6 Ways to Soundproof a Window

Part three of our guide to soundproofing shows you how to soundproof windows yourself. Find out how making your room quieter is easier and cheaper than you think. Here are 6 ways to soundproof a window.


Windows are probably the weakest point in a home when it comes to sound insulation. They provide the thinnest barrier between you and the world outside. When assessing your home for sources of noise pollution, windows should always be considered first.

The easiest way to fix leaky windows is to get soundproof windows fitted. These don’t have to replace your existing windows and can be fitted as an extra window layer. However, these can cost over $1000. If that’s not an issue for you, then a quick Google search will solve your problem. If not, then read on as you can find out how to soundproof your windows much more cheaply.

These are our 6 answers to fix noise coming through a window.

Treatment Number 1: Seal any air gaps

soundproof a window

Sound waves will retain most of their energy and therefore loudness if they are allowed to travel unopposed.

By stopping air-borne sound we can dramatically reduce unwanted noise in the home.

It’s vitally important then that we treat windows for any air gaps. If you live in a modern building, then this shouldn’t be as much of an issue, but it wouldn’t hurt to check anyway.

The most effective way to do this would be to seal the window shut, but this might not be an option for some. There are a few different tools we can use to seal air gaps. Let’s take a look at them…

Green Glue Acoustic SealantGreen Glue Noise-proofing Sealant

This acoustic sealant is specially designed to fill up cracks and gaps. It’s easy to apply and dries in 48 hours.

While traditional glue links surfaces and allows vibrations to transfer easily between them, this stuff inhibits efficient sound transmission. It’s so effective it can help reduce noise transmission by up to 100 times.

It’s commonly used in the building industry to help soundproof surfaces. However, it’s little known outside of the building trade.

foam-tapeHigh Density Foam Tape

This tape has an adhesive layer which means it is easily applied to most surfaces. It is made of a high density material which makes it perfect for treating noise problems. It can be easily stuck to the bottom of an’ up and down’ sliding window.

acoustic-puttyAcoustic Putty

Acoustic putty is an awesome solution for those awkward shapes that can’t easily be treated with tape. It can easily be molded to fit any shape and provides a dense layer of sound insulation. It’s commonly used in the building trade to cover electrical boxes and stop unwanted sound from being emitted.

Treatment Number 2: Upgrade your curtains/blinds


As we learned in part one of our guide to soundproofing, one of our most effective weapons against noise is to add mass to a surface. If you’re wondering how to soundproof a window from traffic noise for example, then adding mass is an important step.

By adding extra mass to a surface we increase its sound absorption. We can add mass to walls so that less sound energy can travel through them, and we can do the same with curtains.

Buying curtains because of how heavy and dense they are isn’t most people’s main consideration when furnishing their homes, but in the war against noise, it is a key one.

Curtains offer another layer of sound insulation, but their effect is usually negligible. However, special curtains do exist that can help us in our quest for peace and quiet.

There are some neat side effects to using these kinds of curtains too. Since they are denser and have more mass, they perform well in other areas too:

  1. They are great at blocking unwanted light. These curtains are often called “blackout” curtains due to their light blocking qualities. They can make a big difference to your quality of sleep if your current bedroom curtains let sunlight in.
  2. They are more energy efficient. They insulate your home much better than regular thin curtains. By retaining more heat in a room they can even impact your energy bills.

noise-reducing-curtainsNicetown Noise Reducing Curtains

These curtains are really dense due to their triple weave design. Great at keeping out light, cold, and noise.

Getting a larger set than usual will allow them to be pleated. This helps by providing more mass for the sound waves to pass through. It’ll also make them even better at insulating your room on cold days.

acoustic-solutions-curtainsResidential Acoustics Soundproof Curtains

These are more expensive than the other options because they are made by a specialist acoustics company. They say that these can reduce sound by 70-90%. These are some of the best sound dampening curtains Amazon sells. But, they are priced accordingly.

Besides being extremely heavy (great for reducing sound) they come as one panel which is rolled up like a blind. This means there’s no air gap in the middle where the 2 curtain panels would otherwise meet. These are specialist sound reducing curtains.

To make the curtains even more effective, try to order a really wide length that enables you to pleat them. By pleating the curtains we make them thicker in places, which will stop more sound from passing through.

