said by blondebaldy:would it be just as plausible to add the polyisocyanurate rigid foam insulation in between the rafters, being that its moisture resistant, instead of going though the mess of ripping the floor scabbing a 2x6 or 8 to the existing floor boards and either removing the blown in or adding insulation as suggested.
Except that you eliminate the attic as a giant unconditioned dead space that is still contained within the envelope of insulation encompasing the house.
In the summer it will just contribute to heating the air conditioned house, or in the winter leeching heat away from the heated house. That's why houses insulate the floor of the attic instead of the rafters when the attic is just used for storage.
Plus their is less square footage to be insulated on the floor then if you do the rafters.
