FEATURE TIMBER PROTECTION
Treated Wood Works Outdoors From time-to-time stories emerge, often driven by other agendas, that treated posts cannot be relied on. Gordon Ewbank, CEO, Wood Protection Association (WPA) reveals that the weight of scientific evidence and the experience of its members proves otherwise.
T
reated wood is the
the ground no significant signs of
mainstay material of
deterioration in treated spruce, pine,
the fencing industry
larch and Douglas fir posts could be
and preservative
detected yet the untreated control
systems do work when applied
posts have already starting to fail.
in accordance with industry
In all markets, there is a choice of
standards and when treated
products and price points. The fence
posts are installed correctly.
post market is no exception. Premium
WPA members produce millions
products with a quality assured
of treated posts every year and,
pedigree and predicted performance
contrary to allegations that failures
do cost more. If a low-priced fence
are widespread, they report that
post is accompanied with a vague
incidents of early onset decay are
description such as ‘green treated’
now relatively uncommon. That’s
then buyer beware! The level of
because treaters have invested
preservative protection could be quite
heavily to underpin confidence in
inadequate for the end use making
treated wood for ground contact
premature failure almost inevitable.
use. These investments include: The WPA BenchmarkTM Scheme •
Enhanced timber drying facilities
•
The introduction of incising
Currently, some fencing contractors are calling for no-strings
technology to improve
performance warranties on treated
preservative penetration
posts including consequential costs it fails prematurely. However, such
•
Innovations in treatment plant design and process control
calls swim against the tide of industry opinion now TTF members have
•
Improved communications to raise awareness about how to specify
adopted third-party certification as the best way to verify treated wood
treated wood correctly
quality. Certification schemes are highly successful in other treated
Offering third-party quality verification that treatment complies
wood markets like USA, Canada and Scandinavia and TTF members
with either 15 or 30 years desired service life requirements in
believe the time has come to use them in the UK too. The QA scheme
industry Standards.
TTF members are most likely to turn to is the WPA BenchmarkTM.
•
The WPA BenchmarkTM for wood impregnated with preservative has Wood preservation is an industry of continuous development where
been operating successfully for over 8 years and has accredited treaters
treatment Standards are based on scientific evidence accumulated
in the UK and the EU. The scheme verifies, under third-party audit, that
from years of laboratory and field testing, constant process innovation
the treatment process and treated product are compliant with industry
and extensive sampling and analysis of treated products. All too often
standards. Whilst the British Standard BS 8417 defines preservative
though, if a post decays prematurely, the finger of blame points at
penetration and retention levels by application ‘use class’ it does not
the preservative. This is wrong. Claims that current preservatives lack
set down how these critical requirements are achieved but points to
efficacy totally ignore the evidence that they do perform.
the recommendations in the WPA Industrial Wood Preservation Code of Practice.
Confirmation of Preservative Efficacy It takes years of research and testing to develop an industrial
An Open Invitation
wood preservative. Before a manufacture can sell any preservative to
WPA is delighted that several major timber trade associations are
UK wood treaters they are required, by law, to get approval from the
collaborating closely in its campaign to promote quality and help grow
Health & Safety Executive (HSE). A key part of the HSE’s assessment
the UK market for treated wood. The offer of collaboration is always
process is close scrutiny of a preservative’s efficacy data and field test
open to those who share our mission to make the most of wood as a
results. Approval for sale will not be granted unless sufficient evidence
sustainable, low environmental impact construction and landscaping
of effective performance has been accepted.
material.
Confidence in the efficacy of current preservatives is further reinforced by early results from the 15- year independent UK field trial
The WPA Industrial Wood Preservation Code of Practice is available
of 1,560 square sawn fence posts managed by BRE. After five years in
as a free download from www.thewpa.org.uk
Timber Trader UK Magazine
Spring 2021
22
www.timbermedia.co.uk
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