Machine Strength Grading of Timber

UK Building regulations require that all timber used for structural purposes is strength graded and grade marked under the control of a third party certification scheme. Visual grading assesses the size, frequency and positions of defects in the timber, such as knots, wane and sloping grain, and compares them to grading rules which define the allowable size, type and number of defects for each grade. Visual grading of softwoods is typically carried out to BS 4978, or for softwoods imported from Canada or the USA to their own standards; NLGA and NGRDL respectively. Machine grading measures the resistance of the timber member to flexing, which gives a measure of the strength of the piece. Machine grading is carried out to the requirements of BS EN 14081 Parts 1-4, the European Harmonised standard for the strength grading of timber for structural purposes.

All strength grading, whether visual or machine, must be carried out under the control of a third party quality assurance scheme. All structural timber members must be clearly marked with their strength grade and/or class and an accredited certification mark.

For further information please call our head office on 01494 569700 or email enquiries@bmtrada.com. We will be happy to advise you on the most cost-effective route to registration.