What Is an Ice Dam?

The mechanism is a temperature split. Warm air leaking into the attic heats the upper roof surface, snow there melts, and the water runs down until it reaches the colder overhang, where it refreezes. Over days, that frozen edge grows into a dam. Water pooling behind it can rise above the shingle overlaps and seep through the roof into the soffit, walls, and ceilings. The lasting fix is keeping the roof deck cold: insulation, air sealing, and ventilation that hold it near outdoor temperature.

In snow country ice dams drive plenty of service calls, and the homeowner often assumes the roof has failed. Investigating attic insulation and ventilation, instead of reaching for a replacement contract, is the kind of diagnosis homeowners remember. Waterproof membrane at the eaves reduces the damage and belongs in the proposal, but it limits leaks while the dam exists and does not stop the dam from forming.

Ice dams and icicles are not the same thing: icicles hang from the edge and are a symptom, while a dam is the frozen buildup that holds water back. Coverage is where reps overreach. Whether a policy pays for interior water damage from an ice dam, for the roof itself, or for attic corrections depends on the policy and the cause. Raking snow and heat cables are temporary measures, and chipping at the ice with tools can damage shingles.