Sunshine pours through the large windows of the just-opened Catalyst Building in Spokane, Wash., bathing the wood beams and laminated wood floor and ceiling panels.

The five-story, 150,000-square-foot structure is the newest of 384 large “mass timber” buildings in the United States. The technique was first used in 2011, and one of the earliest examples was T3, a seven-story, 221,000-square-foot office building in Minneapolis. According to industry figures, 500 more are under construction or planned.

The Catalyst was built by Katerra, a construction company based in Menlo Park, Calif. The cross-laminated wood panels used for it were manufactured at Katerra’s 270,000-square-foot automated plant. The $150 million plant is the newest and largest of nine in the United States that make laminated wood panels, with three more in development.

Both the building and the plant are at the leading edge of the fast-growing market for tall wood buildings constructed of the laminated panels, beams and columns that the industry calls mass timber.

Developers are turning to wood for its versatility and sustainability. And prominent companies like Google, Microsoft and Walmart have expressed support for a renewable resource that some experts believe could challenge steel and cement as favored materials for construction.

“We are making huge headway in the U.S. now,” said Michael Green, a leading mass timber architect for Katerra who designed the Catalyst Building and several more in North America.

Wood has several advantages over other building materials, including the ability to help curb climate disruption, that are driving the interest, he said.

Steel and cement generate significant shares of greenhouse gases during every phase of their production. By contrast, wood stores carbon, offsetting the emission of greenhouse gases.

“The environmental aspects alone are attractive,” Green said. “Cross-laminated timber panels are faster to assemble. There’s much less construction site waste.”

Demand is so strong that the number of construction projects could double annually and reach more than 24,000 by 2034, according to a report released by the Forest Business Network, an industry trade group.

Walmart has turned to mass timber as it replaces its headquarters in Bentonville, Ark., with a 350-acre corporate campus. Demolition is underway to make room for 12 cross-laminated timber buildings encompassing 2.4 million square feet. The largest is 332,000 square feet, and the tallest is five stories.

The Minneapolis impact

Another significant promoter is Hines, a global real estate investment, development and management firm based in Houston. Four years ago, Hines opened T3 at 323 N. Washington Av. in Minneapolis. Also designed by Green, when it opened, it was the nation’s largest mass timber building.

The wood structure cost $60 million, 5 to 10% more than one built with concrete and steel. But the ease and speed of lifting and fitting manufactured pieces into place saves money on labor, said Steve Luthman, a senior managing director at Hines.

In addition to the labor savings, tenants are attracted to wood surfaces in work spaces. Hines sold the building in 2018 for $392 per square foot, a record for a Minneapolis office building.

The company has since built a similar six-story, 200,000-square-foot mass timber office project in Atlanta. It is also constructing a 10-story wood office building on Toronto’s waterfront, one of three it plans in that city. And it is in various stages of design and development for mass timber office buildings in Denver, Nashville and the Raleigh-Durham area in North Carolina.

“Our industry is on the precipice of broad adoption of mass timber for construction,” Luthman said.

One of the biggest critics of the technique has been the $43 billion ready-mix concrete industry, which produces 307 million cubic yards of concrete annually in the United States for building construction, or 83% of total projects. Fearing that wood will nudge concrete aside, the industry’s national association formed Build With Strength, an advocacy group that asserts, among other critiques, that tall wood buildings are not safe.

“Have we not learned our lesson about increased density with combustible construction?” said Gregg Lewis, executive vice president of National Ready Mixed Concrete Association. “We’ve seen what happens when we build cities out of wood.”

To counter claims that mass timber buildings are unsafe, developers have financed scientific studies and collaborated with university research groups to show big wood panels and stout support beams defied fire and performed well in earthquakes.

The findings have persuaded building code regulators and municipal permitting agencies to relax height restrictions for tall wood buildings. In Milwaukee, city authorities allowed New Land Enterprises and Wiechmann Enterprises to build Ascent, a 25-story, $125 million downtown residential building. Ascent is 4 feet higher than the 280-foot Norwegian mass timber building that opened last year and was considered the world’s tallest wood tower.

Environmentalists also are comfortable with mass timber. Katerra engineers say the average diameter of trees used for panels is 12 inches. No old-growth trees are used to produce cross-laminated panels.