We recently purchased a Florida home that has a dropped ceiling (7') in the kitchen. The ceiling is wallboard hung on 2x4 framing hung below trusses spaced at 24”, with ugly vaults with fluorescent lighting inside. The rest of the house has wallboard installed directly onto the truss bottoms for an 8' ceiling. I want to remove the lowered ceiling and install wallboard onto the truss bottoms in the kitchen as well. There is fiberglass batting insulation above the kitchen. My problem is how to deal with the insulation when I open the ceiling & I don't want to leave the room open to the attic while doing the work. Should I first remove all the insulation above this area and place plastic sheeting in the attic area to minimize cooling loss, etc., then replace the insulation. Or, can I leave the insulation in place and install plastic sheeting to the underside of the trusses as I progress in opening up the area when I remove the dropped ceiling & framing, my question being can I leave this sheeting in place when I install wallboard for the new ceiling?