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Wood can actually be a green, fire-resistant building material

Cross-laminated timber, or CLT, is composed of layers of wood glued together at 90º angles and is more fire-resistant than traditional timber.

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Above, cross-laminated timber stacked at a manufacturing facility in Russia.
Above, cross-laminated timber stacked at a manufacturing facility in Russia.
Dimitar Dilkoff/AFP via Getty Images

For many people like me who lost a house to the California wildfires this year, the most pressing question is: Do we have the money to rebuild? But there’s another key question too: How can I rebuild in an environmentally-friendly way that’s also more likely to withstand fires?

Some are thinking about plastic insulation sandwiched between concrete; some like frames of steel. I’ve also been looking at wood.

Yep, you read that correctly. And that’s after the Eaton Fire turned all the wood in my old stick-and-stud house into grey ash.

Earlier this year, I was playing with a toy-sized, 3D-printed truck n a University of Oregon lab (and making incredibly realistic vroom vroom sounds). But then architecture professor Mark Fretz showed me the real attraction: a stack of scale-model wood panels on the truck, ready for hoisting.

I didn’t see any two-by-fours. Where are the studs?

“No studs in this house. This is all a flat panel,” he responded. It’s scaled full-size, and the panels can be tipped up onto a foundation to make a house. “A house that's similar to an IKEA dresser that you can take apart, and flat pack, and bring home.”

But it’s not the classic IKEA particle board: These panels can be made from what’s called cross-laminated timber, or CLT. It’s composed of lots of small boards glued together in criss-cross layers for added strength. In places like Oregon, they see gold in this engineered spruce, pine, or fir.

“To revive the timber economies through the use of mass timber is exciting to everybody,” said Judith Sheine, director of design at the Tallwood Design Institute and a University of Oregon architecture professor. “There's the idea of sustainable forest management and carbon sequestration, which interests people.”

Why would a person who just saw their house burned down want to rebuild with wood?

“It would be reasonable to ask that question, because it's been compared to building with kindling,” said Sheine. “It's a big, thick material that does not burn easily.”

Exposed to fire, mass timber turns black, and that sooty layer stops the fire from eating through the rest of the wood. CLT panels can be made from younger farmed trees or spindly ones culled from forests to lower the risk of wildfire and to allow the big trees to thrive.

And remember: Trees capture climate-altering carbon.

“If you can keep that carbon in a building material, you can sequester that carbon for hundreds of years,” Sheine said.

A government study found that a mass timber commercial building would have a nearly 70% smaller carbon footprint than an equivalent reinforced concrete one. So come for the fire and green benefits but stay for the design, if you like the look of natural wood over drywall.

“It's really — it warms the space,” said Maurice Rahming with O’Neill Construction Group.

He’s an Oregon contractor who’s worked with mass timber, including a piece of PDX, Portland’s wood-forward airport terminal.

“Especially on single-family but also on multi-family homes, it's going to be mostly all prefabricated to engineer specifications a lot quicker, easier,” Rahming said.

That said, CLT panels are more expensive than studs and thin plywood. The hope is that you save money on labor at the job site, where a single-family house can be boxed up in a week or so.

Apartment complexes and commercial buildings made of mass timber are springing up across the country, up to 18 stories tall. But in the U.S., only about 100 single-family homes use mass timber.

Steve Marshall runs the consultancy Mass Timber Strategy after a long career in the U.S. Forest Service. Old stick-and-frame habits die hard, he said, and you need more smaller mills to customize the panels for the smaller jobs. He’s now working on mass timber “microfactories.”

“Buying blank panels from the large manufacturers, and then providing them to these cutting centers, where the unique cutting of the panels will be done for specific buildings,” Marshall said. “And a lot of that target will be multi-family family but it will include single-family homes, as well.”

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