so i built a laundry that goes out into the garage this summer. now that it's snowing, the room is cold and i realize there's no insulation above the ceiling yet. but then that got me to wondering if i need to build some kind of knee walls in the attic above the room? the ceiling is 2 layers of 5/8" drywall for firecode, so i don't need knee walls for fire code. Do I need them for keeping the new room warm? Can I just lay down a blanket of insulation above the new room?