Common roofing term explained by Fortified Roofing of Toms River NJ:
Alligatoring is a process in which a built-up bitumen roof develops an overlapping series of cracks. The cracks stack up to form a pattern that looks like the skin on the back of an alligator.
Toms River FAQ about roofing:
What is the cause of alligatoring on a rooftop?
Alligatoring is primarily caused by the aging process. Many years of exposure to the sun's ultraviolet radiation damages the layers of bitumen and dries them out. The process begins within five years of a bitumen roof's installation. As time continues, snow and ice get into the cracks and cause them to expand as the temperature allows the water to freeze and thaw. The temperature differences between night and day also cause the cracks to expand.