If you are planning to build something out of wood, plywood is always a great option to consider. It’s almost as good as solid wood, but significantly cheaper, and quite versatile too. That said, there are different types of plywood out there. Specifically, today we are talking about the plies or layers themselves.
To be more specific, today we want to compare 3-ply and 4-ply plywood to see which one is best for you.
What Is a Ply?
Before we talk about 3-ply vs. 4-ply plywood, it’s a good idea for you to know what a ply or plies actually are.
Plywood is of course a type of engineered wood. It is made by taking wood veneers, thin and long strips, and laying them next to each other to form one layer. There are then multiple layers stacked on top of each other. These layers are stacked in a cross-grain fashion for strength. In other words, the wood veneers, from one layer to another, are perpendicular to each other.
Now, each one of these layers is called a ply, hence why the name of the product is plywood. It is wood made out of a number of plies.
3-Ply vs. 4-Ply Plywood: What Are the Differences?
Now that you know exactly what a ply is, let’s take a look at the major differences between 3-ply and 4-ply plywood.
1. Number of Plies
As you can probably tell by the name of them, 3-ply plywood has one less layer or ply than 4-ply plywood. This is the most basic difference between the two, the difference that then leads to all of the other differences.
2. Overall Strength and Durability
Perhaps one of the biggest differences here is that 4-ply plywood is much stronger and more durable overall than 3-ply plywood. The reason for this is because it has one extra layer that is perpendicular to the others. This extra layer allows for increased density and cross-grain strength. Although 4-ply plywood is not overly structural in nature, it is more so than 3-ply plywood.
3. Moisture and Element Resistance
The next big difference between the two is that 3-ply plywood is not quite as moisture- or pest-resistant as 4-ply plywood. That extra density and that extra layer that 4-ply plywood has do make quite a bit of difference here. Although most would still not recommend 4-ply for extreme outdoor use, it is still the better of the two in terms of being able to resist the elements.
4. Weight
Another difference between these two types of plywood, although not major, is their weight. Generally speaking, 4-ply plywood, if it is of the same size and thickness as the 3-ply plywood, is going to be a little bit heavier. The difference in weight is not massive, but it’s still a difference nonetheless.
5. Flexibility
Yes, 4-ply plywood is stronger and more durable than 3-ply, but there is a bit of a tradeoff. Due to the fewer layers and slightly lower strength of 3-ply plywood, it also tends to be a bit more flexible. Yes, 4-ply does also have a bit of flexibility, but not quite as much. That said, this increased flexibility usually doesn’t make up for the decreased strength.
6. Appearance
Something else worth noting is that 3-ply plywood generally looks a bit smoother, finer, and just better than 4-ply. 3-ply plywood tends to have a bit of a more decorative appearance, which is why it is often used for indoor purposes and for things like furniture.
7. Uses
When it comes down to it, these two types of plywood are used for different things. Three-ply plywood is reserved mostly for decorative purposes, lightweight interior purposes, and for smaller pieces of furniture. Due to the increased strength of 4-ply plywood, it may be used outdoors and it may also be used for somewhat structural purposes.
8. Availability and Cost
The other thing to keep in mind here is that 3-ply plywood is readily available virtually anywhere. Four-ply plywood, on the other hand, is actually extremely rare and most people, even professionals, usually never come across it. This is honestly something that you may never see in your whole life. In terms of the price, it is safe to assume that 4-ply would cost more than 3-ply. That said, it does all depend on the grade of the plywood and the type of wood used to make the veneers.
When to Use 3-Ply Plywood?
If you need a relatively affordable and versatile type of plywood, then 3-ply is a good option to consider. Just remember that it’s not the most durable or resistant type of plywood out there, so using it for any real weight-bearing applications is not recommended. It’s also not recommended for outdoor use.
However, if you need something relatively lightweight and very decorative, then it’s a good option to go with. This is particularly the case for a variety of small projects, such as indoor furniture.
When to Use 4-Ply Plywood?
If you need something slightly more durable, stronger, and resistant to the elements, and you are willing to invest a bit extra, then 4-ply plywood is a great option to consider. Four-ply plywood is ideal for indoor use, and it can also be used for some outdoor applications. Moreover, it can also bear some weight.
It’s a good all-around type of plywood, although it’s certainly not waterproof. It can be used for furniture, indoor wall sheathing, and for other such purposes.
Alternatives to 3- and 4-Ply Plywood
Let’s take a quick look at some of the best alternatives to both 3-ply and 4-ply plywood:
- If you need something stronger and more durable and are willing to invest extra, 5-ply plywood is a good option to consider.
- If you need something even stronger, and you are willing to invest even more, then 7-ply is also something to consider.
- Lastly, if the plywood is going to be exposed to the elements and even submerged underwater at times, then marine-grade plywood is the way to go.
Summary
As you can see, although theoretically, the difference here is just one ply or layer, the differences that this then creates are quite vast. Although 4-ply is just one ply thicker than 3-ply, this allows for much greater strength, versatility, flexibility, and resistance as well.
That said, 4-ply plywood is going to be more expensive, plus it is also incredibly difficult to find, to the point where even many carpenters and contractors have never even heard of it before.