Soundproof Window Plugs: How To Make Them

We couldn’t and wouldn’t imagine our home without windows.

Windows allow fresh air and natural light to pass through—but they’re also the place where most noise pollution enters our space to disturb us day and night. 

If you’re desperately searching for a way to stop the noise, soundproof window plugs may be the solution you’ve been hoping for.

They allow you to temporarily or permanently seal your windows and prevent almost all noise from entering.

Your window will essentially become a part of the wall when it suits you, muffling sounds and stopping heat loss. 

Let’s take a look at soundproof window plugs in more detail, why you should think about making one, and how to create one for your window. 

What Are Soundproof Window Plugs?

A soundproof window plug is a sponge board with thermal properties that tightly seals the window to block, absorb, and reflect sound.

It’s one of the most effective methods to soundproof a window or skylight, so if you’re desperately looking for ways to block noise pollution, a window plug is ideal.

soundproof window plug

They’re also relatively simple to make and affordable.

Soundproof window plugs can be permanent or removable, depending on your requirements.

They sit on the inside of your window and prevent soundwaves from entering and exiting as well as light and air. 

The plugs feature a high-density material to block soundwaves, along with a dense foam to absorb soundwaves.

A soundproof sealant is used to stick everything together, further decreasing sound transmission.

You construct it according to the dimensions of your window, so it fits snugly into the wall cavity and seals against noise.

Before you start the project, you ideally want to seal and weatherstrip your windows.

Remove any old glue residue from around the window frame, and apply weatherstripping tape.

Then apply an acoustic caulk around the frame where it meets the wall, to ensure no noise can pass through small gaps.

Why Use Soundproof Window Plugs?

Window plugs offer an array of benefits, including:

  • Effectively reduce the transmission of soundwaves and reduce noise disturbance in your home. Gone are the days of hearing trucks, children, animals, generators, lawnmowers, and the like in your home from outside, plus your neighbors won’t be disturbed by your loud noise when the plug is installed.
  • Significantly lower thermal energy loss. With the gaps around the windows sealed, you’ll have no more wasted central heating/air conditioning as well as reduced hot/cold air coming in from outdoors. This can lead to reduced utility bills and a more comfortable living space. 
  • Improved acoustics in your room. If you’re a music enthusiast, this will benefit you hugely. Openings in a wall can ruin the symmetry and balance of the sounds, plus glass adds an unwanted rattle and echo. Once covered with a window plug, your room will have a smooth frequency response, and you can create a soundscape you once only dreamed of. 
  • Provide blackout properties. This is good if you or your kids want to have a lie-in, or take a nap during the day. At the same time, it prevents sun damage to your furniture, flooring, and decor, which causes fading and discoloration. 
  • They are cost-effective. Compared to specialized soundproof windows or other additional soundproofing methods, window plugs are an affordable and easy option. Rather than installing a new window altogether, soundproof window plugs are an easy option for both homeowners and renters.

The Downsides

Like anything in life, soundproof window plugs aren’t for everyone. Here’s some of the reasons people choose other soundproofing methods instead:

  • They’re bulky, so they can be difficult to move around and store when not in use and may not go with your decor. While you can’t prevent the size, you can add handles to make it easier to remove and insert. If you think the plug will be an eyesore in your room, consider painting, upholstering, or wallpapering the back of the plug to make it more presentable. You can also cover it with curtains or furniture to hide it away.
  • They prevent the use of the window, so you can’t get fresh air, natural light, or see the views through the glass. If you experience significant light pollution at night in your area, the plug will help a lot. It’s vital to make your soundproof window plugs removable so you can still let in sunshine and fresh air when it suits. When the plug is in use, you can try using full-spectrum light bulbs, which give the feeling of sunlight inside and will help your home feel brighter. 
  • They don’t block all low-frequency sounds. This usually depends on the thickness and density of the materials used to construct the window plug. If you choose materials that are designed to be soundproof, such as mass loaded vinyl and acoustic foam, you should be able to block the majority of sounds. 
  • Not all windows are built to support soundproof window plugs. If you’re making it yourself, you should be able to construct it to the right size and angles. If it still won’t fit properly, consider adding a stool extension or securing the window plug with straps. 

How To Make Soundproof Window Plugs:

Tools You’ll Need:

  • Tape measure.
  • Saw.
  • Utility knife.
  • Screws.
  • Drill or screwdriver.
  • Level.
  • Square.
  • Caulking gun.
  • Staple gun.
  • Work gloves.

Materials Required

  • MDF: It should also be thin enough to accommodate the other materials you will add to it, so it fits well in the window with enough room for air space. An alternative to MDF is fiberboard or plyboard, which are lighter but don’t reflect sound in the same way as MDF.
  • Mass loaded vinyl: This is your soundproof mat, which is thin and flexible, yet dense and reflects soundwaves.
  • Neoprene mat or acoustic foam panels: This will absorb soundwaves and improve sound quality in your room. Make sure you buy slightly more of this, as you’ll wrap it around the edge of the plug to seal it in the window space. If your window is deep, you can also use matt insulation, but this isn’t as easy to work with.
  • Fabric, wallpaper, or paint of your choice (optional): If you’d like to decorate your window plug.
  • Soundproofing glue: Soundwaves produce vibrations, and this will help reduce those while sealing the materials you use together.
  • Handles: To make it easy to plug and unplug the board from your window. Choose ones designed for cabinets, nylon strap handles, or anything you can find in the hardware store. 
  • Weatherstripping: To use around the window before you insert the window plug.


