Im wanting to put a ceiling in my garage to hold some heat in and was looking for a somewhat cheap materail. I was looking for some styrofoam sheet insulation with a foil backing to use for a ceiling, but for some reason I can't find exactly what I was looking for. I found plain styrofoam with no backing which is flammable, so I don't really want that.
I thought about just plain old OSB with pink rolled insulation above it. What do you guys use?
I thought about just plain old OSB with pink rolled insulation above it. What do you guys use?

there is nothing there. Nothing but bare 2x4's down low. Last year my insulation was putting a garbage bag over the whirlybird on the roof of the garage to keep the torpedo heat from running straight out.