SBS modified membranes resist water penetration and they stretch and recover well even at cold temperatures. This makes them particularly applicable where there may be movement or deflection of the underlying deck. While modified asphalt provides the primary waterproofing characteristics of these membranes a reinforcing ply adds strength and puncture resistance. Glass fiber and polyester plies are the most commonly used reinforcing fabrics. Each has distinctive properties.
Polyester has excellent elongation, tensile strength and recovery.
It provides good puncture resistance and stands up well to foot traffic. Glass fiber resists flame penetration and provides excellent tensile strength and dimensional stability. The combination of asphalt, modifiers and reinforcements determines the characteristics of a specific modified bitumen membrane. To obtain the best roofing system possible, the designer, building owner and contractor should understand the dynamics of the roof as well as the roofing system when specifying either APP or SBS modified roofs. The application of modified bituminous roofing is a construction process that involves the skillful arrangement of several components as specified for the process.