Market approval of wood treatment products requires knowledge and prove of long-term durability. Efficiency of wood treatment with a specific product is evaluated based on variety of tests, including penetration evaluation, leaching studies as well as decay tests. EN 252 standard test is a core method for wood durability evaluation in a ground contact, both for commercial product approval and scientific research. In different climates, treated wood is tested being installed halfway into the ground. The degradation is evaluated annually according to the standard. To provide an alternative and accelerated test method, Nordic Wood Preservation Council (NWPC) initiated a mini-stakes project with a reduced sample size. The project started in 2010 on 5 North European test sites and is still running on 4 of them. The mini-stakes were treated with three commercial Cu based products as well as CCA in several different product retentions. A set of untreated references was also included. The results of the mini-stakes are compared to the standardized EN 252 evaluations. Results show different lifetimes for different product retentions as well as different wood decay rates at different test sites. The study showed no significant acceleration of the EN 252 method.

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