LSL — Laminated Strand Lumber Structural Guidebook

LSL is an engineered wood product made from long wood strands bonded with adhesive into structural billets, beams, or framing members.

What It Is

Laminated strand lumber is manufactured from oriented wood strands under heat and pressure, producing members with more uniform properties than ordinary sawn lumber. It is often used where straightness, size stability, and predictable structural performance matter.

Types

LSL is sold as studs, rim board, headers, beams, tall wall framing, and other engineered framing members. Product ratings vary by manufacturer, so allowable spans and loads must come from the specific engineering tables.

Where It Is Used

It is used in walls, headers, rim boards, tall studs, door and window openings, and other structural framing applications. Builders often use it where conventional lumber might twist, cup, or shrink too much for the design.

How to Identify One

LSL has a dense, textured appearance with visible long wood strands rather than the thin veneer layers seen in LVL or the flakes seen in OSB. It is usually stamped with an engineered lumber brand, grade, and evaluation information.

Replacement

Replacement is structural work and should match the exact size, grade, and design role of the original member. Water damage, insect damage, overcutting, or improper field drilling can all require professional evaluation.