When I built my 40x60 shop for my taxidermy studio, I installed factory seconds white metal on my ceilings on 4 foot center rafters. It was the best $$ I spent on the building since it is plenty strong for any thickness of blown-in insulation and I can put screws anywhere in the metal for light fixtures without having to worry about finding a rafter. The white color also makes lighting much easier. I will do the same in my boat storage garage when I get to that point.

