Here’s a grim fact: The most destructive fires in recent American history swept over a state with the country’s strictest wildfire-specific building code, including in some of the neighborhoods that are now largely smoldering rubble.
California’s wildfire building code, Chapter 7A, went into effect in 2008, and it mandates fire-resistant siding, tempered glass, vegetation management, and vents for attics and crawlspaces designed to resist embers and flames. The code is the “most robust” in the nation, Lisa Dale, a lecturer at the Columbia Climate School and a former environmental policy advisor for the State of Colorado, told me. It applies to nearly any newly built structure in one of the zones mapped out by state and local officials as especially prone to fire hazard.
The adoption of 7A followed years of code development and mapping of hazardous areas, largely in response to devastating urban wildfires such as the Tunnel Fire, which claimed more than 3,000 structures and 25 lives in Oakland and Berkeley in 1991, and kicked off renewed efforts to harden Californian homes.
The Federal Emergency Management Agency’s report on the 1991 fire makes for familiar reading as the Palisades and Eaton fires still smolder. The wildland-urban interface, it says, was put at extreme risk by a combination of dry air, little rainfall, hot winds blowing east to west, built-up vegetation that was too close to homes, steep hills, and limited access to municipal water. The report also castigates the “unregulated use of wood shingles as roof and siding material.”
This was not the first time a destructive fire on the wildland-urban interface had been partially attributed to ignitable building materials. The 1961 Bel-Air fire, for instance, which claimed almost 200 homes, including that of Burt Lancaster, and the 1959 Laurel Canyon fire were both, FEMA said, evidence of “the wood roof and separation from natural fuels problems,” as were fires in 1970 and 1980 near where the Tunnel Fire eventually struck in 1970 and 1980.
But it was the sheer scale of the Tunnel Fire that prompted action by California lawmakers.
Throughout the 1990s, fire-resilient roofing requirements were ramped up, designating which materials were allowed in fire hazard areas and throughout the state. By all accounts, the building code works — but only when and where it’s in force. Dale told me that compliant homes were five times as likely to survive a wildfire. Research by economists Judson Boomhower and Patrick Baylis found that the code “reduced average structure loss risk during a wildfire by 16 percentage points, or about a 40% reduction.”
“The challenge from the perspective of wildfire vulnerability is that those codes are relatively recent, and the housing stock turns over really slowly, so we have this enormous stock of already built homes in dangerous places that are going to be out there for decades,” Boomhower told me.
The 7A building code applies only to new buildings, however. In long-settled areas of California like Pacific Palisades, which has little new housing construction or even existing home turnover due to high costs and permitting complications, especially in areas under the jurisdiction of the California Coastal Commission, many houses are not just failing to comply with Chapter 7A, but also with any housing code at all.
Looking at which homes had survived past fires, Steve Quarles, who helped advise the California State Fire Marshal on developing 7A, told me, “What really mattered was if it was built under any building code.” Many homes destroyed by the fires in Los Angeles likely were not. In Pacific Palisades, fire management is a frequent topic of concern and discussion. But as late as 2018, local media in Pacific Palisades noted that the area still had some homes with wood shingle roofs.
While a complete inventory of homes lost in the Palisades and Eaton fires has yet to be taken, the neighborhoods were full of older homes. According to CalFire incident reports, of the almost 47,000 structures in the zone of the Palisades Fire, more than 8,000 were built before 1939, and 44,560 were built before 2009. For the Eaton Fire area, of the around 41,000 structures, almost 14,000 were built before 1939, and only around 1,000 were built since 2010.
A Pacific Palisades home designed by architect Greg Chasen and built in 2024, however, survived the fire and went viral on X after he posted a photo of it still standing after the flames had moved through. The home embodied some of the best practices for fire-safe building, according to Bloomberg, including keeping vegetation away from the building, a metal roof, tempered glass, and fire-resistant siding.
When Michael Wara, the director of Stanford University’s Climate and Energy Policy Program, spoke with firefighters and insurance industry officials in the process of drafting a 2021 report for the Stanford Woods Institute for the Environment on strategies for mitigating wildfire risk, they told him that, from their perspective, wildfires are often a matter of “home ignition,” meaning that while building near forested areas puts any home at risk, the risk of a home itself igniting varies based on how it’s built and the vegetation clearance around it. “Existing homes in high fire threat areas” built before the implementation of California’s wildfire building codes, Wara wrote, “are a massive problem.” At the time he published the paper, there were somewhere between 700,000 and 1.3 million pre-building code homes still standing in “high or very high threat areas.”
The flipside of focusing on “home ignition” and the building code is that the building code works better over time, as more and more homes comply with it thanks to normal turnover, people extensively renovating, or even tearing down old homes — or rebuilding after fires. Homes that are close to homes that don’t ignite in a fire are more likely to survive.
One study that looked at the 2018 Camp Fire, which destroyed more than 18,000 structures and claimed more than 80 lives in the Northern California town of Paradise, sampled homes built before 1997, between 1997 and 2018, and from 2018 onwards, and found that only 11.5% of pre-1997 homes survived, compared to 38.5% from 1997 and after. The researchers also found that building survivability had a kind of magnifying effect, with distance from the nearest destroyed structure and the number structures destroyed in the immediate area among “the strongest predictors of survival.”
“The more homes that comply, the less chance you get those structural ignitions and the less chance you get those huge disasters like this,” Doug Green, who manages Headwaters Economics’ Community Assistance for Wildfire Program, told me. “It takes people doing the right thing to their own home — dealing with vegetation, making sure roofs are clean, having right roofing. It’s really a community-wide strategy to stop fires that happen like this.”
But just as any home hardening — or just building to code — is more effective the more the homes around you do it as well, it’s just as true in reverse. “If your next door neighbors don’t do that work, the effectiveness of your efforts will be less,” Dale said. “Building codes ultimately work best when we get an entire landscape or neighborhood to adopt them.”
Oh, Canada!EIA
