15 year field trial to assess the durability of UK softwoods

Timber for ground contact applications such as fence posts and stakes must be pre-treated correctly if they are to provide a long, secure and useful life. The British Standard for preservative pre-treatment of wood, BS8417, specifies that a timber component in ground contact must have a minimum desired service life of 15 years. Market concern about the ability of pre-treated wood to provide this performance prompted the Wood Protection Association (WPA) to take a series of initiatives to help the timber supply chain: 

- build buyer confidence in the performance of treated wood and

- counter the threat of the substitution of wood used in ground contact with man-made materials

In 2011 the WPA Benchmark Quality Scheme for treated wood was introduced. The scheme provides third-party verification that a component such as fence post is treated correctly in accordance with the specifications and practices set out in the WPA Wood Preservation Manual to achieve the BS8417 desired service life of 15 years. The scheme is unique as it certificates specific treated products and not the operations of the treater as a whole. Lists of products certificated under the WPA Benchmark quality Scheme can be found on www.wood-protection.org/quality

With a scheme in place, the WPA commenced planning for a major Field Trial to assess the durability of the most popular species used in the UK for ground contact applications - pine, Douglas fir, larch and spruce. In 2014, BRE was commissioned by WPA to establish two field trial sites with differing soil conditions - one in Scotland and one at Watford on the BRE site.These sites were established during 2015 with the installation of some 1,560 sawn posts and the monitoring project to assess performance is now commencing.

The WPA British Softwoods Field Trial has five key objectives:

1. assess the natural durability of the key plantation grown softwoods grown commercially in Britain – spruce, pine, Douglas fir and larch;

2. objectively assess the benefits of incising technology on these species in UK ground conditions;

3. compare the impact of two different pre-treatment drying regimes on Sitka spruce;

4. compare the impact of two different preservative loadings in UK species and UK ground conditions;

5. provide relevant data to better inform future developments in BS 8417 treatment specifications. 

The biggest ever field trial of its kind in the UK

In all the trial comprises 1400 75 x 75mm treated sawn posts, 600 of which have been mechanically incised, and 160 untreated controls, across both sites. In addition, the project includes some smaller EN2521 samples to characterise the test sites. This WPA Field Trial is the biggest project of its type ever undertaken in the UK and will run for up to 15 years.

The wood preservatives, loadings and treatment processes used in the preparation of the samples are in accordance with WPA guidance and approval and independently audited by BRE. 

Actions by the WPA to raise awareness about treatment quality and performance has underpinned the significant improvements seen in some parts of the UK wood protection sector in the last 2-3 years. If the momentum started by the early adoption and support of the WPA Benchmark scheme and the Field Trial can be maintained and expanded within the UK then the long term prospects for growth in demand for industrial wood preservation are excellent.

Who is backing this WPA Project?

The WPA Field Trial has been a long time in the planning but successful bids for matching funding support from Forestry Commission Scotland and Scottish Enterprise and a financial contribution from the Grown in Britain campaign have made this important project possible together with the sponsorship support of WPA members and other organisations involved in home grown timber supply, incising and wood preservation. Here we acknowledge the support given to date:

Major Sponsors: Forestry Commission Scotland; Scottish Enterprise; Grown in Britain; Wood Protection Association

Field test sites: Scotland – James Jones;  England – BRE

Production of posts: BSW; James Jones

Wood preservation: Arch Timber Protection; BASF Wolman; Koppers Performance Chemicals

Project Associates: Confor; TTF; UK Forest Products Association; Timber Decking & Cladding Association

Phase 1:Associate Sponsors: Bond Timber; Burt Boulton & Haywood; Calders & Grandidge; James Davies; Munro Sawmills; Taylormade Timber; M&M Timber; Clifford Jones Timber; Cordiners Sawmills; Ransfords 

Phase 2 is about to commence - become a sponsor and get an inside track on the outcome

In 2016 we commence Phase 2 of this project - the monitoring by BRE that will provide the data on which decisions about future standards are made. Project sponsors will get advanced notice of the results. Sponsorship starts at £250 and if you would like to your firm to become an Associate Sponsor of Phase 2 then simply contact WPA director, Steve Young - steve@wood-protection.org

It is fundamental for the future of wood protection that the industry meets customer performance expectations. The performance and reliability of treated wood in service, in particular in ground contact, underpins future market confidence and will fundamentally influence whether the industry is able to realise the many opportunities for growth it has developed. The WPA is committed to building confidence in the use of treated wood and to providing support through its Benchmark schemes by providing independent verification of a specific components compliance with BS8417 service life specifications.

Want to know how the Benchmark quality scheme can work for your business? Call Steve Young on 0777 4449206 or e-mail steve@wood-protection.org

Posted at 12:00 am on January 5th, 2016