SERVICE CLASSES
When connecting timber structures, the design resistance is influenced by the effect of moisture. The requirements for the fittings’ corrosion protection depend on the service class in which they are used.
The following classification applies (SS-EN 1995-1-1:2004, chapter 2.3.1.3):
Service class 1
The average moisture content in most softwoods will not exceed 12%. This corresponds to a temperature of 20°C and the relative humidity of the surrounding air only exceeding 65 % for a few weeks per year.
For example, fittings mounted in an external wall structure surrounding permanently heated premises and protected by tightly ventilated external cladding.
Service class 2
The average moisture content in most softwoods will not exceed 20%. This corresponds to a temperature of 20°C and the relative humidity of the surrounding air only exceeding 85 % for a few weeks per year.
Structures that are ventilated and protected against direct precipitation, e.g. fittings for roof trusses, attic, and suspended foundation beams. Fittings installed in structures in non-permanently heated ventilated buildings or premises with non-damp-proofing activities or storage such as holiday homes and cold stores.
Service class 3
The average moisture content of most softwoods exceeds 20%, resulting in a higher moisture content of the wood material than that of service class 2.
Fittings that are unprotected from moisture or in direct contact with the ground, e.g. post base, column shoes and concrete angle brackets.
