Types of Plywood

Plywood is a necessity for many projects and the numerous options, different types of plywood at the hardware store can seem overwhelming. Below is Our ultimate guide to plywood and the projects for which they work best should help you narrow your options to find the right kind for your needs. You’ll find various prices matched with multiple materials, ply, sizes, veneers, grades, and more.

I. Plywood Buying Guide

A. Types of Ply

The term “ply,” as it refers to plywood, means the layers manufacturers use to create the boards at various thicknesses. Some projects won’t need a thick board, while others will. Ply achieves the right depth and can also make the boards stronger.

Each layer is known as a wood veneer. A veneer is a thin piece of wood that you can glue together to create a different number of plies. Plywood, then, is the finished product when the manufacturer glues the veneers together.

It’s important to note, though, that veneers can also have various thicknesses. Depending on your location, some parts of the home must meet specific standards for the number of plies required for a board of a certain depth, especially with external walls and roofing.

1. 3-Ply

3-ply is one of the most common types of plywood. This kind has three layers of veneer and is layered enough to be strong and durable but can look more decorative than plywood with more plies, making it a good choice for indoor use.

2. 5-Ply

5-ply pieces of wood have five layers of veneers. This is another common type of plywood used for projects that require less durability and strength than those needed for exterior use.

3. Multi-Ply

Multi-ply plywood is mostly for exterior use and roofing. It can comprise several veneers, usually seven or more, to create an incredibly strong, unyielding frame for a home that can stand up to wind and damage.

B. Types of Plywood

The various types of plywood you’ll find in the hardware store can make your shopping trip seem overwhelming but understanding how they differ is the key to deciphering what the best kind is for your project.

1. Softwood

Softwood is a type of plywood that manufacturers make using softwoods, like pine, redwood, or cedar. Although the name implies that these woods aren’t as strong as others, you might be surprised to know that construction workers typically use softwoods for exterior frame sheathing, roof sheathing, and sub-flooring.

Softwood plywood can also create things like sheds, temporary flooring, doghouses, shelving, and more.

2. Hardwood

Hardwood plywood typically has between three and seven layers and uses hardwoods, like birch, maple, oak, and walnut. Manufacturers glue the layers of wood at right angles to one another to create an incredibly strong finish.

Hardwoods are best for things like furniture, packing cases, sporting equipment, musical instruments, and other intricate projects that require strong frames.

3. Aircraft

According to Woodwork Made Easy Aircraft plywood is among the highest-grade, most durable kind you can find. This wood uses hardwoods, like mahogany or birch, to create an incredibly strong finished piece that can also resist heat and moisture.

The design incorporates some very thin veneers that can keep it light and flexible, while still giving it unyielding strength for the heftiest jobs. You’ll find this type of plywood in projects that need industrial-strength woods, like airplanes, boats, and furniture that’s meant to hold a lot of weight.

4. Exterior

Exterior plywood has weather and water-resistant glue that holds each veneer together. When you create an exterior with plywood, one of the biggest – and most important – concerns is how the wood will handle wind, rain, and other weather. Exterior wood is meant to combat the elements to provide a strong, sturdy frame for years to come.

Exterior plywood sheets typically have several veneers glued together, classifying them as multi-ply. You can also choose various kinds of wood for exterior plywood, depending on the area in which you live. Some locations that experience unusually harsh seasons may fair better with wood like oak, which can resist mildew and mold from damp conditions.

5. Lumber Core

Lumber core plywood is usually made with three plies, with two thin veneers on each side and a thick core. The outer veneers are typically made of a hardwood, while the inner core consists of strips of wood glued into one solid slab.

The inner core helps grasp screws, which makes it a good choice for projects that need a strong screw hold. One disadvantage is that poorly-made lumber core plywood may have voids within the core that diminish its strength and screw holding abilities.

6. Marine

You might think that the name of marine plywood, also known as marine-grade wood indicates that it’s waterproof, but that’s not the case. Instead, wood manufacturers make marine plywood with water-resistant exterior glue using the same layered construction as other woods.

The difference is in the grade of marine types. According to the APA – Engineered Wood Association, marine-grade wood consists of Western Larch or Douglas Fir woods and must have a B-grade or better, which we’ll discuss in the “More Details” section of this guide. This kind of wood is one of the best-constructed, high-graded plywood on the market.

Marine-grade wood isn’t resistant to mold, mildew, or rot from weather and water. Manufacturers don’t treat it with any chemicals, so rot and decay can be a problem unless you treat it with a pressure-preservative, as suggested by the APA.

