COP v3.0:structure; dead-loads

3.9 Dead Loads 

Any permanent load added to the roof cladding or structure is termed superimposed; that includes air conditioning equipment, solar installations, television aerials, anchor points and walkways.

All permanent loads must be fixed to or through the rib of the cladding profile or directly to the primary structure. The rib, even at the purlin line, has limited capacity for an additional load and the roof cladding must be free to expand.
Any attachment to the roof cladding must be compatible with the cladding.

An air conditioning unit correctly installed on a roof, using durable and compatible materials.

No additional equipment must be directly connected to the cladding without considering the effect of increased dead and live loads.
When designing installations for placement on the roof, the roof traffic implications of installing and servicing such must be considered when determining point load resistance requirements