What is Glulam?

‘Glulam’ stands for Glued Laminated Timber. Glulam is made by gluing together, under pressure and heat, laminates of timber that have been accurately planed. The resulting product is strong, stable, and corrosion proof with significant advantages over structural steel and concrete. The beams are made with wood from sustainable forests. Scandinavian forests are some of the best managed in the world, where reforestation and environmental considerations are given high priority. The trees used are usually spruce, though can sometimes be redwood or Siberian larch.

Glulam is used for a range of purposes from joinery timber through to large span structural beams. Large glulam beams can often be seen in swimming pool or sports hall roofs and more recently in several large chain supermarkets. Basically wherever a steel or concrete structure is needed for a building, glulam could also be used.

Good strength to weight ratio:
Timber has a good strength to weight ratio in comparison with steel and concrete. If you consider equivalent beam sizes for the same load bearing capacity in glulam and steel, glulam has approximately 1.5 – 2 times the strength to weight ratio of steel. This means there is a benefit in the build ability of glulam structures – this could be that it becomes possible to manhandle a beam into a roofspace for a loft conversion, or on a larger scale, craning of large prefabricated roof elements becomes feasible. Another advantage is that smaller foundations are needed for a reduced structure weight.

The durability of glulam will depend on its specification. Species of timber, type of glue and preservative type and application are all factors in the durability of glulam. Given the correct specification glulam can be used for the most onerous of conditions. One instance where glulam is chosen for its durability is in swimming pool roofs- this is a particularly corrosive environment with high humidity and chlorine levels and glulam provides a durable low maintenance solution. Glulam is often used for motorway bridges in Scandinavia, designed to last for decades with a minimum of maintenance.

Large section timber elements actually perform very well in fires. This is due to the way in which timber chars at a known rate and does not deform like steel. Fire performance of glulam has been the subject of extensive research and structural glulam members can be designed to last a certain period of time in a fire based on the rate at which it chars. Additional fire protective finishes can be used to further increase the fire performance.