Polyiso water absorption: Should the WRB be inside or outside of exterior foam?
I’m planning exterior foil faced polyiso with a rain screen between the foam and the siding.
My question concerns water absorption of polyiso. I read that polyiso absorbs water quickly and with this in mind does it mean that putting the wrb outside of the polyiso is a more favorable place to put it than putting it between the polyiso and the sheathing.
I assume in foil faced polyiso it only absorbs water at its exposed edges. If those edges are all taped then it doesn’t matter.
I’m asking because I really want to use “outtie” windows (typically wrb outside of foam) but there are two other exterior finishes other than siding on my home such as EIFS (using EPS foam) & rock veneer that require my wrb to be inside of my foam rather than the outside
Second question is it possible to flash a window as an outie window with the wrb on the inside face of the foam. If so can someone point me to a detail.
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