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Service Classes (BS EN1995–1–1 section 2.3.1.3) — (1) P Structures shall be assigned to one of the service classes given below. NOTE: The service class system is mainly aimed at assigning strength values and for calculating deformations under defined environmental conditions. Galvanised Protection Z275 galvanised coating is the minimum corrosion protection recommended for Service Class 2 applications (BS EN1995–1–1 Table 4.1 Examples of minimum specification for material protection against corrosion for fasteners). Z600 galvanised coating gives a greater corrosion protection for use with masonry applications (BS EN845–1 Annex A1, Table A.1 Materials and corrosion protection systems). NOTE: Information on the assignment of structures to service classes given in (2)P, (3)P and 4(P) may be given in the National Annex. — (2) P Service class 1 is characterised by a moisture content in the materials corresponding to a temperature of 20ºC and the relative humidity of the surrounding air only exceeding 65% for a few weeks per year.
— (3) P Service class 2 is characterised by a moisture content in the materials corresponding to a temperature of 20ºC and the relative humidity of the surrounding air only exceeding 85% for a few weeks per year.
NOTE: In service class 2 the average moisture content in most softwoods will not exceed 20%.
— (4) P Service class 3 is characterised by climatic conditions leading to higher moisture contents than in service class 2.
UK National annex to BS EN1995–1–1 states the following service classes for these applications:
Service Class
Type of Construction
Cold roofs Warm roofs
2 1 1 2 1 2 2 3
Intermediate floors
Ground floors
Timber–frame walls, internal and party walls
Timber–frame walls, external walls
External uses where member is protected from direct wetting
External uses, fully exposed
NOTE: In service class 1 the average moisture content in most softwoods will not exceed 12%.
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