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.

  • 3
    Drop Ceiling = massive air leak through all the seams. Having a sealed air envelope is a major step towards heating efficiency. Plasterboard with sealed joints will always be more efficient as it allows you to trap the heat and control air egress instead of chimneying it out through all the cracks. See if some sort of vapor barrier can be used over the ceiling tiles and tee bar under the insulation to cut down on the air flow. Jan 26 '13 at 19:17
  • I would up vote the above as an answer. 40% or more of heat loss is via air leaks, and drop ceilings are far from air tight. Drywall taped and seamed well makes a good air barrier, and it is less expensive and more fire resistant than taped plywood. Once you've sealed all the leaks, blow in at least the EPA recommended amount of insulation over top.
    – mfarver
    Jun 14 '16 at 1:52

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.

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