How to Prevent Ice Dams – Start in Your Attic

How to Prevent Ice Dams – Start in Your Attic

By Mark J. Donovan




 To prevent Ice dams all that is typically required is the installation of additional insulation and better air ventilation in the attic.

Ice Dams occur at the edge of a roof, because the attic is not properly insulated and vented. The attic air temperature should be as close to the outside ambient air temperature as possible to prevent ice dams. If it is above freezing in the attic, while the outside air temperature is below freezing, melting of snow on the roof will occur.

During the night, as the temperature drops, the melting snow will turn to ice, thus forming the ice dams.

If you are observing Ice Dams examine your attic and check for the following:

  • Make sure there is at least R-30 attic insulation between the ceiling joists.
  • Make sure that there are no un-insulated gaps.
  • Make sure all bathroom ceiling fans are vented to the outside and not just vented into the attic. If the ceiling fans are only vented into the attic they will send warm moist air into the attic, which will heat the attic and cause melting on the roof, which leads to the Ice dams.




  • Make sure the ridge vent or gable end vents are free from obstructions that would prevent proper air flow.
  • Make sure there is an air gap between the soffit and the top of the insulation laying between the ceiling joists. You may need to use attic rafter vents to create this air gap. Again, you want to make sure there is air flow from the soffit vents to the ridge or gable end vents. By doing so you prevent any slight heat leaks from the rooms below elevating the temperature of the attic.
 How to resolve Ice dams. Ice melt socks are one solution.

With the above tips you should be able to prevent ice dams and the resulting water and structural damage that comes with them.

For help on Attic Conversion and Attic Renovation Projects, see HomeAdditionPlus.com’s Attic Conversion Bid Sheet. The Attic Conversion Bid sheet will help to ensure that you hire the right contractor so that your attic conversion project is built correctly, on time and budget.

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