Roofing Glossary

Alligatoring

Alligatoring is the pattern of fine, interconnecting surface cracks that develops on aged asphalt roofing — named for its resemblance to alligator hide. It is the visible signature of asphalt that has lost its oils and flexibility to years of sun and heat.

On shingles, alligatoring shows as crazed cracking across the exposed surface — the asphalt is drying out and becoming brittle. On flat and low-slope asphalt roofs (built-up or modified bitumen), alligatoring of the surface coating or cap sheet is a standard end-of-life indicator.

Alligatored asphalt can no longer flex with thermal movement, so cracks propagate deeper with every hot-cold cycle. Surface coatings can buy time on flat roofs, but alligatoring is fundamentally a material-exhaustion signal.

Why It Matters

Alligatoring means the waterproofing material itself is breaking down — not just wearing cosmetically. On shingles it accompanies curling and granule loss in the roof's final phase; on flat roofs it is the standard trigger for recoating or replacement planning.

Questions about your own roof? Request a free estimate or call Nucci Brothers Roofing at (301) 458-1003.