Lexis Coatings » Roof Coating Technical Support » Alligatoring in Roofs and Coatings

Alligatoring on Roofs & Coatings

Alligatoring on Built-Up Roof
Cracking of the surfacing bitumen on a bituminous roof or coating on a SPF roof, producing a pattern of cracks similar to an alligator’s hide. The cracks may not extend completely through the surfacing bitumen or coating. When left unattended, cracks and splits eventually develops. 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.

Severity of Alligatoring

Alligatoring on Built-Up Roof


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.

Alligatoring on Built-Up Roof


Cracks are wide and deep. The scales are mostly larger than 1/2". You may need to use a resaturant to rejuvenate the old asphalt.

Alligatoring FAQ

The following roof repair procedure only applies to mild to moderate alligatoring on a built up roof. Severe alligatoring will use too much product and you may be better off with other alternatives. Don't hesitate to call us for technical support.

  1. Thoroughly clean the roof area to be repaired. If the alligatoring is all over the roof, pressure washing is recommended.
  2. Small hairline cracks can be filled simply by applying EnergyGuard Aromatic Polyurethane and working it in with a roller or putty knife. For larger areas, you can embed SeamStitch Polyester Fabric into the coating and create a smoother, reinforced surface.