To be graded as marine-grade, this wood must have no knotholes in any of its plies and use a top-performing water-resistant glue between plies. This ensures that the glue won’t stop working if the wood becomes damp from weather or wet conditions.

You’ll see marine-grade woods used mostly on outdoor furniture and decorative pieces, like gazebos, planter boxes, and benches.

7. Overlaid Plywood

Overlaid plywood, which can be either high or medium-density (HDO or MDO), is a kind that utilizes the same structure of regular sheets with veneers glued to one another. However, overlaid sheets have an overlaid face that gives it a somewhat finished appearance.

The finished exterior isn’t necessarily for decoration, but instead gives the panels a durable surface that’s also smooth enough to keep water and other particles from damaging or sticking to it. The coating also helps the wood resist scratches and other abrasions that may happen during transport and construction.

Manufacturers bond the exterior surfaces to the rest of the veneers through a process of heat and pressure. High-density overlaid panels have more resin than medium-density panels, making them a bit more expensive. However, both can make a finished project stronger and more durable than can traditional plywood.

8. Structural

Structural plywood, also known as sheathing plywood, is not for looks, but rather, strength for framing and building structures in which you’ll eventually cover the wood. This type of wood needs a very strong adhesive to keep the plies together.

You can use structural woods on the inside or outside of a building, but they aren’t typically as weather-resistant as other types. Structural woods usually have a C or D grade, but no higher, so they’ll be an inexpensive option compared to some woods, but they also may not have the high performance you need for outdoor structures.

A. Wood Grades

We’ve mentioned the grade plywood sheets can have a few times in this article. It’s important to understand why wood has a grading system and what the grades mean for the type of wood you purchase.

The plywood grading system uses letters A, B, C, and D, with A being the best and D being the lowest quality. You’ll see two letters, though, for most woods. One letter designates the grade for the front of the board while the other grades the back, or the part you won’t see when you install it. Typically, one side will have a lower grade than the other, and that’s the side you’d want to use in the back.

Exterior panels will usually have high grades of A-B or A-C. You’ll want to ensure that you choose the highest grade possible for anything that may be exposed to weather or needs excellent strength. A grade of C-D is usually okay for internal structural use but isn’t something you should consider using if it won’t be adequately covered. You might sometimes see an additional grade with an X at the end, like A-CX. This just means that the board has met the standards for external use.

For projects that require a high-end finish, opt for higher grades. These should have little to no knots and voids and should provide a nice, smooth finish for staining or painting.

B. Sheet Sizes

Some lumberyards also tag their sizes in millimeters rather than inches, which can further complicate your shopping. Be sure to have your phone with you to do a quick conversion using Google or a mobile app so that you can make sure you have the correct size.

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C. Materials

We discussed several how hardwood and softwood boards differ and what types of wood qualify as hard and soft. But, what differences will these woods bring to your project? Interestingly, scientists classify hardwoods and softwoods by their trees’ seeds, not the actual density or strength of the wood itself.

However, they do perform slightly differently in woodworking, but mostly in the way that you cut them. You can usually cut softwoods a little more easily than hardwoods, but hardwoods may be able to outlast softwoods in furniture, flooring, and other parts of the home that are subject to wear and tear.

You might prefer the look or feel of one type of wood over the other when it’s made into a sheet of plywood. Your best bet is to look at all the options and feel them. You might even prefer the feel of one over the other which can help you decide on the best kind for your project.

Remember, though, that hardwoods can be more expensive than softwoods. Softwoods tend to be more common and available, so they may not eat into your budget as much.

D. Finishing Plywood

If you don’t want to cover up your wood panels, and instead want to stain or paint them, you’ll need panels that provide the right surface to do so. High-grade panels, those marked with A or B are the best type to use for finishing. If you want to finish both sides, you’ll need to make sure that both letter grades are A or B.

To paint almost any plywood, you should plan to use a primer first, which will give the wood a smoother surface and help the paint adhere to it. You’ll probably need at least two coats of paint to give the wood the right finish. Painting with a brush may help you penetrate the wood better, which will require fewer layers.

If you’d like to stain the wood instead, choose smooth plywood, or you’ll find it difficult to create an even finish with the stain. Allow the stain to dry for at least 24 hours before coating it with a clear varnish, which will help protect the stain and seal your wood.

With both paint and stain, you should consider using a sealant as the last step to prevent molding and rotting in the wood when exposed to moisture.

Above there are types of plywood and buying guide: Hope the information that Fomex is useful to you and thanks to you for your time.

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Fomex Greenwood