We bought a winterized cottage on the Ottawa River, built a basement under it and are using it as our year round home. The problem is the roof, which is made from 2 X 6 rafters on about a 2/12 pitch. the bottom of the rafters is the surface of the ceiling inside. Although the cavity in the rafters is insulated with 6 inches of bats, there is no ventilation, and no room for any either. We get ice damning and leakage all over the roof. I believe my best bet is to build a new roof structure over the old one, by building knee walls over the two main support beams and in the center, and laying new rafters on these knee walls, to about a 6 / 12 pitch. If I insulate over the old roof with fibreglass bats, do I have to remove the old shingles first in order to avoid any double vapour barrier problems? Am I on the right track with building a whole new roof structure?
