When selecting plywood, you might be surprised to find that there is a wide range of different types available. Each meet different standards to fulfill different requirements and it can be easy to get lost amongst them. Most notable is the grading system, which we’re going to take a closer look at here.

When looking for plywood for any DIY or construction project, it’s important to be able to tell the difference between the multiple different grades. The system isn’t too difficult to understand once you know it, but it can seem daunting at the beginning.

The plywood grading system

There are four overall grades when it comes to types of plywood. The grades are A, B, C, and D. However, every piece of plywood has two grades per compound, shown as AB, BB, BC, and so on. The first letter represents the face veneer grade, while the second letter represents the back veneer grade. Simply put, the higher the grade, the better. Just like an exam in school, A is the highest and is the lowest. 

Here, we’re going to take a closer look at some of the common grade combinations, and what they tend to mean for that particular piece of plywood:

AB-Grade

A-grade plywood is very high-quality, and AB is typically the best grading you will see. As such, the material surface will be very clean, with virtually no blemishes or flaws, and a consistent colouring. There may be some small pin knots, but for smoothness and ease of painting, this is undoubtedly the best choice.

B-grade

B-grade plywood is almost perfect in appearance, just like AB-grade, when it comes to flaws and blemishes. Some smooth knots are allowed, but they will rarely be over 35 mm in size. The key difference between B-grade and the A-grades is that B-grade plywood are allowed to have some changes in color that show the pattern of the grain. They may also have had some repairs in the past, but have a smooth surface and reliable foundation.

BR-grade

The R grade added to this one signifies that, while very similar to B-grade plywood, the knots within the wood don’t go over 8mm to diameter. Otherwise, it has the same natural wood appear, including showing the natural color transitions within the grain of the wood. Usually, BR-grade plywood boards are thinner, used in more specialist circumstances where small knots within the wood are more important.

BB-grade

Slightly lower than B-grade plywood. The first B means that it still has the same face veneer grade, but this grade allows for larger knots and more noticeable repairs, up to 50mm in diameter. As such, it may have more repairs, such as wooden plugs. As such, those with a lower back veneer grade tend to get used less often in times when the visual look is essential.

C-grade

C-grade plywood is just as structurally complete as the grades above it, but it tends to have more defects lie open knots, splits, and discolouration. As such, it’s used less commonly for applications where appearance is important. Rather, it’s used where the strength of plywood is required but the strength doesn’t matter all that much.

CC-grade

Similar to C-grade plywood, but with more open knots, discolouration, and splits. As such, it’s usually used for the underside of veneers, rather than on the surfaces of any projects.

D-grade

The cheapest plywood sheets available, yet sometimes hard to find because not every brand wants to be associated with this relatively low quality. This grade can have knots of up to 2.5 inches and doesn’t have any repairs, meaning all flaws are much more noticeable.

Construction and Project Plywood

The grade system mentioned above isn’t the only place you’ll find differences in your plywood. As the names suggest, construction plywood is typically used for construction, while project plywood has more household applications, such as building a set of drawers. They have their own labels, too:

CDX-grade

This relatively inexpensive material is typically made up of both C and D-grade plywoods. The X-grade added to the end means that this plywood also has some moisture-proofing capabilities.

Sanded Pine

This dynamic plywood material is known for its near flawless surface and smoothness. It’s also very good at holding screws and nails. As such, it’s regularly used for building cabinets and other more complex designs.

Indoor and Outdoor Plywood

Most plywood manufacturers are going to be very clear about whether or not their products are suitable for outdoor use. However, it’s also wise to be aware of types commonly used in different environments.

Sanded plywood and oriented strand board are both commonly used for indoor applications. They’re quality materials, but don’t have much ability to tolerate moisture, which makes them unsuitable four outdoors but also makes them less expensive. 

Pressure-treated plywood and CDX sheathing are better for outdoor use. They can withstand some rain, snow, moisture and more. However, no plywood is permanently waterproof. Factors such as heat, humidity, and the like will affect their lifespan.

Which plywood is right for your projects?

Which plywood you opt to use should be based on the project at hand. The thickness of the board and the grading can both play an important role, as well as whether or not it’s suitable for outdoor use. However, hopefully the guide shows you some of the key differences between the grades, as well as what else you may need to consider when choosing a kind of plywood for your next project.