DIY Soundproof Window Plug: How to Make One in 6 Simple Steps

Windows are the main ports through which various sounds come into our homes. Therefore, they’re the first things you should insulate if you want to prevent noise from slipping through the cracks. Building a soundproof window plug allows you to temporarily or permanently seal the windows and muffle or even block outdoor noise.

After all, window inserts put all the materials that would usually be inside a wall on top of the glass. So they’re a great way to close off your window without having to take it out and wall it up. Having established the purpose of today’s project, let’s talk about what window plugs are and why you should make one (or more) for your home.

DIY soundproof window plug: Get some basic materials and tools and, and you can have it build today!

What Is a Soundproof Window Plug?

Simply put, soundproof window plugs are objects that can completely cover your windows. They usually have two main components a wooden board and insulation batts or acoustic foam. Because of that, they’re not very difficult to construct and they’re even easier to install and remove as needed.

So how does it all work? Well, if you make your inserts precisely to your windows’ measurements, they should fit snugly inside the wall cavity. The wall itself will keep the insert in. However, if you don’t find that particularly reassuring, you could use various types of fastenings to make your inserts stay put.

But of course, this project hinges on your having windows that are set into the wall rather than ones that are flush with it. Now ideally, you should only start this project after weatherstripping and sealing your windows.

First, take off any existing rubber and glue residue and install new weatherstripping tape where the window meets its frame. After that’s done, run a bead of acoustic caulk between the window frame and the surrounding wall. That will ensure that no sound can pass through those cracks.

From that point on, you’ll just have to worry about thickening up the glass. There are other ways to do it — namely, you could use plastic film, soundproof blinds, or even thick curtains. However, there are several advantages to using a soundproof window plug instead.

Are Window Plugs the Best Window Insulating Solution?

When it comes to blocking noise from passing through the windows, there are no better solutions than soundproof inserts. When installed properly, they can achieve the same results you’d get if you completely walled up the opening!

After all, window inserts are made of the same materials you’d put up if you wanted to wall off the windows. You’ll have the layer of insulation right next to the window, and you could even put MLV between that and the wooden backing. If you have no use for the window you’re plugging, you could even apply drywall on top of the insert. After you seal and paint the area, it’ll be like the window never existed at all.

In addition to their noise blocking properties, you’d also get a decent amount of thermal insulation. So this solution is fantastic if you’re trying to stop hot air from escaping through the glass. Conversely, the window plug could also prevent heat from entering during the summer. Better still, it’ll create all the shade you need to fend off the harsh sun.

But the best thing about this solution is that it’s pretty cheap, all things considered. You might even be able to do it with things you have around your home! If you recently did some construction on your walls, you may have a spare batt of insulation or two lying around. Just glue that to a rectangular board, add some handles, and you’ve got your DIY window insert ready to go.

The Pros of Window Plugs:

  • Noise reduction
  • Thermal insulation
  • Blocking light
  • Cheap to build

The Disadvantages of Window Plugs

Now there’s no denying that this plan has its flaws too:

  • Not everyone will be happy about not having natural light in their room.
  • The whole thing may just be too clunky for your taste.
  • Some windows simply aren’t built to support an insert like the one you’ll be making.
Window Plugs Negatives.

Fortunately, there are ways to work around every one of these issues. In order, you can:

  • Get full-spectrum light bulbs that simulate sunlight. Even if you use the inserts often or install them permanently, the LED lights should keep you energized.
  • Make the wooden backing of the insert more presentable by painting it, upholstering it, or covering it with wallpaper. You could also just cover the whole window with furniture or curtains after you plug it. That should make your DIY fix more pleasing to the eye or at least get it out of your sight.
  • Extend the interior window sill (otherwise known as the stool) so there’s room to put the plug. This video will show you exactly how to do it. If your window is shallow but not exactly flush with the wall, you could also add straps on the wall around the window to hold the insert up.

I’ll make sure to go into more depth on some of these solutions in the guide below. With that being said, let’s make some soundproof window plugs!

How to Soundproof Windows

How to Make a Soundproof Window Plug

At this point, you should have a better idea of what we want to make and why. However, if you’re confused about the build process, this guide should clear up any misunderstandings.

1. Measure the Window

As always, you’ll want to start by measuring the windows you’re making the inserts for. Use a basic retractable tape measure to get the height and the width of the window cavity. So instead of measuring the window frame itself, jot down the dimensions of the hole in the wall that holds the window.

When measuring the width of the cavity, double-check your results near the top and bottom of the window. Similarly, when you’re measuring the height, check the numbers on both sides. You don’t want to find out that the hole your window is in is irregular after you make your insert.

