First you need a snowfall. The snow on the roof will begin to melt from the sun or heat from the building. The water begins to run off the roof. When the temperature gets cold again the water will freeze at the end of the roof and form a dam. As the temperature fluctuates this happens over and over and the dam gets larger. The water can eventually get under the shingles and saturate the wood, ceilings and walls inside the home or building. This can lead to water stains, property damage and mold and mildew.
How are ice dams prevented?
- Get the snow off your roof. You can hire a contractor or roofer, or buy a roof rake from a hardware store.
- Make sure you have a cold roof. Insulate your attic floor to help provide a consistent temperature from the eaves to the peak of the attic.
- Check to make sure your attic is property ventilated.
- Clean your gutters properly before the winter.