Do my structural timber products require compliance testing?

The simple answer to this question is YES. The onus is now on you, the timber Processor/Manufacturer/Importer, to ensure that the structural timber products you have branded/marked with a stress-grade is in compliance with the structural timber properties applicable to that designated stress-grade, and also ensure that such compliance is capable of being verified. The only manner in which this can be achieved is to have a structural performance test database generated from a suitable compliance testing program.

Mechanically Stress-Graded Timber
Clause 5 of AS/NZS1748 “Timber-Mechanically stress-graded for structural purposes” clearly states that timber branded/marked as mechanically stress-graded timber must be initially evaluated, and also have its properties continuously monitored.
Appendices A1 and A3 (both informative) of that Australian Standard refer to AS/NZS4490 and AS/NZS4063, and provide guidance on issues related to;

  • Definition of resource through a parent population
  • Checking structural properties (in-grade testing)
  • Linkage between reference population and its structural properties
  • Sampling requirements for on-going monitoring
  • On-going monitoring of structural properties

Visually Stress-Graded Timber
The Softwood (AS2858) and Hardwood (AS2082) Visual Grading Standards have now placed the linkages between visual-grades and stress-grades into the informative Appendices. The “Identification of Grade” Clause in both of these visual-grading Standards now make it the Manufacturer’s responsibility to ensure that timber branded/marked with a stress-grade is in compliance with the structural properties applicable to the designated stress-grade, and also ensure that such compliance is capable of being verified. AS2082 Appendix A (Informative) even states;

Validation of the link between structural grade defined by this Standard and stress grade, using in-grade testing in accordance with AS/NZS 4063, is recommended'”
“Any stress grades evaluated through in-grade testing of full sized structural material in accordance with AS/NZS4063 should be taken to supersede all of the information presented in this Appendix.”

The compliance of the New Zealand softwood processing industry’s structural products have been put into doubt, and as a result the industry has been regulated to sampling their production of structural timber products, at the rate of 1 in a 1000 structural boards, to ensure grade compliance. The ACCC in Australia has directed the timber industry itself to find its own solutions, and to self-regulate their quality assurance programs.

One response from the Australian Timber Industry was to draft an Industry Best Practice document, “Guidelines for Verification of Structural Timber Properties”. This project was managed by Australian Plantation Products & Paper (A3P), and the main author being Geoff Boughton, TimberEd Services, who invited the timber processors to provide feedback at each stage of the drafting process. This Guidelines document has been written in Standard-eze, and is due for release in July 2008. The impact of this document will be assessed by most timber processors/importers and other stakeholders over approximately a 12 month period, then it will most likely be quickly adopted and republished as an Australian Standard.

Contact_me to discuss the benefits of setting up an appropriate sampling and testing program for your company’s structural timber products, and the costs involved for this service.


This entry was posted on Monday, June 23rd, 2008 at 11:49 pm and is filed under Compliance Testing. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.


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