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Strength grading and the end user – lessons from the SIRT project at Napier University

  The paper reviews the research that has been undertaken by the Strategic Integrated Research in Timber (SIRT) project at Napier University, with reference to the technologies, techniques and approaches required to grade the UK’s timber resource according to the real needs of the end user. The project has been operating since 2004, and has made significant progress in understanding the nature and variability of UK-grown Sitka spruce.

It has been seen that UK-plantation Sitka spruce can yield timber of grade C24, and that with the right breeding and silviculture it may indeed be economic to aim higher than the current C16 production. Conversely it has also been seen that there are geographic areas where the current resource is of marginal quality for constructional use. In these circumstances it is important to know how to find the best wood within each tree, and how to divert unsuitable material at an early stage. Crucially, it is important to ensure grading of such marginal material is actually delivering what the end user wants.

Indeed a number of important general questions remain about the suitability and robustness of current grading practices. These questions are partly informed by data that has been gathered to-date, but more research is needed and possible approaches are presented for discussion. These include questions around: the variation in the resource and the implications for sawmillers and end users; the potential and pitfalls for resource segregation; and the ‘non-mechanical’ properties that affect utilisation of graded timber (principally distortion and knots).

  • Publication Status:


  • Projects:

    Strategic Integrated Research in Timber Project (SIRT)


Ridley-Ellis, D., Moore, J. & Lyon, A. J. (2008). Strength grading and the end user – lessons from the SIRT project at Napier University



Forestry; Timber; Engineering wood; Strength; Grading techniques; Sitka Spruce;

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