Round timber in construction: Notes for structural design

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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 and this sheet gives basic technical guidelines to building with round timber. This document contains a basic guide to the standards which cover round timber construction as well as some grading and species selection advice, design approaches and a number of references for further, detailed reading.


  • Basic terminology
  • Processing
  • Sizes
    • Measurement of sizes and tolerances to prEN 14544 and prEN 1309-2
    • Permitted deviations from target sizes
  • Measurement of features
    • Measurement of features and tolerances to prEN 14544 and BS EN  1310
  • Visual strength grading
    • Marking
  • Mechanical properties
  • Specification
    • Conditioning, Moisture Content (MC) in service conditions
    • Natural durability and conferred durability (via preservative treatment) of wood
  • Environmental aspects
    • Environmental impact assessment
    • Ecolabelling
    • Sustainable forestry and chain of custody certification
    • Machining - health and safety aspects
    • Waste management

Suggested Reading

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 Information...

01/03/2019 |  Wood Information Sheet  

Appearances can be deceptivenavigation-arrow

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...

01/01/2011 |  Magazine Article  

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
  • Span tables for domestic floor joists: C16 timber
  • Span tables for domestic floor...

01/01/2004 |  Info from other organisation