LSL (Laminated Strand Lumber)

What Is LSL?

Laminated strand lumber fills the gap between dimensional lumber and higher-performance products like LVL. Where solid 2x lumber warps, bows, and varies in quality from stick to stick, LSL provides consistent straightness, uniform strength, and the ability to order long lengths (up to 48 feet) that eliminate waste and splicing.

LSL is manufactured from fast-growing species — primarily aspen and yellow poplar — that are not typically suitable for structural lumber. The logs are flaked into strands approximately 12 inches long and 0.025 inches thick. These strands are coated with isocyanate adhesive (MDI), aligned parallel to the member length, and pressed into billets under steam injection and heat. The resulting product has the appearance of a very fine OSB with the strands running lengthwise.

Primary Applications

• Rim board: LSL rim board is one of the most common applications. At the edge of each floor, a vertical board closes off the floor cavity and transfers loads from the wall above to the wall below. LSL rim board is straighter and more consistent than solid lumber, providing better alignment for sheathing and siding.
• Headers: For standard window and door openings in load-bearing walls, LSL headers provide adequate strength at a lower cost than LVL. Most residential headers carry relatively light loads compared to girder beams, and LSL handles these loads efficiently.
• Tall wall studs: In homes with 9-foot, 10-foot, or higher ceilings, precut studs in dimensional lumber are either unavailable or extremely prone to warping. LSL studs in these lengths are dead straight and consistent, producing flatter walls that allow drywall to hang without waves.
• Plates: Top and bottom plates in tall walls or long wall sections benefit from LSL's consistent straightness, especially when walls will receive tile or stone that makes waviness visible.

Comparison to Alternatives

LSL occupies a value position in the engineered lumber family:

• Vs. dimensional lumber: LSL costs more per foot but eliminates culling waste (sorting through twisted/bowed lumber), provides longer lengths, and produces straighter assemblies. For tall walls and rim board, the installed cost difference is minimal after accounting for waste.
• Vs. LVL: LSL costs less but has lower strength. For headers under moderate loads, LSL is sufficient. For long-span beams or heavy-load headers, LVL is required.
• Vs. finger-jointed studs: Both provide straightness in long lengths. LSL is stronger and more consistent but costs more. Finger-jointed studs are a good compromise for stud-only applications.