As fires in Eaton and Palisades spread rapidly among crowded homes, some residents took proactive steps to retrofit their homes with fire-resistant building materials and clear away flammable brush, becoming an important indicator of the homes’ fate.
A field study released Wednesday by the Insurance Institute for Business and Home Safety found that early adopters who cleared vegetation and flammable materials within the first five feet of their home walls fared better than those who didn’t do so under the state’s controversial draft “Zone Zero” regulations.
For more than a week in January, as the fires continued to burn, insurance teams inspected more than 250 damaged, destroyed and unscathed homes in Altadena and Pacific Palisades.
Fires destroyed 27 percent of homes on properties in Zone Zero, where most of the land was covered by vegetation and flammable materials; on properties where less than a quarter of Zone Zero was covered, only 9 percent were destroyed.
The Insurance Institute for Business and Home Safety, an independent research nonprofit funded by the insurance industry, conducted similar investigations of the 2012 Waldo Canyon Fire in Colorado, the 2023 Lahaina Fire in Hawaii, and the 2017 and 2018 Tubbs, Camp, and Woolsey Fires in California.
While some recent studies have found that homes with sparse vegetation in zone zero are more likely to survive fires, skeptics say there’s no scientific consensus on this.
Travis Longcore, senior associate director and adjunct professor at UCLA’s Institute for the Environment and Sustainability, cautioned that the insurance nonprofit’s results are only exploratory: The team did not analyze whether other factors, such as the age of the homes, affected the Zero Zone analysis, or how the nonprofit characterized the Zero Zone in its report, which he noted does not fully reflect California’s draft regulations.
Meanwhile, Michael Gollner, an associate professor of mechanical engineering at UC Berkeley who studies how wildfires destroy and damage homes, noted that the nonprofit’s sample is not a perfect representation of the entire burned area because the group focuses exclusively on damaged properties and is limited by active firefights.
Still, Gollner said, the nonprofit’s findings help tie together growing evidence of Zone Zero’s effectiveness from laboratory tests designed to determine the path fires take into homes with real-world analyzes of measures to protect homes in wildfires.
one Gollner’s recent research A study of more than 47,000 buildings in California’s five major fires (excluding the Eaton and Palisade fires) found that 37% of buildings that were cleared of vegetation in zone zero survived, compared with 20% that did not.
Once fires spread from wildlands to urban areas, homes become the primary fuel source. When a house catches fire, there is an increased chance that nearby homes will also burn. This is especially true when the house is crowded.
When looking at the full California Department of Forestry and Fire Protection data on the two fires, the insurance team found that “fortified” homes in Altadena and Palisades, with noncombustible roofs, fire-resistant siding, double-paned windows and enclosed eaves, were protected from damage at least 66 percent of the time if they were located at least 20 feet away from other buildings.
But when the distance was less than 10 feet, only 45 percent of the hardened homes escaped unscathed.
“The spacing between structures is the clearest way to distinguish what will survive and what won’t,” said Roy Wright, president and CEO of the Insurance Association for Business and Home Safety. At the same time, Wright said, “changing that is not feasible.”
By studying the steps residents are more likely to take, the nonprofit insurance agency found that the best approach is for homeowners to take as many home-strengthening and defensible space measures as possible. Each of these can reduce the risk of a home burning by a few percentage points, and taken together, the effect can be dramatic.
As for Zone Zero, the insurance team found numerous examples of how vegetation and flammable materials near homes can contribute to property damage.
At one house, embers appeared to ignite some hedges a few feet away from the building. The heat is enough to shatter a glass window, creating the perfect opportunity for embers to enter and burn the home from the inside out. Miraculously it survived.
Elsewhere, embers from the fires fell on trash and recycling bins near homes, sometimes burning holes in plastic lids and igniting the materials inside. At one point, a dumpster fire spread to a nearby garage door, but the house survived.
Wooden decks and fences are also common accomplices in helping embers ignite buildings.
California’s current draft Zone Zero regulations take some of these risks into account. They ban wooden fences within the first five feet of a home; the state’s Zone Zero Commission is also considering whether to ban nearly all vegetation in the zone or just limit it (well-maintained trees are allowed anyway).
On the other hand, the draft regulations do not ban the placement of bins in the area, which the committee believes would be difficult to enforce. They also don’t force homeowners to replace their wood decks.
Controversy surrounding the draft regulations centers on proposals to clear nearly all healthy vegetation, including shrubs and grasses, from the area.
Critics argue that given the financial burden that Zone Zero will place on homeowners, the state should focus on less costly and more effective measures.
“The focus on vegetation is misplaced,” said David Lefkowith, president of the Mandeville Canyon Association.
At the recent Zone Zero meeting, the Forestry and Fire Protection Committee directed staff to further study the affordability of the draft regulations.
“As the Board and subcommittees consider which package of options best balances safety, urgency and public feasibility, we will also turn our focus to implementation and seek state leaders to find resources to implement this first-in-the-nation regulation,” board executive Tony Andersen said in a statement. “The need is urgent, but we also want to invest the time necessary to make this happen.”
Home fortification and defensible space are just two of many strategies for protecting life and property. Insurance teams suspect that many of the near-misses they studied at the scene — homes that nearly burned but didn’t — ultimately survived thanks to firefighters’ intervention. Wildfire experts also recommend developing plans to prevent fires from starting in the first place and to manage wildlands to prevent severe spread of fires.
For Wright, the report is a reminder of the importance of community. The fate of any one home is tied to the fate of those nearby — it will take entire communities fortifying their homes and maintaining their lawns to reach herd immunity and prevent the fire from spreading.
“When collective action is taken, outcomes change,” Wright said. “Wildfire is insidious. It doesn’t stop at the fence line.”
