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That would be open cell foam. About 1# per cf. It is not a vapor barrier but will slow air movement. We use closed cell which is 2# per cf and if you spray 2" is also a vapor barrier. R for closed cell is almost 7 per inch, open cell is about half.
That said both are far better than fiberglass, google R-value myth.
If you want to get all geeky and do research, Buildingscience.com is a good source of unbiased info.
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