Architectural metal roofs are generally water shedding roof systems that have a flat pan and ribs on each side. Because they do not provide advanced waterproofing capabilities, these systems are designed for steep-slopes to allow water to shed off of them. The code requires that the designed slope be no less than 3:12. The code does not require the seams to be watertight.

Structural metal roofs have waterproofing (water barrier) capabilities and can be applied at slopes above 1/2:12. These types of panels are designed to resist water at laps and seams with sealants and tapes designed for metal panels.