A locally available, sustainable material
The first and most obvious benefit of glulam is that its main constituent, timber, grows out of the ground and does not need to be mined and subjected to the high energy demand manufacturing processes that concrete, steel or any of the traditionally used construction materials require. Of course there are also energy requirements for glulam manufacture in the felling, transportation, manufacture of the glue etc., but this is still outweighs that of steel or concrete.
Glulam is often chosen over steel or concrete for its appearance. By its nature wood affords buildings and spaces a warmer, comfortable appearance as appose to other building materials. Also, there are many different species and finishes available for glulam, all bringing their own specific character to a building or space. Glulam has much more flexibility that other traditional materials and can be tailored to suit a vast range of requirements.
Flexibility of shape and size
The lamination process is inherently flexible and Bucklnad can produce glulam in sizes ranging from 75 x 75mm up to 250 x 1800mm at thirty meters in length. Our glulam is made using movable formers which can be arranged in any position to make bespoke curved shapes – our minimum radius is around three meters.
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 to 2 times the strength to weight ratio of steel. This means there is a benefit in the buildability of glulam structures – this can influence manual handling a beam into a tight 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, 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 articularly 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. More information on the correct specification of glulam for differing environments is given in the Glues and Preservatives section of this website.
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 twist, buckle or 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.