OSB can be used outside for walls, roofs, or floors. Oriented strand board that meets US APA Standards or CSA 0325 is code compliant for use on roofs, walls, or sub-floors. The stamp painted on the underside or back of the board indicates use. The information you’re looking for is the panel grade, span rating (16,20,24,32,40, or 48), and exposure rating.
The panel grade may be identified as STURD-I-FLOOR for subfloor use or RATED SHEATHING for walls and roofs. It may also show 1F or 2F noting sub-floor end-use, 1R or 2R for a roof, or W for wall end-use. The ‘1’ identifies that the panel can be used alone, or ‘2’ requires additional support like H-clips.
The exposure rating or bond classification indicates the type of exposure the board can withstand. EXPOSURE 1, EXTERIOR BOND, EXT.BOND or EXTERIOR TYPE BINDER identifies that the panel can be exposed to the elements and withstand common construction delays without adversely affecting its structural properties.
The panel mark identifies the following information: manufacturer, quality control association, panel grade, span rating, spacing, exposure rating, thickness, performance standard, HUD/FHA Recognition, thickness category, strength axis (perpendicular or horizontal to supports). Additional information includes the mill number, manufacture date, and even the shift code.
