KATEPAL elastomer bitumen roofing consists of one or more layers of elastomer bitumen membrane. Elastomer bitumen sheets are manufactured of styrene-butadiene-styrene (SBS) elastomer and bitumen bonded to polyester or glass felt. The waterproofing material of the sheet is crucial for keeping it weatherproof irrespective of the stresses it is subjected to. Thanks to its good stretch and elasticity properties SBS elastomer bitumen withstands high strain caused by movement even at very low temperatures. In this respect it is far superior to other bitumenbased weatherproofing materials (oxidized bitumen and APP modified bitumen). In Finland the lack of elastic properties at low temperatures has been a cause of serious problems in flat roofs.