Visual Stress Grading of Timber for Construction

Douglas Fir Stress Graded by WWM for Arundel Visitors CentreVisual Stress Grading of Timber for Structural Use

We are eager to ensure that our client’s own home grown timber is put to the best possible use for themselves or others. To this end we are delighted to provide visual stress grading (VSG) services to those who need their timber to be passed as fit for structural use, both within and beyond the SW region.

We assess, grade and CE mark clients’ hardwood and softwood timbers to current British and European standards for visually stress graded timber for structural use. Further detail about selecting and milling your own timber ready for stress grading can be found here: Guidelines for selecting and processing timber for visual stress grading for structural use

Structural timber can last for centuries when correctly selected and appropriately used. Medieval buildings provide clear and ongoing evidence of this in the present day.

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These days, knowledge of timber anatomy goes to a far greater depth involving research at a microscopic level , looking at the proportions, angle and arrangement of micrifibrils in the wood and using high precision calibrated machines to test structural strength and stiffness of potential structural timbers. Such research work delivered by TRADA and BRE has helped to inform the Visual Stress Grading process and we are assessed and certified annually for delivering current, up-to-date standards in grading and marking structural timber.

If required we can also offer associate mobile milling services to convert roundwood timber into bespoke section material for structural and/or aesthetic use.

CPR and FPC Documentation

CE Marking was introduced into the construction industry via the Construction Products Directive (CPD). Since 1st July 2013 CPD has been superseded by the Construction Products Regulation (CPR) and this makes CE Marking mandatory for all construction products covered by a harmonised technical specification. It is thus now a requirement that structural graded timber products, covered by the harmonised European Standard (hEN) for timber grading, EN 14081 (and supported by
Standards such as BS 4978 and BS 5756) and placed on the market, will need to be CE Marked. An accompanying commercial document (‘ACD’) can be issued confirming the strength grade of individual pieces of timber if they need to remain ‘clean’ or free of the stress grade stamp and CE mark.

The requirements for CE Marking of structural graded timber are found in Annex ZA of the harmonised European standard EN 14081-1. These requirements for the CE marking of structural graded timber are a relatively small addition to those currently in place under the BM TRADA QMark scheme for visual stress grading. The BM TRADA Q-Mark Scheme continues to assess White
Wood Management on an annual basis with certificate of competence for Jim White as registered grader for hardwoods (VSG BS5756 Hardwoods) and softwoods (VSG BS4978 Softwoods) supplemented by a qualification card which is available for inspection and renewed annually. Members are requested to provide a Factory Product Control manual to BM TRADA for review so that BM TRADA can then issue the member company with a Certificate of Factory Production Control (White Wood Management – Certificate of Conformity of the Factory Production Control).