Ice dams are one of the most common winter roofing problems in Alberta — and one of the most misunderstood. Those icicles hanging off your eaves are often a warning sign, not just a seasonal decoration.
Here is what is actually happening, and how to stop it.
What causes an ice dam
Heat escaping into your attic melts the snow on the upper part of the roof. That meltwater runs down to the cold eaves and refreezes, building a ridge of ice. Water then backs up behind that ridge — and since shingles are designed to shed water, not hold it, it works its way under them and into your home.
The real fix is heat and airflow
Because ice dams start with a warm roof, the long-term fix is keeping the roof deck cold: good attic insulation to stop heat loss, and proper attic ventilation to flush out any warm air. A cold, well-vented attic barely forms ice dams at all.
What helps prevent them
- Seal attic air leaks around lights, hatches, and ductwork so warm air stays in the house.
- Top up attic insulation to recommended levels for Alberta.
- Keep ventilation clear — make sure soffit vents are not blocked by insulation.
- Ice-and-water shield at the eaves during a roof replacement adds a waterproof backup layer.
Already have an ice dam?
Do not climb up and start chipping at it — you can damage the shingles and yourself. If an ice dam is causing an active leak, call for emergency roof help, and plan the insulation and ventilation fixes before next winter.