Napier University publishes new guide on structural timber grading
The Centre for Wood Science & Technology of Edinburgh Napier University has published a new guide on grading of structural timber.
The paper - downloadable here - summarises the processes and normative requirements involved in grading of structural timber, and outlines a number of areas in which matters may be improved, so as to make better use of the true properties of the timber resource used.
"The activities of resource segregation and timber grading are well researched, but what is not commonly realised is that there are opportunities to do things more efficiently. This is especially true when the structural timber is produced with a specific customer, project, or end use in mind", wrote the authors Dan Ridley-Ellis, Steven Adams and Stefan Lehneke.
The guide uses data from research projects, and development of machine grading settings, to illustrate how assignment of timber to a limited set of strength grades can, in exchange for convenience in trade, involve considerable compromise in design properties.
In some cases, this trade convenience is not necessary or can still be obtained while also permitting less of a compromise in design properties.
The paper also explains why, in research, knowledge of the timber grade is not all that useful and why it is necessary to take other steps to characterise the material.