Ice dams are a common roof problem in cold climates and can cause significant damage if left unaddressed. They occur when snow on the roof melts and refreezes at the eaves, forming a dam of ice. This ice dam prevents water from melting snow further up the roof from draining properly, leading to water backup under the shingles. This trapped water can seep into the roof deck, insulation, and even the interior of your home, causing leaks, water damage, mold growth, and structural problems. To prevent ice dams, ensure proper attic insulation and ventilation to maintain a consistent roof temperature and prevent snow from melting unevenly.