[Shop-talk] Lightweight reflective ceiling covering?

[jamesf at groupwbench.org (Jim Franklin)]

My garage is 24 x 24 clear span, with sagging 2x6s tieing the rafters
together. I don't think they'll hold sheetrock unless I get 1/4", at which
point I'm thinking there's something better, maybe already white so I don't
have to paint it? Luan-based paneling looks to be roughly $22/sheet, and my
searches aren't coming up with anything else.

thanks,