How safe are tall mass timber constructions?

 Thursday, January 12, 2023

Timber construction height continues to soar around the world. New empirical research is showing the safety of tall wood buildings. The article “Apartment Buildings Constructed from Combustible and Non-combustible Construction Materials” by Alex Zheng, Len Garis, and Ian Pike, published in the peer-reviewed Fire Technology journal in July 2022, strengthens the argument that contemporary construction methods and protective systems have eliminated the fire risk traditionally associated with combustible building materials.

Exploring the safety aspects and upcoming projects of mass timber

With a mission to disprove the unfounded belief that non-combustible materials like concrete or steel are more secure than wood, the authors examined approximately 14,000 apartment fires across Canada.

Excerpts from the research:

Buildings composed of non-combustible materials performed better when only material considerations were taken into account. However, the type of construction material had little effect on results when variables like building height and safety features were taken into account.

• When sprinklers and smoke alarms were present, the percentage of fires that needed professional extinguishment or spread outside the room of origin was lowest.
• The largest effect on injury rates was the availability of operational sprinklers (there were too few deaths for an adequate comparison).
• Having both systems in place to detect and put out the fire had the greatest protective effect, even if sprinklers had a stronger protective effect than smoke alarms.

Mass timber structures can be built up to 82.2 metres (270 feet) tall, or around 18 stories, according to a 2021 modification to the International Building Code. The B.C. building code only allowed wood structures up to four stories high until 2009. In line with a change predicted in Canada’s next National Building Code, British Columbia now authorises wood building up to six storeys and mass timber construction up to 12 storeys and above with alternate permission processes.

The Brock Commons residence at the University of British Columbia (18 storeys) as well as structures in Milwaukee, Wisconsin (25 storeys), Brumunddal and Bergen, Norway (18 storeys and 14 storeys), London, England (10 storeys), and Melbourne, Australia are some of the tallest completed mass timber structures in the world (10 storeys). Even taller structures, such those with 31 stories in Toronto and 32 storeys in Switzerland, have been proposed by architects.

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