Why is the attic the main fix?
Because heat escaping into the attic causes the roof to warm and the snow to melt. Air sealing and insulation reduce that heat, and ventilation keeps the roof cold.
The attic is the place where warm, moist air from the house collects. A gap around a light fixture, a pipe or the attic hatch lets that air rise into the attic space, where it warms the underside of the roof. The roof warms, the snow melts and the ice dam begins.
Air sealing closes those gaps, insulation keeps the heat in the living space, and ventilation at the eave and the ridge keeps the roof cold. Those steps work together. A roof that is repaired for leaks but not ventilated will see the dam return.
Is it safe to remove ice from a roof?
Not for the homeowner. Ice removal on a roof is dangerous, and the work is done by a crew from a safe position, with the equipment to protect the roof and the gutters.
Ice on a roof is slippery, and the roof edge is a fall hazard. Chipping ice with a tool can damage the shingles, the gutters and the flashing. A crew removes the ice from the eave carefully, with fall protection and the right tools, and without damaging the roof.
A homeowner should not climb onto an iced roof to remove ice. The safer approach is to call, and to keep children and pets away from the area below the eave while the ice is above.
- Do not climb onto an iced roof
- Keep children and pets away from the eave and the icicles
- Do not chip ice with a metal tool from a ladder
- Call for removal from a safe position
What about heated cable at the eave?
It can help keep a channel open in some cases, but it does not fix the cause. The attic work is what reduces the melt that forms the dam.
Heated cable at the eave melts a channel through the ice so the water can drain. It can reduce the damage for a time, but it uses power and it does not address the heat loss from the house. The roofer can discuss it as an option, and the note will say whether it is worth installing alongside the attic work.
The honest position is that cable is a support measure. The attic air sealing, insulation and ventilation are the work that addresses the cause, and they should be the first priority.
What should a homeowner check each winter?
The eave for ice, the ceilings and walls below it for stains, and the attic for frost on the roof boards. An early check finds the dam before it does damage.
After a snowfall, look at the eave and the gutters from the ground. A growing ridge of ice, icicles that are thick and long, or snow that has melted off the upper roof while the eave stays covered are signs that a dam is forming.
Inside, check the ceilings and walls near the exterior for new stains, and check the attic on a cold day for frost on the roof boards. Frost on the underside of the roof is a sign of warm, moist air escaping and a roof that is melting its snow too quickly.
