As a metal-roofing contractor in the Upper Peninsula of Michigan, I am frequently asked to fix “roof leaks” that have less to do with roofing than with the way poorly insulated houses lose heat. For example, warm, moist air from inside a house may escape into the attic and condense on the underside of the roof sheathing; when the homeowners see water stains on the ceiling of the room below, they assume there’s a roof leak.

But by far the most common problem is ice damming, which occurs when heat from the attic melts the snow on the roof. The snowmelt runs down the roof beneath the accumulated snow, refreezes when it hits the cold air at the eaves, and blocks the flow — causing an ice buildup and, often, a leak.

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