10. The facings

10.1 The air gap

Cladding used in external wall cladding must be installed with a continuous, ventilated air gap between the underside of the cladding and the outer surface of the insulation. The air gap allows:

• to dry out the moisture present between the cladding and the insulation;

• any water infiltration to drain away;

• prevent the insulation from coming into direct contact with any water splashes.

It must be at least 20 mm thick, but may be thicker depending on the cladding.

The air gap must be continuous (nothing should block it, such as poorly fixed insulation, for example) and ventilated. Ventilation is...