Plywood is an incredibly common building material. Not only does it use up the smaller pieces of wood that are typically scrap but it is also dimensionally very stable compared to boards of the same thickness. Of course, there are so many types of plywood that it is difficult to know which one to use and when.
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What is Plywood
Plywood is layers of wood and glue that make up a sheet of wood that is typically anywhere from 3/16” to 1-¼” thick. These sheets can be made so that they withstand the exterior elements or in a more decorative fashion for use indoors only.
Plywood is given stability because typically the plies are laid at angles to one another. This keeps all but the thinnest plywood from twisting or cupping. The layers of glue throughout the sheet also help keep plywood stable.
Which Plywood is Best for Interior Use
Most types of plywood for interior use are nicer on at least one side, if not both sides. They may have nicer grain patterns or just be smooth at least. Usually, an interior plywood will not have any holes or plugs. You will find interior plywood in pine, oak, cherry, and birch most often.
What is the Best Type of Plywood for Outdoor Use
Outdoor plywood can be made of any number of different woods but it is typically made with pine. There will be plugs or maybe even holes on outdoor plywood and it will be rougher than interior plywood. Outdoor types of plywood usually has different glue as well.
What are the Main Types of Plywood
There are several specific types of plywood that other sheets are categorized into. Each has their own use in different areas of the home and you need to know at least the basic differences you will find in them.
There are several different types and grades of plywood
Softwood
Softwood plywood is one of the most common types of plywood used in construction. These plywoods have veneers of softwood on the outsides rather than hardwood. Pine is the most common but douglas fir, cedar, and spruce are also commonly used.
Hardwood
Hardwood plywood has faces made of hardwood such as oak, cherry, or maple. Hardwood plywood is usually reserved for furniture or cabinet making applications. This is because hardwoods are seen as higher end and because they are harder wearing than softwoods.
Aircraft
Aircraft plywood has a few specific properties. It is a type of plywood that must be very light and so it is typically made from birch, basswood, or mahogany. Aircraft plywood also needs to be fire and water resistant so it is made with specific resins to give it these properties. Typically, these plywoods come in thinner sheets than other plywoods.
Lumbercore
Lumbercore plywood is made with two veneer sheets of nice wood wrapped around a band of edge-glued lumber in the center. This plywood has incredibly good bending strength and holds screws well. It is well known for having some recoil when it is bent, which is unusual in plywood.
Marine
One of the most specialized types of plywood is marine plywood. It is made with waterproof resins but the plies within the wood are also tighter and closer together. This helps keep water from wicking between the layers which gives it additional ability to resist water. If you’re having trouble finding marine plywood, there are several alternatives.
Overlaid
Overlaid plywood has a rigid core with a resin-impregnated fiber face that resists water and bending incredibly well. This gives overlaid plywood a specific niche in construction such as concrete forms and exterior siding. These sheets can withstand heavy abuse for years.
Structural
Structural plywood is not a specific type of plywood. Typically, structural plywood is softwood plywood. It is used in buildings to give more rigidity to walls and floors as well as provide a flat surface for finish materials.
Decorative
Decorative plywood is exactly like it sounds. It is used for decorative purposes only so it’s usually made out of pressboard or MDF. There are options with embossing on them that will add some texture if you want as well.
What are the Grades of Plywood
There are two major grades of plywood. Each is used for a specific reason in construction, though you can use them interchangeably if necessary. Of course, you’re going to pay more for nicer plywood but it may do the job just as well.
Cabinet Grade
Cabinet grade plywood is free of any holes or defects. There is also nicer veneer used on cabinet grade plywood since this type of plywood is one of the most obvious ever used in a house.
Shop
Shop grade plywood is allowed to have up to 25% defect on the sheet. However, the rest of the board can be perfect. You will typically find plugs or holes in shop grade plywood, so don’t be surprised.
How Many Plies are There in Plywood
You will find that the number of plies within the plywood vary as well. Not only depending on the thickness, obviously you need more layers for thicker plywood, but also based on the quality.
What are “Plies”
Plies are the layers of wood in each plywood sheet. There are typically anywhere between three and nine plies in a sheet. Though high quality plywood could potentially have more.
