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Can You Put Plywood Over Insulation? (How To)

Plywood is one of the most commonly used building materials. It makes a great subfloor and can also be used on walls and even the ceiling. If you have insulation in place, can you still install plywood?

Plywood can be installed directly over insulation. If the insulation is sticking above the joists, however, it should be lowered so that you aren’t compressing the insulation, which would reduce its efficiency.

Man installing plywood

Although yes is the general answer, you might be surprised by how many different options you have available. This includes everything from the type of insulation that is in place, to the thickness of the plywood, to the fasteners that are used to attach it in place.

When you make all of the right decisions, you will find that plywood is one of the best materials for use in these scenarios. That being said, there are also other options available that can be used at times, including OSB and even drywall.

Can You Put Plywood Over Insulation? (How To)

The first thing to consider is the type of insulation that is being covered. If it is blown in foam insulation, this can be a problem because you don’t want to have it compressed. Scoop out some of the insulation so that it is at a level that is below the floor joists where the plywood is attached.

If this seems like you are reducing the effectiveness of the insulation, you’re actually doing the opposite. Putting plywood in place is going to increase the effectiveness of the insulation as long as you aren’t compressing the insulation. When insulation is compressed, it doesn’t work as well.

You will also be happy to know that you are doing more than making the home more livable, you are also making it safer. How can plywood over insulation help in this regard?

If you have any fiberglass insulation in the home, there are times when it may be exposed. This typically happens in areas such as the attic or the basement that are not fully finished.

The problem is, if fiberglass insulation is exposed and people are occupying the area, it can cause some serious health problems. The American Lung Association reports that the symptoms can include coughing, a scratchy throat, and respiratory reactions. Insulation can also be an eye irritant and can irritate the skin.

When you put the plywood in place and cover the fiberglass insulation, this issue goes away. It is going to effectively block the fiberglass from getting out into the living space and causing those difficulties.

Of course, you should be careful anytime you’re working around insulation and wear the proper PPE. This would include a good pair of gloves, long sleeves, long pants, and safety glasses.

We will now consider if there are any problems associated with putting plywood over insulation. We will also look into how it is done and how you would prepare for the job.

Should You Put Plywood Over Insulation?

Square plywood

In almost every case, putting plywood over insulation is going to be a good idea. It helps to insulate the home, provides soundproofing, and can also make the home safer.

From time to time, however, we may run into a problem that needs to be considered in advance. Knowing what problems can occur when you put plywood over insulation can help you to avoid them.

Compression – Although we mentioned this one previously, it is worth mentioning again. If you are putting plywood over insulation and compressing the insulation as a result, you are reducing the effectiveness of the insulation. Essentially, you are not gaining the benefit of additional insulation that the plywood provides.

Lighting – Caution should also be taken when installing plywood over areas with recessed lighting. This sometimes occurs when you are installing plywood in the attic. Why is it a problem?

If you do install plywood over an area with recessed lights, it could cause the recessed light to get hot. Although it may not necessarily be a fire hazard in every case, it could cause the bulbs to burn out frequently. It is better if you build a constructed dam in the area and leave the top exposed.

Toxicity – According to experts, the levels of toxins in plywood are not enough to affect most people. Some of the potential toxins include phenol-formaldehyde and urea-formaldehyde. In most plywood, they are at a very low level and will not affect most people.

The problem occurs if you are installing plywood over insulation in a confined area, such as an attic or a basement. If you don’t have proper ventilation, then the toxins can build up and they can affect some members of your family severely.

Expensive – Undoubtedly, you already realize that plywood is expensive. If you can use other types of building material and accomplish the same purpose, such as plywood or OSB, it may be worth considering.

Support – Most plywood tends to sag if it is not given the proper support. It may offer a degree of stability at first but eventually, it could begin sagging if there is too much room between support beams.

What Tools Do You Need To Put Plywood Over Insulation?

Tools used for insulation

When you’re ready to install plywood over insulation, grab the following tools and get started.

Tape Measure

4 Foot Level

2 Foot Level


Straight Edge



Non-Marking Rubber Mallet

Chalk Line

Drill Gun


Safety Glasses


Dust Mask


What Preparations Do You Need To Put Plywood Over Insulation?

Man installing plywood

There is not too much preparation for installing plywood over insulation. Here are some things to consider so you can prepare properly.

1. Insulation Thickness – If the insulation is so thick that a piece of plywood would compress it in place, it should be reduced so that no compression occurs.

2. Load-bearing – Identify any load-bearing walls or joists that are crucial for the installation of plywood.

Copyright protected content owner: and was initially posted on December 9, 2022.

3. Soffit Vents – Keep the vents cleared that are typically around the edges of the attic. If you block them with plywood, you will likely cause moisture to build up in the area.

How To Put Plywood Over Insulation

confused man standing

Now is the time to attach the plywood. Here are the steps necessary to do so.

1. Measure and Cut – Measure the first sheet of plywood so that the edge of the plywood lands in the middle of the floor joist. Put it in place without attaching it to make sure that it fits properly along all of the edges.

2. Attach – In most cases, you would simply nail down the plywood because it offers strength and it is easy to do. If you are installing an area with something underneath, however, you may find that using screws is a better choice.

3. Continue – Continue to work your way around the room, attaching one sheet of plywood and making sure that they are locked in place with tongue and groove. Cut the edges and put them in place, leaving a slight gap for expansion.

Copyright article owner is for this article. This post was first published on December 9, 2022.

You can install plywood over insulation but you should not compress the insulation in place. Plywood makes a great floor, wall, or ceiling, adding additional insulation to the room.

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ReadyToDIY is the owner of this article. This post was published on December 9, 2022.

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