New construction at the University of Oregon’s Knight Campus for Accelerating Scientific Impact will use mass timber, a category of wood construction material that can replace steel and concrete for load-bearing functions and is considered a more sustainable option. Another university facility, Hayward Field – currently undergoing renovation – will use mass timber for its canopy, according to the Register Guard in Eugene, Oregon.
Mass timber, also known as engineered or composite wood, has commonly been used for construction in Europe since the 1990s and is being increasingly used by builders in the US, particularly in the Pacific Northwest, according to the WoodWorks Wood Products Council, a non-profit organization providing design assistance to the engineering and construction communities. As a construction material, mass timber is favored by designers for its strength, aesthetics, construction efficiency, reduced carbon footprint, and ability to work alongside other materials as a structural element. And, because mass timber allows such large, solid structural elements to be manufactured from relatively small-diameter trees as well as other traditionally low-value resources (such as forests affected by insects), it is increasingly being sought as a sustainable alternative.
WoodWorks says nearly 600 mass timber projects have been finished or are being built in the United States since 2011. California has the most mass timber buildings, followed by Washington, Texas and Oregon.
Constructing tall buildings with structural wood has been a challenge in the US because such a building type tends to be outside the scope of current building codes in the US, wrote Construction Dive in 2017. However, recently approved changes to the 2021 International Building Code will increase the allowable height of wood structures to 18 stories, per WoodWorks, making it a good time for the building and construction industries to explore and understand newer types of wood building systems.
Still, American builders have not yet embraced mass timber at scale yet. “You’ll see a much grander adoption as people get more comfortable with it,” WoodWorks regional director Ethan Martin told the Register.
Replacing steel with mass timber would reduce carbon dioxide emissions by between 15% and 20%, according to Think Wood, an organization that promotes the use of softwood lumber in commercial, community and non-residential building.