I am finishing out an above-garage room that is currently attic space. The roof has radiant barrier sheathing (ie foil-lined OSB). I have a few walls that are currently just studs open into the attic. I plan to add OSB on the back of these walls and insulate them along with the outside walls. I went to price the OSB and found I can get the same foil-lined stuff used on the roof, or regular unlined OSB sheathing.
Looking at the specifications section on the Lowes website, there is an X (as opposed to a checkmark) by the "For use with walls". Why is this? Is there any real reason not to use this for the attic-facing walls? If it is OK to use, should the lining face into the room?
This is in southern US. The floor and garage are already insulated, and I plan to do blown fiberglass or cellulose insulation on the walls and ceiling.