The map is published by the California Department of Forestry and Fire Protection, known as Cal Fire. Towns with areas considered very high risk must adopt the map as an ordinance in their Town Code, which the Danville Town Council voted to do at a recent meeting.
This means effective July 1 any new homes built within the zone must comply with certain building codes, regarding materials and exterior design, established by the state to reduce the risk of fire.
"Obviously with the current fire disasters we've been having it's something that's been very public lately," said Danville's chief building inspector Mike Leontiades. He gave a presentation on the topic at the council meeting.
More than 90 percent of the high-risk area in Danville is in or around Magee Ranch, with the rest mainly in Cameo Acres off Green Valley Road. There are about 200 parcels in the zone and most are already developed. Since the change does not affect existing buildings or even additions, "the impact will be very small," Leontiades said.
To determine an area's risk factor, officials study weather (average temperature, humidity and wind), slope (fires burn faster as they burn up-slope), terrain, access and type of vegetation.
The goal is to protect houses from embers produced by wild land fires. Embers can fly up to a mile away and retain enough heat to potentially ignite a building.
Town staff has compiled all the addresses that are in the zone; when someone applies for a permit to build within the area they will be notified of the high fire risk and told they must comply with special requirements.
"The designer or architect would need to verify that the components they're using ... comply with the standards in the building code," Leontiades said.
The code is part of the Wildland-Urban Interface Fire Area Building Standards adopted by the California Building Commission in 2005. The section that applies to Danville, Chapter 7A, is only three pages long and not difficult or costly to comply with, Leontiades said.
"I don't even think the cost would be more than just building a regular home," he said. "They're just going to make sure the materials you use resist ignition."
At the council's recommendation, Leontiades planned to contact the Homeowners Association for Magee Ranch to make sure the word went out to current and potential homeowners. A letter was also mailed last month to each household in the affected zone informing them of the new ordinance.