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.
The roofing contractor should notify the main contractor, architects or owner when he has completed the scheduled work. It is prudent if he records any damage to the sheets (or lack thereof) at this point, particularly if subsequent trades accessing the roof. Damage of any sort caused by other trades is not the responsibility of the roofer.
All gutters, valleys, roof channels and the roof cladding should be left clean and free from debris on completion of the work, and any roofing related debris on site should be safely removed.