If you live in a cold climate, chances are good that at some point your home may be affected by an ice dam. Ice dams can do quite a bit of damage, but if you're aware of the situation, you can take some proactive steps to minimize or even prevent ice dams from forming.
Why ice dams occur
During the winter, snow builds up on the roof. If the winter temperatures are cold enough, the sun's heat is insufficient to melt off much of the snow layer, so it remains in place, and even continues to grow.