Code of Practice v3.0 Online
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.
All roof cladding with a pitch of less than 8° must be provided with turn-downs after the roof is fixed, using special tools to ensure water flows directly into the gutter.
Where profiles that prevent turning down the pan (such as deep corrugated) are fixed at pitches of less than 8°, an 8.4.4.4 Eaves Flashing must be installed.
14.17A Profile Turndown
Providing a profile with a downturn will provide a positive drip edge and minimise the amount of sediment build-up at the gutter line.
Distortion should be avoided because it causes ponding and the collection of dirt, which in turn causes corrosion.