Ice dams on the roof: why they form and what to do

Icicles along the eaves can mean an ice dam — and water backing up under the shingles.

Why they form

Heat escaping into the attic melts snow on the roof. The water runs down and refreezes at the cold eaves, building a dam.

Thick ice along the edge, big icicles, and water stains on ceilings near outside walls.

Rake snow off the lower few feet of the roof from the ground. Never chip ice with a hammer or climb an icy roof.

More attic insulation and better ventilation keep the roof cold, so snow does not melt and refreeze.

Clear eavestroughs in fall so melt water has somewhere to go.

Are ice dams covered by insurance?

Water damage from ice dams is often covered, but the roof repair itself may not be. Take photos and check your policy.

Should I use heat cables?

They can help in problem spots, but insulation and ventilation fix the cause.