BS/EN 252-2014 pdf download.Field test method for determining the relative protective effectiveness of a wood preservative in ground contact.
This BS/EN 252 describes the ground contact feeld test to assess the effectiveness of a wood preservative applied to solid wood. However, much of the test procedure described is applicable to wood products that fall outside the scope of this standard. This annex offers guidance as to how the standard may be adapted so that these products may be tested.
A.2 Naturally durable wood
When testing the natural durability of wood, this standard should be used with variations as described in
EN 350-1.
k3 Modified solid wood
Modified wood is wood that has been subjected to the action of a chemical, physical or biological agent resulting in property enhancement. Any enhancement in biological durability is by a non-biocidal mode of action.
Where a wood modification treatment can be applied at varying retentions similar to those for wood preservative (described in 5.4) then the wood treatment can be tested in the same way as preservative treated wood. However, for some types of modified wood the treatment process may not involve the application of chemical, or may involve a specific manufacturing process where the application of a range of retentions is either impractical or irrelevant. In such cases the method of sampling the wood product prior to testing will differ.
Modified wood from at least 3 separate batches should be tested. Test stakes should be cut from larger modified boards to the dimensions given in 3.3. Boards should be sampled at random from each batch, A minimum of 5 stakes from each batch and a minimum of 30 stakes in total should be exposed in each field test site. Where possible, the boards from which each test stake is cut should be analysed to determine the extent of modification. Reference stakes should be those as required in EN 350-1, but it is recommended that treated reference stakes described in Clause 7 are also used.
k4 Wood panels or engineered wood products
Wood panels or engineered wood products can be tested in ground contact field sites as described in Clause 9, Clause 10, Clause 11. Clause 12, Clause 13 and Clause 14. Size constraints may mean that dimensions other than those in 3.3 are chosen.
Wood panels or engineered wood products from at least 3 separate batches should be tested. Test stakes should be cut from wood panels or engineered wood products to be as close as possible to the dimensions given in 3.3. The test material should be sampled at random from each batch.
Every year, 10 new untreated stakes should be installed evenly in the field. The control stakes should be seasoned and stored in the same way as treated specimens before installation.
The object of using untreated controls is to give an indication about the type of biological agents present in the field and their aggressiveness.
Stakes treated with the reference preservative will give additional information of the type of decay and virulence,
Prior knowledge of the biological activity of the field over time (e.g. 5 years) is important. Information is provided from untreated stakes and reference preservative.
A specific area selected for the test field should be of uniform soil and surface, on level, moist but well drained land.
In some countries the fire-hazard in summer shall be considered very seriously and the site selected and protected accordingly.
Maintenance of Field Test Sites:
A previously unused test plot is recommended. However, field test sites are often limited in space. Therefore, it is likely that differently treated stakes are installed in the same plot in succession of a previous EN 252 test. There is a need to verify that any remaining components of a previously tested wood preservative or their metabolites do not hinder wood damaging organisms.
At least 5 untreated wood specimens are placed into holes where the stakes with the highest retention of the preservative under test and 5 specimens where the highest concentration of each reference product had previously been situated.
For comparison at least 10 pine sapwood stakes should be installed at the same time in soil where no preservative testing has taken place.
If an area is to be reused the top soil should be turned, mixed and raked level.
Alternatively, a plot may be used as new ground after a period of 5 years following the removal of all stakes.
The used plot should be mixed by physical means taking care to fill any old holes and to keep the plot level. New holes shall not be closer than 15 cm from old holes.
A physical /chemical characterization of the test site should be made available and can be included in the test report. This should include parameters such as vegetation, organic content of the soil, clay content and water holding capacity. Experience in the variability of microbial activity within the test site should also be included in the test report.BS/EN 252-2014 pdf download.