My thoughts for a ceiling air barrier and service cavity
I’ve struggled to find a reasonable cost way to have a good air barrier in the ceiling and really want to protect it with a service cavity. I’ll share my current thoughts and ask for suggestions. I can find nothing better than OSB hung from the bottom chords of deep “energy”heel t trusses, Then, after taped, caulked and otherwise sealed. Followed by screwing 2×4 s cross wise to the trusses 4′ OC. (1 1/2” vertical through the OBB into the to the trusses), then screwing another “layer” of flat wise 2×4’s running parallel to the trusses on 2′ centers, offset from the trusses so more screws can e added if needed. Drywall hangs from the lower layer of flat-wise 2x4s. The 3″ service cavity with no drilling wire in any direction 2 dimensional grid will minimize the trauma to the air barrier and support 18″ of cellulose. A final touch is to glue a strip of foam around the perimeter to dramatically reduce the thermal bridge at the top plates of the perimeter walls. FWIW if I opt to use SIP walls I’ll use a similar “lattice” service cavity on the walls.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part