Ice dams form when warm air from your home melts snow on the roof, and the melt water refreezes at the cold edge. The water backs up under the shingles and can leak into your attic and ceilings. The good news is that most ice dams are preventable.
Seal Air Leaks Into the Attic
Warm air escaping through ceiling light fixtures, attic hatches and gaps around pipes is the main trigger. Sealing these gaps keeps heat in the living space and the roof deck cold, so snow melts evenly instead of refreezing at the eaves.
Check Insulation and Ventilation
Well-insulated attics with open soffit and roof vents keep the roof surface close to the outside temperature. Make sure insulation has not been flattened or moved, and that nothing blocks the vents.
Clear Eavestroughs and Downspouts
Leaves and debris trap water at the roof edge and make freezing worse. Clean eavestroughs in the fall and make sure downspouts carry melt water away from the foundation.
Inspect Shingles and Flashing
Look for lifted, cracked or missing shingles, and for worn flashing around chimneys, vents and skylights. Small repairs before winter are far cheaper than fixing interior damage in spring.
If you already see ice building up or stains forming indoors, avoid chipping at the ice, which can damage the roof. Call a professional to inspect it safely.