A few inches of snow, freezing temperatures and warm air leaking into your attic are a perfect combination for ice dams. What's an ice dam, and why should you be concerned if you have icicles hanging from your gutters?
Ice dams form when heat in the attic melts the snow on the roof and water runs down to the overhang and then refreezes. The ice starts to build up, holding water which can then flow back up the roof under the shingles. This often results in serious water damage to the ceiling and walls inside the home. Often, the damage can't be seen until it's too late, and repairs can be expensive.
Warm air leaking into your cold attic through attic bypasses (the small holes and paths by which heated air flows into the attic) is usually the culprit. Some sources include electrical boxes, exhaust fans, lighting fixtures including recessed lights and wiring penetrations and attic hatches/entrances. These warm air bypasses have to be fixed first to eliminate the problem. A lack of ventilation and/or not enough insulation can add to the trouble.
If you think you have a problem, your best bet is to have a home energy audit performed. An energy professional can do a blower door test to find the leaks and seal them. He also can tell you if you need more attic insulation or ventilation. Remember, this problem is not going to just go away. It will continue to happen year after year when conditions are right.
Contact the Focus on Energy Home Performance with ENERGY STAR® program at 1-800-762-7077 or visit focusonenergy.com to request an energy audit. (Focus on Energy also has a separate program for the income qualified.)