Timber pile foundations are widespread in many areas around Europe and North-America. Especially in areas with weak soils, timber pile foundations have been a very good and economic solution. However, aging of the foundations can become a problem, as physical, biological and/or chemical degradation may occur over time. Now, that foundations can be up to 500 years in cities like Venice, Amsterdam, Hamburg, Boston and many others, questions arise about the reliability and which assessment methods can be used in order to estimate the current load carrying capacity and their residual service life. Residual service life is depending both on the time-to-failure behaviour of wood, as well as, the dead and live loads on the piles below buildings, quay walls and bridges. The approach taken integrates degradation models with a reaction kinetics based damage model. For wood that remains consistently below the waterline, the combination of bacterial degradation and long term loading is considered the most important, but degradation by fungi also may occur depending on soil and groundwater conditions. The integral assessment model will function as a tool for repair and maintenance strategies for asset managers and structural engineers.@en