APP and SBS Modified Bitumen Roofing System
In the 1970s technological advances in asphalt sciences originating in Europe led to the development of modifiers such as APP (atactic polypropylene) and SBS (styrene-butadiene-styrene) which, when added to unblown (unoxidized) asphalt, impart either plastic (APP) or rubber (SBS) characteristics. These additives provide enhanced performance characteristics to traditional asphalt, and when coupled with reinforcements such as polyester (superior elongation abilities) or fiberglass (high tensile strength) create high performance roof membranes.
APP modified bitumen membranes are self-adhering when heated using a roofing torch. SBS modified bitumen membranes can be formulated for torch application, but are more commonly applied using hot asphalt or cold SBS modified bitumen adhesive. The result is a BUR system with significantly enhanced performance capabilities. Continuing improvements in technology have also resulted in self-adhering SBS roof membranes.
When an SBS or APP cap sheet is combined with traditional BUR base sheets and interply sheets, the result is a “hybrid” roof offering the best of both systems, multiple plies and superior performance and longevity.
All of these systems are excellent roofing choices for industrial, commercial, institutional low slope roofing. In choosing, factors such as site access, structural load, finished appearance, desired warranty and performance criteria should all be considered.
GOGOTEC Flat Roofs is a CERTA Certified Torch Down Modified Membrane Applicator
Help save lives, property and your hard-earned name. CERTA — NRCA Certified Roofing Torch Applicator Program.
Safe practices for roofing torch use. Since the implementation of the CERTA program, CNA has helped roofing contractors save over $12 million in potential incurred claims. And thanks to your continued commitment to safety, we’ve also reduced the total number claims from a high of 46 in 2002, to single digits in each of the last five years. Fires, however, can result in the costliest damage. By applying the strategies outlined in this document, together we can continue to keep claims to an absolute minimum, while also reducing the total dollar value of incurred losses.View Our Modified Bitumen Projects