Abstract: A stretchable thin plastic film and a double faces adhesive tape are mountable on exterior surfaces surrounding a building window or door to provide an external weather barrier. One side of the adhesive tape is adapted for mounting on a wide variety of external mounting surfaces at temperatures as low as 40.degree. F., and the plastic film is mountable on the adhesive on the other side of the tape at the same low temperature. The two adhesives have different adhesion strengths which enable the adhesive tape to be adhered to the mounting surface without separation therefrom during the stretching and adhering of the plastic film to the opposite side thereof and which adhesion strengths, with the film so stretched and adhered, provide for the film to be maintained against separation from the adhesive tape and the adhesive tape maintained against separation from the mounting surfaces under adverse weather conditions including gusting winds, rain and temperatures at least as low as 0.degree. F.