I've heard that it's unnecessary with closed-cell spray foam as it actually performs as a vapor barrier itself (some building codes don't even require one when using it). I am not a professional and this advice should be taken with a grain of salt. Regardless, I won't be doing a vapor barrier when I do my insulation here in the next couple of months.
The adventures of two full-time travelers from the Natural State, living in a bus and exploring life, one road at a time.
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