How to Stop Ice Dams from Leaking into Your Attic

Ice dams are a symptom of a warm attic, not a failure of your shingles. When heat escapes through your ceiling, it warms the underside of the roof, melting the snow that has settled on top. As that meltwater runs down to the cold eaves and gutters, it freezes again, creating a wall of ice that forces water back under your shingles and into your home. Stopping this requires changing the temperature profile of your roof deck. You aren't just clearing ice; you are correcting the thermal path of your entire house. A well-executed job keeps the roof uniformly cold, preventing the freeze-thaw cycle that leads to interior water damage and structural rot.

1. Clear Snow from the Edge. Use a long-handled roof rake to pull snow off the lower three to four feet of your roof line. Work from the ground and do not climb onto the slippery roof.
2. Find the Heat Leaks. Enter the attic and look for dark, stained insulation or frost buildup on rafters. These indicate areas where warm, moist household air is escaping into the attic cavity.
3. Block the Air Escapes. Use high-temperature expanding foam or caulk to seal gaps where wires, pipes, and vents penetrate the attic floor. These small holes are the primary sources of heat loss.
4. Unblock the Airflow. Ensure rafter vents, or baffles, are installed between the roof rafters to keep the soffit vents open. If these are blocked by insulation, air cannot flow into the attic to keep the deck cold.
5. Boost Ceiling Insulation. Add blown-in or batt insulation to meet the recommended R-value for your region. Ensure the layer is thickest over the top plates of your exterior walls.
6. Verify Air Is Flowing. Confirm that your ridge vent is clear and that attic air is circulating from the soffit to the peak. A balanced ventilation system is the final step in preventing future dams.