The ceiling gets really hot! And it isn't hot yet.
Google turned up a combination of bubble wrap (moisture barrier) and Styrofoam sheets covered with some sort of paneling. No glue. Friction fit until the ceiling paneling goes up.
Adhesive has an outgassing of toxic fumes and will release as the metal expands and shrinks dramatically each day.
Thinking of a white plastic, thin stuff for the ceiling paneling. Saw some once at a plastics distributor. Will look again in June when I am in Phoenix.
Other suggestions more than welcome.
Not considering the walls at this time. Could change, but I don't plan to LIVE in it!