Damage & Failure
What is Ice Dam?
Roofing Glossary · Damage & Failure
Definition
A ridge of ice that forms at the eave of a roof when heat from the interior melts snow on the warmer upper roof, and that meltwater refreezes at the colder unheated overhang. As ice accumulates, water backs up behind the dam and can penetrate under shingles, through the underlayment, and into the living space. Prevention requires adequate attic insulation, air sealing, and ventilation. Ice-and-water shield is the code-mandated last line of defense.
Related Roofing Terms
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Ice and Water ShieldA self-adhering, waterproof membrane installed on the roof deck in vulnerable areas — typically the ...
→EaveThe lower edge of a roof that overhangs beyond the exterior wall of a building. Eaves direct rainwat...
→Ridge VentA continuous or segmented ventilation product installed along the entire length of the roof ridge th...
→Ventilation CheckAn assessment of the attic ventilation system to ensure adequate airflow from intake (soffit) vents ...
→GutterA trough-shaped channel installed along the eave of a roof to collect rainwater running off the roof...
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