The development of polyurethane (PUR) adhesives for engineered wood products started in Switzerland in 1985. Those adhesives satisfied the need for formaldehyde free adhesives, which is mainly attributed to health and environmental reasons. However, due to new requirements concerning the high temperature resistance of adhesives, especially in North America, newly developed adhesives are basically banned from the market, and adhesive manufacturers face a new barrier to approve their new adhesive technologies on the market. The work presented in this thesis clarifies the influence of adhesives on the fire design of glued-laminated timber beams. Additionally, clear scientifically based requirements are identified, which should be met by adhesives used in glued-laminated timber beams in case of fire.
In this thesis, twelve different adhesives for both structural and non-structural applications were tested in large-scale fire tests on finger-jointed timber lamellas. Those fire tests indicated that structural adhesives certified according to current European testing standards exhibit sufficient strength in fire for the use in glued-laminated timber beams. Taking into account the crack pattern observed in the fire tests, no significant influence on the fire resistance was found between the studied structural adhesives. Therefore, it is not necessary to consider the influence of adhesives in the design of glued-laminated timber beams, given that the adhesive is approved according to current European testing standards.