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Timber used in contact with the ground or freshwater - called Use (or
Hazard) Class 4 in standards(1) - is subject to one of the most challenging
environments for timber. It is therefore most important that if
preservative treatment is required it is applied at the correct rate to give
Class 4 protection.

Changes in regulations(2) introduced over the past two years affecting wood
preservation have resulted largely in a change from the long-established
CCA(3) treatment to a new generation of copper-organic preservatives. One
of the consequences of the change from CCA is that users of treated
timber need to get used to a new way of specifying the product because
the degree of protection given to a component is more precisely tailored
to its use than ever before. This is especially so for Class 4.

The Wood Protection Association is aware that timber treated for example
to Class 3 requirements (above ground exposed to the weather) where
the biological challenge is much reduced can find its way into the Class 4
market. This presents a risk of premature failure and consequent threat to
the reputation of treated timber.

Commenting on the Make Sure It's 4 campaign, Steve Young, director of
the Timber Decking Association said, " Softwood is great for decking so
long as it has been properly pre treated. Where posts and joists will be in
contact with the ground only Class 4 treatment is fit for purpose - nothing
else will do. The TDA is all about promoting quality and good practice and
we very much welcome and support the WPA's campaign to raise user
awareness."

The aims of the Make Sure It's 4 campaign are:

Education - to help create awareness of the Use Class
system and encourage correct specification of treatment

Quality - to promote good practice and support WPA
member treaters, whilst helping to protect timber's
reputation and business against competing materials

Promotion - to raise awareness of the benefits the WPA
bring to the industry and provide a campaign members can
use to promote their business.

The Make Sure It's 4 logo can be used on point-of-sale material, labels for
packs of Class 4 treated timber and in other ways to raise awareness of
the importance of correct treatment for Class 4 uses.

Make Sure It's 4 is a campaign by the UK Wood Protection Association to raise wareness about the levels of protection that can be given to wood and why all timber in contact with freshwater should be treated to End Use (Hazard) Class 4 standard.

For more information please contact:

Mr S J Young
Director
Timber Decking Association
CIRCE Building
Wheldon Road
Castleford, West Yorkshire
WF10 2JT

Tel: 01977 558147
E-mail: director@tda.org.uk

Notes
(1) The relevant standards for wood preservation include:
The WPA Manual - 2005 edition in preparation
BS EN 335-1: Hazard classes of wood and wood-based products against
biological attack - Part 1: Classification of hazard classes.
Divides the many situations in which wood may be used into 5 "hazard classes". It is likely that the
term "use classes "will be introduced when this standard is revised.
BS EN 351-1: Durability of wood and wood-based products - Preservative-
treated solid wood - Part 1: Classification of preservative penetration and
retention.
Provides a "vocabulary" for specifiers to use when specifying penetration and level of chemical
protection.
BS 8417: Preservation of timber - Recommendations
Provides information for the specifier concerning the treatment of timber for use in the UK,
drawing upon appropriate portions of the relevant BS EN documents.

(2) Regulations. EU directive 2003/2/EC was implemented in the UK
through The Environmental Protection (Controls on Dangerous
Substances) Regulations 2003, SI 2003/3274 and The Marketing and
Use of Dangerous Substances (No. 4) Regulations (Northern Ireland)
2003, SR 2003/548. These regulate the uses of arsenic, including in
CCA preservatives.

(3) CCA. This the well-known chromated copper arsenate wood
preservative formulation invented in 1933 and widely used throughout
the world. It remains approved without restriction in many countries.