I have no knowledge of this witchcraft other than what my buddy had done to his shop.... He spent $90k on the building complete.
Anyway... He had 'some people' come in from Arkansas and spray his foam... It's only 2" thick in most places... He said they told him the spray foam didn't have to be as thick as fiberglass or foam board. That bill was $9k as it was!
That makes sense, because I know Owen Corning's pink panther foamular 1" this has an R5 value.
It's much much much denser than regular foam board with reflective Mylar coating.
And their 2" is R10
This is my 1/2" Mylar coated foam board and 1" foamular