First let me say I love this place - I've been through 2 renos with plenty of help from everyone here. so thanks!
we're doing a number of renovations in a 1960's home we moved into about a year ago - including installing pot lights on the second floor. I've taken down the ceiling drywall to reveal paper back insulation. Then I started thinking ...
after I wire-up pot lights, ceiling speakers, etc ... how do I get poly-vapor barrier back up in areas where there's an interior wall? (see pic below).
I can't run the insulation across the entire ceiling because of this wall - any thoughts? i'm hoping I dont' have to take down the interior wall just to run vapor barrier.
Your above suggestion on sealant sounds reasonable. As you're finding out, on a renovation one can't always get it as you like iy w/o tearing it down to the ground. Too, there are man many homes that have no vapor barrier on the ceiling plane...only on the wall insulation