Hello: I have a 1950s 2 story cape cod home with a shed dormer. The ceilings of the 2nd floor are all insulated with fiberglass batts installed about 10 years ago, and the attic is floored with 3/4" plywood. The attic of this house is has a ridge vent the entire length, but only a couple of soffit vents due to the lack of soffits, and one 3'x3' gable vent. In any case i have been reading about a foil faced material that is installed on the rafters which is suposed to dramatically increase the insulation value. Does anyone know if this material performs as advertised? Is it a diy project? If it matters I live in suburban Philadelphia, PA.