Every January we get calls about water coming through upstairs ceilings. The homeowner blames the roof. The roof is usually fine — the attic is the problem.
How an ice dam forms
Warm air leaks from the living space into the attic, heating the roof deck. Snow on the warm section melts, runs down to the cold overhang, and refreezes. The ridge of ice grows and backs water up under the shingles.
The permanent fix
Air seal every penetration between living space and attic — recessed lights, plumbing stacks, top plates, attic hatch. Then bring insulation up to R-49 or better. Then confirm balanced soffit intake and ridge exhaust ventilation.
The roofing side
During any replacement, ice-and-water shield should run at least 6 feet up from the eave in our climate. It won't stop dams, but it stops the water from reaching your ceiling.
What not to do
Don't chip ice with a hammer — you'll destroy the shingles. Heat cables are a band-aid that raises your electric bill and hides the real issue.
Frequently asked questions
- Are ice dams covered by insurance?
- Resulting interior water damage is often covered; the cost of fixing insulation and ventilation is not.
- Will more attic insulation alone fix it?
- Not usually. Air sealing has to come first, or you're insulating over an air leak.
