The main grades for APA’s structural plywood panels are: A-A, A-B, A-C, B-B, B-C;,C-C, C-D, D-D, Sturd-I-Floor, Underlayment, CC plugged, CD plugged. Non-overlaid APA plywood panels come in three levels of surface finish – sanded, touch-sanded and unsanded. APA’s guide identifies each panel’s specific finish, veneer strengths and the wood species used, as well as bond durability.