It must not be assumed that it is safe or permissible to stand on any roof structure or roof cladding.
The manufacturer of the roof sheeting must provide technical literature stating the point load limitations of the profile. The information must indicate the positions on the sheet where persons may safely walk or stand without causing damage or, alternatively, indicate the necessity to provide temporary walkways.
For roofs tested in accordance with MRM testing standards see 17.1 Metal Cladding Testing, a Restricted Access roof will withstand a 100 kg point load applied to the rib or over two pans, and an Unrestricted Access roof will withstand a 100 kg point load to a single rib at mid span. It must be taken into account that a worker laden with tools may weigh more than 100 kg, and impact loads can also contribute to exceeding this limit.
When access to the roof is necessary after construction, it is best practice to in the pan of the profile when walking up the roof, and follow purlin lines when traversing roofs.