Laminated strand lumber

Laminated strand lumber (LSL) is an engineered wood product that is gaining widespread use. It has high strength, high stiffness and dimensional stability.

LSL is commonly manufactured using fibre from poplar trees, including aspens and balsam poplars. The LSL manufacturing process allows for an efficient use of forest resources, as large wood-based members can be produced from relatively small trees.

LSL is used primarily as structural framing for residential, commercial and industrial construction. It can be left exposed as a design feature in certain applications. LSL is also useful for fastener-holding strength.

Some common uses of LSL include:

• headers and beams
• floor panels
• millwork
• rim board
• tall wall studs
• sill plates
• window framing

Technical information

LSL uses flaked wood strands that are long and thin. Combined with a structural adhesive, strands are oriented and formed into a large mat or billet and pressed. LSL resembles oriented strand board (OSB) in appearance, as they both come from similar wood species and contain flaked wood strands. However, unlike OSB, LSL strands are arranged in a parallel formation.

LSL is a proprietary product and the manufacturer typically provides its dimensions and design values. Unlike glue-laminated timber (glulam) or cross-laminated timber (CLT), there are currently no common standards for the manufacturing of LSL in North America. Each producer develops their own engineering design values based on testing, analysis and design guidelines as provided in the Canadian timber design standard (CSA O86), as well as other relevant American Society for Testing and Materials (ASTM) standards.

To ensure acceptance in the Canadian marketplace, LSL manufacturers seek approval from the Canadian Construction Materials Centre (CCMC). Products approved by the CCMC receive an evaluation number as well as evaluation report, which includes engineering design values. These products are then listed in the CCMC’s registry of product assessments.

LSL is one of many products used in mass timber construction projects across Canada.