Copper is used for roofing, wall panels and gutters as well as doors and plumbing. When used for roofing, it changes color over time. But copper is corrosion- and rust-resistant, lightweight, safe, fire-resistant, and does not need maintenance. It is also strong, durable and easy to repair. Due to its cost, copper is typically used only for low slope sections, towers and bay windows as well as roof valleys and flashing.
Stainless steel is preferable in industries where cleanliness and aesthetic are important. However, it is the costliest option due to the multi-step process involved in finishing the end product.