How do I prevent ice dams on my roof?

Keep your attic well-insulated and properly ventilated to prevent warm air from escaping through the roof. Seal gaps around attic hatches, recessed lights, and ducts. After heavy snowfall, use a roof rake to remove snow from the bottom 3 to 4 feet of the roof edge. Ice dams form when snow melts and refreezes at the eaves, blocking drainage.