(Above) A steel-frame home that has survived a bushfire. All images courtesy of NASH, the National Association of Steel-Framed Housing
Wildfires have long posed a severe threat to communities across Australia, destroying homes and taking lives.
At the 2024 CFSEI Expo in Tucson, Arizona, on May 21, Ken Watson, executive director of the National Association of Steel-Framed Housing, presented solutions for designing steel-framed buildings to withstand wildfire attacks in a special keynote address. Watson’s presentation at the annual Cold-Formed Steel Engineers Institute (CFSEI) conference underscored the critical role of cold-formed steel (CFS) in enhancing wildfire resilience while offering cost-effective and robust construction options.
Ken Watson, NASH executive director
Need for Resilient Construction
Watson began by providing historical context for wildfire devastation in Australia. Catastrophic events, such as the 2003 Canberra wildfire and the 2009 Black Saturday wildfire, highlight the vulnerability of traditional housing materials.
- The Black Saturday tragedy alone resulted in 173 deaths, 414 injuries and over 2,000 homes destroyed, primarily due to ember attacks
- These incidents underscored the urgent need for innovative construction solutions to mitigate wildfire risks
Challenges with Australia’s Existing Standards
Australia’s current standard for building in bushfire-prone areas, AS 3959, has limitations. While it establishes design requirements for various Bushfire Attack Levels or BALs, Australia’s testing methods, such as the AS 1530.8.2 fire test, inadequately model real wildfire behavior. It also penalizes thermally conductive yet noncombustible materials like steel, Watson said. He emphasized that the standard’s reliance on compartment fire testing fails to reflect the dynamics of actual wildfires, necessitating a more realistic approach.
The typical Australian steel frame design is resilient.
NASH’s Innovative Approach
NASH has taken a proactive role in developing advanced standards for steel-framed housing. Recognizing steel’s inherent noncombustibility and robustness, NASH initiated a project with the Commonwealth Scientific and Industrial Research Organization to design a cost-effective house capable of surviving a full range of wildfire exposures.
The CSIRO project objectives include:
- Using real wildfire heat profiles for testing
- Maximizing the use of noncombustible materials
- Developing solutions consistent with familiar building practices and energy efficiency standards
The project culminated in the creation of a low-rise, steel-framed test building, which underwent rigorous testing at facilities such as the NSW Rural Fire Service’s Eurobodalla Training Centre.
Key Design Solutions
The NASH bushfire standard incorporates several innovative features to enhance wildfire resilience:
- Noncombustible Cladding and Cavities: Steel cladding and insulated wall systems prevent flame and ember penetration
- Ember-Proof Linings: Specialized linings protect building interiors from ember ingress
- Heat-Resistant Windows and Doors: Enhanced glazing and seals withstand intense radiant heat
- Robust Subfloor Systems: Elevated steel subfloors minimize exposure to ground-level flames
NASH Bushfire Attack Level – Flame Zoon roof solution.
NASH Bushfire Attack Level – Flame Zoon steel clad wall solution.
NASH Bushfire Attack Level – Flame Zoon unenclosed subfloor solution.
Benefits of Steel-Framed Solutions
Steel’s noncombustibility makes it uniquely suited for wildfire-prone areas. NASH’s wildfire solutions deliver significant cost savings and construction efficiencies compared to traditional approaches.
For example, homes built to BAL-FZ (flame zone) standards using NASH methods can save over $30,000 AUD per house. Additionally, these structures offer high post-fire integrity, with reduced repair costs and shorter reconstruction times.
Expanding Steel’s Role in Mid-Rise Construction
Traditionally focused on low-rise buildings, NASH is now expanding its reach into mid-rise construction. This shift involves incorporating advanced research from Australian universities into fire design, acoustic performance and structural robustness.
Watson, who also chairs the NASH Standards Committee, emphasized that these developments would be integrated into future NASH Standards and Handbooks, further solidifying steel’s role in resilient construction.
Watson’s presentation highlighted the transformative potential of cold-formed steel in mitigating wildfire risks. By leveraging rigorous testing, innovative design, and cost-effective solutions, NASH is setting a new benchmark for resilience in bushfire-prone areas. As wildfires continue to challenge communities, steel-framed housing offers a durable and sustainable pathway to protecting lives and properties.
Additional Resources
- As Wildfires Rage On, One Homebuilder Urges a Shift to Steel Construction
- Examining the Surge in Mid-Rise Wood Construction Fires: The Case for Steel Framing
- California Homes Destroyed by Wildfires Being Rebuilt with Steel Framing