BUR: roof systems are commonly referred to as "tar and gravel" roofs. BUR systems generally are composed of alternating layers of bitumen and reinforcing fabrics that create a finished membrane. The number of plies in a cross section is the number of plies on a roof: The term "four plies" denotes a four ply roof membrane construction. Sometimes, a base sheet, used as the bottommost ply, is mechanically fastened. Built up roofs generally are considered to be fully adhered if applied directly to roof decks or insulation.

Modified bitumen systems:

Bitumen is reinforced with fibreglass or polyester for added durability, and manufactured into sheets or rolls for ease of application. There are more than one systems available using modified bitumen materials

APP: membranes provide superior tensile strength while maintaining critical flexibility — even in the coldest environments. Additionally, with APP roofing membranes (coated with a proprietary blend of asphalt and atactic polypropylene), contractors now have an efficient mode of application by heat welding, making hot mopping unnecessary.

SBS: (Styrene Butadiene Styrene) systems are usually installed with hot asphalts or cold adhesives.