Ice dams form when snow on the roof melts during the day and refreezes at the gutters at night to develop into ice on the roof. After several nights the ice can build up to a thick layer that will trap melting snow over your outside wall (see Roof Heat Tape article for additional insight).
If you see ice over an inch thick on top of your gutter, you need to take action. The ice you see is the beginning of an ice dam that can cause water damage to your ceilings and outside walls.
Once a warm day arrives, the snow on the roof will melt and the ice dam will trap the water. The trapped water will weep up through the shingles, drip onto the attic ruining ceilings and to the walls below.
Weather conditions have a lot to do with formation of ice dams. Warm days, cold nights and enough snow on the roof can set the stage for an ice dam.
If you have large icicles or the formation of an ice dam, first remove the snow from the lower three-feet of the roof with a roof rake. It is a wide lightweight blade mounted to a fifteen-foot handle. You use the roof rake to scrape the snow off the roof from the ground. Stay off the roof.
Take extra care not to get close to the electrical lines connecting to your house. Contact with the wires with a metal handle could result in an injury or death. Locate them and start at a safe distance from there first.
Once the snow is removed from the ice dam, use a roof heat tape or ice melting crystals to cut the ice dam into two to three-foot sections. The openings will drain off the water trapped above before it causes any more damage.
Once the ice dam is sectioned up and draining, you can take steps to prevent the formation of new ice dams. Heat rising from the living area below assists in the formation of an ice dam. Check the insulation in the attic and make sure there is at least 12-inches on the ceiling. With rising energy costs this can only be a win, win situation.
Keep the heat in the house with insulation, the roof stays cold, and the snow will not melt. Compare the roofs on your block and you will see who needs insulation by the lack of snow.