Wood sorting

Timber is an indispensable material in construction and is often used for load-bearing structures. To ensure that the timber meets the quality requirements and the demands for load-bearing capacity and resilience, prior timber sorting is essential.

DIN EN 14081 – Wood grading according to strength

Structural timber must be graded according to its strength in accordance with EN 1995. Only in this way can it be classified into classes with different permissible stresses. For this purpose, there is DIN EN 14081, which describes the grading of structural timber for load-bearing purposes with a rectangular cross-section.

Sorting method for sawn softwood

There are two common grading methods for sawn softwood: visual grading and machine grading. In visual grading, various characteristics of the wood are assessed to determine its strength. These include tree edge, knots, annual ring width, fibre inclination, cracks, discolouration, compression wood, insect damage, mistletoe infestation and curvature. In addition, the characteristic pith is taken into account for planks, boards and battens.

Machine sorting, on the other hand, evaluates modulus of elasticity, bulk density, knottiness and fibre deviation, depending on the sorting method. Compared to visual sorting, it usually provides a much more reliable and reproducible result, as it is independent of human judgement.


Correct timber grading is essential to be able to use construction timber according to its load-bearing capacity. Whether to grade visually or mechanically depends on various factors and should be decided depending on the requirements of the structure. In any case, thorough timber grading is the be-all and end-all for the successful use of timber in construction.

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