Wednesday, April 17, 2019

Timberland

Who says only small buildings can be constructed of timber?

The University of Toronto is building a brand new 14-storey academic building using mainly mass timber. Once completed, it will be one of the tallest mass-timber and concrete buildings in North America. The building will use cross-laminated timber, which are engineered panels made with multiple layers of wood connected at right angles.

This building is part of a trend toward timber construction. In 2017, the University of British Columbia completed an 18-storey residence, known as Brock Commons. Because the components were prefabricated off-site, the entire building envelope went up in only 9.5 weeks.

For years, we have avoided constructing large structures out of wood—mainly because of the fire hazard. But today’s mass timber is factory-made to be fire resistant, and both industry and government leaders hope to see it used more in the future.

Advantages

Wood is a renewable resource, unlike concrete, which is a top producer of carbon, and steel, which is made from nonrenewable, mined resources. Concrete and steel are energy-intensive to produce, and as energy prices rise, the price of these materials will also rise. Trees trap carbon and can be replaced in a relatively short period of time. Plus, Canada has many, many trees.
Wood is lightweight.
Wood is more earthquake-resistant.
Mass-timber products can be prefabricated and then shipped to the site for assembly, reducing how long the site is under construction—a bonus in congested downtown areas.

Barriers

Currently, Ontario does not allow for the construction of wood-frame buildings that are taller than six storeys—the new U of T building was granted a building-code exemption as part of the Ontario government’s $3.15 million Mass Timber Program, which it launched last spring to jump-start the industry. The federal government also has a 4-year program in place that provides $40 million in incentives for timber construction.
Limited supply chains and a limited market mean high prices. Brock Commons was 8% more expensive to construct with wood than with traditional steel and concrete. If the building code changes to allow for more mass timber usage, this will likely change.

Sources: tvo.org, globalnews.com

Timberland

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