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.
Structures mounted on the roof requires consideration of all the factors contributing to the performance of the roof cladding.
Some structures which are commonly mounted on roofs include air conditioning units, aerials, photovoltaic systems, and solar water heating units.
Design and installation of these structures should consider at least three areas of performance:
- Structure – the effect of mounting the structures and roof traffic for ongoing maintenance; see 3.9 Dead Loads and 3.6.2 Roof Traffic.
- Durability – corrosion may result from issues such as wet contact, capillary action, unwashed areas, material compatibility, and runoff; see 4.10 Other Causes of Corrosion.
- External Moisture – penetrations influence roof drainage and can affect weatherproofing of the cladding; see 9.3 Penetration Durability and Compatibility.