Severity of exposure
Important notes
The climatic categories listed below are to some extent an over simplification, as on occasions it is necessary to allow for micro climates or areas that are more sheltered or more exposed than the rest of the building. Generally, in sheltered positions which are protected against rain and direct sunlight, e.g. balconies doors inside porches the same systems are suitable but periods between maintenance may be increased. Exposed areas e.g. open south facing may need the maintenance period shortened.
See BS 6150:2006 Section 4.6.2 Exposure conditions
The service life of a conventional coating in a severe environment is likely to be significantly shorter than in a moderate environment. Where it is not possible to modify the environment, or where maximum durability is required, High Performance Coating Systems should be specified.
Mild exposure
| Corrosive category | Exterior | Other exterior factors | Interior | Other interior factors |
|---|---|---|---|---|
| C1 (very low) | - | - | Heated buildings with clean atmospheres, e.g. offices, shops, schools, hotels, and domestic situations | Light soiling, abrasion or handling of surfaces |
| C2 (low) | Inland areas (more than 10km from the coast), non-industrial with low levels of pollution and average rainfall | - | Unheated buildings where condensation might occur, e.g. depots, sports halls | Light soiling, abrasion or handling of surfaces |
Moderate exposure
| Corrosive category | Exterior | Other exterior factors | Interior | Other interior factors |
|---|---|---|---|---|
| C3 (medium) | Urban and industrial atmospheres, moderate sulphur dioxide pollution. Coastal areas with low salinity. | - | More frequent moderate condensation, e.g. in kitchens, bathrooms, washrooms, etc. Production rooms with high humidity and some air pollution, e.g. food-processing plants, laundries, breweries, dairies | Moderate soiling, abrasion and handling of surfaces |
Severe exposure
| Corrosive category | Exterior | Other exterior factors | Interior | Other interior factors |
|---|---|---|---|---|
| C4 (high) | Industrial areas and coastal areas with moderate salinity. Coastal ship- and boat yards | Areas with a driving rain index of 7 or more (see BS 8104 for more information) | Exposure conditions subject to frequent high humidity or heavy condensation, especially if pollutants, e.g. sulphur dioxide or ammonia are present. Chemical plants, swimming pools | Exposure conditions in which heavy soiling or hygiene requirements necessitate frequent cleaning of surfaces. Surfaces subject to heavy abrasion or impact |
Very Severe exposure
| Corrosive category | Exterior | Other exterior factors | Interior | Other interior factors |
|---|---|---|---|---|
| C5-I (very high - industrial) | - | - | Buildings or areas with almost permanent condensation and with high pollution | Surfaces in contact with chemical solutions, process liquors and other aggressive agents |
| C5-I (very high - marine) | - | - | Buildings or areas with almost permanent condensation and with high pollution | Surfaces in contact with chemical solutions, process liquors and other aggressive agents |
NOTE: for wood, the exposure conditions are better classified in accordance with BS EN 927-1, which takes into account the construction and the climate.
© BSI 2006