Ice Dams: Causes, Costs, and How Homeowners Prevent Damage

Ice dams are one of the most damaging — and most misunderstood — winter risks for homeowners in cold climates. Every year, ice dam damage causes hundreds of millions of dollars in roof repairs, interior restoration, and mold remediation across the northern United States and Canada. Yet the root cause isn't the ice itself — it's what's happening inside the house.

An ice dam forms when heat escaping through the roof melts snow from below. The meltwater runs down the roof and refreezes at the colder eaves, creating a ridge of ice that traps water behind it. That trapped water backs up under shingles, into the roof deck, and eventually into the home — causing ceiling damage, insulation failure, mold growth, and structural deterioration.

The critical insight for homeowners: ice dams are not a roofing problem. They're an insulation and ventilation problem. And that means they're preventable — often at a fraction of the cost of the damage they cause.