Portola Valley may change roof rules Portola Valley may change roof rules (August 18, 2004)

** The goal is to make them more fire-resistant.

By David Boyce
Almanac Staff Writer

The roofs of new homes in Portola Valley will have to meet a tougher standard of fire resistance if the Town Council follows the staff recommendation and amends the existing town ordinance.

The change may also apply to any re-roofing job in which 50 percent of a roof's structure -- framing included -- is removed.

The council discussed changing the Class-B requirement for new roofs to a Class-A requirement at its August 11 meeting. A vote on the amendment could come at the next council meeting, scheduled for 8 p.m. Wednesday, August 25, in the Historic Schoolhouse.

The change from Class B to Class A basically consists of adding a layer of fire-retardant material such as sheetrock between the outer layer of roofing material -- often shingles or wood shakes -- and the substrate layer that sits on the rafters, typically plywood.

The staff report estimates the change could add an average of $7,500 in material costs for a 3,000-square-foot roof. And because a Class A roof weighs more than a Class B roof, the change could also raise costs of a re-roofing job to pay for planning department verification of the carrying capacity of existing rafters, the report said.

The staff report notes that a roof is only one of many vulnerabilities to a fire. Balconies, trellises, decks, stairs, and surrounding vegetation are among the other potential fuel sources.

A fire-resistant roof may be all that's left after a fire if the rest of a house is not protected, the report said.

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