Meyer-Veltrup et al.: The combined effect of wetting ability and durability on outdoor performance of wood -development and verification of a new prediction approach Abstract Comprehensive approaches to predict performance of wood products are requested by international standards and the first attempts have been made in the frame of European research projects. However, there is still an imminent need for a methodology to implement the durability and moisture performance of wood in an engineering design method and performance classification system. The aim of this study was therefore to establish an approach to predict service life of wood above ground taking into account the combined effect of wetting ability and durability data. A comprehensive data set was obtained from laboratory durability tests and still ongoing field trials in Norway, Germany, and Sweden. Supplementary, four different wetting ability tests were performed with the same material. Based on a dose-response concept decay rates for specimens exposed above ground were predicted implementing various indicating factors. A model was developed and optimised taking into account the resistance of wood against soft, white and brown rot as well as relevant types of water uptake and release. Decay rates from above ground field tests at different test sites in Norway were predicted with the model. In a second step the model was validated using data from lab and field tests performed in Germany and Sweden. The model was found to be fairly reliable and it has the advantage to get implemented into existing engineering design guidelines. The approach at hand might furthermore be used for implementing wetting ability data into performance classification as requested by European standardisation bodies.

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Abstract:To know the minimum moisture threshold (MMThr) in wood allowing for the initiation of the fungal decay by basidiomycetes is relevant both from a theoretical and a practical point of view. The present work summarizes the knowledge about MMThr and presents experimental data obtained by improved laboratory decay tests on Picea abies (Norway spruce) and Fagus sylvatica (European beech) with the fungi Coniophora puteana and Trametes versicolor under different exposure scenarios well suited for simulation in real applications. The three experimental set-ups, in which the pile tests play a pivotal role, differed in terms of external moisture supply and the inoculation strategies. It was confirmed that wooddestroying basidiomycetes are able to degrade wood at high relative humidity without any external source of available liquid water. The method of moistening the wood samples has an effect on the MMThr before initiation of the fungal decay, but different basidiomycetes were able to cause significant decay at moisture contents considerably below the fiber saturation point.