APA-member manufacturers are located throughout North America. Hundreds of distribution centers in the US and Canada inventory a wide selection of products for transportation applications. Industrial users can rely on a consistent source of readily available, quality products. Find APA members that make products for transportation applications.
In the applications for which they are manufactured, the two products are virtually interchangeable. Although different in composition and appearance, plywood and OSB are manufactured according to the same performance standard criteria. Which product you choose will depend on your requirements for a variety of characteristics including finished size, surface quality and panel density.
Overlaid plywood panels are available with some type of face enhancement. Two common face coverings are Medium Density Overlay (MDO) or High Density Overlay (HDO), which are resin-impregnated fiber surfaces bonded to one or both panel faces under heat and pressure. Other types of enhanced surfaces include fiberglass-reinforced plastic, polyethylene (HDPE), hardboard, metal and other materials for exceptionally smooth or special-use surfaces. The APA product Guide: HDO/MDO Plywood, Form B360, Describes HDO and MDO plywood applications, properties and characteristics, plus shop practice and finishing recommendations.
Sanded plywood panels are structural panels with face and back plies that are sanded smooth in the manufacturing process.
Touch-sanded panels are plywood panels “sized” to uniform thickness by light surface sanding during manufacture. Sander skips are admissible.
A ply is single veneer in a panel. In plywood, a layer consists of one or more adjacent plies having the wood grain in the same direction. For instance, four-ply panels always have three layers with both core plies at right angles to the faces. The two core plies are one layer and each face is a layer. In OSB panels, the reconstituted wood portion is one layer and each face is a layer.
It is important to understand that the term Structural I refers to certain specialized strength and stiffness characteristics of plywood and OSB panels while the term Exposure 1 refers to the glue bond durability of a plywood or OSB panel.
Exterior panels are suitable for applications subject to long-term exposure to weather or moisture.
Exposure 1 panels may be used for applications where construction delays may be expected prior to providing protection. Exposure 1 panels are made with the same exterior adhesives used in Exterior panels. However, because other compositional factors may affect bond performance, only Exterior panels should be used for long-term exposure to weather.
APA Rated Plywood Sheathing Exposure 1, commonly called “CDX” in the trade, is sometimes mistaken as an Exterior plywood panel and incorrectly used in applications for which it does not possess the required resistance to weather. “CDX” is manufactured with a C grade veneer on the face and a D grade veneer on the back. D grade veneers are not suitable for Exterior applications should only be used for applications as outlined under Exposure 1 above. For sheathing grade panels that will be exposed long-term to weather, specify APA Rated Sheathing Exterior (C-C Exterior plywood under PS 1).
APA rated plywood and OSB panels are manufactured to stringent product standards (such as Voluntary Product Standard PS 1, Structural Plywood and Voluntary Product Standard PS 2, Performance Standard for Wood Structural Panels) and under the most rigorous, state-of-the-art quality assurance programs in North America, the APA quality services programs.
Many imported plywood and OSB panels never undergo product qualification testing. Without such tests it is impossible to determine how the panel will perform for the intended use. As an internationally accredited testing laboratory, APA put imported hardwood plywood panels from China and Brazil up against domestic plywood certified to PS 1. As expected, the import test results indicated inferior mechanical and connection properties, severe failure for bond durability, and only one tested sample would have met the formaldehyde limits imposed by CARB when compared to APA rated plywood.
Look for engineered wood panels bearing the APA trademark. It appears only on North American products manufactured by APA members committed to APA's rigorous program of quality inspection and testing.
Learn more about the Performance Panels performance standards.
Marine grade plywood is a specially designed panel made entirely of Douglas fir or Western Larch. The grade of all plies of veneer is B or better, which means it may have knots, but no knotholes. The panels are sanded on both faces, and are also available with Medium Density Overlay (MDO) or High Density Overlay (HDO) faces. The maximum core-gap size permitted is 1/8 inch. Its exposure durability rating is Exterior and the glue used is a moisture-resistant structural adhesive. It is considered a “premium” panel grade for use in situations where these characteristics are required, i.e., for boat hulls and other marine applications where bending is involved.
Marine-grade plywood is available in 4x8-foot sheets of 1/4, 3/8, 1/2, 5/8 and 3/4-inch thickness. Sheets up to 5x12 feet are also available. Available grades are A-A, A-B, B-B (face-back), MDO and HDO.
Marine grade plywood is not treated with any chemicals to enhance its resistance to decay. If decay is a concern, it should be pressure-preservative treated to an appropriate standard.
The detailed description of veneer grades and Marine-grade plywood is contained in Voluntary Product Standard PS 1 , Structural Plywood.