Panel Guide

Selecting the right piece of plywood for your project does not have to be as complex as the grading rules. This guide to the grades of plywood is meant to help you get past the uncertainty by giving you the knowledge of what the grades allow and how to do apples to apples comparisons of what you see.

Navigating Plywood Grains

Follow our guide:

In the Pacific Northwest, our most common sanded and framing plywood are:

  • Sanded Plywood
  • Structural Plywood
  • Oriented Strand Board (OSB)
  • Every panel has different characteristics for strength and appearance, but they are all graded on the same rules from the American Plywood Association (APA). The grades, for all that they do, are not much more than a way of telling the user what kind of quality they are buying. The higher the grade, the better the panel.

Understanding the intricate details of sanded plywood standards can be challenging, but with the appropriate guidance, it’s a hurdle easily overcome. The guide below serves as your one-stop resource for navigating the diverse landscape of panel grades, ranging from the premium A-A to the versatile B-D. We delve into industry standards across critical categories, empowering you to make informed decisions every step of the way.

Panel Size

Every panel thickness has a required number of veneer layers based on the grade. The grade will also determine if the panel allows for voids in the core or if the voids must be filled to meet impact resistance in flooring or other high load applications.This chart provides a clear overview of the minimum number of plies and layers required for various plywood panel sizes.

Performance Rated Panels (PRPs) have revolutionized the construction industry, offering a standardized and reliable way to select plywood and oriented strand board (OSB) sheathing, siding, and subflooring panels. This guide delves into the intricacies of seven key grades:

Panel Span Ratings

APA Rated Panels

On APA rated panels, you will see an individual number or set of numbers divided by “/” that indicate the maximum span for the panel in the application. All APA rated Sturd-I-Floor and Siding panels will have a number followed by an O.C. indicating the on-center span.

APA Rated Sheathing Panels

APA rated Sheathing panels will have two numbers that will be a larger number in front of a smaller one that look similar to 32/16 or 48/24. The first number is the roofing span and the second indicates the span in a subfloor application. When the panel is used in a wall application, any rating at 24 and over is used at 24” on-center and anything less than 24 is used at 16” on-center.

Oversized Panels

Some oversized panels built for wall applications will be rated by the APA as sheathing only. The grade stamp will indicate this by rating them at WALL-24 or WALL-16.

Why APA Rated Panels

Building codes are enforced to make sure that a structure protects the occupants in the event of a natural or man-made disaster. The safety of our buildings is accomplished through uniform standards that make it easy to know what is correct. The APA uses uniform testing standards and grading so that you know every panel you install meets the building code and the grade for which you are buying regardless of the mill where it was made.

Some retailers offer mill certified panels as a way to control cost or achieve a standard that they feel is acceptable for their customer base. This standard allows the mill to produce veneers or use adhesives of their own choosing that may or may not meet the building code. The mills also use their own quality standards that may not be in line with the industry standards.

The APA tests and rates panels on the following criteria

  • Linear expansion from moisture exposure.
  • Racking under a lateral load as part of a complete wall section.
  • Uniform load and deflection tested under vacuum.
  • Concentrated static load testing deflection and ultimate load between joist or wall sections depending on the application of the panel.
  • Concentrated impact load tested by dropping weight onto the panel.
  • Direct fastener withdrawal is measured by pulling apart a previously fastened panel.
  • Lateral fastener strength is measured by forcing a panel laterally against the fastener.
  • Surface profile is measured before and after moisture cycles to determine the stability of the pattern in APA Rated Siding.
  • Peel testing is used to determine how well a panel will hold paint or stain.

Common Application

The most common APA panels are performance panels used in framing process of building a structure. Wall and roof sheathing, siding, subflooring, and crating are among the many everyday uses for APA rated panels.

Other specialty panels exist for specific applications like marine and concrete forming. Specific design criteria and limitations can be found on the APA website for these and many other special uses.

Whatever panel you choose, knowing the grade will help you determine if it is right for your project. Grading used in conjunction with your design will help make sure that your project lasts for as long as you want it to. All you have to do now is insist on rated panels.

For more information on the APA – The Engineered Wood Association rules on panels and grading standards, please visit the APA – The Engineered Wood Association