Cross Laminated Timber. Solid structural panel composed of spruce planks crossed orthogonally and glued. Has revolutionised timber construction by enabling multi-storey buildings.
The 90 degree crossed orientation of planks compensates for natural shrinkage and swelling, giving the panel absolute dimensional stability.
Developed in Europe in the 1990s, X-LAM (or CLT) transformed timber from a linear element (beam or column) into an isotropic planar material, equivalent to a prestressed concrete slab but at a fraction of its weight.
The production process eliminates the natural defects of timber. The boards are kiln-dried to 12% moisture, scanned to remove loose knots, planed and finger-jointed. They are then arranged in superimposed layers crossed at 90 degrees in an odd number (3, 5 or 7), glued at very high pressure with polyurethane or melamine resins.
Despite popular belief, X-LAM has excellent fire behaviour. Wood burns at a constant and predictable rate (charring rate about 0.65 mm/min); the outer charred layer acts as a thermal insulator, protecting the structural core far longer than bare steel. In seismic zones, the stiffness of the panels combined with the high ductility of the mechanical joints ensures excellent dissipation of seismic energy.
European and international references applicable.
Designed for Service Class 1 and 2 only (covered structures). Ground contact must always be kept clear of foundations to prevent capillary-rise rot.
Shear walls and load-bearing panels for timber high-rises up to 20+ storeys.
PRC.03 · Open the processHorizontal diaphragms with very high in-plane stiffness for roofs.
PRC.03 · Open the processAdditional volumes on historical buildings thanks to exceptional lightness (1/5 of R.C.).
PRC.03 · Open the processPrefabricated lift shafts and fire stairs for rapid dry-assembly.
PRC.03 · Open the processVolumetric density (kg/m3). CLT at 500 kg/m3 is 16x lighter than steel and 5x lighter than reinforced concrete. This transforms multi-storey construction: existing masonry buildings that cannot support heavy concrete additions can receive 3-5 CLT floors without foundation strengthening.
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