Alligatoring on BUR

Cracking of the surfacing bitumen on a bituminous roof or coating on a spray foam roof and produces a pattern of cracks similar to an alligator’s hide. The cracks may not extend completely through the surfacing bitumen or coating.

Alligatoring is commonly found on smooth surface asphalt roofs. It is caused by the drying out of the exposed asphalt surfacing by the sun.

When left unattended, cracks and splits eventually develop. Water will enter the roofing system and cause unseen damage in the roof system. As the surfacing layer fails, the fiberglass reinforcement underneath is exposed and becomes brittle. Membrane failure inevitably follows.

Smooth built-up roofs should be inspected annually for damage. A roof coating may be applied to reflect harmful ultraviolet rays and reduce thermal cycling.

Above: The cracks are bigger than hairline to about the thickness of a credit card. The scales are mostly no bigger than 1/2" and do not easy come off the roof. When the defects are tiny, it's referred to as checking.