Most roofing materials depend heavily (pun intended) on gravity to hold them together. When you have a low to moderate sloped roof, gravity works in favor of most roofing materials. It helps hold the roofing product to the roof. This is the case with standard shingles, wood shakes, slate, tile, and many of the newer polymer-based products.

For that reason, very steeply pitched mansard roofs present a problem. In the case of these types of roofs. gravity is acting against you, trying to cause materials to slip off of the roof, not be held down to the roof.

Most metal roofing products, though, feature interlocking panels. These panels are held together one to the next by an actual mechanical lock.

For that reason, in comparison to gravity-bound products (which sometimes are not even warranted on steep mansard roofs), metal products are ideal for these applications. Another issue with heavier gravity-held products on steel roofs is that, if the products crack or split or somehow slip out of place, the heavy material slipping from the roof can pose a personal injury threat to anyone it might hit on its way down to the ground.