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Resource Centre

All WPA publications are free to view and download - simply click-on the relevant document image.

Select the subject field and resource topic from choices below.

Please contact us if you have queries about any aspect of wood protection not featured here.

The WPA Wood Selection Guide

Exploring flame retardant treated wood, naturally durable wood, preservative treated wood, modified wood, wood-based sheet materials and engineered wood products.

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The Buyers Guide to Preservative Treated Wood

Preservative treatment provides wood with added durability but it’s a mistake to assume that all pressure treated wood is the same. Make sure you buy and use treated wood correctly.

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Environmental and economical aspects

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WPA Flame Retardant Specification Manual

Industrial flame retardant treatment of wood and wood-based panel products

Providing architects, developers, project engineers and building control officers with essential guidance about the flame retardant treatment of wood and wood based panel products. 

FR FAQs and Guidance Notes
WPA.TTF Guidance Note - FR No.1 Resistan

Q. What's the difference between 'reaction to fire' and 'fire resistance'?

WPA FR 1: Understanding Fire Protection Terms - Reaction to Fire and Fire Resistance

The WPA gets asked many questions about the fire protection of wood used in construction, this being one of the most frequent. These terms do have very different definitions and it's fundamental to know the difference when specifying flame retardants.

WPA.TTF Guidance Note - FR No.2 Combusti

Q. What's does 'combustibility' actually mean in terms of building materials?

WPA FR 2: Understanding Fire Protection Terms - Combustibility

Detailing what is meant by the combustibility of wood and the test standards that define the reaction to fire properties of FR treated wood/wood based panels and building materials in general. 

WPA.TTF Guidance Note - FR No.3 Service

Q. How do I specify the Flame Retardant treated wood for its Service Environment ?

WPA FR 3: Understanding Fire Protection Terms - the Service Environment

Before specifying enhancement using a flame retardant, two specification fundamentals must be established: what reaction to fire performance is required and what is the service environment? 

WPA.TTF Guidance Note - FR No.4 (2) Timb

Q. How does the Construction Products Regulation (CPR) affect FR treated wood?

WPA FR 4: FR Rated Timber Products and the CPR

Those who manufacture construction products for which a harmonised standard exists have an obligation to draw up a Declaration of Performance (DoP) and apply a CE mark when the product is first placed on the market. 

WPA.TTF Guidance Note - FR No.5 (2) Timb

Q. What do current building regs say about timber cladding and fire treatment?

WPA FR 5: External Timber Cladding: Guidance to amended Building Regulations (09.2019)

The outcome of the UK government’s assessment of the use of different cladding materials in the wake of Grenfell confirmed that timber, where necessary enhanced with flame retardant (depending on aspect), remains fit for purpose and compliant with revised Building Regulations. 

WPA.TTF Guidance Note - FR No.6 (2) Spec

Q. What do I need to know when specifying flame retardants for timber?

WPA FR 6: FR Specification Checklist

This check-list provides a step by step guide to ensuring that fire retardant treatments for wood-based materials are fit for purpose. Further guidance on the fire protection of wood is available in the WPA FR Specification Manual.

WPA.TTF Guidance Note - FR No.7 Test Cla

Q. What is a Fire Test Classification Report?

WPA FR 7: Understanding a Fire Test Classification Report to EN13501-1

Evidence of the efficacy of an FR enhancement of timber, following appropriate testing, will be found in a Classification Report. This guidance note explains the elements found in a report and details what a specifier should be looking for.

WPA.TTF Guidance Note - FR No.8 Understa

Q. Who's responsible for the DoP and CE marking of Flame Retardant (FR) treated timbers?

WPA FR 8: Understanding the Flame Retardant Treated Wood Supply Chain

This note examines the different routes to Construction Product Regulation (CPR) compliance and sets out in simple terms the responsibilities of FR teated wood manufacturers, suppliers and distributors.

WPA.TTF Guidance Note - FR No.9 Treated

Q. What are my responsibilities as a distributor of FR treated wood products?

WPA FR 9: Effective Traceability throughout the Flame Retardant Treated Wood Supply Chain

This Guidance Note addresses the more complex situation where distributors/owners of non-FR stock send material to a third-party service company for FR treatment before selling it on to the open market. 

WPA.TTF Guidance Note - FR No.10 Treated

Q. How can I be assured of quality flame retardant treatments and products?

WPA FR 10: Assuring Quality through the Flame Retardant Treated Wood Supply Chain

From treatment, through manufacture and distribution - see how WPA's Benchmark quality approval schemes can help.

