SBS versus APP: it’s a wonderful world of bitumen


Chances are you already know that bitumen, a viscous liquid, makes for an ideal waterproofing material. And perhaps you are also aware that bituminous roofing has been around for more than 30 years, is UV-resistant and can be walked on without a problem. However, did you know that bitumen must be specially treated before it can be used for roofing? More specifically, polymers and reinforcement must be added. Beware, though, that there are different types of bituminous roof sealing membranes on the market. Depending on the type of treatment received, they each offer different properties. This article compares SBS bitumen and APP bitumen, enabling you to make a well-informed decision.

SBS bitumen are renowned for its longevity

SBS bitumen is composed of elastomer. SBS is short for styrene-butadiene styrene, a synthetic rubber that gives bituminous roofing membranes a greater elasticity. It’s this flexibility that allows the roofing membranes to stretch without interfering with underlying applications such as insulation. In addition, bituminous SBS membranes adhere particularly well, minimizing the chance of leaks.

For SBS bitumen to retain its strength, only a minimal amount of plastic must be added. As this makes the membranes less UV-resistant, they must be covered with slate or ballasted with gravel to keep sunlight from penetrating the bitumen. That’s where Sopralene MF 5500 comes in. Containing fire-retardant additives and polyester-composite reinforcements, they are suitable for both single-layer and multi-layer roofing. Sopralene MF 5500 is renowned for its longevity.

APP bitumen is particularly UV-resistant

APP bitumen roofing membranes are a combination of bitumen and a plastic called Atactic Polypropylene; a polymer which ensures that the roofing remains supple even under extreme temperatures as the roofing takes over the properties of the plastic. Thanks to the APP, the softening point (the temperature at which a substance changes from solid to liquid) – increases from 50 degrees to 140-150 degrees. Moreover, it makes the membrane UV-resistant and gives it a longer life.

SOPREMA’s Sopragum Techno Venti membranes from SOPREMA are reinforced with polyester-composite and are four millimeters thick. They are used for single-ply roofing.

Ask an expert for advice

Are you not quite sure which type of bitumen is the best solution for your project? SOPREMA offers both types and is more than happy to give you sound advice. Don’t hesitate to contact our experts.