By Kira Barrett
North America is on the cusp of a mass timber revolution, and the Waterfront Toronto project is leading the way. But the material faces major obstacles.
Abuilding made primarily of wood conjures public fear of fire, but for a growing number of developers, it evokes opportunity. From constructing towering wooden condominiums, to timber college dormitories, to an entire neighborhood built from trees, experts in “mass timber” are creating buildings of the future.
Sidewalk Labs’ master plan for a futuristic smart city on the waterfront in Toronto includes an entire neighborhood made of wood, called Quayside, with 10 mixed-use building up to 35 stories.
The plan is audacious, considering that in the U.S., there are only 221 mass timber buildings in the works or fully built, according to the American Wood Council’s Kenneth Bland.
In most U.S. cities, mass timber buildings, and specifically tall mass timber buildings, are a rarity, if they exist at all.
But architects, city officials and timber advocates across North America are pushing conventional building codes and public perception because of the drastic impact these structures can have on reducing CO2 through carbon sequestration, compared to traditional concrete and steel.
“I think it’s a big opportunity for a lot of cities out there … The impact on reducing carbon emissions on earth could be dramatic,” Karim Khalifa, director of buildings innovation at Sidewalk Labs, told Smart Cities Dive. “And that gets me excited.”
What is mass timber?
One of the biggest obstacles for city officials is understanding the material. They are more than buildings made of wood — they’re defined by their structure. Steel or concrete buildings with wood accents don’t count, according to Andrew Tsay Jacobs from architecture firm Perkins and Will.
Mass timber buildings use solid wood panels to frame a building’s walls, floors and roofs, creating structures that can reach at least 18 stories, as is the case with the tallest mass timber building in the world in Norway. But these buildings aren’t just pure wood. Mass timber construction utilizes engineered wood, or panels glued together, and there are several types: cross-laminated (CLT), glue-laminated and dowel-laminated timber, with CLT being the most common.
While shorter wood buildings have existed for centuries, CLT panel technology is relatively new. It was developed in Europe in the 1990s, the material was only added to the international building code in 2015. Even then, all-wood buildings were capped at six stories, though that will change to allow taller structures in 2021.