Cultured stone veneer with interior XPS
Sorry if this has been covered, but I have searched all over and cannot find definitive answer.
I am in Climate 4, but within few miles of 5 on East Coast, averaging 47” of rainfall. I have a house with cultured stone veneer about 2 ft above the rim board on the front of the house. The builder used D paper with another layer of JumboTex, lath, then cultured stone over the OSB and rim board. I know this is not the best solution, but it is what I have.
The walkout basement is conditioned. Currently, the interior rim is insulated with unfaced fiberglass batt. I would think this would allow warm moist air during winter to contact the rim board and condense, so I wanted to remove and apply 2” of XPS. So here is my hang up…..If I apply XPS to the interior of the rim, wouldn’t this reduce the vapor permeance, not allowing the rim board (covered in cultured stone on the exterior) to dry to the interior efficiency? I realize XPS is still permeable and depending on thickness can be semi-impermeable or semi-permeable. With its reduced permeance over unfaced batt, would I be creating a worse scenario by using XPS? And would 2” of XPS be worse than 1” with the given situation?
Thanks in advance! Appreciate any feedback.
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