Glulam produced for specific building-projects is also generally manufactured of spruce timber. More rarely, glulam is manufactured from fir, larch or Douglas fir as well as from pine in certain regions.
Use of the durable wood species larch and Douglas fir is frequently considered for members that are subject to weathering at least part of the time. For use in members subject to weathering, the lamella thicknesses for glulam of larch or Douglass fir should be selected at less than 33 mm due to the strong tendency toward swell and shrink. In the explanations on the former DIN 1052-1: 1988-04, a lamella thickness of only 24 mm is recommended for such members. In principle, the direct weathering of glulam members should be prevented by design measures.
With regard to the wood-species for load-bearing members listed in DIN 1052:2008, Annex H.2 (3), the low availability of southern pine, western hemlock and yellow cedar in the German market should be considered. Without sufficient lead-in times, it may not be possible to procure the required quantities of timber for larger structures in some circumstances.
Not all wood species listed in DIN 1052:2008, Annex H.2 (3) can be graded at present by machine. For glulam of a wood-species other than spruce and fir with a strength class of BS 16 or BS 18, the manufacturer should be asked in good time.
For special structures and applications in monument protection, broadleaf-timber such as ash, locust tree, oak and many tropical timbers have been glued in the past based on the basis of an individual case approval (which is only valid for a specific building). However, these timbers show problematic properties compared to coniferous timbers; extensive manufacturer experience is required to glue them. The use of glued durable broadleaf-timbers in weathering has only occurred in exceptional cases to date; use in interiors is less problematic by comparison.
Hybrid members of high-strength beech lamellas in the edge with is subjected to tensile stress combined with spruce timber lamellas are currently being investigated. The initial results are promising; however, the use of beech timber in glulam members is only possible in the foreseeable future based on an individual case approval.
