Cross-laminated timber (CLT) manufacturing for the construction industry uses standard dimension lumber and adhesives to create solid, monolithic timber panels of varying thicknesses. At Element5, we use SPF lumber to create CLT “billets” that can be as large as 16m long by 3.5m wide. From these raw billets, we cut out the individual structural components of a building (floors, roofs, walls, stairwells, and elevator cores, etc.).
The process can be likened to cutting donuts from a rolled-out piece of dough. Of course, in the case of CLT, the ‘donut cutter’ is a massive CNC machine with an overhead 5-axis bridge with a variety of tools that includes a chainsaw, routers, and sawblades that range up to 800 mm in diameter.
The CNC machine enables us to achieve any cut that we need to for a given design. At a minimum, we trim the four raw edges of the billet square. Suppose the full-sized panel is not required for a building. In that case, we cut out the smaller panels based on how they have been optimally nested in the billet and then execute any details the engineering department has incorporated into the design. These detailed cuts include pre-drilled holes and slots for connections, as well as windows, doors, and openings for mechanical, electrical, and plumbing services.
This form of off-site manufacturing is valued because it improves the construction process’s efficiency, both in terms of human resources and material resources. But as efficient as CLT manufacturing is, that doesn’t mean it is a waste-free process. Fortunately, wood ‘waste’ is desirable and can be easily streamed into secondary uses. The sawdust we generate, for example, is collected by a waste management company and repurposed as animal bedding. This particular outcome is possible because the adhesives we use do not emit VOCs. Naturally, the intended beneficiaries of this clean technology are the human occupants of our buildings because our mass timber buildings are healthier and offer superior indoor air quality. Still, this high standard also means our wood waste is entirely safe for animals too.
One of the more interesting by-products of our process is the off-cuts – or to pick up on the donut analogy again, the donut holes – that are removed from the panels when we create window and door openings. These relatively large blocks of solid wood are being transformed into furniture, stairs, and other feature elements. They are often incorporated into the mass timber buildings from which they’ve been cut. This effort adds value, reduces waste, and helps realize the greatest possible benefit from each panel that we press.
MCH, one of the talented design-build companies we work with, regularly finds creative uses for the CLT off-cuts from their builds.
This innovative, sustainable practice of maximizing downstream value, combined with clean manufacturing technologies and responsibly sourced lumber inputs, results in low carbon buildings and products that optimize the use of our forest resources.
Sarah Hicks is a Marketing and Communications Coordinator at Element5 based in Toronto, Ontario. Previously, Sarah was a Spokesperson at the Canadian Wood Council. With more than 15 years in the industry, Sarah brings excellent insight into the growing role of mass timber in Canada.