Ice Dam

Roofing terms · plain-language definition, with its source

Roofing terms · definition

A ridge of ice at the eave from attic heat melting and refreezing snow, forcing water back under shingles. Fixed by air-sealing, insulation, ventilation, and ice-and-water membrane.

Source: Wikipedia — Ice Dam (Roof)

Where this comes up on this site

  • Eave

    The lower roof edge that overhangs the wall. Ice-and-water protection, drip edge, and gutters all key off the eave.

  • Insulation

    Material that resists heat flow, rated by R-value, installed in walls, ceilings, and floors. Opened walls are the opportunity to upgrade…

  • Ridge

    The horizontal top line where two roof planes meet — the highest point and a key ventilation location (ridge vent).

  • Impact-Rated Shingle

    A Class 4 (UL 2218) hail-resistant shingle that may earn an insurance premium discount in hail-prone regions.

  • Ice & Water Shield

    A self-adhered waterproof membrane at eaves, valleys, and penetrations that blocks ice-dam and wind-driven-rain leaks. Code-required at e…

  • Insulation Baffle

    A chute at the eave keeping insulation from blocking soffit-vent airflow into the attic.

  • Hip & Ridge Cap

    Specialized shingles that wrap and seal the roof's hips and ridges. Upgraded caps improve wind rating and appearance.

  • Low-Slope vs. Steep-Slope

    The dividing line (about 3:12) that determines whether shingles can be used or a membrane system is required.

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