Trusjoist produces a range of patented engineered timbers made by drying short or long veneer ‘fibres’ or panels, joining them with glue or resins and subjecting them to high pressure and/or heat. They produce three ‘timbers’ Parallam®PSL., Timberstrand®LSL., Microllam®LVL, and a special composite structural timber floor cross-beam, the Silent Floor® joist. They claim improved strenght and avoidance of defects such as cracking and wraping for all their timbres. Furthermore, thanks to the raw veneer ingredients, they can use virtually the whole diameter of a sawn log and small-diameter second-growth trees. This results in a considerable avingon raw materials to produce the same amount of structural timber as sawn wood. For exaémple, the Silent Floor® crossbeam system uses one tree to every two ore three trees for a conventional sawn-wood flooring system.
Microllam® LVL uses 30% more of the timber from each tree,and being stronger than solid timber, provides almost double the structural value per unit volume of raw material sawn wood. However quite a lot of energy is needed to make this composite timbers, so detailed examination of the used energy versus sawn timber should be made on a case-by-case basis.