Flame-retardant treated wood

Jennie Ward
Timber Development UK

Jennie Ward outlines the legal obligations for businesses supplying flame-retardant treated timber—highlighting documentation, traceability, and manufacturing responsibilities under UK regulation, and how to stay compliant with critical fire safety standards.

As part of its role as the UK Construction Products Regulator, the Office for Product Safety and Standards (OPSS) is now actively reviewing how flame-retardant (FR) treated wood products—including timber cladding—are placed on the market. Several timber businesses have already been contacted to verify compliance.

These products are inherently Safety-critical, and ensuring their traceability and performance claims meet the legal requirements of the Construction Products Regulation (CPR) is now a top priority for regulators. A key issue that OPSS is focusing on relates to the Declaration of Performance (DoP) required to support FR treated wood products when they are placed on the market.

As a business, if you are sending a wood product to a treatment plant for FR treatment so you can make an additional claim about its performance then, legally, you must take on the responsibilities as the manufacturer of that product – this includes producing a new DoP.

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What does this mean for suppliers?

If you are sending wood products such as cladding to a third-party for fire-retardant treatment and then supplying it to market with an enhanced performance claim, you are legally classed as the manufacturer of that treated product.

This comes with a set of legal obligations, including:

  • producing a new Declaration of Performance (DoP),
  • affixing the correct CE or UKCA marking,
  • maintaining a certified Factory Production Control (FPC) system.

Even if your operation is not a factory—for example, a warehouse or distribution hub—these responsibilities still apply.

Key compliance requirements

1. Product performance evidence

Before placing FR-treated wood products on the market and in partnership with the treatment provider a valid Fire-test classification report must be obtained from a notified (EU) or approved (UK) body. This will include all of the product’s description and forms the basis of your DoP.

2. Factory Production Control (FPC)

A certified FPC system must track and trace all treated products. This includes:

  • Batch IDs
  • Staff training logs
  • Stock documentation
  • Archiving of treatment certificates
  • Procedures for non-conforming materials

3. Issuing a DoP and CE/UKCA Marking

Once the treatment process and traceability system are in place, and the product has a valid fire classification report, you are required to issue a DoP in compliance with Annex III of the CPR. This document supports the CE or UKCA marking, which must then be affixed to the product.

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The role of the treater

The FR service treater does not own the product; they are responsible for the correct application of the treatment and play a critical subcontracting role. They must:

  • Validate the product’s physical characteristics (e.g. thickness, species, moisture content).
  • Ensure alignment between the supplied material, classification report, and end-user specifications.
  • Apply approved FR formulations in controlled plant conditions.
  • Maintain their own certified FPC system and undergo regular audits by an approved (GB)/notified (EU) body.

Any inconsistencies between the product description and the fire classification test report (e.g. wrong species, profile, or thickness), treatment should not proceed.

Support and guidance for members

To help you get this right, the Wood Protection Association (WPA)—in collaboration with TDUK—has produced a set of detailed FR guidance notes covering:

  • roles and responsibilities of the Supplier and Treater,
  • when and how a new DoP must be issued,
  • legal obligations around traceability.

Of particular importance is Guidance Note WPA FR 91 , which outlines responsibilities throughout the FR treatment supply chain – including cladding—and which references other guidance notes that are relevant.

Act now to stay compliant

Fire performance in construction is under intense scrutiny, and regulators are placing more responsibility on suppliers to uphold safety standards for all the right reasons.

If you’re supplying FR-treated wood products, now is the time to ensure your procedures, documentation, and legal obligations are watertight.

For more information or support, please contact Nick Boulton, Head of Technical and Trade, Timber Development UK.

Reference

  • Wood Protection Association (WPA). (2023). Benchmark Quality Scheme for Fire Retardant Treated Wood Products: Guidance for Treaters, Specifiers and Users [PDF]. Castleford: WPA. www.thewpa.org.uk/files/ugd/65ba63 c7f05c23195d4f979ea132b916278824.pdf [Accessed 17 Jul. 2025].