If you've found that one of your rental properties has an ice dam, you should take immediate action. First, remove the snow from that area of the roof, because it will remove one of the important ingredients for the formation of an ice dam. You can use a roof rake for this, but keep in mind it may damage the roofing materials. If water is literally flowing into the structure, you will need to deal with this immediately. Make channels through the ice dam lets the water stuck behind the dam to run off the roof. Warm up the ice