Last December, I was contacted by a couple in their mid-60s who were having repeated ice damming issues on their home. The husband noted that he’d been diligent about raking the roof’s perimeter after snow events over the years, but it was becoming too hard for him to manage. In addition to raking, he said he’d often get up on a ladder and attempt to knock the ice dams off as a last resort—a dangerous task at any age.
Their modified Cape-style home, built in 2006, was situated on a fairly exposed lot in central Vermont. The homeowners said the ice damming seemed worse on the roof sections above the home’s garage wing. (The garage wing’s roof planed into the main house, forming an L-shaped roof with two valleys). Ice would form along both eaves of the wing, in the bottom of the valleys, and along portions of the north-facing cantilevered eaves of the main house, which served as a covered entry.
We started with the garage. I inspected the “unheated” space and found it relatively warm (the outside temperature was in the mid-30s). In a corner of the room was a Modine gas heater, which the homeowners said was used intermittently. The garage wing was 26 feet wide by 34 feet long. The unheated garage comprised roughly two-thirds of the wing, while the remaining third was conditioned space. The homeowners mentioned that a bonus room ran the length of the second floor above. I surmised that warm air exfiltrating from the conditioned space and the garage was finding its way to the underside of the roof sheathing and melting the snow, causing icicles and ice dams to form along the entire garage wing and in the two valleys.
Walking the first-floor interior with the couple, I noticed it was warm; 75°F plus. When asked about their heating habits, they informed me that they liked it warm and didn’t use temperature set-backs at night or when the home was unoccupied. I suggested that the temperature differential between the above-average warm interior and the cold exterior may be exacerbating heat drive out of the home through unwanted ceiling leaks and recommended lowering the thermostat and using set-backs to help reduce the ice damming, though this would not eliminate the problem.
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