Ice dam (roof)

Freezing at the eave impedes the drainage of meltwater, which adds to the ice dam and causes backup of the meltwater, which may cause water leakage into the roof and consequent damage to the building and its contents if the water leaks through the roof.

Ice dams occur on heated buildings with sloping roofs in cold climates with deep snow accumulation.

Instead, building heat coming through the roof's surface melts the snow resting on it.

[1] The melting of roof snow comes from the combination of three basic causes:[2] If any of these factors is absent, ice dams cannot form.

[2] Ice dams on sloped roofs can be mitigated in several ways:[3][2][4][5] When an ice dam occurs there are some maintenance options to remove it:[5] Assuring integrity of the roof's waterproofing prevents leaks and consequent damage.