What is stronger plywood or osb?

Answer 1

When used as intended structural plywood and oriented strand board (OSB) are interchangeable. Both products, although different in composition and appearance, are manufactured according to a set of standards that assure very similar performance when used in applications such as subfloor, wall and roof sheathing, single-layer flooring, and exterior siding.

Performance rated structural plywood and OSB panels are made with resin adhesives that provide a moisture resistant bond. Such panels are identified as EXTERIOR or EXPOSURE 1. Because other factors may affect bond performance, however, only EXTERIOR panels are recommended for applications subject to long-term exposure to weather or moisture, such as siding. EXPOSURE 1 panels are designed to temporarily withstand exposure to the weather or moisture during construction, but are intended to eventually be protected from such exposure.

Performance standards for wood structural panels (plywood and OSB) were developed in the late 1970s and early 1980s by the American Plywood Association (now APA - The Engineered Wood Association). There are three basic criteria for qualifying wood structural panel products under performance standards - structural adequacy, dimensional stability and glue bond performance. Performance tests evaluate a panel's ability to perform to the expected and necessary level for the intended end use.

Performance rated panels, whether plywood or OSB, can also be used for engineered applications such as shear walls, diaphragms, and materials handling applications using established design capacities and specifications.

Where skepticism about OSB exists, it usually involves concern about the product's performance after exposure to moisture. While thickness swelling caused by exposure to moisture has long been known to be greater in OSB than in plywood, such swelling does not affect panel structural performance in the applications for which it is intended. Fastener withdrawal and other structural performance tests which plywood and OSB must pass in order to qualify for trademarking are conducted under both dry and wet conditions.

Additional information about performance rated plywood and OSB panels is available from APA, which maintains a comprehensive inventory of product guides, design/construction literature, and research reports. These publications are available free of charge from the APA website.