LVL & LSL Print E-mail
Laminated Veneer Lumber - LVL and Laminated Strand Lumber - LSL are engineered structural products. They are produced by assembling wood veneers (thin sheets of wood of uniform thickness) or strands and bonding them together with a structural adhesive to form a solid product. The grain direction of each veneer or strand is usually oriented to be parallel with the length of the piece but may be cross-banded for specialty applications. The laminated structure disperses strength - reducing characteristics more evenly giving LVL and LSL a higher bending strength and stiffness than the equivalent solid timber section of the same species.

LVL and LSL are produced as a seasoned product in wide billets. These billets are sawn to produce products with a range of standard cross-sections up to 105mm in thickness and 1200mm in width. Lengths of up to at least 12 meters are available with the only limit being manufacturing, transport and handling capabilities.

In the case of LVL, the veneering process significantly improves the structural properties of LVL over the parent wood due to the randomization of defects. Defects such as knots, when peeled into a veneer, which is then assembled into LVL, are no longer concentrated in one location. In sawn timber all of the strength-reducing effect of a defect is concentrated around the one cross-sectional area of the beam, but in LVL the effect is distributed in the beam effectively, increasing the proportion of the good wood at any cross-section. This process can considerably increase the strength and stiffness properties when compared with solid timber from the same resource.

Veneers used in the manufacture of LVL are usually 3.0 mm thick but may be as thin as 1.0 mm and as thick as 6.0 mm. There is no standard to describe a veneer grade for LVL. Veneer of any grade may be utilized provided that it is free of active insect attack and decay and is of uniform thickness within each sheet. LVL is typically used in structural applications where the high strength and stiffness, long lengths and large section sizes are advantageous. These applications include floor joists, lintels, purlins, roof truss components, and portal frames.

Each manufacturer of LVL or LSL designs and tests products in accordance with AS/NZS 4063 to determine each product's design properties. This engineering data is available from the relevant manufacturer.

Not all LVL and LSL are the same. When a design is based on a particular size and brand of a product, substitution with another brand should not be made without engineering advice. Product-specific information, including span tables for common applications, is available from each individual manufacturer.

LVL and LSL are not appearance products because the glue lines are often quite visible. Where necessary, the surface maybe lightly sanded to reduce the visual effect of the glue and then coated with a finish.

LVL is bonded using only "type A" phenolic adhesive which provides a waterproof bond that is able to withstand exposure to the weather for a long period without deterioration. Although the use of a durable adhesive provides a bond of long-term effectiveness, it does not imply that the veneers being bonded together will have any long-term durability. If LVL is to be used in service conditions that are liable to encourage decay, then it should be preservative treated to the appropriate hazard level. (See: Treated Timber)

Most LVL can be made termite resistant by preservative treatment to H2 level. (See: Treated Timber)