Built-up roofing is a flat or low pitched roof consisting of multiple layers of saturated felts, coated felts or fiberglass felts, mopped down with hot asphalt bitumen or cold tar bitumen and covered with an aggregate surface.  Built up roofs are generally used on commercial projects and some residential homes with flat areas.

Cribbs, Inc. recommends the following manufacturers:
Certainteed, Garland, Johns Manville, and Koppers