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Credit: Courtesy Rancho Santa Fe Fire Protection District

When last October's out-of-control wildfires pushed toward The Bridges, a Lennar Homes luxury development in Rancho Santa Fe, Calif., Lennar manager Key Ayers stayed put. After sending 140 employees home and seeing the community's well-heeled residents safely off, Ayers (who is also president of The Bridges' homeowners association) manned a water truck in the deserted neighborhood. For several hours, he and a handful of workers hosed down the occasional flaming bush or patch of windblown embers.

"I'm not going to tell you it was pleasant, because it wasn't," says Ayers. "The fire was 200 yards away, and it was hot and smoky. But we had good firebreaks [including the community's golf course], and the fire department was here too. And it worked out." When the flames had passed, not one of the development's multimillion-dollar houses had burned. Strict rules governing home siting, construction materials, landscape plantings, and brush clearing had done their job.

The fire district of Rancho Santa Fe lost 61 houses in the fire, and the rest of San Diego County lost hundreds more. But in the five Rancho Santa Fe developments designated "shelter-in-place" communities — including The Bridges — only one house suffered any damage. (In that case, a piece of pegboard leaning against a door caught fire and burned through the door into the garage — but sprinklers in the garage put the fire out in minutes.)

Rancho Santa Fe fire marshal Cliff Hunter says October's events were a true test of the fire-resistant concepts his district has begun to apply. The five successful developments faced the same onrushing wildfire as other areas of town where the destruction was much worse. But because homes were set back from slopes, and vegetative fuel near buildings had been thinned or removed; and because there were no vulnerable vents, windows, or lightly framed wood decks where embers could collect and ignite, fires raging up canyon slopes stopped cold at the edges of all five neighborhoods. According to a press report, a firefighter responded to thanks from residents of one community by saying, "We didn't really do anything."

Emphasis on Prevention

That anecdote contrasts sharply with the typical firefighter experience in runaway "conflagration" fires. More commonly, exhausted firefighters find themselves frustrated literally to tears by their inability to make even a dent in the raging fire as house after house is lost and crews are forced to retreat from unsafe — even deadly — conditions.

Reluctantly, the state's firefighting community has been forced to accept the reality that it will never have enough engines and crews to protect the increasing number of homes being constructed in rugged terrain subject to extreme, wind-driven wildfires. This realization has lead to greater emphasis on prevention. The California Department of Forestry and Fire Protection ("Cal Fire" for short) has resolved to build on the success of tough codes adopted at the municipal level in places like San Diego County. Although traditional efforts to fight the fires on the ground will continue, officials have adopted the toughest statewide code in the nation for ignition-resistant construction and landscaping in the "wildland urban interface" — or WUI — where so many houses have been lost over the years.

A new subchapter, Chapter 7A, in California's Title 24 ( the statewide building code) spells out strict requirements for ignition-resistant roof, wall, and deck construction in areas where wildfires are known to be likely. And rules for landscaping and site maintenance — already part of the state's fire code — have gotten tougher: Instead of a 30-foot brush-clearing requirement around homes, state law now calls for a 100-foot safety zone of "fuel modification."

Hazard zones. California is creating detailed new maps to go along with the new regs; they define the wildfire danger, dividing the whole state into zones officially labeled as having "moderate," "high," or "very high" wildfire hazard. (There is no "low" severity zone in California, says University of California, Berkeley, scientist Stephen Quarles: Aside from parts of the inner city and a few heavily managed agricultural areas, the whole state is at risk.)

As of January 1 of this year, the new Chapter 7A already applies to all three hazard severity zones throughout the State Responsibility Area, where Cal Fire has jurisdiction. Starting in June, authorities in the Local Responsibility Area, where municipal fire authorities have jurisdiction, must begin to enforce Chapter 7A, too — but only in the "very high" severity zone.

Some localities, including San Diego County, have already implemented rules as tough as — or even tougher than — the ones in Chapter 7A. Rancho Santa Fe's shelter-in-place neighborhoods may be a special case: The high-end developments, built in what Forbes magazine rates as the wealthiest zip code in America, have ample budgets to pay for the best in landscape maintenance and building details, and Cliff Hunter's office has the expert manpower to stay on the case with annual site surveys, intensive enforcement, and proactive education.

Cost of compliance. But building official Clay Westling, senior structural engineer for the San Diego County Department of Planning and Land Use, who has jurisdiction over Rancho Santa Fe as well as other, much less prosperous rural areas, says that it doesn't necessarily take a fat wallet to comply with his department's strict building rules.

"We have mobile homes in our county that comply," he notes. "If you take a simple, 1,000-square-foot slab-on-grade house, what do they need? It's not much. They need an ignition-resistant siding, such as fiber-cement board or stucco. They need a Class A roof: Asphalt composition shingles will qualify. They need dual-pane windows with tempered glazing; that adds maybe a thousand dollars. They need ignition-resistant soffit and eave materials, and they need to locate their vents on top of the roof instead of in the soffit. Overall it might come to $5,000. I don't think that's prohibitive."

The Ignition-Resistant House

Under contract to the state fire marshal, Stephen Quarles is now taking on the challenge of teaching interested parties the details of California's new statewide rules. In the last year, he has presented his comprehensive class more than 45 times to rooms filled with "everyone this code touches," he says, including "manufacturers, distributors, fire officials, building officials, contractors, architects, and designers."

For the benefit of builders, whose main responsibility is the structure, I asked Quarles in February to walk me through Chapter 7A's requirements for new homes and compare them with the additional measures required by Rancho Santa Fe's stricter rules. Here's what I learned.


In "very high" hazard severity zones, Chapter 7A requires a Class A roof. For "high" severity zones, builders can use Class B roofing, and in "moderate" zones, Class C. All these classes are defined elsewhere in the building code — the ratings depend on national standardized fire testing protocols — but in any case, Quarles points out, most builders already apply Class A roofs on houses throughout the state (as do most builders nationwide). "Class A roofs are the popular types," he says, "asphalt composition shingles, cement tile, and clay tile. All those either are noncombustible or else they pass the Class A test."

A few roof coverings — including, surprisingly, many metal roofing products — require additional fire-resistant underlayment or cementitious sheathing to achieve a Class A rating for the assembly. But fiberglass asphalt shingles, clay tile, and cement tile create a Class A roof system when applied over ordinary plywood and felt paper.

Roof valleys require special attention under Chapter 7A. Metal valley flashing has to be underlain with "cap sheet" (fiberglass-asphalt roll roofing) because flaming brands and embers can melt through sheet aluminum and ignite the roof sheathing and framing. Woven shingle valleys, however, don't require the underlayment.

Some roofing types (clay barrel tiles, for example) leave space between the roof covering and the roof sheathing — gaps that allow birds to enter and build nests, or windblown debris to accumulate. "These fine fuels are readily ignitable by embers that can blow up under there," says Quarles, "which will support flaming fire that can then ignite sheathing and roof framing."


Clay barrel-tile roofs are noncombustible and meet California's toughest standards. However, gaps under the tiles must be sealed to prevent debris accumulation and ember intrusion. Cement (top) and manufactured "bird stops" (bottom) are acceptable solutions.


So the gaps must be plugged, typically with manufactured "bird stops," but other materials — such as cement — are permissible with local approval. Cliff Hunter says cement is fine by him, and so are some types of metal mesh, though he recently denied a builder permission to use fine steel wool as a bird stop; exposed to flame and heat, the material can actually burn.