Skip to Content

How Thick Should a Plywood Subfloor Be? (Read This First!)

There are different flooring options, but plywood subfloors are the best for insulation and comfort. So, you decided to install subfloors in your house but are not sure what is a suitable thickness for a subfloor; and what factors affect subfloor thickness? 

This article will answer all the questions related to subfloor thickness.

Plywood subfloor thickness

Generally, the plywood subfloor should be ¾ inch. ¾-inch subfloors will work with most flooring options, such as carpet or tiles. The minimum thickness of plywood subfloors is ⅝ inch. It’s best to determine all the factors to consider the best thickness for a subfloor.

Choosing the proper subfloor is one of the most important decisions you will have to make when installing floors. Why is it so important? You can change your bathroom mirror anytime, but if you want to change your subfloor, you will need to take a lot of hustles.

So, you choose plywood for your subfloor, but what should be the thickness. Choosing a thin subfloor can save you a lot of money, but your floor will be prone to collapse. Choosing more thick plywood than necessary is simply a waste of money. 

So, to get the best value from your plywood, you should get the right thickness. 

For most situations, ¾-inch plywoods are the most versatile type for subfloors. But the joist distance should not be more than 16 inches. Why does joist space matter? The joists will add more support to the plywood when the joist space is closed. 

Some other factors are related to plywood thickness. We will discuss them in the following sections.

If you are going to use heavier materials on the subfloor, such as natural stones or tiles. You can also choose ⅞ inch plywood for your subfloor to be safe. Heavy materials will add loads to your subfloor, and the subfloor can collapse if you choose thin plywood.

If the joist is far from each other than usual, you will need thicker plywood. Use ⅞ inch plywood in those situations. When joists are further from each other, the plywood must take more load.

Are you looking for a cheap solution for your subfloor and also want to use plywood? You can use ⅝ inch plywood. It’s thick, but enough to take most loads of joist distance is average. But to make your subfloor more dependable, ¾ inch is the best option.

There is also ½-inch plywood available in the market. Usually, those are not suitable for subfloors. If you buy ½-inch plywood for the subfloor, you can return the plywood and choose a thicker one. If that’s not possible, you can also add two ½ inch plywood and make it one inch.

Tiles are one of the popular items that people use on their subfloor. But when you decide to install tiles on your subfloor, you need to be more careful about the thickness of the plywood. Thin wood can move, and that can cause tile breakage.

Wood also has some other characteristics you should keep in mind. Wood does not usually stay unchanged. There are tiny pores in the wood that can absorb moisture. Wood can shrink or swell a bit depending on the humidity in the air and weather. 

That’s why you should follow some strict methods when installing tiles on plywood. Make sure to do some research before you start your project.

You should also consider the amount of traffic the floor has to handle. Such as, a gathering room needs thicker plywood as the floor will have to take more load.

Can I use 1/2 inch plywood for a subfloor?

½ inch plywood is not suitable for a subfloor. It’s too thick to take loads of subfloor. However, if the joists are close enough and the floor will not have heavy traffic, you can consider using ½-inch plywoods for a subfloor, but it’s not recommended. 

You can not use heavy materials such as tiles or natural stone floors in a half-inch subfloor. Carpets will be best for ½-inch subfloors.

If you want to use thin plywood for your subfloor, you should go for ⅝ inch plywood. It’s the minimum thickness requirement, according to experts. 

Plywood for the subfloor also needs to be moisture resistant as it can make the subfloor swell up and cause cracks, especially if you use tiles on them. Before starting your DIY subfloor installation project, do a lot of research on the procedure. 

You will need to glue the plywood with the joist and add screws every 6-8 inches.

How many layers of plywood for the subfloor?

Only one layer of plywood is enough for the subfloor, but make sure the plywood is AC labeled and ¾ inch thick. You can use a particle board for a completely flat surface for best results. Professional floor builders will add particle boards most of the time.

Plywood can hold most types of flooring with one layer. But for ceramic tiles, cement sheets do better than plywood. Vinyl tiles are lighter than the ceramic ones, and you can use them if you have ⅝ inch plywood to reduce the load. 

However, vinyl tiles also need a flat surface, so that you will need particle boards.

If you have closer joists, the plywood will have more support. Read the following sections for more information on the factors.

3 factors that determine plywood subfloor thickness

Some factors help you choose the perfect thickness for your subfloors. Check out the following points to get a clear understanding of the factors.

Spacing of the joists:

The spacing of the joist plays the most crucial role in determining the subfloor’s plywood thickness. In a nutshell, the closer the joist will be, the plywood will get support. 

Therefore, if the joists are far from each other, you will need thick plywood, and the closer the joists are, you can work with thicker plywood.

Generally, there are two types of joists, 16 and 24 inches apart from the center. 16 inches are more common for the joists. However, the joist spacing can also be different from those. 

If the joists are farther than 16 inches, you should not go for any plywood less than ¾ inch.

The material you are using:

Different flooring materials have different natures and loads. Such as vinyl tiles and carpets are low in weight and add too much load on the plywood floors.

On the other hand, natural stone flooring or ceramic tiles adds some weight to the plywood. Moreover, the tile joints can break down if the subfloor moves. 

Considering those, you will need thicker plywood for heavy materials and low-weight materials for thin floors.


Thin plywood subfloors will not be suitable for heavy use. So, you should also consider this factor while choosing plywood for your subfloor.

What type of plywood is best for subfloor?

There are different types of plywood you can find in the market. It’s better to keep some ideas about the plywood types so that you can pre-determine the kind and don’t have to be confused to choose one. Check out the list of plywood you can select for your subfloor.

Tongue-and-groove plywood:

Tongue-and-groove plywoods have interlock edges, making them less likely to move when set. It is the best option if you want a tough and rigid subfloor. Those types of plywoods are a bit hard to install for the intersection parts. 

But once the floor is set, you will have the best quality subfloor. You can also hire professionals to install the subfloor.

Standard plywood:

You can also use standard plywood for the subfloor, but some are made just for subflooring. Naturally, they work better than regular subfloors. However, regular subfloors are cheaper than specialized ones. 

Make sure to buy ¾-inch subfloors to be on the safe side. Standard subfloors are more affordable than other types of subfloors.

AC labeled plywood:

AC labeled plywood are one of the rigid types of plywood. It works pretty fine for subflooring. AC labeled plywoods are made of many layers of thin wood sheets that are compressed together for maximum strength. 

One side of the plywood is nicely finished and sanded, called the A-side. And another side of the plywood is not sanded, named the C-side.

Final Thoughts

¾-inch plywoods are the most common and reliable type of plywood for subfloors. You should consider joist spacing, flooring material, and other factors before choosing the perfect plywood thickness. ⅝ inches of plywood is the minimum thickness you can choose for your subfloors.