FR Online Training
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Free RIBA accredited CPD: Fire Safety and FR-Rated Timber

Working with Wood Campus and Local Authority Building Control (LABC), the WPA have produced several on-line training resources. This RIBA accredited CPD can be taken free of charge  (you don’t need to pre-register for access) ideal for architects, specifiers and Building Control Officers.

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Webinar: Enhancing the performance of wood-based products in fire

WPA CEO - Gordon Ewbank presented at the Chartered Association of Building Engineers (CABE) on 24 July 2019. 

Webinar: Understanding the Supply Chain of Flame Retardant treated wood products

WPA CEO - Gordon Ewbank presented this webinar to members of the Timber Trade Federation and WPA in May 2020.  

Modified Wood FAQs and Guidance Notes
WPA MW1 Understanding Modified

Q. What is Modified Wood?

WPA MW 1: Understanding Modified Wood

Wood modification technologies provide designers, builders and users of wood and wood-based products with another option where enhanced performance, including durability and dimensional stability, is required. 

WPA MW2 Establishing performance of modi

Wood Modification

Q. How do I choose a modified wood to meet all the performance requirements for my project?

WPA MW 2: Establishing the Performance of Modified Wood

Although a range of wood properties may be affected by the modification process, the suitability of modified wood for a given end use is based on three main criteria: durability, strength and dimensional stability. 

Preservative Treatments for Wood Buyer's Guide
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Q. What kind of treated timber should I buy and what's the difference?

The Buyers Guide to Preservative Treated Wood

Preservative treatment provides wood with added durability. However, 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 

Preservative Treatments for Wood FAQs and Guidance Notes
WPA-TTF Guidance Note TW 1 (2) Wood Trea

Q. How do UK preservative treatment requirements (of BS 8417) relate to the Nordic NTR Scheme?

WPA TW 1: Guidance for Wood Treaters in the NTR Region

Timber treaters in the NTR region do not normally treat spruce for external, uncoated applications. However, this is permitted by BS 8417, the relevant UK standard. This fact sheet provides guidance to NTR treaters on how the treatment of spruce to meet a BS 8417 Use Class 3 specification aligns with current NTR classes and specifications. 

WPA-TTF Guidance Note TW 2 (2) Improving

Q. How can wood treaters assure effective quality timber treatments?

WPA TW 2: Guidance on Achieving Quality Treated Wood

 In 2017 TTF & WPA collaborated on a survey to identify the strategic priorities needed in order to grow demand for preservative treated timber. Analysis of the responses identified three priority areas for action. This note concentrates on the last point: To ensure independent verification of the treatment process. 

WPA-TTF Guidance Note TW 3 Brexit & the

Q. If and when we leave the EU will this affect the treatment or supply of treated timber?

WPA TW 3: Brexit and the Biocidal Products Regulation (BPR)

Every industry sector has its’ own particular concerns about the implications of Brexit and in particular, a ‘no deal’ outcome. The preservative treated wood supply chain is no exception 

WPA Guidance Note TW 4 Indoor Air Qualit

Q. What impact does treated timber have on our indoor air quality?

WPA TW 4: Preservative Pre-treated wood and Indoor Air Quality

The indoor air environment is a complex subject that needs to consider the nature and source of any chemical, its ability to pass into the indoor air, its effect on humans when in the air, and the ability to remove it from the air by ventilation. 

WPA Guidance Note TW 5 Mould

Q. How do you prevent mould growth on treated wood products?

WPA TW 5: Preventing Mould Growth on Treated Wood Products

Mould fungi can grow in the water layer on wet and damp timber surfaces. The growth is often fluffy and may be white, green, black or coloured, depending on the species and presence of spores. 

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Q. What are the current rules about creosote treated timber?

WPA TW 6: Use of Creosote and Creosote-treated Wood

There are specific permitted uses for creosote in the UK under the Biocidal Products Regulation - read all the details in this publication.

WPA TW 7 Benchmark Treaters Scheme - Exe

Q. I'm a timber service treater, how do I get WPA Benchmark Approved Treater accreditation?

WPA TW 7: Benchmark Scheme for Preservative Treated Wood - Executive Summary 

The WPA offer two compliance routes to Benchmark accreditation. This note summarises assessment criteria and itemises costs - including discounts for Timber Trade Federation (TTF) members.  

WPA TW 8 Understanding Use Class 4 2020-

Q. How do I know if my ground contact treated timber will last and be fit for purpose?

WPA TW 8: Understanding Use Class 4 - Preservative Treated Wood  

For wood in permanent ground or fresh water contact, or providing exterior structural support, Use Class 4 levels of protection MUST be achieved. Read why this is important and how it can be achieved through correct specification and treatment.