An even more effective solution would be to hang 2 sets of curtains. If you go down this route, just make sure your curtain rod is strong enough. These curtains are heavier than your average set.

Treatment Number 3: Make your own acoustic curtains


Perhaps you don’t think acoustic curtains would be enough, or you don’t like the styles they come in. A more personal approach to the noise problem and to the color scheme in your bedroom would be to make your own soundproof curtains.

When looking for material to hang over windows, we should remember these key points:

  • Thick and heavy (dense) material is better.
    • Heavy fabrics like suede, velvet, and synthetic velour are effective while still attractive to look at.
    • Be warned that these fabrics are highly flammable!
  • The material should reach from above the window height to the floor.
  • Ideally we want to pleat any curtain material.
    • This makes a thicker barrier and stops more sound.
    • Plan for the extra curtain size. It should be at least double the window width, but we can also go up to three times bigger for a stronger effect.
  • Our curtain is going to be really heavy, so we need a strong curtain rod of at least 1 inch in thickness. A standard size rod might not be strong enough.

There are lots of different materials that you can use for this. Let’s take a look at what’s available and how it can be put to use.

Pleated Curtains

By hanging a double set of thick blackout curtains (preferably with a small air gap between them), we can reduce the noise coming into our home. Remember to buy big as we want to pleat or drape them too.

A further step to seal air gaps would be to add velcro strips to the edges. This means we can attach the curtain to the wall. With this set-up there will be absolutely no air gaps that allow noise to travel easily.

blackout curtainsBlackout Curtains

Reasonably priced thick curtains that are well reviewed. Sound blocking curtains like these come in many styles too.

For even more sound insulation layers we can add blackout panels or window liners. These can be attached easily to existing curtains, and add a little more mass to our curtains.

thermalogic window-linerWindow Liner

Polyester and cotton insulation for heat, noise, and light. They are easily attached to grommet rings.

If you’re quite attached to your current curtains then you can upgrade them to noise reducing curtains with the help of this liner.

Moving blankets

Moving blankets are designed to protect cargo in transit. This means they are really thick and well padded. It is this characteristic that makes them a popular choice in recording studios to absorb sound.

They’re actually a bit of an industry secret, as they are effective at absorbing sound, but come at a fraction of the cost of specialist acoustic panels and absorbers.

Using a layer or two of moving blankets over a window could stop a lot of air-borne sound from entering your room. They might not be the most attractive curtains, but they could be very effective noise reducing curtains.

moving-blanketUS Cargo Control- Supreme Mover

These blankets weigh 8 lbs each. That’s a big amount of noise insulation at a cheaper price than specially made acoustic panels. You’ll find cheaper moving blankets, but you’ll be hard pushed to match the weight of these guys.

Treatment Number 4: Make a window plug or use a barrier

A window plug is an acoustic barrier that we can fit into the window sill to absorb sound. It will be dense and thick, and will block out light too. It’ll even help with the heat insulation in your home. However, we need to make this light enough that we can remove it during the day.

How to make a window plug


Step 1: We need to measure the frame of the window to see how deep the window sill is. If our window sill is 2 inches deep then we will need 1 inch thick of acoustic mat, for a 4 inch depth we’ll use 2 inch thick mat etc. It’s important that we leave an air gap, and that our window plug doesn’t press against the window pane.

soundproof matAcoustic mat

Acoustic or soundproofing mats like these are commonly used in cars to reduce engine noise. They come in a variety of thicknesses, and have an adhesive backing so that they can be easily applied. If you were to use your window plug during the day, a bonus with this type of mat is that it can easily withstand high temperatures of direct sunlight.

Our sound proof window mat needs to cover an area of 1 inch longer and wider than the window sill. We need this overlap so that we don’t have an air gap. By making it slightly big it should squeeze into the window sill area and fit snugly. You can add extra layers of soundproof mat as you see fit. The thicker the better, but remember we need to leave an air gap between it and the window pane.

Step 2: We need to make a backing board for our window plug. This will serve two purposes: It will add extra mass (sound insulation) to our plug, and it will give us the chance to fit handles.

The dimensions of our backing board should ideally match the dimensions of the window sill. This means our acoustic foam will stick out 1 inch around the sides.

As for our material, we want to use something as dense as possible, but we also don’t want to make it too heavy. We don’t want it to take three people to put our window plug in each night!

