Glulam

Glulam, or glue laminated timber, is an engineered wood product made of two or more layers of lumber that are glued together. Adhesives used to bind the timber boards may be polyurethane or formaldehyde resins such as phenol-resorcinol-formaldehyde (PRF), melamine-urea-formaldehyde (MUF), melamine-formaldehyde (MF), and resorcinol-formaldehyde. The common contents of this CP describes glulam with a polyurethane adhesive, though others are listed in the All Contents tab. Glulam manufacturing begins with kiln-drying lumber (aka lamstock) to a maximum moisture content of 16%. When glulam beams are specified beyond typical lumber sizes, lumber is finger-jointed and bound with an adhesive. Adhesives used for finger-jointing and between layers may be the same within a product or may be different. This CP assumes the same adhesive for both applications. The lamstock is layered in specific arrangements called layups with adhesive applied between each layer. The adhesive is cured via cold set, which uses pressure and ambient heat, or radio frequency, which uses pressure and heat at 200+ degrees Fahrenheit. A sealer is commonly applied to beam ends to impart water resistance. Sealers may be used on the faces of beams as well, however, this is not standard and sealers may vary by manufacturer. In exterior applications where the glulam is exposed to weather or high moisture conditions, a preservative treatment may be needed. Such treatments were beyond the scope of this CP, but chemicals identified in these treatments have been included in the All Contents tab for reference. Species resistant to decay and insects such as Alaskan Yellow Cedar and Port Oxford Cedar may also be specified to avoid the use of preservative treatments.

A historical version of this CP is available here: Historical: Glulam - 2015.