Foam board + backed fiberglass insulation -- bad?

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Old 03-24-19, 07:27 PM
J
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Foam board + backed fiberglass insulation -- bad?

I've installed foam board along the exterior walls of our basement where I'm building a guest room. I've framed the 2x4 walls along the foam board. Soon I need to insulate those walls.

I bought insulation already but it has a backing. Now I'm thinking I should have got non-backed so I don't create a "vapor trap" between the foam board and sheetrock.

Should I use what I have?
 
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Old 03-24-19, 08:14 PM
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Yes, that would have been better. You can return it... tear off the kraft facing... or cut a lot of slits in the paper after its up.
 
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Old 04-01-19, 10:14 PM
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How thick was the foam board insulation? Xps foam?
 
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Old 04-02-19, 06:25 AM
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3/4" foam board. Exterior walls are 3" brick + 8" cinder block. Foam board is being used as a thermal break as well as vapor barrier against the cinder block. I built out 2x4 walls after that, and filled with R-15 insulation (removed the facing). Yes, it is XPS foam.
 
 

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