What is an ice dam?
An ice dam is a ridge of ice that builds up at the edge of a roof and stops melting snow from draining off. The trapped water pools behind the ice and works its way under your shingles, into the roof deck, and eventually into your ceilings and walls.
What causes ice dams in Northeastern PA?
Ice dams are a heat problem, not just a snow problem. Warm air escaping from your living space heats the underside of the roof deck. That warmth melts the snow on the upper roof; the water runs down to the cold eaves and gutters, where it refreezes. Repeat that cycle through a Northeastern PA winter — lake-effect snow around Scranton, hard freeze-thaw swings across Wyoming and Luzerne counties — and the dam grows.
Three things make it worse:
- Under-insulated attics that let heat reach the roof deck
- Poor attic ventilation that traps warm air instead of flushing it out
- Clogged or undersized gutters that give ice a place to start
How do I prevent ice dams?
Prevention is about keeping the roof deck cold and evenly temperatured. In order of impact:
- Air-seal and insulate the attic floor so heated air stays in your living space
- Add balanced intake and exhaust ventilation so the attic stays close to the outdoor temperature
- Install ice-and-water shield along the eaves and valleys — a self-sealing membrane that blocks backed-up water even if a dam forms
- Keep gutters and downspouts clear before the first snow
On every roof we replace, ice-and-water shield at the eaves and valleys is standard for exactly this climate.
How do I get rid of an ice dam that already formed?
Do not climb up and chip at it — you will damage the shingles and risk yourself. Rake fresh snow off the lower few feet of the roof with a roof rake from the ground, and if water is already coming inside, call a professional to steam the dam out safely. A calcium-chloride "salt sock" laid across the dam can open a drainage channel in a pinch. Never use rock salt — it corrodes gutters and flashing.
Do ice dams mean I need a new roof?
Not always. One bad winter usually calls for a repair plus better insulation and ventilation. But if you get ice dams every year, or you are already seeing interior stains and rotted decking, a full replacement with proper ice-and-water protection is often cheaper than paying for repairs and interior damage season after season. A free inspection tells you which camp you are in.
Worried about your eaves before winter? Rail Roofing Group gives free roof inspections across Northeastern and Central PA — call (570) 996-7357 and we will tell you honestly what your roof needs.