Ice dams are formed when heat from the inside the home escapes into the attic and warms the roof decking during the winter.
This continual thaw and re-freeze process creates ice dams. The result is water backing up under the roof shingles where it can soak through the roof decking or wall sheathing, causing damage to attics, ceilings and walls.
This heat, combined with heat from the sun, can melt snow on the roof. Melting snow then runs down toward the lower edges of the roof (soffits) as water. When it reaches the cold soffits and gutters it refreezes.
Many homes in our area do have ice damming issues. Ice damming is difficult to repair once the ice is present. The best time to address ice damming is before the ice builds up.
Once ice is present, there are a few things that can be done to minimize the damage to your house.
First, carefully and safely remove as much of the icicles as possible from the lower edges of the roof. This will reduce the weight on the rain gutters and minimize damage.
Next, remove as much of the snow from the roof as possible. Long roof rakes, that can be purchased at the home centers, are probably the easiest and safest way to do that. Removing the excess snow will reduce addition water from building up behind the existing ice dams.
The long term fix for ice damming is to properly insulate and ventilate the attic. Reducing the amount of heat loss in the home will not only address the ice damming issue, but will also make the home more energy efficient.
About 60% of a homes heat loss is through the roof. The proper amount of insulation in the attic should be approximately 14"-16". This can either be blown in insulation or rolls of fiberglass insulation.
Ventilation is also very important. The proper amount of ventilation in an attic is 1 square foot of ventilation for every 150 square feet of attic space. Of that, 50% of the vents should be high (ridge vents) and 50% should be low (soffit vents). A properly vented attic will move the air inside the attic to reduce heat buildup and drastically minimizing ice damming.