The invention relates to an improved multi-component flashing system for controlling water and air that intrudes at windows, doors, louvers and other wall penetrations. It accomplishes this through the use of several known commercially available products which are applied to the areas to be protected in a unique manner thus saving time and providing a heretofore unknown measure of protection. The first product is an elastomeric adhesive sealant which readily bonds to most building materials as well as the components of this system. The second product is a clay coated polyethylene film which can be folded, cut and shaped to fit various opening conditions. A third, optional component, is a uniquely designed preformed flexible termination accessory which also readily bonds to the clay coated film material through the use of the elastomeric adhesive sealant. The clay coated film material is readily available in roll form and can readily be hand cut to the dimensions of the particular job. In some instances, the flashing will be completed through the use of the coated polyethylene sheet flashing in combination with the elastomeric rubber adhesive sealant. Optionally, termination accessories may be used in combination with the coated polyethylene sheet flashing material, and the elastomeric adhesive sealant. The termination accessory has been specially designed to allow the same unit to be used in opposite corners of an area to be protected, thus reducing the types of units required on a single job by fifty percent.