Appearances can be deceptive

TRADA image

Philip O'Leary, head of TRADA Technology's Structural Investigations team, highlights his concerns about a lack of understanding in the industry about timber strength grading issues.

Timber as a natural material, is inherently variable, even within a single species. Strength grading of softwood and hardwood overcomes this, by assessing the strength and stiffness of individual pieces intended for structural use and assigning them to a strength grade and/or strength class. Specifiers can then work with known and dependable mechanical properties.

Article from the TRADA Timber Industry Yearbook 2011

Suggested Reading

Round timber in construction: Notes for structural designnavigation-arrow

The use of round timber for structural applications can provide designers with attractive features in sympathy with local surrounding in a range of applications from housing and agricultural buildings to major engineering structures such as bridges.

Structural engineers are often faced with little information on designing with round timber...

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Constructional timber: Fact sheet no. 3navigation-arrow

This wood for good fact sheet is an introductory document to constructional timber.

The sheet contains tips, guides to marking and span tables for C16 and C24 floor joists. 


  • Tips
  • Markings
  • Species
  • Specifications
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Softwood sizesnavigation-arrow

Timber is an internationally traded material and the UK has traditionally imported timber from a wide range of countries, as well as producing its own. A large range of sizes are available throughout Europe, with individual countries having different traditions as to the sizes in common use.


This Wood...

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