Insulating a garage ceiling
I am designing a conditioned space over a garage in Chicago (Climate zone 5). The floor/garage ceiling structure will be 18″ deep wood floor trusses, with 3/4″ plywood floor sheathing and 5/8″ gyp on the underside of the garage ceiling.
Code (IECC 2012) says R-30 insulation is needed here, which would be a 9 1/2″ thick fiberglass batt. Typically this would get installed from below with the Kraft paper facing on the bottom (so that it would be in contact with the gypsum board). However, the kraft paper should be on the “warm-in-winter” side, which it’s not, and the floor trusses end up uninsulated (and the 2×4 members have the 3-1/2″ side against the ceiling, not the 1-1/2″ side).
Does anyone have recommendations of a better approach to insulating a system like this?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part