According to louie :
First, you need to get some special screws or nails that have a large
plastic washer to prevent them from being pulled through the
insulation.

There's a different type of washer that might be easier to find. Old
fashioned and/or rural Hardware stores will often have boxes of
these things sold by the pound. It's galvanized steel, about 1"
square with a dimpled centre hole.

If I recall correctly, if the stuff has a foil side, the foil should be facing
_in_.

Drywall over foam board is okay provided it's the right foam board and
reasonably well fastened, and that the drywall screws (don't use nails!)
are properly driven into the ply (or better, studs - mark where they are
so you can find them later).
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.