Technical Booklet C Site Preparation and Resistance to Contaminants and Moisture·Page 33·6.18
Framed external walls with vented and drained cavity
Framed external walls must have cladding separated from insulation by a vented and drained cavity with a vapour-permeable but water-resistant membrane (such as a breather membrane) on the cavity interior.
Any framed external wall will meet the requirement if the cladding is separated from the insulation or sheathing by a vented and drained cavity with a membrane that is vapour permeable, but resists the passage of liquid water e.g. a breather membrane, on the inside of the cavity (see Diagram 6.4(f)).
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