TRADA comments on strength graded timber

TRADA Technology is concerned that strength graded timber may be being remachined and sold on without being re-graded where necessary.

According to Philip O'Leary of the company's Structural Investigations Section, recent enquiries to the TRADA Helpline suggest a lack of understanding about the possibilities.

It may be argued that the limits for strength reducing characteristics in BS 4978: 2007 Softwood grades for structural use may at times be open to interpretation, the rules governing remachining, which are the same for machine graded timber, are clear.

TRADA Technology has run visual strength grading courses for many years and has sympathy with individuals trying to come to grips with parts of the British Standard.

When TRADA Technology technical consultants have been called in to check the grading of timber, the outcome has varied hugely, from more than half of the consignment being rejected, to the parcel being totally in keeping with the rules.

Philip O'Leary commented: 'The industry needs to be aware that generally machine grading will allow a higher yield than visual strength grading.

That said, there are manual overrides for machine grading.

With grading generally, much of it comes down to the grader's knowledge and experience at the end of the day.

Companies who employ qualified graders know how valuable they can be, if the grading of timber coming into the yard or perhaps more critically going out comes into question'.

Back to top