The challenges of fire-resistant rebuilding

A year after the fires in California, homeowners are worried about whether rebuilt homes can be insurance. Building and landscaping to keep fire out should help. We lost our house in Altadena, but we’re finding building in new ways for fire prevention isn’t easy.

Part of that is because many single-family homes in the United States are still built piece by piece on site, rather than being produced at scale in factories like so much else these days.

“You're back in the 19th century,” University of San Diego architecture professor Daniel López-Pérez said. “You’re building one two-by-four at a time. Our mission is to accelerate the production of housing, bringing technologies that are revolutionizing much larger buildings down to that individual house scale.”

One technology is called cross-laminated timber or CLT: thick wooden panels the size of garage doors that screw together quickly for walls, ceilings and floors. López-Pérez built a small house in San Diego from panels customized at a CLT factory. “Polyhaus,” as he calls it, was framed up by a crew of three in just two-and-a-half days.

“We optimize labor, right, where small general contractors building individual standalone houses are able to just build more units,” he said.

Building more faster is a big deal after a disaster like those fires a year ago. It also addresses the housing affordability crisis if, as López-Pérez calculates, with these panels you could get maybe five single-family homes enclosed in the time and with the labor it takes to get one home done by more traditional methods.

On the factory floor at Mercer Mass Timber in Spokane, Washington, general manager Matt Kramer walked me through the production process. You end up with clusters of thin boards of spruce ready to be pressed together, then glued into a wood sandwich.

That makes chunky panels as thick as your arm, or maybe your thigh, depending on the strength needed. Mercer customizes, grinding out rectangles for windows, doors, whatever, all right here.

“We're doing a lot of the front-end work off site in our manufacturing facilities,” said Nate Foster, Mercer’s director of preconstruction and project delivery. “So that when this product shows up on site, it's picked up with a crane, dropped into the correct location, and we're able to continue moving. We're sometimes seeing, you know, 15%, 20% savings on schedules.”

But after that firestorm a year ago, not one iota of wood was left at my ash pit of a property in Altadena. Me? Using wooden CLT to rebuild? Not crazy, according to López-Pérez.

“It's like trying to burn a phonebook,” he said. “It has this extraordinary resilience.”

Think about it. You use twigs as kindling. Not a stump. When I look at a chunk of CLT blasted with flame cannons at a government test lab, I see some of it charred away, but most stayed structurally intact.

In 2014, Seattle Architect Susan Jones designed and built one of the first single-family CLT homes in America, for herself. Inside of it I saw a whole lot of wood, wood and more wood — minimal drywall.

Jones also designed a 126-unit CLT apartment building recently opened in Seattle to get people housed using way less carbon-intensive concrete.

“We're talking about a replacement for our our 19th-century extraction economy from the forests, into a 21st-century high-tech wood material that can still provide the beautiful, biophilic experience of living with wood,” Jones said.

CLT can be made from sustainably-farmed lumber or from smaller trees taken out of forests, so the bigger trees can thrive, and to keep forests from catching fire. If this tech catches on, it could bring more jobs to downtrodden rural economies from forest to sawmill.

So why, one year after the fire, am I speaking from my still-empty lot in Altadena? The answer’s about money and expertise. The vibe from some builders has been, “Why can’t you just do it the old-fashioned way?”

CLT panels themselves are nearly twice as expensive as two-by-fours and plywood. You’re supposed to be able to make that up by deleting the usual cost of the labor for old-school framing and drywalling. We have pulled together a Volvo or Lexus-level rebuilding budget, but we don’t have Maserati-level money. Our plan is to keep trying to build a fire-hardy, single-story house at a price that makes long-term economic sense.