What is Glued Laminated Timber?

Glued laminated timber (also called glulam timber) is an industrially manufactured product for load-bearing structures. It is primarily used in construction of carports, winter gardens and residential buildings as well as in all areas of hall construction.

Glued laminated timber consists of at least three dried boards or board lamellas of coniferous wood glued together by their broad sides with the fibers running in parallel. Due to the strength sorting of the initial material and the homogenization through layered construction, it exhibits improved properties with respect to the raw timber.

In addition to simple, straight components, forms with variable height and/or simple curvature are typical.

In older publications, glulam timber is also referred to as laminated beams, laminated wood or "Hetzer beams".

Manufacture

Boards with thicknesses up to 40 mm are first technically dried to a wood moisture of approximately 10%, then planed. The dried boards are visually sorted according to strength, a process that is increasingly being automated.

By milling in dovetail joints at the ends of the lamellas, the individual boards are joined together lengthwise into, in principle, arbitrarily long lamellas and glued together under pressure. In theory, endless lamellas are therefore possible.

The lamellas are capped at the required length, planed, coated with glue and layered atop one another. The resulting glued laminated timber component then hardens under pressure. Primarily melamine resins are used for the gluing. Depending on the application, however, urea resin or resorcin resin glues are also used.

After the gluing, the beams are planed on all sides. In addition, the blemishes in the wood are planed to achieve a surface quality appropriate for use in visible areas. If no demands are placed on the appearance, the glulam timber can also be produced in industrial quality.

The drying, homogenizing and strength sorting result in a product that is dimensionally stabile and exhibits less crack formation than solid wood. It can withstand loads up to 80% higher than typical sawn structural timber. Because the individual lamellas are easy to shape before the gluing, curved components can be manufactured with relatively minimal effort.