Probabilistic methods for perfromance based service life evaluation of wooden components

A performance-based service life design format based on climatic exposure on one hand and “biological wood resistance” on the other hand is presented in this paper. Limit states for onset of mould growth and rot decay are defined. Performance models for the biological processes are proposed by which onset of deterioration can be predicted for arbitrary climate histories. Models were applied to assess risk for onset of mould growth and decay under natural outdoor climate. The results indicate that quantitative models can be used as a powerful tool for durability design of wood in the building envelope and in exterior applications. It is demonstrated that the uncertainty originating from climate variability between years and between different geographical locations is significant. It is discussed how performance based durability design can be implemented in practice and how reliability and risk concepts can be implemented into the service life design process for wood.