taller mass timber

Thinking bigger and taller with mass timber

Moving the needle on climate change with renewable materials
Wednesday, September 15, 2021
By Hardy Wentzel

The National Building Code of Canada is due for an update in 2025, and we already have a pretty good idea of what changes to expect. The National Research Council has said that the next edition of the code will include new standards to protect buildings and their occupants against floods, wildfires, and extreme weather events that result from climate change.

Making buildings more resilient in the face of high winds, and basements more resistant to flooding? These are excellent ideas, and this seems like a sensible starting point for addressing the effects of global warming. What our building codes should be addressing, though, is the causes of climate change. To do that, we need to think bigger — and taller.

It all starts with wood. Mass timber is a renewable building material that can be regenerated through sustainable forestry practices, and harvested timber helps mitigate climate change by storing its carbon throughout the life of the building. Mass timber construction can help move the needle on carbon emissions, but for that to happen we need to modernize our building codes to allow for wood structures taller than the currently mandated 12 storeys.

How we build is hurting us 

Under the 2015 Paris Agreement, Canada committed to reducing its greenhouse gas emissions by 30 per cent below 2005 levels by 2030. According to the World Green Building Council, buildings are currently responsible for 39 per cent of global energy-related carbon emissions. Operational emissions — from energy needed to heat, cool, and power buildings — account for 28 per cent, with the remaining 11 per cent from materials and construction.

Efficiency Canada, a research and advocacy organization at Carleton University, released a report last year that noted a disconnect between Canada’s climate targets and our building codes. The organization called on various ministers to issue a joint directive clarifying the role of building codes as “a tool for market transformation”. Efficiency Canada hopes to see building codes that “encourage the construction of new buildings more likely to mitigate emissions” as well as “incorporation of embodied and operational carbon to help Canada meet its climate objectives”.

We know it can be done 

Several years ago, my company supplied materials for a project called Brock Commons Tallwood House. When Tallwood House opened in the summer of 2017, it was the tallest mass timber structure in the world, standing 53 metres high. The 18-storey student residence at the University of British Columbia is exceptional — literally, in that it was an exception to the B.C. building code, which at the time limited wood buildings to six storeys. Getting it built required special permission and two structural reviews.

Although it was built on a concrete podium and does contain some steel elements, the frame of Tallwood House was built of engineered wood, with cross-laminated timber floors supported on glue-laminated timber columns. The amount of avoided and sequestered greenhouse gases from the wood used in Tallwood House is estimated to be equivalent to taking 511 cars off the road for a year. Using wood products over other materials reduced carbon dioxide emissions by 2,432 metric tons.

Tallwood House is a major reason that both B.C.’s code and the National Building Code of Canada were amended to allow construction of wood buildings up to 12 storeys.

The political will exists 

In recent years, Tallwood House has had to relinquish its “world’s tallest” title to Mjøstårnet, an 85.4 metre, 18-storey mixed-use building in Brumunddal, Norway, completed in March 2019. That’s due to be nudged out of the top spot next year by Ascent, a 21-storey building in Milwaukee, Wisconsin, that will soar to 86.5 meters.

What’s stopping us from reaching similar heights here in Canada? We know that the political will exists, especially here in B.C. This summer, the provincial government announced that it will invest an additional $2 million in its Mass Timber Demonstration Program. This follows up on the commitment Premier John Horgan previously made to expand the use of mass timber as a means to drive economic growth and achieve the province’s own sustainability goals.

Confirming what we already know  

Our provincial and federal governments are certainly to be commended for the progress they have made in approving the construction of wood buildings up to 12 storeys. To get even taller projects into the codes, however, will require government-sponsored research to confirm what the industry already knows about mass timber’s properties in several key areas, including:

  • Fire resistance: When exposed to fire, the outer layer of mass timber chars and acts as a protective coating, which insulates the wood underneath. Cross-laminated timber (CLT) was first recognized in the 2015 International Building Code (the standard followed by most jurisdictions in the U.S.) after a test of a five-ply CLT wall. The wall was exposed to a fire that reached over 980 degrees Celsius. The building-code provisions required a two-hour fire rating, but the test specimen lasted just over three hours.
  • Earthquake safety: Mass timber structures weigh approximately one-fifth of equivalent concrete buildings, and that lightweight nature helps reduce seismic forces, which are proportional to weight. Wood-frame construction also exhibits ductile behaviour, which essentially means it can bend without breaking.

Demand will move the needle 

That research is not likely to happen, however, unless architects, engineers, and developers demand it. In particular, it is up to architects and designers to break out of their concrete-and-steel comfort zones and embrace wood.

Public education will also be important, with the main takeaway being that, from an environmental and safety standpoint, wood is good. Developers will make the buildings that consumers want, and if those consumers start asking more questions about sustainability in design and construction, that’s what will really move the needle.

If we expect to live up to our Paris Agreement commitments and hit our ambitious climate targets, we clearly need to rethink the way we build, and especially what we build with. Renewable materials such as mass timber are the future of construction, and the future is looking up — way, way up.

Hardy Wentzel is CEO of Structurlam Mass Timber Corporation, located in Penticton, B.C.

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