What are ice dams?
An ice dam is a ridge of ice that forms at the edge of the roof (referred to as eaves) and prevents water (melting snow) from properly draining.
How are ice dams formed?
Heat from the inside of a home warms the roof decking during the winter, and combined with heat from the sun, this can melt snow on the roof. Melting snow on the upper roof then runs down toward the eaves as water. Unfortunately, when it reaches the cold eaves and gutters it refreezes. The continual thaw and re-freeze process creates ice dams. The result: water backup under the roof shingles where it can soak through the roof decking or wall sheathing, causing damage to attics, ceilings and walls.