Foam board and spray in foam go in 2 basic R values R 5- 5.5 per inch
and R 7.2 per inch, R 7 spray in is an outgassing type that needs time
to release harmfull chemicals. Actualy Foamboard even foilfaced exposed
to suns heat as in a roof deck theoreticly will cook and outgas. For
sensitive animals " people too" a Non Fordmaldehide Fiberglass is
available, usualy white and labeled. Rock wool might be better but who
knows, and im not sure on the R value being higher than fiberglass. Also
the double roof or tent is interesting. Vermiculite is non toxic, I
think, out gassing is an issue not fully apreciated like smoking but can
and does harm people every day in new construction.