One inch of Closed-cell spray foam insulation is an approved vapor barrier with permeability being at, or below most asphalt and rubber based waterproofing membranes on the market. Closed-cell foam is approved for exterior and sub-grade applications.

Whether you are building a new structure or gutting and renovating an existing home/building I think that getting the best insulation for your buck is going to come up at some point.

Whether or not you decide to read the article that my comment below is posted on (http://houseblog.ottopohl.com/2010/02/05/foaming-about-insulation/comment-page-1/#comment-41). I think you will find my information informative and revealing.
–Wow!!!
You did your research! I am very impressed that you were able to calculate all of those figures and actually obtain some of the “secret” information that you did.
I [...]