Quality control over grading is important to ensure that products are able to deliver the performance that designers expect, and conform to the grade specifications of each of the timbers used in structural applications. This applies equally well to appearance grading and structural grading. In-grade testing of structural products can be used to verify structural properties.

Timber producers will have their own quality control systems and manuals, and in some cases seek endorsement for their quality system under ISO 9002 or AS 3902. This is not a requirement for every producer, but many of the larger producers see the value in having checks and balances on their quality systems to ensure that their grading is as effective as possible.

Just as with lumber, there is no such thing as a perfect piece of plywood. All pieces of plywood have a certain number of defects. The number and location of these defects determines the plywood grade. Standards for construction and industrial plywoods are defined by Product Standard PS1 prepared by the National Bureau of Standards and the American Plywood Association. Standards for hardwood and decorative plywoods are defined by ANSIIHPMA HP prepared by the American National Standards Institute and the Hardwood Plywood Manufacturers' Association. These standards not only establish the grading systems for plywood, but also specify construction, performance, and application criteria.