I have an 11-yr-old house that has a guest room over the attached garage. The garage walls and ceiling are insulated (bats). Problem is it's not enough -- the guest room is very cold in winter (Arlington, VA). The heat for the room comes through ducts in the attic, which is insulated with blown-in cellulose. The ceiling is very high in the garage. Would it make sense to add a "second ceiling" with more insulation? Or would it help to open the ceiling and replace the bats with foam? The garage door is insulated and has the standard weather stripping but the garage is always cold in winter.