Field trial to determine the relative protective efficacy of a wood preservative in contact with soil

04.022026

Field test, Mushroom, Preservation, Rot fungi, Termite, Use class 4

Biological tests

Biology - Construction

2de transfo & Construction

The NF EN 252 standard corresponds to an outdoor test designed to determine the effectiveness of a wood treatment product against termites and wood-destroying fungi, for use in use class 4, i.e. in contact with the ground or in a particularly humid environment. All manufacturers of use class 4 products use this test to validate their products in real-world conditions.

This trial aims to evaluate the effectiveness of treatment products, as well as the durability of natural and modified wood.

The BioForBois laboratory has two sites located in forests with different climates. The first is on the Île d’Oléron, in a temperate zone with an oceanic climate. The organisms present reflect the degradation agents found in mainland France (subterranean termites and rot fungi). The second site is located in a tropical zone in Guadeloupe and reflects the specific risks in this region. For other test sites, partnerships have also been established in the French overseas departments and territories in French Guiana and Réunion.

For this test, which aims to determine the effectiveness of a wood treatment product, wooden stakes are treated by impregnation with the product to be tested at different concentrations. They are planted in the ground on a test site and evaluated annually for a period of five years. Comparison with controls treated with a reference product makes it possible to determine the effective retention of the product being tested in protecting wood from subterranean termites and wood-decaying fungi.

The test report is used to determine the biological reference value (BRV), which corresponds to the effective retention of the product to protect wood for use in service class 4, according to the criteria of EN599-1.

Modified or heat-treated wood may also be subjected to this type of test. In this case, its durability is assessed according to the criteria of standard EN350.