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Grown in Britain supported field trials ‘showing promise’

Grown in Britain have been supporting a Wood Protection Association field trial which was established to create a robust and independent test of the performance of preservative treated fence posts made from UK grown softwoods.

This innovative project is the largest field trial of its type held in the UK in the last 50 years and is one of Grown in Britain’s first projects in it’s expanding research and development programme aimed at enhancing the sustainability of home grown supply chains..

The field trial includes: 

  • The installation of 1360 matched fence posts made from UK grown softwoods: pine, spruce, larch, Douglas fir and 150 EN252 stakes at two test sites with different ground conditions
  • Conducting inspections of condition of posts and stakes
  • Providing reports on the field trial data and draw conclusions from the data obtained.

When the project was established in 2015, one set of posts was installed in BRE Garston, Watford and the other set in Birnie Wood, Elgin. The above ground cut end of each post was effectively capped to protect the end grain.

At each site pine sapwood EN252 stakes untreated and treated with reference wood preservative as an internal reference control were installed along with EN252 stakes of untreated Sitka spruce, Douglas fir, larch and pine heartwood. These stakes provide vital information on: 

  • The characterisation of the biological hazard at the field sites
  • Natural durability data in an accelerated ground contact field test

The performance assessment of the timber in the field trial after 3 years in ground contact has shown significant failure of untreated EN252 stakes and fence posts at both the BRE Garston and the Birnie Wood sites. However, the inspections of preservative treated fence posts show no signs of change or deterioration.

The nature of this type of performance testing is long term as the test specimen is a ‘product test’, i.e. a replica of a preservative treated fence post aiming to meet a minimum of a 15-year desired service life. The fact that no signs of deterioration are observed after three years exposure of unincised Sitka spruce (KD) fence posts treated with all test preservative systems ensures confidence that all the other preservative treated material will be performing better.

Grown in Britain will continue to support this vital work that is supporting our woods and forests for the future.