Medium density fiber board is dense, but quite heavy. Other fiberboards would do also. Our acoustic mat has an adhesive backing, but contact cement can be used too.

Step 3: Now we have our acoustic mat stuck to a backing board. To make our window plug easy to fit and remove, we can make handles. Cupboard handles or simple straps would suffice.

We can add a further layer of acoustic mat to the back of our window plug too, if so desired.

Acoustic Barrier

An acoustic barrier is specially designed to limit sound transmission. It is filled with dense material, ideal for sound absorption. An acoustic barrier hung over a window with hooks would form an extra layer of sound insulation over your window. This treatment is much like the window plug, but it would be for homes where the window plug wouldn’t be an option

singer-safety-double-faced-quilted-fiberglass-panelFiberglass Panel

This barrier is filled with dense fiberglass to reduce sound transmission. It can easily be attached with hooks to a curtain rod.

tms-acoustic-barrierMass Loaded Vinyl

Mass loaded vinyl is super dense to make it really good at absorbing sound energy. At only 1/8 of an inch thick it doesn’t have to take up much room either. It’s specially designed to stop sound.

Treatment Number 5: Make a second window


Much cheaper and easier than completely replacing your windows, is to add an extra sound insulating layer. By attaching a layer of acrylic over the window, you can reduce the noise that is able to travel through it.

This can be done with a custom designed soundproofing window kit, or if you are a bit more confident in your DIY skills, or are on a budget then you could do this yourself.

With a layer of acrylic you need to make an air tight seal over the existing window. This is a similar method to the window plug, but differs in a couple of ways. By using acrylic this means that it is transparent and will let light into the room. This means it doesn’t need to be removed during the day. Using only acrylic also means that it is not quite as effective as the window plug.

magnetseal-soundproofing-window-kitSoundproofing Window Kits

These window kits come with the fittings needed to make your own soundproof window. You’ll need to purchase your own acrylic, but kits like this will guide you through the whole process.

Treatment Number 6: Upgrade your windows


If you live in an older building then you might have the misfortune of having ageing windows too. Old single pane windows offer a really poor level of sound and heat insulation. Furthermore, the frames are often badly sealed and leave air gaps.

As we learned in part one of our guide to soundproofing, we want to stop things from vibrating as that’s how sound travels through surfaces. These single pane windows offer little resistance to sound, and vibrate freely in its presence. Air gaps also offer an easy route for sound to travel unchallenged.

This is an expensive option, but getting double panel (glaze) windows with modern frames would make a big difference to the amount of sound that comes into your home.

The double panels offer a little more sound insulation, but more importantly, the new frames are really well sealed and stop any sound from leaking through air gaps.

We’ve given a lot of options on what you can use. It depends on your budget and circumstance as to what would be best. Certainly the most effective treatment would be to use a bit of everything, or by using more layers, but you might notice results by using only one of them. We’d love to know how you got on, so we can share with the rest of our readers.

That concludes part three of our guide to soundproofing. You should now know how to soundproof a window and get a better nights sleep. Next in part four, we’ll show you how you can soundproof a door.

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Harbor All Glass & Mirror Inc.

  1. Thank You! This is just what I was looking for. Neighbor has been doing ‘noise harassment’ under my 2nd story bedroom window (double paned) for the last 2-3 years and now has begun building his dogs a chain link kennel under my window. The dogs are a Black Labrador and a Red Foxhound… needless to say at 6:45 am every morning their barking is very ‘alarming’.
    Your Tips are going to be put to use and I’ll be grateful for a nice ‘sleep in’ in the mornings since I’m almost 64 and retired I don’t feel the need to rise with the sun anymore.
    I’ll be checking out the ‘Soundproof a Room’ too since the upstairs room is large and I don’t think it was very well insulated at the time it was added on – all the sound outside travels ‘up’ so that should help me as well. I’ll be copying the Tips into a Word doc so I can use them later instead of trying to find your page again. But I’ll save the website link too, and refer anyone to it that needs a bit of soundproofing.
    Again Thank You for all this information… it will save me a lot in soundproof ‘windows’ costs and I can do most of it myself.
    You are a great source of help!

    • Hi Linda,

      That’s really nice of you to say! It’s great to hear our readers are getting value from the guide.

      Noise pollution is a terrible problem and if some people could just be a bit more considerate it would make a huge difference.

      I really hope things improve for you soon!

      Best of luck,


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