The highrises of tomorrow are ‘plyscrapers’

Humans have been crafting shelters out of good old reliable wood ever since our ancestors solved the problem of chopping down trees. In everything from simple huts made of branches, to broad pavilions with large timbers set in post-holes, wood has always featured prominently.

In Europe, there’s evidence of wooden structures from at least 4000 B.C., and we were building probably well before that, given that wood typically doesn’t hold up well after being buried for millennia. And the ones that are still standing today aren’t mere hovels: Switzerland claims the House of Bethlehem, from 1287 A.D.; the famous Urnes stave church in Norway was erected around 1130 A.D.; and the great-grandtemple of them all, standing at 122 feet tall, is Japan’s Horyu-ji pagoda, built in 607 A.D.

But wood can only build so high, so as cities grew, builders began to use new materials. The modern skyline in many cities is almost exclusively shiny glass and polished stone, supported by steel and concrete.

Yet now, wood is making a comeback in a new way.

One big boon—which architects and engineers hope will make big buildings lighter, cheaper to build and more environmentally friendly—is a material called cross-laminated timber, or CLT.

“I’ve been here for nearly 30 years now, and during that time there’ve only been a few items that have generated a bit of buzz and interest. This is one of those items,” said David Kretschmann, a research engineer with the U.S. Forest Service’s Forest Products Laboratory (FPL) in Madison, Wis. “It’s energized the wood product community and a lot of people want to see it succeed.”

In use in Europe for nearly 20 years, CLT and other so-called mass timber products have been key design elements of projects like Puukuokka in Finland, an eight-story residential building; and Norway’s Treet, at 14 stories, the world’s current tallest timber building. When finished, University of British Columbia’s Brock Commons 18-story building will hold the record for tallest CLT-constructed structure. And 18 stories is by no means the limit: Swedish architects have proposed a 34-story wooden building, called “Trätoppen,” for Stockholm’s city center, and Cambridge researchers and architects have designed an 80-story, one million square-foot giant at the Barbican in London, primarily made of wood. At 984 feet tall, it would rank as the world’s 18th tallest building, just ahead of Four World Trade Center in New York City.

The tallest proposals are likely years away from reality, but plenty of others have already been pushing wood in that direction: up.

CLT differs primarily from currently available glued or nailed products already on the market in that it is made from boards that are stacked and glued in alternating, rather than parallel, layers. Panels can be very large, and very thick: one of the two CLT manufacturers in the U.S. is capable of producing CLT panels 98 feet long, 18 feet wide and 19 inches thick.

Smithsonian