I will be stapling 5-1/2" (R21) kraft paper faced fiberglass above it. Can I get away with 1/2 inch low sag or should I up it to 5/8" thick? There's nothing above that but the roof holding the shingles and the walls are bare studs for now. Other options? This will be a workshop. via /r/DIY https://ift.tt/2RIoTQf
