It's hard to find now. Noplace around here has it, I'd have to drive 40 minutes to get any. After what I've read here, probably not worth it. But Norm did use it for a ceiling in the garage workshop episode, and it looked something like drywall.
I would like to use something not too heavy, since I will have to put it up myself and lift it over my head on a ladder. (My ceiling is only 8' high, but I'm only 5' high )