ (Flame Zone): Extreme risk, with direct exposure to flames and high levels of radiant heat exceeding 40 kW/m².

Your proximity to bushland and vegetation, and the slope of your land, can affect your BAL assessment.

• Slope: Because fire climbs, it moves faster up a slope than downwards. If you are uphill from vegetation, it will increase your BAL rating.
• Proximity: The closer you are to vegetation, the higher the fire risk, and therefore, your BAL rating will be higher.
• Vegetation Type: Does forest surround your property? Or grassland? Forests have a higher fuel load than grassland, so a separation of only 50m from your home to grassland can result in a BAL-LOW rating, while a home in a forest requires 100m or more of separation to earn the same rating.

The following table outlines basic construction requirements for the different BAL levels:

The compliance process begins with having the latest version of the standard, which is AS 3959:2018. The design process starts with determining the BAL of the proposed residence or building. The BAL calculations should be fully documented for compliance reasons. The building design should be carried out, with all building materials and components meeting the specifications as required in AS 3959 for that BAL. Again, this must be documented for compliance. 

During and upon completion of construction, the building inspectors will verify that AS 3959 (and other relevant codes) have been adhered to. Then submit the design and construction documentation to the council or building certifier to obtain certification.

AS 3959 is legally enforceable by state regulators, such as the Victorian Building Authority (VBA), the New South Wales Rural Fire Service (NSW RFS), and the Queensland Fire Department (QFD), among others.

The AS 3959:2018 standard can be obtained from Intertek Inform’s official purchase page, in hard copy or PDF form, by following this link.

Another solution for continual updates is to obtain a subscription from Intertek Inform, such as our Small Business Sets (in particular, the Building Essentials Set), which are available in 12-, 24-, and 36-month subscription terms.

Here are practical steps for applying AS 3959:2018:

1. Is the property in a designated Bushfire Prone Area (BPA)?
2. Is your property in a Bushfire Management Overlay (BMO) area? If so, you will have to submit a Bushfire Hazard Plan with your planning permit application.
3. Determine the Bushfire Attack Level (BAL) of the property. THE CSIRO provides a BAL assessment guide and a BAL Assessment Tool to help you with your calculations.
4. Follow the specific construction requirements outlined in AS 3959 for your BAL during design and construction, and document each phase to ensure compliance.

How much training is available on AS 3959 for you and your team? Intertek Inform can provide you with training courses, webinars and CPD (Continuing Professional Development) programs to ensure you have the knowledge and compliance skills to operate confidently with this standard. We can also provide certification refreshers or audit preparation services.

In addition to providing access to the latest version of AS 3959, Intertek Inform offers expertise in standards interpretation, compliance audits, product certification, site assessments, training, and update alerts.
 Contact us for a bushfire compliance review today!

The purpose of AS 3959:2018 is to improve the resistance of buildings in Bushfire Prone Areas to bushfire attack. Compliance with these mandatory regulations improves the safety of local residents.

To ensure your full compliance with the AS 3959 standard, you can contact Intertek Inform for assistance or purchase the standard directly through this link today!