If you are building walls, floors or anything in between, two of the common materials that you may run into are plywood and cement board. Yes, both of these materials come in the form of thin sheets, but other than that they are not at all the same things.
While both cement board and plywood are great building materials, they have greatly different properties, and this means that they are not ideal for the same tasks. So between plywood and cement board, which one are you going to choose?
Plywood and Cement Board: The Basics
Before we get into talking about the differences between cement board and plywood, let’s first figure out which each of these are.
What is Plywood?
First off, we have plywood, which is a very specific type of engineered wood. For those of you who don’t know, engineered wood is made by breaking down solid wood, mixing it with special types of adhesives, and then reforming it back into solid pieces. Plywood specifically is made by taking solid lumber and breaking it down into very thin strips, also known as wood veneers.
Strips of wood veneer are laid beside each other to create layers. A piece of plywood can be made out of as many as 21 layers of wooden veneers. All of the layers are perpendicular to one another, or in other words, one layer of the strips left to right, and the next layer faces front to back, and so on and so forth.
This creates what is called a cross-grain pattern, which means that the grains of the wood constantly cross one another, which is very strong and ideal for holding in screws. Plywood has a wide variety of applications including the underlaying of floors, walls, roofing, the building of furniture and cabinets, and virtually everything in between.
What is Cement Board?
Cement board, on the other hand, is not engineered wood at all. As you can tell by the name of it, cement board is indeed made out of cement. This building material is made by combining cement with various reinforcing fibers, such as fiberglass, into large sheets.
Now, something important to keep in mind is that there are two main types of cement boards, which include cement-bonded particle boards, which use wood flakes as reinforcement, as well as cement fiberboards, which use plant extract for reinforcement.
Once the mixtures are made, they are then poured into molds, where they are left to dry and cure. Once a cement board is dry and cured, it can then be used for building purposes. In essence, a cement board is a very thin sheet made out of cement and other materials.
Plywood vs. Cement Board: What Are the Differences?
Now that you know what both plywood and cement board are, let’s figure out what the main differences between them are so you can make an informed choice between the two.
Plywood is a very versatile material, one that has many applications. Just some of the common uses of plywood include making external walls, formwork, flooring, roofing, walling, for cabinetry and furniture, and even for building things like guitars and skateboard ramps.
The number one primary purpose of cement boards is to serve as a backing for tile. What is also important to note is that cement board is the go-to choice for tile backing as it is much more durable and water-resistant than paper-covered gypsum, otherwise known as sheetrock or drywall. To see how plywood compares with drywall, read this article.
Cement board is often used as a backing for tile and stone countertops, tile floors, tile walls, and tile showers and bathtubs.
One major difference between these two is that plywood is quite flexible, whereas cement board is not.
Now, when it comes to tile installation, not being flexible is actually a good thing, because it will not flex and cause the tile on top to crack. On the other hand, if you need a thin and flexible piece of wood to build anything with a curve, such as a skateboard ramp or guitar, then it is plywood that you will need.
The weight is another important factor that needs to be taken into account here, mainly because of ease of installation, as well as how much weight the structures underneath will be able to bear. The cement board is the much heavier of the two.
If you have a piece of cement board and a piece of plywood, both of the same size, then you can expect the cement board to weigh between 100% and 150% more than the plywood. Yes, it is that heavy, and this means that it usually always takes two people to move, lift, and install it.
In terms of workability, both are pretty even, although if you have the right tools, a cement board is probably easier to work with. The reason for this is because as long as you have a nice carbide blade on your circular saw, then cutting through cement board should not be difficult.
You can score, cut, and snap cement board without much issue. It also does not create much of a mess when being cut.
Plywood is quite the opposite. Sure, there are many types of tools that can cut plywood, but due to its cross-grain pattern, there is a lot of mess created, and it usually suffers from tear-out and splintering too.
Adhesion and Load Bearing Capacity
One big advantage that cement board has over plywood, especially when it comes to attaching tile for vertical applications, is that its very smooth finish allows for easy adhesion, plus it can bear a lot of weight too.
Plywood is much rougher, does not allow for tile to adhere as well, and can bear less weight.
In terms of moisture resistance, neither of these materials is overly ideal. That being said, there are special types of plywood that are nearly 100% waterproof.
Cement board does absorb moisture quite easily, but it also dries out fast. That said, if cement board is being used as a tile backing for your shower, then a layer of waterproofing is called for.
Cement board is much more heat resistant than plywood, which is why it is often used as a backing for fireplaces.
Cement board is very smooth and can thus be painted if need be. Plywood, unless you get the highest grade, is not smooth and just does not look all that nice.
Which of the Two Should You Choose for Underlayment and Other Uses?
Generally speaking, if you are laying tile on top of it, then cement board is the better option. However, for wood and other types of floors, it is plywood that is generally the preferred choice.
Plywood is also the preferred choice for roofing underlayment, as it is much lighter in weight. Simply put, if tile goes on top, then cement board is the better choice, and plywood for everything else.
At the end of the day, if you are working with tile, then there is one clear choice to go with cement board. For nearly everything else, it’s plywood you want to use.
How Does Cement Board Compare with Other Materials?
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