I am currently insulating a new room in my house. I am planning to put up a drop ceiling. I have insulated between my roof trusses. Do I need anything else between my drop ceiling and attic space other than insulation. I thought of putting either drywall or plywood but not sure if I need it or not.
If your in a cold weather area a layer of poly creates a vapor barrier, otherwise Drywall and plywood have no insulation value. Notes for the insulation between roof trusses:
4" cavity space: R-13 or R-15 batts, 6" cavity space: R-19 or R-21 batts, if it's a wide open attic, use an R-30 or R-38 batt.