USA — An insurance industry study of the 2007 Witch Creek wildfire, which destroyed 1,700 structures in San Diego County, concluded that wind-blown embers caused most of the home fires and that homes less than 15 feet apart were more likely to burn – in clusters.
The study, the first of its kind, had indirect application to Stockton, where two large residential fires in June and July destroyed apartment units, condominiums and single-family homes.
Proximity to brush and undergrowth, as well as building materials, contributed to the June 10 Quail Lakes fire, which destroyed some houses while only damaging others. It started in the heavy vegetation along Interstate 5 south of the Benjamin Holt Drive offramp and was fanned by a stiff north wind.
The study by the Institute for Business & Home Safety concluded that in areas where houses are built near wildland, those structures on the perimeter of developments – basically any undeveloped, unfarmed rural area with at least heavy brush vegetation – were three to eight times more likely to burn than houses farther back in the development.
And the value of a house did not make any difference in its ability to survive a fire, according to the study.
The houses that fared best were those in three communities in which every home had common fire-resistant construction features, and a fire district-approved maintenance program kept away any nearby vegetation that could serve as fire fodder, concluded the study released Tuesday in Sacramento.
The research found that combustible fences and decks connected to houses were so effective in drawing a wildfire into structures that they might as well be called wicks.
The findings are especially relevant because of the growing danger from wildfires in the United States, where one-third of homes are in wildland areas where fires pose high risk to houses, institute President and CEO Julie Rochman said. Thirty-eight states have wildfire risks, and the risk keeps growing, she said.
“We are building and building and building in the wildlands,” she said.
The study said 5 million California homes are in wildland/urban areas. It recommended:
» Homeowners should retrofit their homes with affordable options to be more protected against wildfires.
» New home construction in wildfire-prone areas should have common fire-resistant construction features and have a maintenance program to control surrounding vegetation.
» New homes should be built and marketed for the ability to survive in wildfire-prone areas.
» Government leaders should be more proactive in ensuring adequate firefighting resources and prevention measures.
» Financial and real estate markets should start recognizing the value added to existing homes that have been retrofitted to withstand better the threat of wildfires.
The institute is a nonprofit research organization funded by the property insurance industry that looks at all kinds of catastrophic events, from storms to wildfires.
In October, the Witch Creek wildfire burned nearly 200,000 acres and damaged or destroyed more than 1,200 homes and 500 outbuildings, causing $1 billion in damage. That fire served as a good case study of why certain structures burned and others didn’t, Rochman said.
The study looked at nearly 3,000 homes in three “conventional” communities and three communities dubbed by San Diego County as “shelter-in-place” communities, where every home shared the same fire-resistive design qualities, including a fire district-approved plan to keep fire-fodder vegetation away from structures.
Recommended preventive features included noncombustible siding, decking and roofing materials; covered vents; fences not connected directly to the house; combustible yard structures, such as playground equipment, kept at least 30 feet from a structure; and reducing the vegetation within 100 feet of the house.
The study also found that while houses built within 15 feet of one another didn’t just burn but burned in clusters, not a single house burned that was at least 45 feet from others.
“That’s not a lot of difference, but it’s a hugely important factor when laying out a community,” Rochman said.
She praised a new update to California’s wildland urban building code that requires more fire-resistant construction practices. The code includes such requirements as attic vents, noncombustible siding, vegetation clearance around the house and a ban on wood in decking.
David Hillman, fire prevention and law enforcement chief with the State Fire Marshal’s Office, called the report “good stuff – right on point.”
Hillman said he’ll be working with the institute to use the study findings to help educate the public about wildfire risk and prevention.
Some cities and counties are starting to look at restricting construction in wildlife areas, he said. Or if they do allow it, they’re requiring wider roads and ample water supplies for firefighting, Hillman said.
But these lessons can be applied anywhere, he said, citing the recent fires in Stockton in which fire that started in overgrown weeds spread on a windy day and moved from one residence to another.
Steve Quarles, a University of California Cooperative Extension adviser in Richmond, said the new state code benefits owners of existing homes as well, because it details what they need to do and what materials they need to retrofit a house to be more resistant to a wildfire.
“It was harder to do two years ago,” he said.
The code also forces manufacturers to produce fire-resistant construction materials, said Quarles, a wood durability specialist who acts as a consultant to the institute as well as the State Fire Marshal’s Office.
Rochman said the study results can be used by insurance companies in working with customers on fire prevention measures, by government when considering new development and fire-fighting resources, and for educating people about wildfire risk and prevention.
Peter DeMarco, a senior corporate relations manager for Allstate Insurance Co., attended the news conference and said the study will help the company work better with customers when evaluating property for fire risks.
“The more steps people can take ahead of time, the better chance they’ll have to protect their homes from a fire,” he said.
Allstate paid $318 million on 7,000 claims from California wildfires last year, he said, and this year looks as if it’s on pace to be a record year at least for acreage burned and firefighters dispatched.