Council members said they would consider incentives to encourage residents to replace aging ignitable roofs, of which there are too many to count within the district, Ms. Enea noted. Grants are one possible funding source for such incentives, she said.
The small audience of about 15 people included two who spoke in defense of treated shake roofs, two local roofers, and three representatives of the insurance industry.
Shake roofs, Ms. Enea said, can be a source of firebrands — burning embers that can become airborne and spread a fire beyond its current boundaries. "Wood shakes traditionally have posed significant problems in fire spread and ember propagation," Ms. Enea told the Almanac. Insurance companies "very often" won't insure houses with shake roofs even if they're treated for fire resistance.
If chemically treated shakes, over time, lose even some of their resistance, it puts the home and the neighborhood at risk, she added.
"We try (to) reduce risks by mitigating potential ignitions and methods of spread, often using information from previous fires," she said. "For example we know and have experienced the extreme flammability of eucalyptus and its significant ember propagation, and many property owners are electing to remove them. We have also experienced wood-shake roof fires and understand the vulnerability and spread characteristics."
Go to tinyurl.com/fire32 for a September 2013 New York Times article on wildfire, which Ms. Enea recommends people read.
About treated shakes
Bill Hendricks, a consultant from Clarksburg, California, and spokesman for Chemco treated wood shakes, told the council members of tests that show Chemco shakes charring rather than burning, and that the charring will stop without an external flame to encourage it.
"We're no different than a lot of the other materials out there," he said. "There are no reports of embers landing on a treated roof and having it catch on fire. (Flame on a shake) creates a char barrier that starves oxygen."
Chemco has come up with a process that "actually works," said Don Oaks, a former fire marshal in Santa Barbara County and a fire-protection consultant now based in Solvang in Central California. "It works.You have a safe roof," Mr. Oaks said. The fear among insurance companies, fire districts and the public is result of "a bumper sticker approach, but not a lot of research."
Tully Lehman, the Northern California spokesman for the Insurance Information Network of California, told the councils that there are as many different takes on shake roofs as there are among the 135 insurance companies in California. It's best to ask one's neighbors, he said.
Homes in the hills above Woodside are particularly hard to insure, especially those with shake roofs, said Gregg Georgakas of Woodside Insurance Services in Woodside. A non-standard insurer may take it on, but at two to three times the expense, he said.
San Mateo County has 270,000 homes, Mr. Lehman said, and 39,000 of them are in areas of high to severe risks of wildfire. Roofs are the first line of defense, and a self-extinguishing fire-resistant roof "is your chance to actually become a firefighter to help save your house," he said.
More data needed
Ms. Enea said she has questions that, so far, have gone unanswered: What are the chemicals used in the treatment? How much do they leach into the environment and drainage systems? How effective will the fire retardant be over a roof's life?
"I don't know of many home building products that are as good in 10, 20 or 30 years as they were the day they were installed," she told the Almanac.
At the meeting. Mr. Hendricks said he had no data on effectiveness beyond 10 years and that the fire-retardant formulas are a trade secret. As for leaching, he dismissed it. "Every roof is going to get runoff," he said. "You're not going to get tap water."
Portola Valley and Woodside have come a long way in defending against wildfire, Ms. Enea told the Almanac. In her early days as fire marshal, she said the towns weren't interested in mitigating the fuel load or creating adequate defensible spaces around their structures. "We've come 180 degrees," she said.
The drought is very serious and the speakers before the council don't live here, she added. "I think we've got to be very careful."
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