Skip to Content

Can You Put Concrete Over Plywood

If you have a plywood subfloor or if you are putting down plywood, you might be considering putting concrete over it. Is it possible?

Contrary to popular opinion, it certainly is possible to put concrete over plywood. As long as you make the proper preparations and consider the weight of the concrete, it is a relatively easy job for someone experienced with pouring concrete. There are also some alternatives that may be considered under certain circumstances.

Trowel on concrete floor installation

When you go looking for information about pouring concrete over plywood, you are going to find a lot of opinions. Some of it is worth considering and others are better avoided.

It is important to understand that concrete has been used over plywood for as long as the two products were available. There are some things to consider, however, that will make the job easier and perhaps even better when all is said and done.

Can You Put Concrete Over Plywood Flooring?

Man putting a concrete tile over a plywood

One of the most important factors to consider when pouring concrete over plywood is safety. Of course, you always need to consider safety when doing any type of construction work but making a wrong decision could damage the integrity of the home.

The primary reason why it is important to consider pouring concrete is the fact that concrete is extremely heavy. Unlike many other building products, concrete can add up very quickly and if you are putting down a typical 2-inch pour, it will tax the subfloor and may even cause it to fail.

That is why it is a good idea to consider some of the alternatives. You can still have the concrete look and in many ways, you are using concrete but it will not come with as many problems.

Some of the mixtures that are available will be just as durable as true concrete but they are a solution that is used in the home. They tend to float out very nicely over plywood and will provide a thin veneer that you can stain and work with.

Typically, you will find some of these mixtures at your local hardware store. You might also want to do some research on the various options that are available before you choose one.

Then again, there may be times when it is desirable to do an actual concrete pour. As long as the floor joists are able to handle the weight, there is no reason why you would not do it.

Another thing to consider is the possibility that concrete will not level properly over plywood. This is something that is often discussed when the subject comes up.

Plywood is a very porous product and as the concrete settles into the plywood, it may have a difficult time staying level on the surface. You can work with it, float it, and continue to work with it and the product will be just fine.

Then again, you might want to consider putting something over the plywood that would reduce its porous nature. This could be anything from some type of lacquer or finish or perhaps even some plastic. Bear in mind that it is not going to adhere, but it is an option to consider.

One more thing to consider is the possibility that the subfloor could become damaged as the concrete dries. Since you are putting something wet on wood, it could swell or have other difficulties.

Using some type of quick-dry cement or perhaps floating a layer over the cement is one way to get beyond this issue. It does add another layer to the end product and another step to the job, but it may be well worth it.

Should You Put Concrete Over Plywood Flooring? Reasons Why Not And Why Yes

Man putting a tile

Now that we have considered the possibility of using concrete over plywood flooring, let’s examine it from a different angle. Is it something that you should do?

The top reasons why you would want to use concrete over plywood is that it will look great and last for many years. Some preparation is necessary to ensure that it works properly and concrete is not suitable for every environment. Taking a close look at both the good and the bad of pouring concrete over plywood helps you to make a decision you can live with.

Pros:

Beautiful – There is no doubt that a concrete floor is beautiful. It adds an industrial look to the home that can be adjusted and changed in many ways by staining or painting.

Durable – You will have a difficult time finding a flooring product that is more durable than concrete. It is a solid product that will last for many years.

Options – Another reason why concrete may be of benefit is that it gives you options. Provided you keep safety in mind and the weight of the concrete, you can continue to build on it with other floors. Concrete makes an excellent subfloor.

Cons:

Weight – The most important thing to consider when pouring concrete over plywood is the weight of the concrete. That is especially true if you are using a true concrete pour that would be at least 2 inches.

Although it may seem as if the floor can take it, most floor joists are not going to handle the weight of the concrete. They could buckle and eventually, may even sag or fail. This could cause injury or death to the homeowners.

Of course, there are some ways to get around the weight of the concrete, such as using a similar material that would be floated in a very thin layer. Some of those options are not any heavier than tile.

Cold – If you are changing from wood to a concrete floor over a plywood subfloor, you should be prepared to wear something on your feet. Concrete is a very cold material and it is not as comfortable to walk on as other types of flooring.

Reinforcement – If you are in a position where the floor joists can handle the weight of the concrete, you will have to reinforce it if you are doing a full pour. Using rebar or other reinforcement will keep the concrete from cracking but it will also add to the project.

Moisture – When you pour concrete, it will be wet. In other words, the water that is on the plywood subfloor could potentially damage the subfloor and cause additional problems.

As you can see, there certainly are things to consider when pouring concrete over plywood. It’s something that is done all of the time, but doing so without thinking of the consequences is asking for trouble.

How To Put Concrete Over Plywood Flooring

Man putting a concrete tile over a plywood

There are a few steps necessary to properly pour concrete over plywood flooring.

The most important part of the process is preparing the plywood. This includes ensuring that it is able to handle the weight of the concrete and removing anything that may be on or under the plywood. You want the surface to be flat as possible so the concrete will float and level easily.

Consider the following steps for putting concrete over plywood.

Prepare – Clean the area thoroughly by removing any debris that may be on the plywood. If you are just now putting down the subfloor, ensure that there is nothing loose underneath it.

Take time to fasten the boards so that they don’t move after the concrete is poured. If the boards move, the concrete will eventually crack.

Prepare the Joints – It is a good idea to use some quick-drying cement for the joints. It will help to reduce any issues with the cement settling into the joints and ending up with an unlevel floor.

Mix the Concrete – Follow the manufacturer’s instructions for mixing the concrete. If you are using a thin mixture instead of concrete, this may differ from one manufacturer to another.

Float the Concrete – Work with the concrete so that the surface is flat and smooth. It sometimes may be necessary to work with it multiple times in order to get the look you desire.

Cure – Don’t try painting or staining the concrete or even walking on it until it is fully cured. It may take a day or longer for the process to happen.

What Tools And Preparation Are Needed?

Man cleaning the floor

Don’t overlook the preparation process when it comes to pouring concrete over plywood. Doing so would potentially ruin the job.

Generally speaking, the preparation will involve ensuring that any debris has been removed from the plywood and it is swept clean. You should also have all of your tools on hand and ready to go so you don’t have any delay in the process. Any delay may keep you from having the smooth, level concrete surface you desire.

Have the following tools on hand:

5-gallon buckets – You really can’t understate how important it is to have 5-gallon buckets. You will use them for mixing the concrete as well as for hauling water.

Mixer – If you are doing a small floor you may be able to mix the concrete by hand. Otherwise, you can rent a mixer.

PPE – Working with concrete, and particularly dry concrete poses some serious health risks. Make sure that you have all of the appropriate PPE, including safety glasses, boots, gloves, and an N95 mask.

Screed – You will use the screed for the initial leveling process. Some of the concrete products you may use for flooring can be self-leveling.

Float – You may need to work the concrete with the float to get rid of any ridges and voids. It will help to make the surface smooth.

Trowels – These will be used for multiple purposes during the entire project.

Typically, it is possible to pour concrete over plywood and have a nice, finished product. As long as you keep the weight of the concrete in mind and ensure that you carefully prepare the plywood, a concrete floor will last for many years after being poured.

Related Articles

Can/Should You Put Concrete Over Hardwood Floor?

Can You Put Plywood Over Concrete

Can You Put Epoxy Over Concrete?

Can You Remove Epoxy From Concrete/Tile?