Field Above Ground Double Layer Test Method


This method is a test for wood preservatives that are intended for use in wood to be exposed to the weather out of contact with the ground without the additional protection of a surface coating (i.e. Use Category 3B).

This method is quite widely used in Europe and Scandinavia. Several configurations of the method exist. Basically the methodology involves placing two or more samples horizontally in overlapping layers, usually not in direct contact with the ground but often with the bottom surface of the "layers" in close proximity to the ground. Both untreated and treated material can be used in the layers, with configuration designed to simulate a deck or similar construction. The layers of samples are dismantled and examined at intervals. The extent of fungal attack on the external surfaces and within the joint areas is rated according to a specified rating system. Data for test samples treated with the test product are compared with those generated using a reference preservative and untreated samples to assess relative effectiveness.

A standardized version of this test method can be found in EU Standard xxxx (contact yyyy).