Ice dams and air sealing

Why the edge of the roof ices up, and what we do about it.

Ice dams form when heat escaping the house melts snow on the roof and the meltwater refreezes at the cold eaves. Every Wisconsin winter shows them off, and the cause is usually air leaking into the attic and too little insulation, not the gutters.

The usual answer is sealing air leaks first, then adding insulation, with foam at the trouble spots. Tell us where the ice forms and how old the house is. No one can promise an ice dam never comes back, and we will not either.