Ice dams can form when a roof that is warmer than the eaves causes snow on the roof to melt, the water to flow down to the colder eave, and then re freeze. As this cycle repeats , ice can back up or “dam” under shingles. allowing water to accumulate behind it. The water can leak through the roof and cause serious damage to walls, insulation, ceilings, and painted surfaces inside the home that may only get worse over time. However there are some relatively simple steps one can take to prevent ice dams.Next post will describe them.