Two types of oxidized bitumen coated roofing materials are available; built up roofs, and roofs made of roofing shingles. Built up roofing is the type used on horizontal type roof structures which are typically commercial or apartment type buildings. For the built up roofs, oxidized bitumen is heated to 400°-450° F., and then mopped on. The saturated bitumen felt is then rolled over. The asphalt which acts both as an adhesive as well as a water-proofing coating, is applied as the roof is being layed down. Because the oxidised asphalt for built up roofing must retain adhesive properties, it is less cross linked or mildly oxidized compared to asphalt prepared for roofing shingles. Roofing stone aggregate is spread over the entire built up roof to provide weather resistance to the built up roof. Roofing stone aggregate can be stone or slag. Its purpose is to prevent ultraviolet rays from degrading the roof coating. The stone allows walking over the roof without disturbing the asphalt.
Roofing shingles are another type of roofing material coated with oxidized bitumen. The bitumen is cross linked or oxidized and is coated onto the roofing felt in a manufacturing step. Generally, the asphalt is filled with stone dust. The asphalt is heated to about 400°-450° F. and spread on and pressed into the roofing felt. Roofing granules are then fed onto the saturated asphalt felt and pressed in.