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.
It must not be assumed that it is safe or permissible to stand on any roof structure or roof cladding.
All roof cladding has access restrictions that are described in 3.6.2 Roof Traffic.
Where free access or heavy walking traffic is expected on the roof cladding, using 0.55 mm coated steel or 0.9 mm aluminium cladding should be considered.
Roof cladding on roofs with a pitch of less than 10° is particularly susceptible to traffic damage. Low pitched roofs using 0.4 mm thickness steel or 0.7 mm aluminium are considered unsuitable for foot traffic and should be provided with walkways.
The people employed for maintenance work on air conditioning plant, chimneys, painting, or fitting television aerials often don't know where to stand and consequently cause permanent deformation that can lead to ponding and eventual failure.
If permanent walkways are not provided, cat ladders should be available for use at any time when inspection or repairs to the roof are necessary. They should be designed to be at least 375 mm wide, and the battens or steps should not project beyond the edges of the board or stringers.
It is the responsibility of the main contractor to inform the owner of any restrictions concerning roof accessibility.