The NZ Metal Roof and Wall Cladding Code of Practice is a comprehensive design & installation guide, and a recognised related document for Acceptable Solution E2/AS1 of the NZ Building Code.
COP v3.0:external-moisture; nzbc-clause-e2-external-moisture
The objective of this provision is to safeguard people from illness or injury which could result from external moisture entering the building.
Buildings should be constructed to provide adequate resistance to penetration by, and the accumulation of, moisture from the outside.
- Roofs shall shed precipitated moisture and snow.
- Roofs and external walls shall prevent the penetration of water that will cause dampness or damage to the building elements.
Other performance requirements quoted relate to transmission of ground moisture, areas below suspended floors, condensation in concealed cavities, and construction moisture.