1: Measure

Measure the dimensions of the window, making a note of the length, width, and depth. Rather than measuring the window frame, we want to measure the window cavity—the hole in the wall where the window sits. Depending on the depth of your window cavity, you’ll allocate about half of it for dead-air space (in a similar way to glazed windows) that will help prevent low-frequency noise. 

Make sure to check the height on both sides and the width at the top and bottom, as not all window spaces will be accurately square and you don’t want to get it wrong. The efficiency of soundproof window plugs comes from the snugness in the window, so the size needs to be right to avoid letting noise and light through small gaps.

2: Cut

This is probably the most difficult part of the project, but it won’t take long. According to your measurements, cut the MDF board using a saw (or if you have the tools, a circular saw or table saw will do the job quickly). Do this outside or in your garage, as it will be a dusty affair. 

Your local hardware shop where you buy the MDF may offer to cut the wood to size, so if you take your measurements when you go, you can save yourself some effort. 

Keep in mind that you want the soundproof window plug to be as snug as possible, so start large rather than small. Test the board in the window frame to check the sizing is right before you continue. 

3: Add MLV & Foam Layers

Measure the same dimensions for the mass loaded vinyl and neoprene foam or acoustic foam and cut using your utility knife or sharp scissors.

For the foam, extend the size by an inch or two on each edge to be able to fold it over the board.

If you have chosen a fabric to decorate the outside of your window plug, cut this to size, too.

4: Glue

Start by lying the best side of the MDF board face-down on the floor. Wear your safety gloves and pour the glue, spreading it across the whole area. If you’re using a soundproof glue such as Green Glue, spread it across the board in a thin layer to provide another soundproof barrier.

Lay the mass loaded vinyl on to the glue and press down from the middle to the edges, pushing out any air bubbles and ensuring it’s a smooth surface. To further secure the edges, you can use a staple gun around the sides. 

Spread another thin layer of glue, and lay the acoustic foam or neoprene mat. Again, push any creases or air bubbles out and ensure the whole area is pressing on the glue. Fold the sides of the foam around the edge of the board using extra glue, so it will seal properly in your window cavity. For extra security, use staples or even nails to hold the layers together. 

Leave the window plug for several hours to allow the glue to completely set. 

5: Decoration

Now it’s time to work on the presentation of your board. Flip the board over once it’s dry and prime the wood. Then paint it or glue on your fabric, wallpaper, poster, or tapestry. Again, leave to dry. You can also use tacks or nails to secure the fabric or paper, in case you’d like to change it later on. 

Alternatively, you can push a large piece of furniture over it to cover the window and plug completely, or draw the curtains (use soundproof curtains for more effectiveness).

6: Handles

Attach your handles using a drill or screwdriver and screws to the edges of the board, so you’ll easily be able to lift the plug in and out of the window frame. They can be located anywhere on the plug; wherever you feel is more comfortable for you to lift it in and out of the window cavity (make sure you can grab both without stretching).

It’s best to make them at the same height on either side, and a couple of inches away from the edge of the board.

7: Weatherstripping

Before fitting your newly created window plug to your window frame, consider adding weatherstripping tape and acoustic caulk if you don’t already have it. This will help create a good seal and prevent any air or sound leaks from the edges. 

8: Insert the Plug

Now it’s time to try out your new soundproof window plug.

Make sure to leave at least a couple of inches of air space between the window itself and where you insert the plug.

Where To Buy Soundproof Window Plugs?

You’ll find that soundproof window plugs aren’t readily available both online and in hardware stores.

window plug

This is because they have to be custom-built to your window’s style and measurements. 

If you really don’t have the time or tools to build your own, you may be lucky to find a company that manufactures soundproof window plugs in your area.

You’ll either send your accurate measurements and wait for them to build it to your specifications, or you order a one-size-fits-all product and cut it down to size to fit your window. 

What If My Window Isn’t the Right Shape?

There are some windows out there that simply aren’t designed to support something like a soundproof window plug.

An answer to this may be to extend the interior stool of the window (the window sill).

You can do this by removing it and adding a larger, deeper shelf to the area, which can better accommodate a window plug. 

If your window cavity is shallow, you can fit the window plug and install straps on the wall to hold it into place.

Add one to the top and one to the bottom across the window plug to ensure it doesn’t fall back from the window cavity. 

Plug It In

Hopefully, now you fully understand all there is to know about soundproof window plugs.

There are plenty of benefits of using them, and they are one of the easiest and cheapest options out there to fight noise pollution.

Whether you want it to be permanent or temporary, you’ll be able to enjoy some peace and quiet in your home without spending big bucks. 

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