Emily Cabin — Ice Dam Remediation

This part of Crow Wing County averages close to four feet of snow a season, and the cold snaps that come through from November to March can sit well below zero for days at a stretch. Ice dams form when heat leaking out of an under-insulated attic warms the roof deck, melts the snowpack above, and that meltwater refreezes right at the cold eave. The result is a ridge of ice at the drip edge that backs water up under the shingles — sometimes six to eight feet up the slope — and into the wall cavity behind it.

This cabin north of town is a second home, which made the problem worse. Nobody's there in January to notice an ice ridge building along the eave, and the vaulted great room the owners added in 2015 gave the warm air a straight shot up to the roof deck with no air barrier to stop it. The owners had been living with water stains on the porch ceiling for two winters and had paid someone to chip the ice off by hand the previous January — which damaged two courses of shingles and fixed nothing.

We came out in February of the second winter. First step was low-pressure steam removal, not chipping, not salt, not hot water. Steam clears the ice without damaging the shingles or gutters underneath. Once the eave was clear we could see the real problem: R-19 batt insulation with no air barrier at the top plates, and soffit vents blocked solid by insulation pushed against them during the great-room remodel.

The fix had two parts. On the ventilation side: polystyrene rafter baffles at every rafter bay to restore airflow from soffit to ridge — 22 baffles across the eave span — plus new ridge vent where there'd been none, and spray foam to seal the top-plate air leaks. On the roofing side: we pulled and relaid the first three courses of shingles above each eave, ran ice-and-water shield six feet up from the drip edge, and set the shingles back down. The following winter: no ice dam, no ceiling stains, no call.