Adding fiberglass batts over top of XPS board insulation: will this create a double vapor barrier?
I'm finishing an attic space above an unheated garage; I'll be running a mini split for heat/AC, but want to do a good job of insulating. I have 2x12 rafters with a ton of nails poking through the roof, so installing those cheap plastic provents (for an air gap to the ridge vent) sounded like a hassle. Instead, I started cutting 1" thick XPS foamular board (two small strips on each side) because i can just press it into the nails - then put EPS board on top to form an air channel. Then I'd put either fiberglass or rockwool on top of the board. Inside the attic, I'll be doing drywall, so I always heard you should use faced insulation for that. However, since Im installing foamular boards behind that insulation, should I avoid the faced stuff and go unfaced to prevent sandwiching moisture? Or will those boards not do much in that regard? submitted by /u/DesignDev [link] [comments]
I'm finishing an attic space above an unheated garage; I'll be running a mini split for heat/AC, but want to do a good job of insulating. I have 2x12 rafters with a ton of nails poking through the roof, so installing those cheap plastic provents (for an air gap to the ridge vent) sounded like a hassle. Instead, I started cutting 1" thick XPS foamular board (two small strips on each side) because i can just press it into the nails - then put EPS board on top to form an air channel. Then I'd put either fiberglass or rockwool on top of the board.
Inside the attic, I'll be doing drywall, so I always heard you should use faced insulation for that. However, since Im installing foamular boards behind that insulation, should I avoid the faced stuff and go unfaced to prevent sandwiching moisture? Or will those boards not do much in that regard?
[link] [comments]
