Ice Dams They occur when heavy snow buildup melts during the day and then refreezes when temperatures drop overnight. After several days of melting-freezing cycles, it’s common for the melted water and ice to work up under the shingles until water enters the attic and eventually does damage to the ceilings, wall and contents. Attic Condensation If your attic isn’t well insulated, warm, moist air from your home can enter. Because attic temperatures are cooler