How to Design a Home that Can Better Withstand Wildfires

Carly Olson
·6-min read
Photo credit: Alice Morgan
Photo credit: Alice Morgan

From House Beautiful

In 2020, the LNU Complex fires in Northern California burned more than 375,000 acres and destroyed nearly 1,500 buildings. In September, smoke and ash caused the sky in San Francisco to turn an eerie orange—it looked apocalyptic, as if the sun never rose. The past decade alone has seen eight of the ten largest fires in California history. Homes are whisked away in seconds when a wildfire barrels through. And even hundreds of miles from a fire, ashes may rain down from the sky. As the worst wildfire season in California history draws to a close and many homeowners consider rebuilding, it’s time to decide how.

Though there are some statewide codes intended to protect homes against fire—like using tempered glass windows and sprinklers—they are not guaranteed to be effective. Some architects, designers, and homeowners are taking matters into their own hands, and have discovered some of the best ways to prepare one’s home for a potential wildfire.

Use non-flammable exterior materials

Randall Hauser, an architect and the founder and CEO of environmental consulting company ENPLAN, explains that choosing a proper exterior is one of the most effective ways to protect it from fire. “The part of the house that receives the brunt of the fire should all be some sort of non-burnable material,” he explains. When it came time to build his own home in Northern California 25 years ago, a rectangular prism built into the slope of the hill behind it, Hauser chose a stucco exterior, metal roofing, and minimal landscaping; the home is surrounded by pea gravel and concrete, no lush greenery. And that’s just what the eye can see—the walls and roof are extremely well insulated, while the windows are strong tempered glass. Hauser even used the natural hill on his property as added protection.

When the Carr Fire blazed through Redding, a small city in Northern California where Hauser lives, in 2018, the 16 homes closest to his burned to the ground—but Hauser's home was unaffected.

Surprisingly, even in Hauser’s neighborhood, wood exteriors are still some of the most popular. “Houses are made up of so much resin and hydrocarbon-based material,” Hauser says, citing plywood and its derivatives, like oriented strand board (OSB). OSB is made by combining bits of wood with resin and compressing it, and is especially at risk during a fire. Newer homes are often made using OSB, and, according to Hauser, “are far more vulnerable to wildfire… because it just peels apart when it starts to burn. And all of these layers of wood that were pressed together then become airborne. So they're a huge generator of a fire risk.”

Katherine Schwertner, architect and technical director at Richard Beard Architects, is also rethinking exterior materials in her projects. Few wood materials can be used for roofing in California, unless they are deemed compliant by the State Fire Marshal. But wood can still be used for exterior walls as long as it’s proven to be fire retardant or withstand a certain amount of fire. Though this doesn’t mean wood siding has to be entirely immune to fire, it’s whittled down some of the options previously used. “Those materials need to be tested,” Schwerner explains.

Or treat your exterior to be fire retardant

Swapping out siding is no small project. Which is why some folks have turned, instead, to treating their home's exterior to make it fire-proof. Jim Moseley—founder and CEO of Sun FireDefense, which devises fire prevention technologies—explains that one of his company’s most popular products called an “Intumescent Coating” is an invisible layer sprayed onto a home’s exterior, usually mixed in with a coat of paint. “We have a very high temperature, long lasting formula that basically is an aerospace-grade fire retardant,” Moseley explains. (The team developed this formula by using the aerospace technology that protects rockets upon their re-entry into the earth’s atmosphere!)

Even materials thought to be nonflammable—like stucco—can still burn, says Moseley, and should be treated accordingly. These intumescent coatings are usually just one part of Sun FireDefense’s treatment plan for a home or commercial building—they also utilize sprinkler systems, window treatments, and fireproof insulation. Moseley says, “There are a lot of things that we do to really shore up the house to give it its best shot.”

Simplify layouts and landscaping

Some of today’s most coveted home layouts (and those we’ve come to expect in the pages of our favorite shelter magazines) are not set up to withstand fires. Homes like Hauser’s—simple, rectangular, and nestled into a hillside—are better prepared for a blaze than a residence with terraces and wings. Hauser explains that “minimal exposure,” like a single-volume, is ideal. By keeping a home contained, there are fewer areas for a fire to penetrate and less roof surface area to inevitably become filled with tree leaves and pine needles, which would become a tinderbox. (Hauser says gutters and roofs should be cleaned once a week during fire season.)

Landscaping, too, should be rethought. In California, codes currently prohibit vegetation planted directly up to the side of a house. Instead, there should be a 30-foot gap between the home and trees, bushes, and gardens. Like Hauser’s advice on roofing, this is to prevent the vegetation from becoming kindling and catching a home on fire.

Schwertner says this has been a big adjustment in her work. She’s currently rebuilding a home in Napa, California that was burned in the fires over the summer. “I think that the biggest change has been the lack of landscaping, and having to keep that away from the building,” she explains. Clients want a lush look—but safety comes first.

Hauser, of course, went the extra mile, eschewing any landscaping at all around his home. “So there's nothing on the outside of the house itself that can burn,” he explains, only gravel. ”We can walk on it, we can run a wheelbarrow on it, and it's really handy, actually.”

Choose a fire-conscious design team

Though Hauser convinced one of his neighbors to put on a metal roof, most are rebuilding their new homes quite similarly to the ones that were lost during the Carr Fire. Hauser thinks that just following the state codes is not enough, and homeowners and architects should be doing more. “Are they using tempered glass? I would expect so. Are people avoiding wooden decks on the outside of the house? Probably, they're going to use something more fire resistant," he says. "I think I've seen a couple of houses in my neighborhood doing that.”

Despite all the damage of this year's fire season, Schwertner believes that the desire for a stylish home will continue to prevail over safety concerns, and the look of homes across the state won’t change that much. Which means it’s the job of the architect to create a compliant home that suits the client’s aesthetic vision. “There's ways that you can still achieve the look and feel that they might want, as well as make the building comply with the requirements of the state,” she says. “If people want what they want, then I think that will drive the market more.”

Follow House Beautiful on Instagram.

You Might Also Like