I have an old two bay garage that's 28'x50', that I would like to convert into a home. One thing I'm trying to figure out is how to do the ceiling. The ceiling is held up by metal joists approximately 12" high. The ceilings are 13' high and I would like to drywall them. I plan on spray foaming the roof prior to installing drywall. The bottom of the joists have a gap where I could run a bolt or toggle type fastener through. What should I use for studding and spacing?