Fab room ceiling height?

It's easier to build it tall & decide later you didn't need all that space than to add space later.... I have 10 & 12 ft materials standing in racks along one wall, moving them I use all my ceiling height...
Agreed, I build with deck screws and a screw gun just for the fact that its not permanent. I can take it apart to modify it and reuse all old materials if it suits the change. Buy good quality screws, not dry wall screws that are prone to pop the heads off.