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How Thick Should My Plywood Subfloor Be? (Answered)

You need to install the plywood subfloor if you have susceptible floor tiles. You must cover the floors using the plywood subfloor. But the fact is the size of the plywood since there are different sizes available.

The plywood subfloor works as the best protector of your tile floor. You have to be sure about the quality of the plywood subfloor. Although the name is subfloor, it will work like the core. It will resist all the pressure.

How thick should my plywood subfloor be?

Your plywood subfloor should be ⅝ or 23/32 inch thick. It’s the ideal thickness for every plywood subfloor since you will use it as the best-protected layer on your tile floor. You may find different plywood thicknesses, but they will not give you the best protection as the ⅝ inch plywood.

When selecting the perfect-sized plywood subfloor, you should consider some easy and simple criteria. Quality, requirements, and floor size will play a crucial role here. You cannot ignore these requirements and expect to get the best or perfectly matched plywood subfloor.

You have to know your floor tiles or what you use as the main components. It will help you to decide on the perfect size plywood subfloor.

Besides, the size of the plywood will also vary from place to place. For example, you cannot install the kitchen plywood subfloor in your living room.

It indicates the place requirements, so you must know all the factors before choosing the right-sized plywood subfloor. Typically, most living rooms or regular floors will be a perfect match with ⅝ inch plywood thickness. You can also install the 23/32 inch plywood if needed.

But the difference will be higher if you mistakenly install the wrong-sized plywood subfloor. It might be broken after a few days of use because of the load-bearing ability.

In your living room, you cannot install weak plywood or more undersized quality plywood. This place will need high-quality plywood and better thickness.

in other words, you may not need to install similar plywood in your kitchen. It will be useless there; you should list your requirements, including size, load-bearing capacity, minimum coverage area, and your budget.

Only then can you expect to find your perfectly matched plywood subfloor.

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

You can use ½ inch plywood for a subfloor. You can install the ½ inch plywood in low hardworking areas where you don’t walk through regularly; the perfect example might be the shed area or the less useable space in your house.

In other words, you can use the ½ inch plywood for a subfloor only for the small and shed areas.

You cannot use the ½ inch plywood for a subfloor in your living room or where you spend your time. If you have an empty place and want to spend your leisure time there, you can install the half-inch plywood there. But it will not become the strongest subfloor to use regularly.

So, you need to find the perfect place for your house to use the ½ inch plywood as a subfloor since you cannot use it everywhere. You must avoid using this plywood in your living room or where you walk through regularly.

How thick should plywood be to walk on?

The plywood should be ¾ inch thick to walk on securely. You cannot install the half-inch plywood and expect to walk on it securely; you must install bear-loaded plywood to make the surface walk-friendly.

There is no role in installing only ¾ inch plywood; you can install the bigger one.

But the plywood must be compatible with your floor tiles. You will have different sizes of plywood to walk on it safely. 23/32 would be another perfect size for the plywood to walk on. You can install it in your entire house; it will give you secure fittings.

3 factors that determine the subfloor plywood thickness

You need to consider three factors to determine the subfloor plywood thickness. We will explain all of them one by one.

Joists Distance:

The thickness of the subfloor is largely determined by the distance between the floor joists, which is also an important consideration.

The joists need to be spaced further apart for the subflooring to have a greater required thickness. This is for structural reasons.

Vertical Spacing:

The insulating capacity of a product, also known as its “R-value,” should also be considered when choosing the thickness of the flooring material.

Building materials with a higher R-value can prevent heat from escaping the flooring during the winter and keep it out during the summer.

Underlayment Alternatives:

If the underlayment membrane you select provides a high level of insulation, for instance, you can get away with installing a less thick subfloor.

If you choose an underlayment product that maximizes comfort at the expense of insulation, then selecting a subflooring material that is either more substantial in thickness or has a higher R-value might be a good idea.

What are plywood subfloor code requirements?

You will find mostly two plywood subfloor code requirements. One is considered the joist span, and the other is for general use.

Here, the joist span could vary from 19.2-to 24 inches, and the plywood or OSB will vary or remain fixed for that range. If your joist span falls in this range, you can use the ⅞- inch plywood thickness.

The second code requirement related to the minimum building code is to use a 23/32 inch plywood subfloor. You cannot use any plywood which is less than this thickness. It will be weak, and you cannot use it safely in your house.

These two codes of the plywood subfloor requirements are from the NWFA. You will find these requirements in the “Installation Guidelines” of NWFA.

If needed, you may read other code requirements to install the perfect plywood or OSB in your house safely. It will also help to know about the other requirements you must follow.

If you have any queries regarding the plywood type, other thickness requirements, and anything related to plywood or OSB, you should read the Installation Guidelines. All the codes are there; you need to go there and get the required code.

What kind of plywood do you use for the subfloor?

You will mostly find four different categories of plywood to use for the subfloor. Keep reading and explore them.

Interior Plywood:

The plywood used on the inside of a building is designed to withstand relatively dry conditions.

They are ideal for use as a subfloor beneath materials such as engineered wood laminate flooring, hardwood flooring, carpeting, and tiles. You can use plywood in damp environments if you have an underlayment that helps protect it from moisture.

Exterior Plywood:

Plywood intended for exterior use is the superior material to use in areas that experience high humidity levels. In some instances, we will use these in place of interior grades in areas such as kitchens and bathrooms.

Structural Plywood:

Structural plywood may be used in areas of a building that are required to support an exceptionally heavy load. In residential homes, we employ this strategy only infrequently.

Marine Plywood:

The type of plywood known as marine plywood is notable for having the highest strength and resistance to water. It is not suitable for use internally in the house.

How to measure the required plywood subfloor thickness?

You can measure the required plywood subfloor thickness by following three steps. Let’s follow the steps and measure the thickness.

Span Rating:

The distance between the joists in a subfloor determines the maximum permissible thickness of the plywood panels used in the subfloor.

For floor joists that are 16 inches apart or less, some industry professionals recommend using plywood with a thickness of 15/32 inches as the standard.

However, for floor joists that are further apart than 16 inches, they recommend using plywood with a thickness of 3/4 inches.


Another essential aspect that might assist you in measuring the required plywood subfloor thickness is the material used for the floor’s finish.

You may begin the installation of your tile by laying down a layer of plywood, followed by another subfloor layer such as a cement board.

In order to create fiberglass flooring, two layers of plywood flooring must be installed crosswise to one another. To avoid cracking, the floor needs to be highly sturdy and rigid.


A sheet that is 5/8-inch-thick is more than sufficient for the typical domestic setting. If, on the other hand, you are going to be supporting something very heavy, you might want to add another layer of plywood.

Final Thoughts

Since the plywood thicknesses are available, you should select the perfect size. In most cases, ⅝-inch or 23/32-inch plywood thickness would be the best for your subfloor. It will bear most of the load and will be durable. If you have less hardworking areas, you can use ½ inch thickness.