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Timber Treatment Action Plan: 
Audit deadline approaches for T
imber Development UK (TDUK) members

4 December 2023

In 2020, the WPA/TDUK collaboration identified three priority areas for action, which have since been adopted as TDUK policy:

  1. To address the common failure to specify treated wood correctly;

  2. To address the lack of understanding on how to correctly install and use treated wood;

  3. To ensure independent verification of the treatment process.


This Preservative Treatment Action Plan is now part of the TDUK Code of Conduct


As 2024 approaches, the final stages of the Plan (point 3) are now being implemented.


The following priorities have been set by TDUK's Governing Body, to concentrate on structural, higher risk treated timber elements:

  • ​ALL TDUK members and their suppliers who have not already done so, must undergo an independent treatment plant audit by WPA Benchmark or equivalent before 31 December 2023. This audit will consist of at least the WPA Benchmark Approved Treater audit for the plant and process controls, plus a WPA Benchmark Approved Product audit for Use Class 4 where the member is treating fence posts, deck joists or other designated UC4 products.

  • TDUK remains fully committed to independent auditing of UC3 products and want members to achieve this as soon as possible. Those who have not done so, should prepare for these audits by working with their treatment supplier to get samples of their UC3 products tested for compliance with the requirements of the WPA Code of Practice and/or BS 8417.

  • To ensure sufficient audit capacity over the next three months and to achieve the first two priorities, the governing body will seek to gather further evidence on the commercial preparedness of members and their customers before setting the final implementation date for compulsory UC3 product audits.

  • It is the intention of the governing body to review the final implementation date for compulsory UC3 product audits in Q1 2024.

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TDUK and WPA Members

Download our Guidance Note TW7 for details of the pricing structure for WPA Benchmark audits

TDUK Action Plan Summary

For more information around the TDUK, 3 point action plan and what this means for TDUK members - follow this link to their Trade Note.

WPA Benchmark Treated Wood Scheme TW7
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