garage insulation

I worked in a small garage maybe 24x24 that was paneled with 1\2 in. r-max type sheets and taped. While maybe not ideal it made it 100% better in both hot and cold weather than what it was, and taping it up cut the draft. The stuff is light and easy to trim just maybe with metal studs might have to go with a self tapping screw with a washer instead of the plastic washered nails. It available in different thicknesses and r values but the 1\2 inch made a huge difference on a 20 degree day in my friends garage. Just an idea.