Due to the rash of roof leaks from the recent cold weather, it's important to understand that a roof leak in the winter has nothing to do with the water shedding ability of the shingles. As snow melts off the roof, it saturates the c​older area ​of the soffit and gutter. That saturated area freezes solid, creating an ice dam. The subsequent snowmelt will then back up and escape wherever it can find the least resistant path, generally into the ceiling of the living space below, and coming out seams in the drywall or openings for light fixtures.

Heat loss through the attic is the primary culprit in an ice dam situation, most homes have nowhere near enough insulation. The other problem is inadequate ventilation, trapping escaping heat in the attic. With proper ventilation and insulation, the attic temperature will closely reflect the exterior temperature and snow ​will melt at a gradual pace instead of the current accelerated pace. The Department of Energy recommends R-49 in our climate, 16-18".