A.Ice dams can be controlled in two ways: Ensure that the entire roof surface remains cold so that continual melting and refreezing do not occur, or build a roof that can't leak if an ice dam forms.

To prevent warm indoor air from reaching the roof sheathing, make sure you have a continuous air barrier separating the living space from the underside of the roof. Sealing all pathways like recessed lighting, wires, pipes, and seams may be difficult in an existing house, however. So have plenty of ceiling insulation as well. In cold climates,...

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