Summary
• The WPA Benchmark is a quality scheme specific to treated wood.
• It provides assurance of conformity with an individual treatment plant’s quality systems and the WPA’s treatment guidance.
• It was developed by industry representatives, the WPA and the BRE.
• Benchmark FR Build is a quality scheme for flame retardant-treated materials for timber frame.

In the world’s major wood treating markets, third-party quality assurance schemes have operated for many years with great success. They provide independent attestation of conformity with a national specification and give added value to treated wood products by providing customers with reassurance that the products they buy are fit for purpose. Many schemes like NTR in Scandinavia, RAL in Germany and the ALSC scheme in America are internationally recognised and respected.

Despite the UK’s history of influencing the development of wood preservation worldwide, a quality scheme specific to treated wood has never been introduced here. Until now that is.

The Wood Protection Association’s (WPA) Benchmark scheme started to operate this autumn. It was developed in response to growing calls for a more credible method of providing reassurance about treated wood performance than the various individual warranties and guarantees that had become a feature of certain sectors, fencing in particular. The need for a third-party quality scheme specific to treated wood is rooted in the reality of current wood-processing practice and wood preservation technology.

Only a few years ago, the preservatives used in vacuum pressure impregnation processes were very similar in terms of both their formulation and loadings for any given application. But wood preservation science has advanced and changed.

While copper is still the principal ingredient of modern preservatives, substances of concern, such as chrome and arsenic, have been replaced with a mix of different organic biocides.

Specific treatments

No two preservative brands are identical in formulation; and no two timber treatment plants are identical in how a particular Use Class specification is achieved. This means that achieving the appropriate preservative penetration and retention for, say, a Use Class 4 ground contact fence post will vary from plant to plant and by preservative formulation. What is known as the “safe relationship” between the individual treatment process solution strength, vacuum and pressure periods and preservative penetration and retention must be established not only for each individual Use Class, but also for the wood species being used, its moisture content and the service life that is desired by the customer.

Typically, 15 years is the default service life for copper-based preservatives unless the higher 30-year specification defined in BS 8417 is called for, such as in highways fencing contracts, while 60-year life can be specified for creosote.

The safe relationship is established through a scientific process of sampling and analysing treated components by the preservative supplier working in collaboration with the treater. Once defined, it is the key to ensuring conformity with BS 8417, fitness for purpose and customer satisfaction.

Some companies have their timber treatment plants included in the scope of their ISO 9001 quality accreditation but this does not mean that the products produced by the plant are fit for purpose. It’s the ability to consistently achieve the penetration and retention requirements either directly, or via the safe relationship that does this and that is not covered in ISO 9001 audits – but it is the sole focus of the WPA Benchmark scheme.

WPA Benchmark provides a third-party attestation of conformity with an individual treatment plant’s unique quality systems or safe relationship specifications and the treatment guidance set out in the WPA manual: Industrial Wood Preservation-Specification and Practice. This manual and its commodity code specification system is widely referenced as the bible on preservative-treated wood in the UK by organisations such as National Building Specification, NHBC and the Highways Agency and its guidance is tailored to achieving compliance with BS 8417.

Independent auditors

WPA-appointed independent auditors will also be checking that plants are operated in line with the guidance set out in our Quality Guidance Note 2 (QGN2) for timber treatment installations. QGN2 is considered an essential document in the quality manuals of firms whose treatment operations are included within the scope of ISO 9001, which QGN2 supplements with specific guidance about treatment plant operation.

To achieve Benchmark certification a treater must have established and be achieving the safe relationship specifications and operate in accordance with the WPA manual and QGN2 and be in possession of the 2011 edition of BS 8417.

The Benchmark scheme has been developed by a steering committee made up of the four major preservative suppliers, seven leading timber treaters, and representatives from the WPA and BRE. This committee will continue to be responsible for overseeing the scheme. During the development of the Scheme Document, treatment members put a lot of emphasis on making Benchmark workable from a treater’s point of view.

The first phase of audits has been carried out at Walford Timber (the first UK firm to achieve certification), James Davies, M&M Timber, Burt Boulton & Haywood, Calders & Grandidge and WJ Components. A second phase is due to be completed by the year end.

Certified products

The first Benchmark certificates are starting to be awarded and the first treated products quality assured under the scheme will be available over the next few months.

Although at this stage the priority has been given to WPA members, Benchmark is being made available to any wood-treating business manufacturing for the UK market so long as it can demonstrate compliance with the scheme’s requirements.

WPA is pleased to announce that the significance of the association establishing a quality scheme has already been recognised by UK Timber Frame Association (UKTFA) and Benchmark FR Build has been established. This is a quality scheme for flame retardant-treated materials used in timber frame structures in accordance with UKTFA FR Build specifications. It has been developed in collaboration with UKTFA and relates to all products applied under factory-controlled conditions to give timber frame components appropriate protection from fire during the construction phase.

The first WPA Benchmark FR Build audits are under way at Glenalmond Timber, Perth and at WJ Components, Hull.

For details of the WPA Benchmark and Benchmark FR Build schemes e-mail: info@wood-protection.org.