Crack Formation - Note on Damp-Proofing, Sound Insulation and Noise Control
Predominantly the outer layers of the glulam absorb moisture whilst under construction. This construction moisture content must gradually be converted to the equilibrium moisture content for later use. This is done by careful heating and ventilation and the resultant slow reduction in the relative humidity and the corresponding moisture content of the timber which accompanies this.
Shrinkage cracks may arise on the surfaces of the glulam components – even along the glued joint. Such shrinkage cracks may be tolerated up to a depth of 1/6 of the component width (per side) in components without system-relevant transverse tensile stress.
The tendency towards crack formation increases when the timber is directly exposed to the weather and when subject to severe changes in climatic conditions.

Emissions
The smell of freshly produced glulam, which most people find pleasant, is attributable to the softwood’s natural resin components and disperses within a short time. The adhesives used for gluing of the glulam are solvent-free.
Emissions of volatile organic substances (known as VOC) other than the softwood resins are of no significance in glulam. Most of the basic substances in the polymer adhesives are also non-volatile and become permanently incorporated during condensation of the adhesive resins. Only formaldehyde may be given off subsequently by some adhesive resins. However, in this case too the emission values of modern adhesive systems are low and differ very little from those of wood left in its natural state. The emission values are significantly below the legislative requirements when gluing is carried out properly.