COP v3.0:penetrations; penetration-durability

9.3 Penetration Durability 

All fittings and materials above a penetration must be made from compatible materials and there must be no runoff onto the roof from incompatible materials or corrosive discharge.
Condensate and outflow from any sources such as air conditioning units, solar units or hot water pipes must not be discharged onto metal roof cladding but must be separately drained to an inert gutter or downpipe.

Level back curbs will not have the same durability as arrowhead or cricket designs and may require maintenance of the coating to match the durability of the roof cladding.