"Can You Build A Safe, Sustainable Skyscraper Out Of Wood?"
CREDIT: Province Of British Columbia/Flickr
North America’s tallest modern all-wood building is nearing completion in Prince George, British Columbia, but it might not hold that high rank for long. Other wood buildings are in the works across the world as it gains a reputation for climate friendliness, beauty, and yes, even fire safety.
The Wood Innovation Design Centre will be a six-story building, the maximum for a wood building under British Columbia’s building code, but the Centre’s high ceilings mean it will be about as tall as the average 10-floor building. It’ll join the current highest and second-highest modern wood buildings, respectively, a ten-story Melbourne residential building and a nine-story London apartment building.
But no new wood building yet has surpassed the world’s tallest, built in the 18th century. The Kizhi Pogost is a UNESCO World Heritage Site located on an island in northern Russia, and has a central cupola 37 meters high, a few meters above the tops of the new wood high-rises. But it likely won’t hold onto the title of tallest wood building for long.
A lot of wood’s appeal is counter-intuitive. It’s not a bigger fire risk — in fact, thick wood planks stay strong in a fire, forming a protective char that keeps the integrity of the material intact. Steel can lose its strength when it burns, becoming “like spaghetti,” according to B.J. Yeh of the Engineered Wood Association.
This new interest in wood is driven in part by the rise of cross-laminated timber (CLT), essentially a highly advanced form of plywood that can rival steel in strength. It works, basically, by gluing and pressing small beams together into giant boards that can be up to six inches thick, and are custom-sized for their part of a construction project.
Though the Lorax turned a generation off to logging, cutting down trees is actually a sustainable way to build. Trees collect CO2 from the air as they grow, storing it in their wood. If the tree is cut down and its wood used to build, that carbon is sequestered, unable to contribute to warming. That’s especially notable in comparison to the amount of carbon emitted in the manufacture of steel and concrete. The benefit of carbon storage is so great that Stadthaus, the wood high-rise in London, will actually be carbon negative for the first 20 years of operation due to its construction materials. And of course, trees are a renewable resource when farmed sustainably.
And lumber construction could help out with another climate-related problem. Pine beetles, in a population explosion fueled by climate change, have killed tens of thousands of square miles of forests across the country. But trees killed by pine beetles are still suitable for use in construction. And when communities afflicted by pine beetles are paying just to get rid of huge areas of dead trees, a booming lumber market could make sure they’re put to good use, with their carbon stored in buildings rather than burned into the atmosphere.
Building codes in cities and countries around the world limit the height of new wood buildings, reflecting safety concerns that new technologies have solved. So the wood boom will depend, at least in part, on getting the new reality: wood high-rises are safer, and more sustainable, than ever.