A modified bitumen roofing membrane system is composed primarily of polymer modified bitumen reinforced with one or more plies of fabric such as polyester, glass fiber, or a combination of both. This technology was developed in Europe in the 1960’s and has been gaining ground in the U.S. since the oil embargo of 1973. Thus the system utilizes the European convention of calling the mastic bitumen rather than asphalt as commonly used in U.S. terminology. The two polymer systems used in Modified Bitumen roofing today are APP (Atactic polypropylene) and SBS, with SBS being the faster growing of the two. SBS modified membranes are highly modified (10 - 15%) such that the oil-enriched polymer phase is the continuous phase and the blend, when cooled, acts somewhat like rubber. The membranes will stretch and recover well from thermal expansion/contraction stresses even at cold temperatures and maintain resistance to water penetration. These SBS membrane systems are usually applied by mopping in hot asphalt, self-adhered or adhered, with cold-process adhesives. Waterproofing membranes and base sheets for underlayment may have bare surfaces, while granule surfacing provides long-term protection from ultraviolet rays as well as an attractive roof surface for cap sheets. For more information about this application please contact : Ed Myatt |