Any combination of the above-mentioned grades are available as face and back surface for the plywood panel.
The grade system of classification includes:
• C-D Interior and C-C exterior (both are unsanded) sheathing panels are designated APA Rated Sheathing.
• Touch sanded underlayment panels 19/32 in. or thicker are designated APA Rated Sturd-I-Floor.
• Rated sheathing may be modified by the terms structural I or II.
• Plywood panels conforming to this system are designated by a thickness, or span, rating without reference to veneer species. Span rating is written in the form 48/24, where the numerator indicates the maximum recommended span in inches when used for roofing and the denominator indicates the maximum recommended span in inches when used for subroofing. These values are based on a 35 lb/ft2 (170.94 kg/m2) roof load and a 100 lb/ft2 (488.24 kg/m2) floor load. The floor load limitation is a deflection of L/ 360 where L represents the span.