In the planning stages for my barn and thought I was going to go with 4' OC truss. I have a friend who did this in his barn and he was going to install a ceiling by putting purlins on the bottom side of trusses and install metal ceiling so he could blow in insulation. I dont have the bottom cord load rating from any quotes yet, but wanted to get educated thoughts on running a metal ceiling with 8' OC truss spacing.. who has done it? do you know your truss bottom chord load rating? thanks for the help. The quotes are 2-3 k lower with the 8' OC truss spacing. 