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Need to insulate and drywall for new bathroom in attic

Need to insulate and drywall for new bathroom in attic


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Old 05-16-16, 10:07 AM
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Need to insulate and drywall for new bathroom in attic

My house was built last year. It's mostly a one story with finished bonus room over the garage. We had the rough plumbing installed and the bathroom walls framed out for the upstairs bathroom to eventually make a guest suite.

I'm starting to think about working on that. The room is accessed through a hallway on the 9 foot side. The other 9 foot side is an exterior wall. One of the 6 foot sides is a finished closet. The other 6 foot wall is the framed wall, but it's unconditioned attic space with no floor in that section and an angled roofline with a truss diagonal running from the base of the wall up to the roof - no place to put down temp flooring and put up a ladder.
At first, I'm thinking no biggie - insulate, drywall, paint,etc. When I actually start thinking about how to insulate though, I run into some questions.
2x4 trusses overhead. do I install drywall and then try to insulate the ceilingfrom the attic wall side? I'll have to attach some rungs to the 2x4 truss that forms that wall. Not sure if that's a good idea either. Those trusses weren't really designed for a 200 lb man to climb them, were they?
I need R38 above. Can I attach 4 mil plastic and then blow the insulation up, by piercing the vapor barrier?
Can I use batt insulation and the spring clips like I would for insulating the floor from the crawlspace?
 
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Old 05-16-16, 04:25 PM
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You'll never get R38 in a 2x4 cavity. Best you can hope for is R15 with Roxul. Even then if it is a vaulted ceiling, you must run baffles up and over to allow for air to move over the insulation, so now you are cutting into your minimal R value. Can you post a picture or two of what the project looks like so we can see what you are seeing?
 
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Old 05-22-16, 05:28 AM
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I know I can't get R38 in a 2x4 cavity and I didn't mean to imply there was only a 2x4 space above the room. There is room, but it's very tight going from the attic side.

I hope the pictures help. I had the builder put the shower stall in there to avoid problems with it now that the walls are up.
 
 

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