Abstract: A method of weather-proofing surfaces, particularly concrete roofs, is described wherein first applied is an inner layer of a soft asphalt (bitumen) having a softening point of 100.degree.-140.degree. F. and including reinforcing fibers, and then an overlying layer of an asphalt-saturated-felt. In one preferred example, the overlying layer is a glass-fiber mat saturated with a hard air-blown asphalt having a softening point of at least 180.degree. F.; and in a second described example, it is paper saturated with soft (non-blown) asphalt and coated on its outer faces with the hard air-blown asphalt. The combination of the soft asphalt inner layer and the asphalt-saturated-felt outer layer has been found to produce a barrier impermeable to water travelling inwardly, but permeable to vapor travelling outwardly thereby avoiding the formation of blisters.