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Prevent future ice dams by sealing attic air leaks

With the mix of snow, thaws, and sub-zero temperatures, ice dams are once again a major problem for Minnesota homeowners. If ice dams must be removed, the Minnesota Department of Commerce suggests hiring a professional ice dam removal company that uses steamers. It also suggests some basic measures to prevent future ice dams and costly home repairs.

Removing ice from roofs with shovels, chippers, axes, chemicals or heat can damage shingles, gutters and other building components, and it can be very dangerous. To prevent future ice dams, the best course of action is to attack the root cause of ice dams—attic air leaks. Sealing those air leaks will help prevent ice dams and save on your energy bill.

Cause of ice dams

Ice dams occur when heat leaks into the attic and melts the underside of the snow on the roof. The melted snow then flows down the roof surface until it reaches a cold spot (such as the eaves or soffit), where it forms a frozen dam, behind which more snowmelt and ice pile up. The ice buildup can back up under the shingles, damaging them and allowing water to leak to the ceilings and walls below.

The solution

To avoid these types of problems and eliminate most ice dams, attic air leaks around wires, plumbing vents, light fixtures, and chimneys must be sealed with caulking or expanding spray foam, and attic insulation should be installed to a minimum R-50 as space allows.

The Commerce Department’s Division of Energy Resources (DER) offers a fact sheet on ice dams called “Solving Ice Dams” (pdf). For more information on ice dams and ways to conserve energy in your home, check out the DER energy guide “Home Envelope” (pdf).

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Minnesota Energy Tips is provided twice a month by the Minnesota Department of Commerce, Division of Energy Resources. Contact the division’s Energy Information Center at or 800-657-3710 with energy questions.