I have trusses on four foot centers. I plan on installinf between the trusses 2x4 material every 4 feet so I can hang drywall or some other board for a ceiling. My idea is to install these boards flat rather than on edge so I can use r-30 insulation which is 30 inches wide. Also, there are some places where I have wire that is in the way if I put the boards on edge. I plan to nail or screw each end of these boards between the bottom chord of the trusses.
I know the edge of the board is stronger than when layed flat. WIll I have trouble with sagging? SHould I also space every 2 feet or will 4 be enough?