Climate-Proofing Your Home: Upgrades to Protect Against Wildfires
Climate-Proofing Your Home: Upgrades to Protect Against Wildfires
(Bloomberg) -- In the early hours of a sweltering Sunday in late September, a wildfire ignited in Deer Park, California, incinerating dozens of homes in the wine country hamlet. One home remained standing.
“I was sure it would be gone as this house is smack in the middle of where the fire started,” says Brendan Kelly, an architect whose Napa County firm designed a remodel and expansion of the 1970s concrete masonry home. The project was three-quarters done by the time the Glass Fire struck.
The erratic nature of wildfire means that it’s impossible to know for certain why any particular building is spared. But Kelly credits survival of the house and a separate garage at least in part to sound construction and the owners’ creation of a “defensible space” around the structures. “They’ve done a lot of clearing of oaks and pine trees, and there was no fuel load around the house,” he says. The house and garage also had metal roofs and sealed attics, preventing burning embers from infiltrating the buildings through air vents.
Making homes fire-resistant is no longer just a preoccupation of those who live in the so-called wildland-urban interface. That’s the overlap of development and woodlands where fire risk is high. The scale and ferocity of climate-driven conflagrations increasingly poses a risk to neighborhoods once thought safe from wildfire. Since August, 4.1 million acres in California have burned along with another two million acres throughout the Western U.S., forcing the evacuation of tens of thousands of residents, killing more than 30 people, and destroying thousands of houses.
The future of fire-resistant construction can be seen in the new homes rising from the ashes of the wildfires that have devastated California over the past four years. The materials and techniques that make them more impervious to fire can also be used to retrofit existing houses.
1. It takes a village
Michele Steinberg, director of the wildfire division at the nonprofit National Fire Protection Association, says urban and suburban areas, with their expanses of asphalt and concrete, have historically been considered “unburnable” and classified as at low risk from wildfires. Not anymore. Rising temperatures and dense, tinder-dry forests have resulted in uncontrollable, fast-moving infernos that spawn their own weather systems and shoot showers of embers over long distances.
“This is the new reality,” says James LeCron, a principal with Arri/LeCron Architects, a firm in Santa Barbara, California, that specializes in fire-resistant design. “You could be miles away from the actual fire and burning embers will fall on your roof and around your house.”
That’s what happened in Coffey Park. The state had designated the middle-class subdivision in the Northern California city of Santa Rosa as a low-hazard area before a 2017 wildfire burned the neighborhood to the ground.
Experts caution that fire-resistant construction increases the odds of surviving a wildfire, but is not a guarantee, particularly when embers rain down on an entire neighborhood. “If you’re in a place like Coffey Park, then your neighbor’s unprotected house can be a threat to your home,” says Stephen Quarles, an authority on fire-resistant construction and a former official at the University of California, Berkeley Center for Fire Research and Outreach. “It has to be a community-wide effort so that all homes are resistant to wildfire.”
“There’s a long list of things that can be done to retrofit a home,” he added, “but it’s difficult to give a generic prescription for all homes.
2. Finding the weakest spots
To start, says LeCron, “you want to harden the house from the exterior and look for weak links.” Begin at the top with the roof. Roofs made of wood or other combustible materials should be replaced with metal, clay tiles, or non-flammable composite shingles. The same goes for decks and balconies. Attic and foundation vents can suck in burning embers and burn the house down from the inside. Attach fine mesh screens to the vents or swap them for screens coated in materials that expand and seal the vent when exposed to high temperatures. Gutters and roofs should be kept clear of debris and vegetation pruned back at least five feet from the house.
LeCron and partner Karen Arri-LeCron say windows are often overlooked as a significant vulnerability to fire. Building codes may require double or triple-paned tempered glass to withstand fires but don’t specify the material to frame the windows. Commonly used vinyl frames will melt when exposed to high temperatures, causing the window to fall out and exposing a house’s interior to flames. Homeowners should make sure frames are fire-resistant. One option is installing shutters that automatically close when exposed to fire.
3. Don’t ignore the garage
Garage doors are another weak link. “They are usually cheap and not fire resistant,” says LeCron. “That’s a big entry point for fires.”
Exterior walls can be retrofitted with fire-resistant stucco or synthetic siding, such as environmentally friendly poly-ash, which is made of polymers and a byproduct from coal burning called fly-ash. “It won’t rot, it won’t burn, and you can work it and nail it like wood,” says Kelly.
“But there’s no one silver bullet,” he added, noting the effectiveness of a retrofit or new construction depends as much on the design and way the materials are assembled as the materials themselves.
4. The foam future of fireproofing
Wildfires often spur innovation. The 1923 Berkeley Hills fire destroyed nearly 600 houses in the Bay Area city, including the Bernard Maybeck-designed home of Kelly’s grandmother. In its wake, Berkeley’s iconic wood-shingled homes gave way to more fire-resistant stucco.
Arri/LeCron Architects are promoting another such transition with steel-and-foam building systems. A Nevada company called GigaCrete manufactures panels made with expanded polystyrene insulation foam that slot into steel frames to form walls. Once assembled at a building site, the exterior and interior surfaces are coated with a proprietary non-combustible material that resists temperatures up to 1,700 degrees Fahrenheit.
GigaCrete structures have also been rated to withstand wind speeds of 245 miles per hour. Kelly’s firm, Kelly + Morgan, designed a rebuild of a Santa Rosa home destroyed in the 2017 wildfires using a similar steel system called Bone Structure.
“Houses can be erected in matter of days, saving three to four months of labor costs,” says Arri-LeCron, adding that modern architecture, which typically eschews fire-prone attics, eaves and gutters, is particularly well-suited to such building systems. One downside: Training contractors how to build steel-and-foam homes.
Tom Laughlin moved into his new GigaCrete home in March near Clearlake, a rural community 110 miles northeast of San Francisco that has suffered back-to-back wildfires in recent years. “We’re seeing cost savings from the energy efficiency of the home and our ability to defend against fire,” says Laughlin, noting that the building’s tight seal also repels wildfire smoke, an increasingly frequent, health-threatening nuisance.
He’s keeping the vegetation around the home in check and the deck is made of fire-resistant material. “I think the house will stand for a long, long time,” he says.
The more homes that are retrofitted for fire-resistance, the greater the chance entire communities will survive extreme wildfires, notes Steinberg. “Are you going to lose a few homes? Probably,” she says. “Do you have to lose 10,000 homes? I don’t think so.”
©2020 Bloomberg L.P.