I'm framing my basement ceiling for drywall. I ran new joists perpendicular to the old joists and will run the drywall perpendicular to the new joists. There are soffits on three sides of this room, so in essence I have a tray ceiling. So to my question.... Because of the soffit the long edges of the drywall on the ceiling won't be supported by a ledger board. Is this a problem? Should I add cross pieces between the new joists to fix this? I"m using 5/8" drywall if that makes a difference.