Ice dam on a home in winter

Act now to prevent ice dams and costly home repairs

Before winter gets into full swing, Minnesota homeowners have the opportunity to act now to help prevent ice dams and costly water damage to ceilings and walls.

What’s the problem?

Ice dam diagram Ice dams are primarily caused by the presence of warm air in the attic, combined with snow on the roof and the right weather conditions, with outside air temperatures near freezing.

When heat leaks into the attic, it melts the underside of the snow on the roof. The water then flows down the roof surface until it reaches a cold spot, such as the eaves or soffit, where it forms a frozen dam. The ice buildup can back up under the shingles, damaging the roof and allowing water to leak to the ceilings and walls below.

Any penetration into the attic space (around wires, plumbing vents, light fixtures, chimneys, knee walls) is a potential for air leaks. Inadequate insulation, especially near the eaves, is also a contributing factor.

What’s the solution?

To avoid ice dams, attic air leaks must be sealed with caulking or expanding spray foam, and attic insulation should be installed to a minimum R-50 as space allows.

A first step to solving ice dams and making your home more energy efficient is to have an advanced energy assessment. The assessment will use equipment such as infrared cameras to identify attic air leaks and then offer action steps to prevent ice dams.

Advanced energy audits can be arranged through your gas or electric utility, nonprofit energy groups and HVAC professionals. Once the problem areas are detected, get bids from at least two licensed contractors for the work .

What shouldn’t you do?


  • Don’t install heating cables which will shorten the life of your roof and cost you money to operate.

  • Don’t remove the ice with chippers, chemicals or heat that can damage shingles, gutters and other building components.
  • Don’t add roof vents, including powered vents, which will not eliminate ice dams and often make the problems worse.
  • If ice dams must be removed, it is best to hire a professional ice dam removal company that uses steamers.
  • To prevent future ice dams, the best course of action is to attack the root cause, which are attic air leaks. Sealing those leaks will help prevent ice dams and save on your energy bill.

For more information

For more info on preventing ice dams and air sealing and insulation, check out the Minnesota Commerce Department’s Home Energy Guide (pdf) (pages 8-20).

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