We are renovating/finishing the attic on a 1925 "craftsman" style bungalow house. The roof consists of true 2X6's. Because of ceiling height issues we are not able to make the roof rafter space deeper. Right now, we are planning to install "Dura-vent", then 4" of kraft paper backed fiberglass (R-13 or 15), then a 1/4" foil-foam-foil type insulation before sheetrock goes up. Do you all think this will work well? The foil stuff is a little expensive, will it be worth it? The foil company claims R-14.5 but I am skeptical because they only talk about "radiant heat". Any other suggestions?