A sealing device including a waterproofing membrane, a sealant layer covering at least a portion of the second primary exterior surface of the waterproofing membrane and an adhesive layer covering a portion of the outer major surface of the sealant layer facing away from the second primary exterior surface of the waterproofing membrane, wherein the sealant layer is composed of an adhesive sealant composition comprising at least one elastomer, at least one at 25° C. liquid polyolefin resin, and at least one inert mineral filler. A method produces a sealing device, a method waterproofs a substrate, and a waterproofed substrate.