What Is an Ice Dam? Causes, Prevention, and Damage Repair #88225 (License: Personal Use)

This illustration depicts an ice dam-a ridge of ice that forms at the edge of a roof, preventing melting snow from draining off. As heat escapes from the attic, snow melts on the upper roof surface, then refreezes at the colder eaves, creating a barrier that forces water to back up under shingles. This can lead to leaks, ceiling damage, and mold growth if not addressed promptly.

Used on home maintenance, roofing, or winter preparedness web pages to explain ice dam formation; matches user intent for understanding causes, risks, and solutions for ice dams on residential roofs.