What is an ice dam?
An ice dam is a ridge of frozen water that builds up along a roof's eave edge during winter, preventing meltwater from draining and forcing it backward under shingles.
On Connecticut roofs during winter thaw cycles, ice dams form as ridges of frozen meltwater at the eave edge where the roof overhangs the exterior wall. They occur when snow on the roof melts from heat loss through the attic or from direct sun, then refreezes as it reaches the colder overhang that lacks the same heat source. The dam itself is a barrier of solid ice that stops meltwater from flowing off the roof and into gutters and downspouts.
The danger lies in what happens to trapped water. Meltwater backs up behind the ice dam and seeps under the shingles, finding its way into the attic, insulation, and interior walls. Once inside, this water causes rot in framing, staining on ceilings, mold growth, and structural damage. Connecticut's freeze-thaw winters make ice dams a common roofing concern, especially after heavy snow followed by milder days.
Ice dams typically develop on lower-pitched sections of the roof and at the transition points between heated and unheated spaces. Homes with inadequate attic ventilation or insulation are at higher risk, as excess heat creates more meltwater. A roof repair contractor can assess ventilation issues, recommend preventive measures like ice and water barriers, or address interior water damage once it has occurred.