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.
GRP Sheeting is measured in weight per square metre. The test provisions of AS/NZS 4257 require the measure to be calculated from the area of the profile, including the overlap. Because the mass of plastic sheeting varies between profiles, the thickness will vary for different profiles of a given weight per square metre. Deeper profiled products are usually supplied as standard at a greater weight per square metre than more material-efficient profiles.