If you find that your window is level but the wall around it isn’t, fix the edge before making your inserts. Alternatively, you could make the insert as crooked as the window hole. After all, the wall is what’s going to keep the insert in place. Besides, leaving gaps around the window plug will let noise and light enter the room.

Lastly, you should also measure the depth of your window. The finished window plug shouldn’t be thick enough to completely fill that space. When you press the wooden board flush against the wall, there should be a pocket of air between it and the glass. That will trap the low-frequency sounds of passing traffic, among other things.

2. Gather Your Supplies

Once you have measured your windows, you’ll need to get:

When choosing the wood for your insert, you should know that OSB is lighter than Medium-Density Fiberboard. But even though OSB would more easily stay on the window without fasteners, it won’t be as insulating as MDF. So you might have to combine it with MLV before attaching the insulation or foam. Conversely, the rubber layer would be optional if you went with a denser board.

At this point, you could also purchase whatever materials you need to make the finished insert look presentable when you install it. You could paint it to match your wall or use it as an artistic canvas before you attach the other materials. Just remember to prime the wood before painting it!

Alternatively, you could upholster the board with fabric and a thin sponge or foam mat. After gluing the mat on, stretch your fabric over it and staple it on the other side of the board. This solution would even add some sound-absorbing properties to the side of the insert that will end up facing the room.

3. Precut the Boards and Acoustic Materials

Cutting the materials you’ve purchased will probably be the most difficult part of the whole project. However, if you get your board from a hardware store that offers to cut your materials for you, you could significantly reduce the amount of time you spend putting the whole thing together.

Either way, I certainly wouldn’t recommend cutting the boards in your workshop unless you have a fantastic dust collection system. Additionally, cutting the pieces with a circular or table saw would make the chore go by faster than it would have gone if you were to use a manual bow saw.

When you have your boards cut according to the measurements you took earlier, trimming the other materials should be a piece of cake. A simple utility knife should be all you need to cut through acoustic foam, rubber, and even mass loaded vinyl.

For the latter, you might have to score the surface of the material several times before the knife goes through it but it should still work. And if you grow tired of pressing down on the knife, you may be able to swap it out with regular scissors.

4. Assemble the Plug

After your materials are cut and ready for assembly, everything else should be a piece of cake. You just have to glue and screw it all together. But, you may be wondering: what’s the correct order to stack everything you have?

To begin with, put your wooden board down with the presentable side facing the floor (or whichever surface you’re using). Put on a pair of work gloves and pour some glue onto the board. Apply as much adhesive as you need, stopping an inch from the edge. Use some kind of tool or a piece of cardboard to even everything out and bring the glue as close to the edge as it can go without spilling over.

After the glue gets tacky, lay a sheet of rubber or vinyl on top. Press down in the middle of the insert and run your hands toward the sides to get the air pockets out. If the edges of the MLV don’t seem very secure, staple them down before you bring out the foam.

For this project, acoustic foam will be a better choice than the kind of insulation you use for walls and ceilings. Even if it’s not better at trapping sound, foam is thinner and easier to glue onto MLV. However, if you have a particularly deep window, by all means, go for matt insulation.

You should be able to attach it to the insert by using Green Glue or another kind of adhesive. However, for insulation especially, you might want to use staples, nails, or screws too. When you finish building the main part of the plug, let it rest for however long it takes the glue to set.

5. Attach the Handles

When the adhesive is completely dry, you’ll be able to flip over your soundproof window plug and attach the handles. You could also do this step first if the handles won’t affect your ability to attach the other materials to the board. Depending on the kind of vibe you’re going for, you could use:

It’s best to keep the handles at the same height, at least two inches away from either side of the board. Alternatively, if the insert is a bit on the wider side, just make sure you’re able to grab both handles without completely stretching out your arms.

6. Work on the Presentation

I’ve already brought up the idea of painting or upholstering the wooden part of your window plug to make it more presentable. However, those are some things you’d have to do before you assemble the insert. Now, let’s talk about how you could make it less noticeable through other means.

If the window insert turns into an eyesore, there are several things you can do. Namely, if you don’t think you’ll want to take the insert off any time soon, you could:

  • Cover the whole window with a tapestry or large poster — you could use nails, tacks, or hook and loop tape
  • Push a large piece of furniture over the window

On the other hand, if you just want to cover up the insert, you could simply hang up some soundproof curtains and keep them shut.

Best Soundproof Curtains

Final Thoughts On Window Plugs

By this point, you can probably see exactly how easy it is to make your very own soundproof window plug. Whether you want to close off your window temporarily or permanently, these kinds of inserts are certainly the cheapest way to get it done.

And if you’re lucky enough to go to a hardware store that offers to cut your materials for you, you could have the whole project done in a matter of hours! So what are you waiting for?


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