Vapor Retarder for Below-Grade Cinder-Block Wall
I’m going to be remodeling the lower level of a bi-level house in climate zone 5 (Northern Illinois).
I’m confused on the correct way to do a vapor barrier on a cinder block wall that is approx 42” below grade as is common in the bi-levels.
If I used 2” XPS rigid foam against the blocks and then framed my wall in front and filled stud bays with Rockwool, is a vapor barrier needed ?
I’m thinking the XPS would block vapor at the block so that would cause me to not need an air/vapor barrier such as Certainteed’s Smart Membrane?
If I decided to use Rockwool’s ComfortBoard 80 against the block instead of XPS (since bugs like to burrow in foam), how would I approach an air/vapor barrier in that circumstance?
Thanks in advanced!!
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