CDX is not the span rating. Refer to the APA plywood grade stamp. The APA plywood grade stamp will have 2 numbers (Panel index number): i.e: 24/16 this indicates that the sheathing may span 24" on the roof and 16" for a floor. The “CDX” is only a reference to the grade of the face panels and the type of glue. For any structural application the Panel Index number must be specified and checked. Reject any structural sheathing material that does not have the APA Plywood Grade Stamp.