We own a 110 year old farmhouse in south eastern PA, and want to convert the attic to usable living space. There are NO SOFFIT or ROOF VENTS, there are windows in the gables. I want to insulate the roof rafters but have been told I'll have a condensation problem with fiberglass battts, even if I use a poly vapor barrier. Have had quotes for both open and closed cell foam, both have good arguments. The floor is currently "insulated" under the floor boards with a few inches of very old blown fiberglass...does this have to be removed? One contractor says yes another no. Can or should I add another 3 inches of fiberglass over 3 inches of closed cell foam or will this cause condensation? Do I insulate the knee walls? After 4 contractor bids I am more confused than ever.