Ice Dam

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Ice Dam

What is Ice Dam?

A ridge of ice that forms at the edge of a roof and prevents melting snow from draining off, causing water to back up under shingles and potentially leak into the building, commonly occurring in cold climates due to heat loss from the building and inadequate insulation or ventilation.

Description

An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow from draining off, causing water to back up under shingles and potentially leak into the building, commonly occurring in cold climates due to heat loss from the building and inadequate insulation or ventilation. This problematic condition can cause significant water damage to roofs, walls, ceilings, and interior spaces, making it one of the most costly winter-related building problems. Understanding ice dam formation and prevention is essential for maintaining building integrity in cold climates.

The primary causes include inadequate attic insulation allowing heat loss to the roof, insufficient attic ventilation preventing proper air circulation, air leaks from living spaces into the attic, uneven roof temperatures creating melting and refreezing cycles, snow accumulation providing the raw material for ice formation, and architectural features that trap snow and create thermal bridges.

Formation process involves heat from the building warming the roof surface, snow melting on the warm upper roof areas, meltwater flowing down to the cold roof edge, water refreezing at the eaves where temperatures are below freezing, ice accumulation creating a dam that blocks further drainage, and continued melting causing water to back up under shingles.

FAQs

  • What is an ice dam?

    An ice dam is a ridge of ice that forms at the edge of a roof, preventing melting snow from draining and causing water to back up under shingles, potentially leading to leaks and water damage.

  • What causes ice dams to form?

    Ice dams form due to heat loss from the building warming the roof, causing snow to melt and refreeze at cold roof edges, often due to inadequate insulation, ventilation, or air sealing.

  • How can ice dams be prevented?

    Prevention includes proper attic insulation, adequate ventilation, air sealing, vapor barriers, regular maintenance, and architectural design considerations for cold climates.

  • What damage can ice dams cause?

    Ice dams can cause water infiltration, roof and structural damage, interior water damage, insulation problems, mold growth, gutter damage, and potential structural issues from ice weight.

  • How should ice dams be removed?

    Safe removal methods include professional steam removal, calcium chloride application, careful mechanical removal, and temporary heating cables, avoiding dangerous roof access.

  • Are ice dams covered by insurance?

    Coverage varies by policy, but many insurers have limitations for ice dam damage and may require proper maintenance and prevention measures for coverage.

  • When should I call a professional?

    Call professionals for safe ice dam removal, significant water damage, recurring problems, comprehensive prevention solutions, or when safety concerns exist.

Fun Fact

Fun Fact: Ice dams have been a problem for centuries, with historical records showing they plagued colonial American buildings! The term “ice dam” wasn’t commonly used until the 1970s when building science began studying the phenomenon. A single ice dam can weigh several tons and create water pressure equivalent to a 2-story building. Interestingly, ice dams are actually a sign of energy waste – a properly insulated and ventilated building in cold climates should have a uniformly cold roof that prevents ice dam formation!

CSI Code

07 10 00

NAHB Code

710