University of California

Fire Safe Structures in Wildland Urban Interface


Wildfires roar through tens of thousands of California’s forests every year. They devour dozens to hundreds of homes built in high- risk areas known as the wildland urban interface.

As a result, more than 100 Fire Safe Councils have been established in the state over the last few years, and communities, such as those in San Diego County, which have seen tremendous damage to whole neighborhoods, are allocated hundreds of thousands of dollars to wildfire education and outreach.

Steve Quarles, a UC Cooperative Extension advisor, does research into fire-safe structures. At the University of California Richmond Field Station, he and other fire experts tested materials and structures at the UC Forest Products Laboratory.

They evaluated different types of roof coverings, exterior siding, windows, vents, gutters, and decking materials, including solid wood and the newer plastic and plastic lumber composites.

“Except for roof materials, there weren’t really any standard tests to evaluate materials located on the outside of structures and exposed to wildfires,” explains Quarles. The protocols they developed were handed over to California Office of the State Fire Marshal, whose office developed building codes for homes located in the urban interface areas.

“This would affect new construction,” says Quarles, “and the objective would be to make homes more fire safe under wildfire conditions.”

They also built a demonstration house to show the results of that research.

“In this building, we show features that would be considered good from a fire-safe perspective for a house, but also features that are not good,” says Quarles as he conducts a tour through the tiny structure. “And some features that are conflicting so that we can discuss advantages and disadvantages and tradeoffs in terms of material performance and design.”

Until recently, most fire-prevention in the wildland urban interface had focused on vegetation. Homeowners were advised to keep a wide buffer around their houses, to keep grasses mowed and large bushes away from structures. But little emphasis had been placed on the structure itself.

That’s not a good thing, says Quarles. And if you think about the difference between how a normal house fire is handled and how a wildfire, especially a catastrophic wildfire, moves and is fought, it’s easy to understand why fire-prevention experts advise homeowners who live in high-risk areas to build or modify structures to be fire-safe.

In a normal house fire, one that starts on the inside, the fire department sends fire trucks and firefighters to battle just that fire and to keep it from spreading to adjacent structures. But for the extraordinarily fast-moving wildfires, which can move 40 miles a day, the focus is mostly on stopping the blaze, whose front may extend for miles. Firefighters do their best to prevent the fire from burning homes, but it’s often impossible to do.

“Once fire gets into your house, then the chances of your house surviving are far less,” explains Quarles, “particularly if you’ve evacuated. It’s really hard to guarantee that a firefighter would be available for your house. There are a lot of houses out there that would be threatened, and it’s just hard to guarantee that a firefighter would be able to protect every house out there. You need to do what you can to protect your own house, assuming that the firefighter won’t be there.”

That’s why it’s so important for those who live in these areas to look at fire-prevention as a whole system ­ that includes the vegetation, the terrain, and the house.

With funding from the Renewable Resources Extension Act, which is administered by UC Cooperative Extension, Quarles and other fire- prevention experts were able to host workshops for homeowners, landowners, agencies and planners. Quarles and Professor Emeritus Frank Beall have developed an online guide to help homeowners called the Homeowner’s Wildfire Mitigation Guide. It can be found at http://groups.ucanr.org/HWMG/.

by Jane Ellen Stevens
July 2006

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