Abstract: Disclosed herein are various membranes that may be applied to an opening in a building structure to seal around and/or waterproof the opening. To provide improved conformance of the membrane to underlying surfaces the membrane utilizes a facer film that permits permanent stretching without the application of little or any elastic/retractive forces by the facer film. In one embodiment, the length of the facer film is in excess of the length of an adhesive substrate of the membrane to allow stretching of the substrate without stretching the facer film. In another embodiment, the facer film has low elastic memory such that it plastically detail is as the underlying adhesive substrate stretches.