I Know I Have an Ice Dam, How Do I Fix It?
Removing an ice dam is extremely intricate, and relatively unsafe, work. The ice must be delicately broken into small pieces with a blunt tool, both on the eaves and inside gutters and downspouts. Even experienced professionals have trouble with this, as it’s possible to tear or damage individual shingles off the roof with the ice. You should absolutely avoid climbing on your roof as your body weight can cause frozen shingles to break.
You can use heat cable to melt the ice, but this will take some time for the ice to fully melt.
After large chunks have been removed, pour calcium chloride onto the ice dam. A helpful tip is to leave it inside of a bag with many holes so that it stays in one spot, melting it away.