Loss of Granules and Alligatoring

Granules on the surface of modified bituminous cap sheet protect the asphalt from degrading by UV light. As the membrane ages granular loss occurs. The first phase of this aging is called alligatoring - see Image 3. If the insulation is dry there is a good chance this roof can be recovered and the life of the roof extended for a considerable length of time at a reasonable cost. In advanced aging of the membrane the surface develops deep cracks and cannot likely be successfully recovered - see Image 4 and 5.