Rim joist foam sandwich between impermeable layers
I apologize I am re-posting a similar question that I asked a few days ago but I want to make sure this question gets answered as I am worrying sick over it! Basically, I cut and cobbled 2” XPS into all my rim joists without realizing I already had exterior 1/2” foam board under my siding and against the wall. The issue I am worried about is that, after recently examining the outside more closely, the exterior foam board is wrapped with facings, which as I understand are very vapor impermeable. Am I asking for trouble with this assembly, or will there somehow be sufficient drying to the interior?
A slightly similar question has been asked before, and I know i’ve seen martin say that it’s OK to sandwich the rim joists between foam boards, but I’ve never seen an example where both foam boards are very impermeable. https://www.greenbuildingadvisor.com/question/how-to-insulate-rim-joist-that-doesnt-breathe-on-the-exterior-side
GBA Detail Library
A collection of one thousand construction details organized by climate and house part