Laboratory methods for assessing wood decay resistance are being investigated in the framework of an ongoing European research project. This paper summarizes the main results obtained for soil-bed tests based on the European prestandard ENV 807-Test 2. The data suggest that this testing methodology is suitable for evaluating the natural durability of timber species in soil-contact under conditions which promote soft rot. Results after 16 weeks of exposure were found to enable the assessment of wood durability. Both, mass and strength (MOE) loss determination proved suitable for hardwood testing. In contrast, only the MOE losses recorded for softwood species were correlated with their expected decay resistance. The lack of correlation between mass loss and durability data is likely related to the very slow decay rates found for softwood timbers in the soil bed. Furthermore, artificial weathering prior to testing was shown to affect the susceptibility of some timber species to soft rot decay. This suggests that a weathering step may be required prior to biological testing. Wood leaching by the protocol described in EN 84 deserves attention as a possible alternative to the very expensive and time consuming artificial weathering pretreatment. In conclusion, laboratory soil testing using a modified ENV 807-Test 2 methodology can be recommended for assessing the durability of timbers to be used in ground contact. Such tests can provide useful information to complement the results from basidiomycete tests. The potentials of basidiomycete tests based on EN 113 to assess the natural durability of timbers were also investigated. The main findings will be presented at this conference by van Acker et al. (1998).

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