If you've seen thick ice and icicles building along your roof's edge in winter, that's an ice dam — and it's one of the most common causes of winter roof leaks in New Jersey.
What causes an ice dam
It's a heat problem, not just a weather problem. Warm air escaping into the attic melts snow on the upper roof. That meltwater runs down to the cold eaves (which overhang the unheated exterior), where it refreezes into a dam. Water then pools behind the dam and backs up under the shingles — into your ceilings and walls.
The three real fixes
- Air sealing & insulation: stop warm air from leaking into the attic in the first place.
- Ventilation: a balanced ridge-and-soffit system keeps the roof deck cold so snow doesn't melt unevenly (see our ventilation guide).
- Ice-and-water shield: a self-sealing membrane installed at the eaves and valleys that blocks backed-up water from reaching the deck. New Jersey code and best practice call for it, and Lightning installs it on every roof.
What NOT to do
Don't chip at ice with hammers or axes (you'll damage shingles), and skip the salt-filled pantyhose tricks. If you have an active leak, a roofer can safely steam the dam and address the source.
Prevent it for good
The permanent fix is a properly insulated, ventilated roof with ice-and-water shield — exactly how we build them. If you fight ice dams every winter, a new or corrected roof solves it. Get a free inspection.