My shop currently has no ceiling. The lights are mounted to the rafters, which are 8' high and sometimes get bumped when moving lumber. My goal this year is to install flush-mount fixtures and replace the fluorescent bulbs with LED tubes, and I'd like to put up a ceiling at the same time. Question is - what is the best material for a shop ceiling? I was thinking something like 7/16" OSB or similar, but I'd like to know what others have used with good success. Since my shop is not climate-controlled I would think sheetrock might sag over time, though I do plan to install a heater or maybe even a heat pump eventually. Thoughts?