Plywood and OSB sheathing are some of the most common materials on a jobsite yet are frequently misused. The APA-The Engineered Wood Association trademark stamp goes a long way in helping you choose the right product.

1 Type of Sheathing APA-rated sheathing is designed for walls, roofs, and subfloors. Sturd-I-Floor is intended for light-frame subfloors. Graded plywood is multi-use depending on veneer grade, group number, and exposure.

2 Span Rating Rated sheathing: The numbers separated by a slash are the maximum intended spans for roofs/floors under typical residential conditions and with sheets spanning at least three supports. Sturd-I-Floor: A single number indicates span rating for floor use with carpet and pad. Graded Plywood: Group number indicates strength of wood, from 1 to 5, strongest to weakest.

3 Exposure Exterior—intended for permanent exposure to moisture. Exposure 1—fully waterproof bond, intended for high-moisture conditions. Exposure 2—intermediate glue, for moderate exposure to moisture. Interior—interior, non-wet applications.

4 Performance Category A panel designation related to the panel thickness range that is linked to the nominal panel thickness designations used in the International Building Code and the International Residential Code.