On 28-Nov-2005, "RicodJour" wrote:

Go with polyisocyanurate insulation (~R14 for 2") if you feel
it's worth the money, extruded polystyrene (~R8 for 2") if not.

Since there is no constraint on thickness, you could use expanded
polystyrene foam (beadboard) that's thicker. Why pay for a high-
priced insulation that's volume efficient when you can just go with
thicker and cheaper insulation?

Mike