Safety and serviceability assessment of timber Structures in service has to deal to the high varaibility associated to timber members and connections. The capacity to maintain timber structures fit to use requires the existing of punctual or continuous (monitoring) evaluation methods allowing to respond to the need to adapt to new uses or to assist in defining and establishing strengthening works. The present scenario deals mainly with the use of concepts and rules mentioned in applicable European standardization and not easily fit to existing structures.

Different international committes have been working on establishing common principles to support more reliable assessment procedures for existing structures: