Strength classes

Strength classes are used to determine the quality of wood products. Here, the properties of the wood such as density, moisture content or tensile strength are evaluated and divided into certain classes. The higher the strength class, the higher the quality of the wood. Different strength classes are used for the production of glulam and X-LAM.

For the production of glulam, the wood is divided into so-called T-classes according to EN 1408. The classification of the wood is based on the predicted tensile strength (T=tension) of the lamellas. The classes T10, T14 and T22 are usually used. Within a cross-section, only one of these classes is used in a homogeneous structure. However, to optimise the strength of the beam and the timber yield, several of these grading classes can also be used in combination within a cross-section structure / beam. The figures also indicate the permissible characteristic tensile strength of the lamella in N/mm². The strength class T22 thus has a minimum tensile strength of 22 N/mm².

For the production of X-LAM, the lamellas are sorted into so-called C classes according to EN 338 or EN 14081-1. The strength class C24 is mainly used in practice. This class is characterised by a high bending strength and a high load-bearing capacity. The strength class C24 is mostly used for load-bearing constructions that require a high load-bearing capacity. Wood is graded into C classes based on the stiffness and density of the wood. The wood is divided into classes that have different properties. Class C24, for example, has a permissible bending stress of 24 N/mm².