Glulam (Glue-Laminated Timber)
Glulam (glue-laminated timber) is an engineered wood product made by bonding layers of dimensional lumber together with structural adhesive to create large beams, arches, and columns. Glulam combines the strength of engineered wood with the appearance of natural timber.
In Detail
Glulam is manufactured by stacking individual lumber laminations (typically 1-1/2" thick for straight members or 3/4" thick for curved members) and bonding them with waterproof structural adhesive under pressure. The laminations are finger-jointed end-to-end to create lengths far beyond what is available in solid timber.
A key feature of glulam design is that laminations can be strategically placed: higher-grade lumber goes on the outer faces where bending stresses are highest, while lower-grade lumber is used in the core where stresses are lower. This optimized layup is what the "balanced" and "unbalanced" designations refer to.
Common designations include 24F-V4 (architectural, four-side appearance), 24F-V8 (framing grade), and 20F-V7. The first number indicates the allowable bending stress in hundreds of psi. Glulam is available in stock sizes (3-1/8" x 9", 3-1/8" x 12", 5-1/8" x 12", etc.) and custom sizes for large commercial or architectural projects.
Related Terms
Laminated Veneer Lumber (LVL)
Laminated Veneer Lumber (LVL) is an engineered wood product made by bonding thin wood veneers together with all grain running parallel, creating a beam material that is stronger, straighter, and more dimensionally stable than solid sawn lumber of the same size.
Parallel Strand Lumber (PSL)
Parallel Strand Lumber (PSL) is an engineered wood product made by bonding long, thin strands of wood veneer together under heat and pressure, with all strands oriented parallel to the length. PSL is used for heavy-duty beams, headers, and columns where high strength and stiffness are required.
Modulus of Elasticity (MOE)
Modulus of Elasticity (MOE) is a measure of a material stiffness — how much it resists bending under load. In lumber and engineered wood, MOE is expressed in millions of pounds per square inch (psi) and determines how far a beam or joist will deflect under a given load. Higher MOE means less deflection.
Related Materials
Glulam (Glued Laminated Timber)
Glulam (glued laminated timber) is a structural engineered wood product made by bonding multiple layers of dimensional lumber with waterproof adhesive. Available in architectural and industrial grades, glulam is used for beams, columns, arches, and exposed structural applications where both strength and appearance matter.
LVL (Laminated Veneer Lumber)
Laminated veneer lumber (LVL) is a high-strength engineered wood product made from thin wood veneers bonded with structural adhesive under heat and pressure. It is the most commonly specified engineered beam and header material in residential and light commercial construction.