The European standard "EN 1310 Round and sawn timber - Method for measuring properties" describes the methods for measuring properties that are taken into account in the visual classification of sawn, processed and round timber in order to assess their appearance or mechanical properties. These methods do not apply to the strength classification of structural timber. The standards "EN 518 Structural timber - Classification - Requirements for visual strength classification standards" and "EN 519 Structural timber - Classification - Requirements for machine strength classified timber and grading machines" apply in this regard.
The EN 1310 standard applies to hardwood and softwood sawn timber, engineered timber and round timber, both square-edged and unedged. The standard does not apply to tropical timber.
For the purposes of this standard, knots in sawn timber are classified according to their shape, size and location. The size is derived from formulas given in the standard and is expressed in millimetres or as a percentage of a dimension of the surface on which the knot occurs.
Two methods are given for measuring knots:
If power rating is required, reference should be made to EN 518 for visual rating and EN 519 for machine rating. When the standard is applied, it should be stated whether the general method or the alternative method is used.
In the general method, each knot is considered individually. Knots on a portion or the entire surface of the measured surfaces or edges are measured according to the grading rule used. The figures given in the standard show the knot categories to be measured: round knot, oval knot, arris knot, pointed knot, flat knot, branched knot, knot cluster, cat's claw. Each figure is usually accompanied by a corresponding formula, which is the arithmetic mean of the width along the minor and major axes of the knot. Then, the width along the minor and major axes is measured, and the dimension is calculated using the formula.
The alternative method is not used for uncut lumber. Only knots on a surface or edge that appear to be cross-cut or oblique are considered. The figures given in the standard indicate the categories of knots to be measured: round knot, oval knot, arris knot, pointed knot, spreading knot, branched knot, cluster of knots, cat's claw. The dimension is the width of the knot or cluster of knots measured perpendicular to the longitudinal axis of the piece.
Trunk straightness is a primary determinant of timber log value. Straighter trunks provide more processing options and higher sawnwood recovery. Effective valuation techniques allow higher quality trees or areas to be identified and marketed according to specific processor requirements, optimizing the use of forests and adding value to all parties.
Knots in trees are imperfections in branches that allow live wood grain to grow around them. These imperfections are just part of what makes wood a beautiful material to work with, but they can also contribute to potential deficiencies in structural strength for construction lumber.
Among the numerous testing, measuring, analyzing and evaluating studies that our organization has carried out for businesses in various sectors, it also provides testing services defined in the standard “EN 1310 Round and sawn timber - Method of measuring properties” with its trained and expert staff and advanced technological equipment.
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