Are California’s wildfire building codes enough?
are california's wildfire building codes enough?
New perspective of Chapter 7A requirements reveals coverage gaps
The images from the Palisades and Eaton Fires are devastating…entire neighborhoods reduced to ash, homes built just years ago to the current wildfire standards completely destroyed alongside their older neighbors. For architects, builders, and homeowners in California's wildland-urban interface zones, these fires have forced an uncomfortable question: Are our current building codes actually protecting structures from wildfire?
We wanted answers. So we conducted a detailed comparison of three major wildfire building codes: California's Chapter 7A, the International Wildland-Urban Interface Code (IWUIC) used in six other states, and Australia's AS 3959 standard (developed in a country with decades of bushfire construction experience).
What we discovered is both enlightening and concerning.
the testing gap: when lab standards don't match reality
In reviewing dozens of rebuilding projects from the Palisades and Eaton Fires, we made a troubling observation: homes built after 2008 with full Chapter 7A compliance details in their permitted drawings were completely destroyed. This includes homes with products specifically listed under California's SFM 12-7A-1 standard.
Why would code-compliant homes fail? The answer lies in how materials are tested versus how wildfires actually attack buildings.
California's SFM 12-7A-1 standard relies on NFPA 285, a test designed to evaluate vertical fire spread from an interior compartment fire. But wildfires don't behave like interior fires. They subject buildings to:
- Hours of radiant heat exposure (not minutes)
- Continuous ember bombardment accumulating on surfaces
- Direct flame contact from multiple sources
Research from Western Sydney University found that some materials like brick vastly outperform others in real wildfire conditions despite all passing the same standard tests. The testing gap is real, and it matters.
three different approaches to wildfire protection
California Chapter 7A
- Blanket requirements regardless of site-specific hazard
- Multiple compliance options with varying protection levels
- Leaves design teams to tend toward least-cost options
- Strengths: Rigorous roof and vent requirements
IWUIC (6 US States)
- Site-specific hazard analysis required
- Four classes of Ignition-Resistant construction
- Graduated requirements based on assessment
- Strengths: Balanced approach with flexibility
Australia AS 3959
- Detailed site hazard assessment
- Six Bushfire Attack Levels (BALs)
- Progressively restrictive by hazard level
- Strengths: Most comprehensive glazing and detail requirements
the window problem: a 100% failure rate
One of our most concerning findings relates to windows, often the most vulnerable point in a building's fire defense.
Chapter 7A allows window frames of any material as long as there's one pane of tempered glass. But a Fire Safety Research Institute study revealed a shocking result: 100% of vinyl-framed windows failed during fire exposure testing, while 70% of wood-framed windows with the same glass survived.
The Detail Matters
Australia's AS 3959 recognizes this vulnerability and requires:
- Metal-reinforced PVC frames minimum (not unreinforced vinyl)
- 4mm tempered glass minimum (vs. the common 1/8" [3 mm] in California)
- 6mm glass with metal frames in highest hazard zones
- Option for bushfire shutters at any hazard level
These aren't arbitrary requirements…they're based on real-world experience.
the suburban conflagration factor
Perhaps the most critical insight from our research is how poorly Chapter 7A addresses structure-to-structure ignition in dense suburban development.
The code requires 100 feet of defensible space, but what happens when your lot is only 50 by 120 feet and your neighbor's wood fence is 5 feet away? Chapter 7A was designed for rural scattered development, not the dense suburban neighborhoods we're now seeing burn.
what design professionals should do now
We shouldn't wait for code updates. Based on our analysis, here are four specific recommendations architects and builders can implement immediately:
1. Conduct Site-Specific Hazard Assessment
Use methodologies from IWUIC and AS 3959 to evaluate your actual exposure: adjacent structures, vegetation proximity, topography, and prevailing weather patterns. This assessment should drive construction selection, not just minimum code compliance.
2. Prioritize Fire-Rated Assemblies in High-Exposure Conditions
Where radiant heat from adjacent structures is likely, specify 1-hour fire-rated assemblies rather than relying on material listings alone. The marginal cost increase is negligible compared to total loss.
3. Add Type X Sheathing Under Vulnerable Cladding
Fiber cement can explosively fail when superheated. Metal siding transfers heat directly to combustible framing. Adding 5/8" Type X gypsum sheathing under these materials provides critical redundancy that Chapter 7A allows but doesn't require.
4. Upgrade Window Specifications
Avoid unreinforced vinyl frames entirely. Specify metal or metal-reinforced polymer frames with 5/32" (4mm) minimum tempered glass on the interior pane, increasing to 3/16" or 1/4" for higher hazard exposures.
download the complete research report
Our detailed white paper compares all three codes side-by-side across 22 construction and site improvement categories, with a comprehensive 15-page reference table showing specific requirements for roofs, walls, openings, and more.
DOWNLOAD WHITE PAPER (PDF)beyond prescriptive compliance
The fundamental lesson from comparing these three wildfire codes is this: prescriptive compliance isn't enough when faced with a spectrum of hazard conditions.
Chapter 7A's strength, offering multiple compliance pathways, becomes its weakness when design teams default to minimum requirements without understanding actual site hazards. The code allows SFM-listed cedar shingle siding and 1-hour stucco walls as equivalent options, despite dramatically different fire performance.
Australia's approach, progressively more restrictive requirements as hazard levels increase, makes intuitive sense. A home surrounded by dense eucalyptus forest on a steep slope should not be built to the same standard as one in an open grassland.
The lesson is a paradigm shift for design professionals: from accepting blanket requirements with permissive options to using site-specific assessment driving appropriate construction methods.
the path forward
Even a 20% improvement in structure survivability rates would save thousands of homes and billions in losses when the next major wildfire strikes a populated area. The knowledge to achieve this exists and is growing each year.
We don't need to reinvent the wheel. We need to:
- Adopt site-specific hazard identification similar to AS 3959
- Implement construction methods that match identified hazard levels
- Push for systematic performance data from every major fire event
The responsibility falls on design professionals and informed property owners to go beyond minimum code compliance. Understanding the actual hazards your building faces, and selecting construction methods that address those specific threats, is the most effective path to improved survivability.
The next fire will come. The only question is whether we'll use the knowledge we have to build structures that can withstand it.