Recent wildfires inspire builders to make homes more fire resistant

Two major fires in Sonoma County since 2017 are inspiring builders and their clients to incorporate new measures to defend their homes against the onslaught of a raging fire.|

On a ridge above Geyserville, one new house stands alone in the burn zone.

The home, roughly 80% finished when the Kincade fire roared through the area in late October, is perfectly intact - not a single shingle out of place. Everything around it is black and charred.

Yes, firefighters beat back flames to protect the structure. But the home also saved itself.

Tempered windows withstood extreme temperatures and did not shatter. Fire-retardant siding made with cement stopped flames from overtaking the exterior. A metal roof prevented embers from penetrating the top. On top of this, a total of 100 feet of defensible space around the house minimized the likelihood that the place would catch fire.

In short, teams from Santa Rosa general contractor HybridBuild developed the 2,000-square-foot home to withstand a major wildfire and it did.

“The fire couldn’t take the house because of the upgrades,” said Tony Negri, co-owner of the company. “You could look at what happened and say, ‘They got lucky,’ and they did, but really it was just a case of some of these extra (innovations) working the way they were supposed to work.”

The Geyserville house is a perfect example of how careful construction and an emphasis on fire resilience can put homes in a better position to withstand the onslaught of a raging fire.

Put differently, as climate change and other, naturally occurring factors wreak havoc on Sonoma County ecosystems, the anecdote offers textbook examples for the kinds of features and construction methods that homes of the future likely will need as wildfires become a more regular part of our collective reality.

“Nature (will) always be in charge,” said Tennis Wick, director of the county’s Permit and Resource Management Department. “We can no longer afford to armor our way out of risk with concrete, steel and bunkers. We need to respect nature and work with it.”

As Wick suggested, a key component to making homes more resilient is preparing for the worst.

For many developers, this means abiding by rules and regulations for building in what is known as the Wildland-Urban Interface, or WUI. (Contractors colloquially refer to this as woo-ey.)

These rules are laid out in Chapter 7A of the California Building Code. Currently, at least in Sonoma County, this means all new structures must be “built with exterior construction that will minimize the impact on life and property and help structure to resist the intrusion of flames and burning embers projected by a wildland fire and contributes to a reduction of losses.”

Contractors have responded by implementing several different tools and products to “harden” homes to fire. Negri’s company has turned to tempered glass windows, metal roofs and fiber cement siding. One particular project, a spacious new home under construction in downtown Healdsburg, features fiber cement siding.

Other firms have experimented with rammed earth construction, as well as Insulated Concrete Form (ICF) products such as Rastra blocks, which are made with foam, and Faswall blocks, which are made with wood chips and particles.

While many of these products make homes more resistant to fire, they also are more expensive.

Prices for ICF and fiber cement products can run as much as 20% higher than current industry standards. At last check, a standard wood-frame and stucco wall cost about $12 per foot, while a rammed earth wall usually costs about $100 per foot.

Budget has been one of the driving factors behind the recovery effort at Pepperwood Preserve, which lost some buildings during the Tubbs fire in 2017. In order to keep costs down, the Pepperwood Foundation hired San Francisco-based architectural firm Mithun to redesign and rebuild key structures with steel, metal roofs and stucco walls.

Antonio Pares, principal at Mithun and lead designer on the Pepperwood project, said his clients considered more expensive options but ultimately decided to choose a strategy laypeople could afford.

“They shied away from expensive stuff, figuring that most people don’t have endless pocketbooks, and set out to rebuild in the smartest and most economical way possible,” said Pares, who noted that some of the new structures also have thick timber beams. “They wanted to set an example.”

The case of Pepperwood is particularly interesting, since the 3,100-acre parcel of open space is part of a swath of the Mayacamas Mountains that endured both the Tubbs and the Kincade fires. For this reason, Pares said Mithun also has focused on landscape architecture, creating more space between buildings and 100-year-old oak trees and replanting native grasses that don’t catch fire as easily as some of the underbrush that was there.

As contractors look to the future, many are considering additional improvements to make homes more resilient to wildfire.

Several of these innovations fall into the category of fire suppression.

At some homes, for instance, landscape architects are getting creative with how they design defensible space and how irrigation systems can contribute to keeping the main structure safe. Negri said his team has contributed to a few jobs with sprinklers that are kicked on during a fire and hit the property with consistent water to keep things wet.

He added that other clients have requested external sprinkler systems in the eaves of their homes so that if a fire does reach the structures, the homes essentially can defend themselves.

“I see this becoming common in high-risk areas,” he said. “Something like this obviously never would take the place of a firefighting crew, but maybe it helps the homeowner buy some more time until the crew arrives.”

Many of these systems need reliable power to function property, so contractors also have started specializing in ways to deliver electricity. Especially with the recent spate of preemptive power shut-offs from PG&E, companies have seen a spike in demand for backup power generators with an automatic transfer switch - a device that turns on backup power as soon as the regular power source goes out.

Negri noted that depending on the size of the home and the generator, these systems usually cost between $12,000 and $20,000.

“There are plenty of options these days to make a home more resilient to fire,” he said. “Whether we’re talking about materials or design, it’s my responsibility as a contractor to provide information so clients can make knowledgeable decisions to put their homes in position to (make it through the next event).”

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