Modified Bitumen Flat Roofs

Modified Bitumen Roofing

Modified bitumen membranes are "hybrids" that incorporate the high tech formulation and prefabrication advantages of single-ply with some of the traditional installation techniques used in built-up roofing. These materials are factory-fabricated layers of asphalt, "modified" using a rubber or plastic ingredient for increased flexibility, and combined with reinforcement for added strength and stability. The finished modified-bitumen roofing system is usually a two-to four-ply system consisting of a modified bitumen membrane and a base sheet, with additional plies for added strength.

There are two common bitumen modifiers: SBS and APP. SBS ( Styrene-Butadiene-Styrene) modifies the asphalt by forming a polymer network within the bitumen. SBS gives the bitumen rubber-like characteristics and improved resistance to aging and weathering. Most SBS-modified bitumen sheets are either set in hot asphalt, torch-applied, or adhered with cold-process adhesives. APP (Atactic Polypropylene) is a thermoplastic polymer which forms a uniform matrix within the asphalt. This enhances the bitumen's performance by increasing its UV resistance, increasing its flexibility at low temperatures and improving its flow resistance at high temperatures. APP-modified bitumen sheets are generally applied using a propane-fueled torch but some can be applied with cold process adhesives.

For low-sloped areas where shingles are not recommended, Tamko offers Awaplan 170

modified bitumen. It exhibits tremendous elasticity and strength with superior resistance

to thermal shock and punctures and is suitable for flashing as well as field roofing.

This product also comes in multiple colors to help match shingles.