An ice dam can be described to be a ridge of ice that accumulates on the roof edge thus preventing water from draining off the roof. The water which accumulates behind the ice dams can then seep into a house and damage walls and other
parts of the house.
An intricate interaction among the quantity of snow cover, external temperatures, and amount of heat loss has been associated with the formation of ice dams. For the formation of ice dams, snow must be present on the rooftop and the outer higher surface of the roof must have temperature of 320 F and above while the lower surfaces of the roof-temperatures lower than 320 F. The snow at the regions with higher temperatures melts; water flows down to the cooler part and freezes resulting in the formation of an ice dam. This process continues, and growth of the ice dam is limited to the regions of lower temperatures to the effect that as water above piles up behind the ice dam and remains in liquid state. Such waters the find cracks on the outer covering of the roof and seeps through the attic space into the ceiling installation.