The recent destructive bushfires in Angeles saw thousands of houses destroyed in fast-moving wildfires. Australia has its own history of devastating bushfires, which increasingly don’t just affect those who are attracted to the bush and its natural beauty.

It’s cities and the urban interface that spreads into the forested fringe. Here, people increasingly accept the responsibility of being adapted to living with the risk.

So, is Australia more prepared? If not, where should the focus be and how much can be gained?

Today, it’s random that during a bushfire, one home is destroyed while another is not. However, at early settlement, home loss was almost inevitable.

How modern codes address bushfire building material risk

In Australia, when an area is considered bushfire-prone, the area on which the land sits has been designated under a power of legislation as being subject, or likely to be subject, to bushfires.

Building in bushfire-prone areas comprises three main elements, firstly a declaration by a local authority that an area is bushfire-prone, a site assessment and the application of construction standards to respond to the specific nature of the threat.

This triggers building-permit requirements where new buildings are required to build to a national bushfire construction standard AS 3959: 2018 Building in bushfire prone areas.

In both cases, specific standards are determined following a site assessment to determine the Bushfire Attack Level (BAL). The state specific fire danger index, the building’s distance from predominant vegetation and the slope of the ground on which it sits all influence this assessment.

How BALs affect materials

Construction standards are contained in AS 3959 and apply both generally and specifically based on the BAL.

As the BAL increases, so does the likelihood of radiant heat or flame contact, so material suitability and choice reduce to either non-combustible materials or materials and assemblies that have been specifically tested. Standards have evolved to recognise the safe appropriate use of materials like timber without increasing risk.

Timber

Timber framing is a suitable method for construction under bushfire standards in given applications, behind compliant envelope. Timber is also suitable in lower BALs in exposed situations for unenclosed sub-floors, wall cladding, windows and both glazed doors, sidelights, solid panel doors, facias, gables and balustrades.

Bushfire-resisting timber is deemed to be acceptable to withstand exposure up to a BAL 29 condition, without further testing.

Non-combustible materials

Obviously, materials such as masonry, steel and concrete are non-combustible materials which can be used through all BALs in certain applications. Other materials that claim non-combustibility rely on testing. Glass similarly can be safely used in applications 400mm above the ground, a deck carport roofs or meet testing standards.

Steel framing, like timber, is acceptable. Yet as even metal can warp and deform when exposed to radiant heat or direct flame potentially creating gaps where embers can encroach; BAL 40 and BAL FZ require that fascia and bargeboards or wall cladding in BAL FZ be tested to other stringent bushfire standards.

Are our buildings more prepared than those in LA?

Standards are constantly under pressure to do more to address residual risks or new objectives, particularly in the wake of natural disasters. Along with other policies, codes and standards are a key reason that occupant safety across all hazards has improved.

In Australia, our attraction to the bush and tragic past mean national standards have been supported by a practice of learning through evidence-based research and continual improvement.

Relevant standards for bushfire are currently under review, last being significantly amended in 2018 and HIA participate actively in the consideration of changes. Previous changes in the past followed the experience gained from Black Saturday.

More recently, the Black Summer Bushfires in 2019-20 have informed changes proposed. This received hundreds of public responses and shows researchers and the building industry are well-engaged with proposed updates and their impacts.

What is often overlooked is when deficiencies in bushfire construction standards are identified. New and higher standards only apply to new buildings and building work, which represent a small proportion of all building stock. These new buildings are also already more likely to be resistant to bushfire than older buildings thanks to learnings of the past.

Homes in Australia built to modern standards were found to have around 25% the vulnerability to loss from fire as those built in the 1990s, according to one study. In California, other research suggests homes built since 2008 are around 40% less likely to be destroyed.

Risk posed by any major natural disaster event is influenced by the accumulation of decades of building, planning and policy, and home-owner decisions. However, applying more ambitious modern standards to existing buildings can be cost prohibitive or discourage upgrades that could otherwise reduce other vulnerabilities or climate resilience, while doing little to address the risk.

The future regarding building codes and standards

Australians accepting regulation has its place, and while new standards have had a measurable effect, there’s a point after it that regulation can’t control – typically when occupation begins. There’s a growing body of information on how choices made by an owner affect a building’s survivability.

Outside of standards and academic publications, there has been little consistent and national advice available on bushfire hazard in Australia. Owners/occupants, designers and builders all benefit from understanding the intent of bushfire responsive design and inform choices that might otherwise undermine it.

Authoritative advice has a place to manage risks where regulatory control is either inappropriate or cost prohibitive, and occupant actions do not undermine the intended building controls by:

• maintaining clear space and vegetation
• ensuring landscaping choices are appropriate
• appropriate storage of combustible materials.

Thankfully, this advice is already in development by the Australian Standards committee, through HB-208 Part 2 a Consumer guide to the bushfire standard along with Part 1, a companion handbook to using the standard.

These will prove invaluable to those seeking to do more, and those whose assets and lives depend on their choices long after a building is approved.

Other tools and objectives

The current primary objectives of life safety and structural safety remain the primary focus of the NCC. Yet, regulatory changes to address other objectives have been proposed – focusing on benefits of property and asset protection which are not the role of building codes to address – and have still been proven not to produce a net benefit.

In June 2024, Building Ministers agreed to include climate resilience an objective (goal) of the ABCB. They also requested the ABCB to scope out potential future NCC changes that would be necessary to achieve this objective. ABCB was also asked to ensure any changes are made in ways that are practical, cost effective and fit-for-purpose – a challenge if recent proposals are any guide.

Careful design and siting of buildings allow a building to be built and stand the best chance of affordable resilience and risk mitigation. However, the approach to Hazard mapping can also change over time. In some states’ planning requirements, such as Victoria, its bushfire management overlay requires specific additional features to be provided. So, building and planning can interact, and changes are not considered holistically.

Evolving over decades

Codes and standards have evolved over decades and new buildings are better prepared for the next major bushfire. A holistic approach to planning and building, and support and advice where buildings are occupied, is needed and will be aided by materials already in development.

But we must not overlook the vulnerability of our existing housing stock. Where new work on existing buildings is contemplated, approval can require energy efficiency and accessibility upgrades that compete for the same resources as sensible natural hazard mitigations.

Solely focusing on changes to new standards, which are only practical and applied in already higher performing new buildings, leaves us less prepared than we might otherwise be.

For more information

Watch this informative story on SBS: 'What the hell is going on?': Top firefighter's warning for Australian cities after LA fires’.

First published on 27 May 2025