No OSB is rated for moisture.
Manufactures will tell you all kinds of crap to get you to buy there product.
Exterior glue OSB just means it can get wet 5 times vs once for interior before falling apart.
Exterior glue OSB contains toxic formaldehyde glue, and should not be installed indoors.
OSB is just plain crap. I won't use it for anything in a bus conversion.
Spray foam sprayed directly onto the inside of the outer skin is the only thing that will stop that condensation from forming, and running down the inside of the walls. If there is a air space between your insulation and the outer skin, you will have condensation.
Avoid using poor quality wood products if you can. All wood has mold spores in it from the day it was cut from the tree. Any moisture content over 19% for longer than a few hours, mold starts to grow.
So do you want to build a mold pit?
Radiant barrier's on rigid Styrofoam are also a joke. Again, just a false selling feature. That's why only the low end Styrofoams have it.
However, due to cost and not knowing any better, many fellow skoolies still use OSB.
"Don't argue with stupid people. They will just drag you down to their level, and beat you up with experience."
Patently waiting for the apocalypses to level the playing field in this physiological game of life commonly known as Civilization