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Q. How do I know if my above ground treated timber will last and be fit for purpose?

WPA TW 9: Understanding Use Class 3 - Preservative Treated Wood  

For outdoor wood used above the ground, such as decking or cladding boards, Use Class 3 levels of protection apply. Read why this is important and how it can be achieved through correct specification and treatment.

WPA TW 10 Understanding Use Class

Q. Do internal construction timbers need to be preservative treated?

WPA TW 10: Understanding Use Class 2 - Preservative Treated Wood  

Where wood is used indoors, above ground and within the building envelope, but with an occasional risk of wetting, Use Class 2 levels of protection are required. Read why this is important and how it can be achieved through correct specification and treatment.


Treated Wood, a Sustainable Choice - Executive Summary  WEI / EWPM

Summary of a report by the trade bodies representing and working in the European pressure treated wood industry examining the sustainability of treated timber and the balance of social, economic and environmental aspects.

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Q. What do I do with unwanted treated wood / How do I dispose of treated wood waste safely?

Guidance Note 02/09: Dealing with Treated Wood Related Waste Streams

For those involved in the business of industrial wood preservation, this publication is intended to provide information about current waste minimisation options and regulatory responsibilities as a basis for decision-making.

 Trackwork  who are WPA Members, run a dedicated treated wood disposal service. Energy from their waste plant is audited, monitored and licensed by the Environment Agency and burns hazardous waste wood to generate electricity. This goes on to power their Doncaster site and exports surplus energy to the National Grid.

Quality Guidance Note 2 (QGN2): For use with BS EN ISO 9001:2015

Relating to the controlled preservation of wood and wood-based materials to improve their durability.


This document can be used as part of a Quality Management System audited by a Certification Body and as part of a quality plan audited under the WPA Benchmark scheme. QGN2 forms the basis of the National Highways Sector Scheme 4 for the preservative treatment of fencing and is referred to directly in Highways England quality scheme documents. QGN2 is an operating document of the WPA. It is a ‘controlled document’ in Sector Scheme 4 and is an essential part of the verification audits required by the scheme and carried out by UKAS accredited Certification Bodies.

Preservative Treatments for Wood Codes of Practice
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WPA Code of Practice: Timber Treatment Plants

Safe Design, Installation and Operation

This publication was produced in collaboration with UK Regulatory bodies and is designed to guide those responsible for the design, installation or operation of timber treatment plants.

Preservative Treatments for Wood Online Training
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Free On-Line Courses from Wood Campus

Dip into these free CPD courses, many RIBA accredited, for information about a specific topic, or complete the full course. You don’t need to pre-register for access. On successful completion of a course and assessment, you will be asked for your email so Wood Campus can send you a CPD certificate.

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Preservative Treatments for Wood Research Projects
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WPA Field Trial of Preservative Treated British Softwoods - Year 5 Observations

To assess the durability in differing test site conditions

WPA in collaboration BRE commissioned a long term controlled field trial of sawn and pressure treated British Softwood posts at two sites with differing soil conditions - here's a summary of the results so far. 

WPA Guidance Note TW 4 Indoor Air Qualit

Preservative Treated Wood and Indoor Air Quality

The WPA commissioned Building Research Establishment (BRE) to help them understand how treated timber performs in the context of air quality within buildings to actively support the continued safe and appropriate use of wood preservatives to enhance the performance of timber used in construction.

The environmental,  sustainable and economical benefits of using Wood

Wood - Building the Bio-economy CEI-Bois

Published by the European Confederation of Woodworking Industries this book sets out the environmental arguments for using wood over alternative building materials at the same time as putting the industry’s economic contribution in context. 

How the timber industries can help solve

How the Timber Industries can help solve the housing crisis Confederation of Timber Industries

A recent inquiry by the All Party Parliamentary Group for the Timber Industries (2019) examined the role that timber could play in a changing world – by providing skilled jobs, delivering sustainable and affordable homes and being at the forefront of addressing climate change. 


The WPA are ardent supporters of Wood for Good and their Wood CO2ts less campaign - for more information visit here.

Wood CO2ts less is a collective mark of Wood for Good Ltd. Using wood from sustainably-managed forests instead of other materials is a good way to reduce CO2 emissions. 

Need to get in touch?

If you cannot find the answer to your question within any of the listed publications, please get in touch.


We have knowledgable people based in the UK office as well as numerous technical consultant members we can call upon to assist you.

Go to CONTACT US page or give us a call.

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