APP
The abbreviation for A-Tactical Polypropylene is APP.
APP are bitumen composed of plastomer. This means that the bitumen have been processed with an elastic plastic, which makes them flexible at certain ambient temperatures. This means that APP bitumen roof coverings are more resistant to the sun and UV radiation than SBS bitumen roof coverings.
When the top layer of the roof covering becomes bitumen low, the choice goes to APP .
SBS
The abbreviation for Styrene Butadiene Styrene is SBS.
SBS are bitumen composed of elastomer. This material is a plastic that already has the elastic properties. The great advantage of SBS bitumen roofing is that it can properly absorb the working of underlying structures (such as insulation), because it can stretch. The big disadvantage is that it is not well protected against the exposure of a lot of UV radiation.
When choosing SBS bitumen, a layer of gravel / slate over the roofing will have to be protected.
