In building construction, window capping refers to the application of one material over another to provide a weather-proof layer intended to control the infiltration of weather elements. Window capping does need to provide a water-proof condition that provides protection to the original materials. This control element must serve to safely direct water or wind in order to control run-off and prevent infiltration into the window structure. Cladding applied to windows is often referred to as window capping.
External links
John's Window Capping - an information site by a capping contractor based in Canada