Q: I’m considering investing in a rental property, and the home inspector pointed out an attic ventilation problem, saying the attic may get hot in winter and lead to ice dams. How can heat lead to ice problems?
A: Ice dams can pose a real problem in colder climates and can usually be prevented with proper attic insulation and ventilation, as well as waterproof shingle underlayment on the roof deck. Insulation and ventilation keep the roof cool in the winter when you’re heating your home. However, if these systems aren’t functioning properly, then the accumulated heat in the roof can melt snow in the winter. The water from the melted snow runs to the eaves, where it then refreezes to form an ice dam because the eaves are not heated.
As the ice builds up, the melting and refreezing water backs up the roof, working into nail holes and between seams in the shingles. As the dam melts the water can then leak into the house and damage the walls and ceilings.