Modified roof systems consist of a base sheet followed by one or more layers of a modified membrane covered by a granular surfaced cap sheet.

Modified roof systems have many of the same characteristics of a built up roof, and are normally installed on low sloped areas on both commercial and residential roofing projects.

The two most common types of modified roof systems are APP (Atatic Polypropylene) which is a torch applied system, and SBS (Styrene Butadiene Styrene Copolymer) which is a mopped down system, and is Cribbs, Inc. preferred application procedure.