Plies are the layers inside the plywood sheet
What is the Benefit to More Plies
The more plies for the thickness, the better. So, for example, if a half inch thick plywood has three plies, it is less stable than a sheet with five plies. Generally, the more plies a piece has, the smaller the voids will be when you cut into it as well.
How do You Choose Good Plywood
With so many different types of plywood, it’s really hard to know how to choose a good sheet. Fortunately, the general rules apply regardless of what type of plywood you are looking for.
Flatness
Flatness is the most important factor when you are choosing plywood sheets. This is probably obvious to you. But in all seriousness, look for any signs of cupping or twisting in the sheets as you pick it. While plywood is more stable than a board, it is still liable to bend.
Edges
It is important that the edges of the plywood you choose are in decent shape. You won’t find a sheet that’s perfect. But as much of the edge as possible should be in good condition.
Size
Don’t be afraid to ask if the type of plywood you want comes in a different size that is more appropriate for your project. Plywood sheets are usually 4×8 but they come in both larger and smaller sizes.
Grade
If you are covering your plywood, you can make do with a lesser grade that may have some defects or plugs in it. If you are not covering it and you need it to look good as a finished product, you will want to select a sheet that has some decent grain to it.
What is Plywood Used For
Plywood has a number of different uses in the construction industry. In fact, there is probably more plywood in your home than regular lumber. And contrary to what you may think, plywood is not a sub-par product.
Cabinets
The main use for plywood that people see on a daily basis is in cabinetry. Plywood offers more stability in cabinetry than planks of wood that are attached and glued together. It also gives a nice, flat surface on the face of the cabinet.
Furniture
Similar to using plywood in cabinetry, plywood is frequently used in furniture making. For example, underneath a bed on a platform bed, the surface is typically a piece of plywood. There are several types of plywood that offer more springback and support than lumber.
Floors
Plywood is laid down over the subfloor planking in order to give a flat surface and stability for flooring to go over. Especially if you are laying down thin flooring like vinyl or linoleum, you have to have an incredibly flat and smooth surface to lay it over.
Roofs
The deck of a roof is usually made up of 7/16” OSB plywood. This is an inexpensive plywood that spans the roof rafters or roof trusses and gives the shingles something to lay on top of. Not only is the plywood more stable than the planks that used to be used, but it is less expensive, faster, and easier.
The use of plywood revolutionized the roofing industry
Plywood FAQs
Is OSB as Good as Plywood
OSB is a type of plywood. It is slightly different from what most people consider plywood because it doesn’t have the veneer top or bottom. Instead, OSB has small wafer plies that are glued together. The real benefit of OSB is that, since the plies are going in a bunch of different directions, the sheet is strong in every direction.
Is MDF Stronger than Plywood
MDF is less likely to “break” than plywood. Instead, MDF bends. Because MDF bends rather than breaks, it could be seen as stronger than plywood. But it can’t really take more weight than plywood. So it depends what you are using it for.
What Happens if Plywood Gets Wet
Plywood will typically swell and possibly delaminate, the plies peel apart, when it gets wet. Of course, this depends on what type of plywood you are using. For instance, marine plywood will not swell or delaminate.
Can Plywood be Stained
Of course plywood can be stained! If you struggle to imagine what that looks like, just remember that kitchen cabinets are made of plywood and they are often stained. Minwax makes some excellent interior stains in a variety of colors.
Can Plywood be Bent
Plywood can be bent but it isn’t something that can be done at home. Bending plywood requires you to get it warm and damp to wrap it around your bend. Most homeowners don’t have the ability to bend plywood.
Which Plywood is Best for Roofing
Usually OSB is the best type of plywood for roofing. Of course, this is just because of how stable it is and how inexpensive it is. When there was a huge shortage of OSB in the middle of 2021, many contractors moved to shop plywood for this purpose. So you can substitute it if necessary.
Which Plywood is Best for Flooring/Underlayment
Flooring underlayment really depends on what you are using for flooring as well as what type of subfloor you have. For example, if you don’t need a super smooth subfloor, you can use tongue and groove plywood to give your floor more stability. If you need something smooth, you should use particle board.
Conclusion
There are so many different types of plywood that they can get confusing. But remember that plywood really breaks down into what size you need and how pretty you need it. There is always a substitute if you can’t find the one you need. When you go to the hardware store, prepare to answer some questions on what you’re using plywood for in case you need to a substitute.