30 August 2017

Update to Timber strength grading WIS

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As a result of species, environment and growing conditions timber is inherently variable, not only between species but even between individual pieces of timber from the same tree. This variability affects the stiffness and strength of timber, which must be graded before being used structurally.


It is important to ensure that structural timber is strong enough to carry the highest possible load. Strength grading provides a basic prediction of the strength of individual pieces of timber, ensuring that the weakest pieces are rejected and the remainder are assigned to an appropriate strength grade and/or strength class.


Since the last update of Wood Information Sheet (WIS): Timber strength grading and strength classes, several standards have been written or amended, including BS EN 14081, BS EN 16737, BS EN 338, BS EN 1912, BS EN 350, and BS EN 336. TRADA experts have completely rewritten this WIS in order to reflect the current requirements for strength grading and strength classes.


From data tables, the difference between CE marks and certification marks, right through to the availability of strength-graded material, this WIS helps members keep up to date with the regulations and standards involved in strength grading and strength classes.


Members can download a free copy of the WIS Timber strength grading and strength classes. If you are not a member, WIS sheets are available to purchase online in PDF and hardcopy at the Bookshop.