What is CLT wood? CLT is a sustainable building material

The construction industry consumes vast quantities of concrete, steel made from iron ore, and stone, and it is steadily depleting this resource. It is one of the world's largest sources of solid waste. Bill Gates once unexpectedly posted a chart comparing cement consumption in China and the United States on his personal blog. The chart showed that between 2011 and 2013, China consumed 6.6 billion tons of cement, exceeding the United States' consumption throughout the entire 20th century.

But if most of the building materials we use are non-renewable, how can we change this?

Cross Laminated Timber (CLT) is a new type of engineered wood material that originated in Europe and has gained widespread acclaim over the past decade, gradually gaining attention in other parts of the world. It stands out for its strength, which rivals concrete, its beautiful and natural appearance, its versatility, ease of assembly, and its sustainability.

Image © Photolux Studio

CLT is composed of sawn, glued, and layered dimensional lumber, with each layer laid perpendicular to the adjacent layers. By gluing the lumber at perpendicular angles, CLT panels achieve equal structural stiffness in both directions. This results in panels with excellent tensile and compressive properties.

CLT is a sustainable material because wood is the world's only renewable building material and does not require the burning of fossil fuels during production. Dimension lumber and glulam products have been widely used in a wide range of large-scale construction projects, from stadiums to bridges to residential buildings. Its natural appearance and structural strength make it an ideal material for skyscrapers.

Photo: UBC 18-story student housing construction site

CLT can be conveniently CNC-machined in the factory, with drilling and metal connector installation pre-installed according to BIM designs. On-site construction is like building with Lego blocks, achieving an assembly rate exceeding 90%. Furthermore, because CLT is a heavy-duty engineered wood material, it can be left exposed within the permitted floor heights as required by fire regulations, significantly reducing the number of interior finishing steps. CLT project sites typically generate virtually no construction waste.

Although the production cost of CLT materials is still high, it is still an excellent choice to replace concrete and steel if factors such as shorter construction time, better quality and environmental protection are taken into consideration.