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Campaign to promote 'fit for purpose' treated timber

Preservative Treatment Action Plan

Since 2017, the Timber Trade Association (TTF) and the Wood Protection Association have collaborated to enhance the education and quality of preservative treated timber products.


At the TTF AGM on 17 November 2020, TTF members unanimously voted to implement the Preservative Treatment Action Plan into the TTF Code of Conduct.


As a result, Members must adhere to the guidance provided in BS8417 (2014) and the 2021 WPA Code of Practice: Industrial Wood Preservation for the choice, use, and application of wood preservatives.

Is your treated timber 'fit for purpose'?

On-going Campaign 2020 - 2021



Background to the campaign

Results from ‘mystery shopper’ research sponsored by the WPA, confirmed that understanding amongst many users of preservative treated wood is very poor indeed. 


  • When asked if there was a specific treatment specification for timber in ground contact, over 90% of people surveyed said they didn’t know.

  • When asked if they understood what ‘Use Class 4’ means, 72% said they didn’t know.

It’s a mistake to assume that all pressure treated wood is the same. Whilst one piece of treated wood may look very much like any other, the level of preservative protection could be very different.


British Standards for wood preservation – BS 8417 and the new WPA Code of Practice: Industrial Wood Preservation,  require that the loading and penetration of preservative impregnated into the wood is tailored to the desired end use. Applications for treated wood are therefore grouped into Use Classes, the three main being 2, 3(u) and 4.

Messaging to target markets

The challenge is how best to simplify this message whilst not losing technical accuracy. Therefore, WPA has launched an educational campaign in partnership with the Timber Trade Federation (TTF) and the Timber Decking & Cladding Association (TDCA).


For the fencing, garden and landscaping sector, the focus is on promoting the use of the term Use Class 4 for treated wood used in contact with or close to the ground, using the medium of the WPA’s Make Sure it’s 4 logo and communications package.

For the broader timber supply chain, the focus also includes differentiating between interior and exterior applications for treated wood – using a bold, colour coded 'Use Class 2, 3 or 4?' message and simplified product descriptions. See the full descriptions HERE.

Select the images to download and share the WPA Code of Practice, the Buyer's Guide to Treated Wood and the Use Class 2, 3 or 4 Poster

WPA Industrial Wood Preservation Code of
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To support the campaign four new Guidance Notes on Understanding Use Class 2, 3 and 4 preservative treated wood are available for further guidance on what the most critical Use Classes mean in practice.

These include a simple explanation of what national standards require for each application, what species are most suitable, what preservative penetration to expect in different treated commodities and the necessary quality control criteria.

NEW Making the most of wood WEBINAR 2021

Hosted by WPA CEO Gordon Ewbank this educational training webinar details the principles involved with the correct specification and use of preservative treated wood.

Take a look around the

Resource Centre

FAQs - Manuals - Guidance Notes - Training

All of our resources are free to view and download. Please contact us if you have questions about any aspect of wood protection specification, quality assurance or application good practice.

WOOD: designed by nature, protected by innovation

The Wood Protection Association

5c Flemming Court, Castleford, West Yorkshire

WF10 5HW. United Kingdom

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