Towers of wood, not steel

The movement to construct tall buildings largely with wood as an environmentally friendlier alternative to steel and concrete has received a boost from an unusual source — a leading architectural firm known for its towers of steel and concrete.

Skidmore, Owings & Merrill, the Chicago-based firm that has designed a long list of skyscrapers, including the new One World Trade Center in Lower Manhattan, has developed a structural system that uses so-called mass timber — columns and thick slabs that are laminated from smaller pieces of wood. In a report this year, the firm showed how the system could be used to build a 42-story residential tower that would have a lower carbon footprint than a conventional structure.

“We wanted to see what we can do to help on the sustainability side,” said William F. Baker, a partner in the firm. With its system, about 70 percent of the structural material is wood; most of the rest, including the foundation, is concrete.

Benton Johnson, an engineer who worked on the report, said wooden high-rises could help solve the problem of providing adequate housing to the billions of people living in cities — while also addressing climate change.

“We know that we need to build a lot more buildings,” Mr. Johnson said. “And we know that we need to lower CO2.”

Until now, tall wooden buildings had been championed by architects and engineers mostly from smaller firms outside the United States. They welcomed the Skidmore, Owings & Merrill report.

Michael Green, an architect in Vancouver, British Columbia, who helped devise a different structural system for wooden towers that was detailed in a report last year, said: “This is the first new way to build in a hundred years. ”

Few modern tall wooden buildings have been built around the world, and only one, an apartment building that was completed this year in Melbourne, Australia, has reached 10 stories. Mr. Green’s design of a 27-meter mixed-use building in Prince George, British Columbia, will make it the tallest wooden building in North America when it is completed next year.

Constructing more and taller towers will require changes in building codes — most of which limit wood structures to four

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