By the Swedish Wood Council
Glulam (glued laminated timber) comprises a number of wood laminates glued together. The fibres in the laminates run parallel to the length of the piece.
In straight glulam products, the laminates are 45mm thick. For curved products, the thickness is less, generally 33mm.
Glulam is a construction material that comes in a range of strength classes. The manufacturing standard for the Swedish market is strength class GL30. Some glulam beams are made by splitting glulam beams of class GL30 to create split timber beams, which then have a strength class of GL28.
Glulam sets no limits on the potential for wood construction techniques.
Glulam beams are made with laminates of a higher strength class on the bottom and top, where the maximum tensile and compressive stresses occur. The rest of the cross-section, where the stresses are lower, uses laminates of a lower strength class. The manufacturing method is called ‘combined glulam’ and is usually indicated with the letter ‘c’ after the strength class designation.
This allows more efficient use of material compared with only using wood of the same strength class.
Alternatively, glulam may be made with laminates of the same high strength class throughout, and this is represented with an ‘h’ for homogeneous after the strength class designation. Glulam is available in a number of dimensions.
Where large spans, loads or other circumstances define the design, glulam is made to the drawings and accompanying specifications as required, in consultation with the glulam manufacturer’s structural engineers. Custom-made glulam elements are available in practically any shape and dimension to meet the architect’s vision and other parameters. Examples of common custom glulam products include curved beams, pitched beams, portals and arches.
Advantages of Glulam: