Ice dams form when melting snow refreezes at the roof edge, trapping water that can leak into your home and damage the roof, gutters, and interior.

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What Causes Ice Dams

Ice dams occur when warm air from the attic melts snow on the upper roof, and the water runs down to the colder eaves where it refreezes, forming a ridge of ice. This traps water behind the ice ridge, which can seep under shingles and into the home, causing leaks, insulation damage, and structural issues. Uneven roof temperatures, poor insulation, and inadequate ventilation are common contributors, as heat escaping from the house warms the roof unevenly.
 

The PDF below is an article is from The University of Minnesota. It is an extensive dive into ice damming, it's causes, the negative effects and damage that it can cause and ways to mitigate suffering the consequences of ice damming.  It's very informative. If there's anywhere that ice damming is an issue and where the specialists on it live, it's probably Minnesota and their winters!
 

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