Built-up Roofing Systems: Provide a relatively economical, sturdy, and long-lasting all-around roof for commercial and industrial buildings. It gets its strength from multiple layers, usually at least four. This redundancy makes for a time proven, economical system, especially suited for new or reroofing.

Under the category of built-up roofing are Modified Bitumen systems. These offer a very flexible and strong membrane, often using only two or three layers of material.