The study will assess preservative loadings, the impact of different pre-treatment drying regimes, the natural durability of species, objectively examine the benefits of incising and provide relevant data to better inform recommendations in BS 8417.
It has been made possible by recent successful bids for matched funding support from Forestry Commission Scotland and Scottish Enterprise, plus a financial contribution from the Grown in Britain campaign.
The treated softwood posts being trialled at two UK sites – in Scotland and England – are spruce, pine, Douglas fir and larch.
The WPA believes strengthening the 15-year specification should only be based on data derived from a controlled field trial of commercially sized sawn posts of domestic softwoods.
The trial will include batches of untreated posts and batches treated to BS 8417 Use Class 4 retentions, with some treated to higher retentions.
Incised and treated posts will also be trialled. Some 600 75x75mm treated samples (300 incised) and 80 untreated posts will be in the field trial, as well as some EN252 samples.
Test sample post preparation, quality control, project logistics and management will be carried out by the WPA, in partnership with key commercial organisations with an interest in British softwoods. Auditing, test site monitoring and annual reporting will be completed by BRE.
“BRE has extensive experience of timber field trials and their role in this WPA project is essential to maintain the objectivity and independence of the project outcomes,” said WPA director Steve Young.
Sourcing, conditioning and incising of posts is sponsored by BSW and James Jones, while preservative treatment and analysis of performance is sponsored by BASF, Lonza and Osmose.
The Scottish test site is provided by James Jones and the English site is courtesy of BRE and Grown in Britain.
