It is widely accepted that besides temperature wood moisture content (MC) is the key factor when it comes to durability of wooden structures exposed to weathering. Many approaches to predict the service life of wooden structures have therefore been based on using wood MC as one major input-variable to develop dose-response relationships between material climate and decay response. However, to improve these approaches and to model the decay and service life of timber structures more precise information about the minimum MC threshold for the onset and development of fungal decay are needed. MC thresholds determined in two different studies have shown that different fungi were able to degrade wood clearly below fiber saturation. This data has been summarized in the present paper and applied to moisture monitoring data recorded in above ground tests. Different thresholds were comparatively used for quantifying the moisture induced risk for decay. The results have shown that setting material-specific MC thresholds determined in a pile test led to a remarkable higher number of wet days with critical MC compared to commonly used MC thresholds.

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