Technical Booklet C Site Preparation and Resistance to Contaminants and Moisture·Page 29·6.7
Resistance to moisture from the outside - General
External walls must resist moisture from precipitation through one of several methods: damp proof courses, trays and flashings, solid walls of sufficient thickness, cavity walls, or weather-resistant cladding.
As well as resisting the passage of moisture from the ground, an external wall should give protection against precipitation. This protection can be given by damp proof courses, trays and flashings (see paragraph 6.8), by a solid wall of sufficient thickness (see paragraphs 6.9 to 6.12), by a cavity wall (see paragraphs 6.13 to 6.17), or by an impervious or weather resisting cladding (see paragraphs 6.20 to 6.30).
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