Roof curbs and HVAC

[Foxman]

Are roof curbs mandatory on an HVAC unit going atop a metal building for permitting? We don't get much rain or snow here in the desert so if its drainage that's not a concern but polystyrene...sounds like plasticif we get just one hail storm...I think so much for the roof curbs.

[Tossup]

They are not mandatory but I think they are always recommended. They are not just watertight but also allow for expansion and contraction, rust resistance features, etc.

[Foxman]

Yeah I found out more online Tossup. Thanks.