This British Standard code of practice describes the causes and effects of surface and interstitial condensation in buildings, and gives recommendations for their control. The principles of control, and the recommendations given, can be applied generally to both new and existing buildings. Some constructions, e.g. curtain walling, or those around cold stores and those buildings with unusually high internal humidities, such as swimming pools or buildings with wet industrial processes, are outside the scope of this standard as they require specialized treatment. This standard provides guidance for building designers, contractors, owners, managers, and occupiers and includes recommendations for heating, ventilation and construction which can control condensation. Methods of calculation are also given to help assess and quantify risk. Methods are given to determine the occurrence and assess the effects of: a) surface condensation, or mould growth, one of its associated effects; and, b) interstitial condensation.