Stopping the rot28 April 2012 by Stephen Powney
The timber and wood preservation sectors have been working hard to tackle the problem of premature post failures
• Early failures of treated fence posts are widespread.
• The WPA has launched its Benchmark quality assurance scheme.
• Incised post production is gaining momentum.
• Performance information about industrial wood preservatives will be listed in a WPA manual.
When I set out to write an update on the problem of premature treated fence post failures I never imagined I would get so personally involved in the subject.
I have just become another statistic in this debate – with a 2.7m post installed only two years ago in my garden having failed.
I examined the post with my neighbour, seeing the soft rotting timber which had presumably caused it to keel over. We nervously looked at the four other posts we had installed at the same time with closeboard fencing.
A few weeks earlier I had ordered two panels and a post for another part of my garden. The supplier said it was now recommending using the Postsaver protective sleeve on its in-ground contact posts because of reports of early fence post failures.
When I asked its opinion on the failures the company blamed the new post-CCA generation of timber treatments, saying they were not as effective.
To protect itself, the supplier now stipulates on its invoices that in-ground contact treated posts should have “additional” protection – which I guess means Postsaver.
Up and down the country discussions on this thorny issue are taking place – involving consumers, fencing contractors, suppliers (both merchants and fencing manufacturers) and the timber preservative manufacturers.
Of course, various factors can contribute to fence posts failing early and I suspect my fencing supplier – an independent which buys in its treated products from three suppliers – does not know the whole story.
For the Wood Protection Association (WPA) the issue has been top of its technical committees agenda and says it is now time to benchmark treated wood quality.
“Ever since reports about the premature failure of fence posts started to emerge in 2008, the WPA has taken a series of actions designed to help preservative suppliers, treaters and other timber trade associations restore confidence in treated wood, particularly in the fencing sector,” said WPA director Steve Young.
WPA action includes investigating reports of fence posts failures, issuing a findings “fact file” and publishing a guidance note about achieving the best results when treating spruce – a species classified in British Standards as resistant to preservative impregnation.
It also launched “Make Sure It’s 4”, a communications initiative to help the industry raise buyer awareness about the need to specify the correct treatment for timber destined for ground contact applications.
More recently it unveiled the WPA Benchmark quality assurance scheme for treated wood, based on a third-party assessment of a specific components treatment and fitness for purpose. Individual components are marked as evidence of quality and traceability.
Since the launch, 10 treaters have either achieved full certification or are in the process of certification, with more applications in the pipeline.
In addition, a new programme of performance trials with various softwood species in ground contact has been agreed between the WPA and BRE.
Other current action includes reviewing all species’ durability data and looking at the benefits to service life of mechanically incising timber classed as resistant to treatment.
Incising [regular, small machine cuts into the post], says the WPA, is shown to deliver treatment penetration and loadings required to meet not only a desired service life of 15 years but also 30-year specifications too.
“It is almost inevitable that techniques to enhance the durability performance of resistant species and exposed heartwood will be standard procedures in the UK as they are in other major treated wood-consuming markets,” said Mr Young.
Also, the WPA now requires major chemical suppliers to submit to a WPA product approval scheme for verification of their recommendations such as preservative loadings for the different “use classes” in British Standards. Approved products will be listed in the WPA Wood Preservation Specification & Practice Manual that is the basis of the Benchmark quality scheme.
This will bring Benchmark closely in line with other major treated wood-using countries that operate quality schemes for treated wood over and above ISO 9001 certification of management systems, said Mr Young.
It is intended that details of individual preservatives will be listed in the WPA manual.
The Benchmark quality scheme is based on the manual’s guidance and, in particular, the establishment of what’s known as the “safe relationship” between the species, its condition, intended application, preservative solution strength and plant pressure cycles. The safe relationship is specific to an individual treatment plant and requires extensive analytical work to establish in collaboration with the preservative supplier.
“It is time-consuming work but necessary to achieve the quality consistency required to satisfy customers.
“There will always be several sectors with different price points in any market and the use class 4 market is no different,” added Mr Young. “The price of any product or service will almost always have a direct relationship to its quality.”
The wood preservative manufacturers have been active in addressing the concerns.
“There’s a lack of confidence out there with in-ground contact fence posts but we have to educate the market,” said David Law, marketing services manager at Lonza Wood Protection.
He pointed out that most preservative manufacturers used the same formulations in the CCA days, but now modern treatments differed from provider to provider.
He listed five important considerations for successful in-ground posts: species, preparation (correct moisture content), the type of wood preservative used, the correct treatment process and installation of the post.
“Some wood species are slightly easier to treat than others but you can still get good results with spruce if it is handled properly.”
Lonza has installed an incising machine test rig at its headquarters. “It will allow a better penetration of the treatment into the timber,” said Mr Law. Other companies installing incisers include James Jones & Sons and Walford Timber.
Osmose has just launched a document to help the timber industry with regard to in-ground contact wood, designed to give more information and improve effectiveness of products.
“We want to work with any company that wants to improve,” said Andy Hodge, marketing director of Osmose Europe.
He believes the debate has matured and moved on from an initial backlash against CCA-replacement wood preservatives and positive work was being done to educate treaters about using them.
“We have to be pragmatic and you have to work with UK indigenous species [such as spruce]. The new preservatives are not as forgiving as CCA but we have to work with them, work within the new legislative framework and they have to be applied properly.”
Treaters could not use the same processes as they did with CCA, he added. “There is nothing out there which is not designed to do the job. CCA was a very good product, but even that had some failures.”
The Postsaver bitumen-lined fence post sleeve has benefited from the lack of confidence in treated posts. Company director Richard George told TTJ that in the last three to four years there had been a “dramatic shift” in its sales, further accelerated by the product’s appearance on Dragons’ Den last August.
He directly linked issues surrounding premature fence post failures to fencing contractors and stockists adopting Postsaver as a solution, aided by reduced production/sale costs and easy blowtorch application.
“We’ve seen product uptake and sales growth treble in the last 18 months; we’re already planning a £230,000 investment in production equipment at our Wakefield site,” said Mr George.
He said sleeves cost 51p and application with a blow-torch typically cost 25p.