An integral vapor barrier for use on electrical boxes located in external walls of structures is herein disclosed. The vapor barrier is applied to, or forming an integral part thereof, an interior surface of an electrical cover plate and particularly useful for exterior electrical boxes prior to installation. The vapor barrier extends outwardly therefrom the exterior periphery of the electrical cover plate at a distance to ensure a total barrier. It can be used on new construction as well as remodeling work. When in place, it greatly reduces heat loss or gain through electrical boxes and stops drafts around said boxes. It can be used in any wall or ceiling that is typically insulated. It can even be used on inside walls to help with noise control and abatement as well.