If you live in a snowy region, you already know about the damaging affects of ice dams. Clogged gutters fill up with ice, then water runoff from the roof gets trapped by the dam and eventually backs up the roof, because the water is moving up the roof it travels under the shingles and leaks into the house.
While a permanent fix for ice dams usually requires increasing the insulation, sealing and ventilation in the attic, there is a simple way to diminish the damage after the dam has formed. Fill an ice melt sock with a calcium chloride ice melter (do not use rock salt). Lay the sock onto the roof so it crosses the ice dam and overhangs the gutter. The calcium chloride will quickly melt through the snow and ice and create a channel for water to flow down, continuing to melt the ice in the gutters or off the roof. The best part is the refillable ice melt sock only uses the calcium chloride it needs to get the job done. Then it stands by to continue to prevent roof ice dams for the rest of the season.