Plywood roof sheathing is placed over rafters spaced at 24″ O/C. The plywood is placed perpendicular to the rafters, edges are blocked. The panel span rating is 24/0. The total roof load is 40 psf. What is the minumum allowable thickness?

Plywood roof sheathing is placed over rafters spaced at 24″ O/C. The plywood is placed perpendicular to the rafters, edges are blocked. The panel span rating is 24/0. The total roof load is 40 psf. What is the minumum allowable thickness?