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The Home Depot

How to Prevent an Ice Dam on the Roof

Pro Referral > Home Guides > Roofing > How to Prevent an Ice Dam on the Roof
How to Prevent an Ice Dam on the Roof

If you live in areas where winter involves snow and ice, you’ll have a variety of winter issues to watch regarding your home. One common situation that often occurs on houses involves ice dams along the edges of the roof. An ice dam happens when melting snow refreezes at the edge of the roof, possibly causing damage to the roof, insulation under the roof and even the ceiling below.


It’s important to monitor your roof carefully during the winter, to make sure ice dams don’t happen. Armed with three ways to prevent an ice dam, you’ll be able to maintain your roof throughout the winter to make sure that expensive and serious damage doesn’t occur.

  1. 1.Insulation

    When your roof warms enough to melt snow, the snow runs down the pitch of the roof and pools along the edge at the eaves.

    With enough insulation present above your ceiling, you can prevent ice dams from forming. The main cause of ice dams is a warm roof. When your roof warms enough to melt snow, the snow runs down the pitch of the roof and pools along the edge at the eaves. Generally, the deck area of the roof is warmer than the edge area due to the sun shining directly down on the roof.


    With at least 12 inches of insulation above the ceiling, you can stop heat from escaping through the ceiling and up onto the roof. It’s also important to seal the insulation to stop warm air from leaking through to the roof.

  2. 2.Ventilation

    Adequate ventilation is another key to keeping your roof cool. While most roofs have vents or turbines, this ventilation isn’t usually adequate. Add baffled ridge and soffit vents along the entire length of the roof to expel attic air. These vents will also suck cold air back into the attic to keep the air immediately under the roof cold. This cold space directly under the roof will keep the roof colder and minimize snow melting over the deck of the roof.


    Check for areas in the ceiling where warm air can escape from the living areas into the attic. These leaks might occur around light fixtures, plumbing, chimneys or wires. If you find these leaks, seal them with spray foam or weather stripping.

  4. 3.Snow/Ice Belts

    Install a 2-foot-wide belt along the edge of the roof to minimize ice dams. Usually made of sheet metal, these belts will be slippery enough to prevent snow and ice from sticking at the edge of the roof. When snow and ice won’t stick here, you won’t have ice dams accumulating along the edge of your roof.


    Be sure to watch the area immediately above the snow or ice belt to make sure that secondary ice dams don’t occur here, either.


    Some people opt for heated snow/ice belts as another way to prevent snow and ice from accumulating along the edge of the roof. These heated snow/ice belts have limited effectiveness – usually only a slippery metal sheet is necessary to prevent ice dams.


    Because the damage to your house from ice dams could be so extensive, it’s important to make sure they don’t happen.

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