Use Classes are defined by British and European Standards (as defined in BS.EN. 335-1), providing a guide to the risk of decay or insect attack to timber components, depending upon their end use. The higher the use Class, the higher the level of preservative protection is required.
UC1 Internal building timbers with no risk of wetting or condensation.
UC2 Internal building timbers with a risk of wetting or condensation.
UC3 External building, fencing and landscaping timbers used out of ground contact.
UC4 External building, fencing and landscaping timbers used in ground contact.