Biological durability of wood in relation to end-use

The determination of biological durability of wood is an issue requiring sufficient reliability regarding end-use related prediction of performance. Five test institutes joined efforts to check standard test methods and to improve methodology and data interpretation for assessment of natural durability of timber species. A range of softwood and hardwood species was tested using both basidiomycete and soil soft rot testing. Based on combined processing of all data collected, an improved and simplified durability classification system was established. The test methods and the interpretation of results are proposed to be used to assess suitability and service life for applications under European hazard class 3 and 4. The methodology for basidiomycete testing only requires two test fungi and allows direct classification based on median mass loss, while for soil bed testing, which is only required when hazard class 4 applications are envisaged, a slightly more complicated approach proved to be necessary mainly due to variation in test soil parameters. Since service life can be based on natural durability classes, it is evident that these are identified differently for uses in or out of ground contact and for softwoods or hardwoods.