I have never taken the time to put a ceiling in my shop. It currently is just rafters (on 16" centers) with insulation stapled in between. I need to do something before winter. Any suggestions on an easy and inexpensive material for this? The shop is 20' x 40' with 10' high rafters. The walls are 1/2 " plywood. I almost always have to do these projects by myself, so large sheets are a concern.