From 21st May, the update to BS8417 has been in force and this has an impact on the treatment of fence posts with exposed heartwood, depending on the Use Class. The changes have impacted on our timber treatment services, mainly for NHSS4, however non-incised posts can still be treated to Use Class 4 and be covered with a 10 year warranty, underwritten by leading chemical preservative supplier, BASF-Wolman.
WJ Group is fully approved to treat timber to National Highways Sector Scheme 4 (NHSS4) in accordance with BS8417. The recent updates to the British Standard mean that all posts treated under this scheme must now be incised on all exposed heartwood surfaces prior to treatment to allow for 6mm penetration of preservative chemicals. This is the new specification for a 30 year desired service life.
WJ offers a 15 year warranty for NHSS4 timber treatment, underwritten by BASF-Wolman and this will continue to be available on all incised posts.
In addition to NHSS4, WJ Group treats timber to Use Class 3 and 4 using Wolmanit CX-10 and offers a 10 year timber treatment warranty, underwritten by BASF-Wolman. Holding test data on chemical retention to back up its decision, BASF-Wolman will continue to support this warranty on non-incised redwood timber posts. There is no actual long term data available for incised posts using the current generation of environmentally advanced, low hazard copper and organic biocides preservative treatment chemicals.
Mark Eggleston, WJ Group MD comments: “What this means in practice is that whether incised or not, WJ will continue to offer all sizes of business 10 and 15 year timber treatment warranties in addition to NHSS4 treatment in accordance with BS8417. Given that the most important thing is to use timber that has been effectively and comprehensively treated for its intended use, this is perhaps the best of both worlds and should reassure timber and fencing businesses of the quality level available at WJ Group. We’re proud to work closely with BASF-Wolman, the leading chemical preservative supplier and believe that we have the most robust solution for every specification of timber treatment”.