6 Ways to Soundproof Home Ventilation Air Ducts


There are so many different places within a home that can cause noise issues if not treated properly. There are ventilation air ducts virtually everywhere scattered around to provide a much more comfortable living situation, but also some sound problems if not set up correctly.

All the tips below are great for people who are looking to make the ducts and vents a little quieter overall. Since ducts and vents are connected, it makes sense to soundproof both.

At times, it might seem inevitable to make a replacement. The good news is before jumping into that costly solution, try a few other ideas.

1. Creating a Sound Maze of Sound Inside the Vent and Ducts

Air Vent Sound Maze
Air Vent Sound Maze

Although this might sound a little complicated to some people, this is one of the most effective ways to control sounds without having to put in too much effort.

The best thing is that the ducts and vents continue to work as they should, and the effectiveness is almost there right away.

So how exactly is a sound maze created? It is a combination of using acoustic foam to kill the sound waves and plywood dividers that can bounce any sound waves out of the air vents completely.

These two types of materials are explicitly picked to make sure that the air vent continues to work as it should and keep things under budget overall.

There is always the option of having a professional create a sound maze inside the air vents, but it can actually be done by individuals who want to put effort into it as well.

It requires a small amount of cutting, screwing in, and gluing, but it is not incredibly difficult to the point that people can mess things up quickly.

Below is a full set of materials and tools needed to pull off an air duct and vent maze. A lot of people have most of these around already, so the overall cost of the sound maze will not be too much.

  • Screwdriver
  • 1/2 thick plywood
  • Acoustic foam
  • Green Glue (Amazon)
  • Knife
  • Measuring tape
  • Wood saw
  • Ladder

Building the Sound Maze

After opening up the air vent with a vent, people will be able to examine the inside pretty well. It is essential to get proper measurements inside the air vent to see how much material is needed.

Once these measurements are taken, cut the pieces of plywood to about 2/3 to 3/4 of the size of the air vents. This means that air will still be able to pass through, but there will be no direct path to the back.

The goal should be at least four pieces of plywood in the end. They will be able to glue to most vent surfaces easily, and before jumping to that, make sure to line both sides, and the plywood itself, with acoustic foam.

With the acoustic foam, there are no flat areas inside the air ducts and vents now. It kills off any echo and makes a difference pretty much right away.

Just make sure that the vent is closed off properly once again so that it operates as it should. Anytime a person opens up their vents, they are perhaps making it a challenge to put it right back as it should. This can cause some rattling issues that were not around before.

Here’s an article talking about how flow noise from spoilers in duct.

2. Sealant inside a ducts and vents

Foam Sealant for air duct soundproofing

One of the easiest ways to close any type of gap in a vent or air duct is to use some sort of Expandable Foam Sealant (Amazon). Expanding foam will be able to fill the entire gap, and that is what some people use for a quick soundproofing solution.

The process is pretty simple, as the sealant just needs to be liberally applied inside the event. It will be able to expand to fill space, but leaving it that way is not going to help out all that much. Instead, once it starts a little, that is when it is important to push the sealant towards the two walls on the sides.

There is not an easier or simpler solution out there, but it might not be the most effective method imaginable. A lot of people try this at first, and then maybe jump to something else if they do not feel like they are getting that much out of the setup.

3. Acoustic Foam

Acoustic foam in air ducts

There is a lot of misinformation out there that Acoustic Foam (Amazon) by itself is a soundproofing material. The truth of the matter is, it is something that helps kill echo, but it does not soundproof an area particularly well.

Inside a duct or vent, it can work because reducing the echo is one are the major reasons why there is noise in the first place. Metal vents, in particular, are noisy with echoes, so looking into this process might be best.

Acoustic foam is readily available from many different manufacturers, and it is pretty cheap to invest in enough to fill all the air vents. Maybe this is enough to soundproof everything and make life a lot quieter.

Where does the acoustic foam go inside the ducts and vents? Put the acoustic foam towards the sides to make the walls a lot more challenging to produce an echo. This is the best method to go about things, just simply using glue to attach the acoustic foam.

4. Block or Cover the Vents

Air vents are installed for a reason, but they might not be needed in every room at the end of the day. If that seems to be the case, simply block the vents to help with cutting down noise. This will cut down on a noisy vent, and therefore, noisy air ducts as well.

The best way to completely block a vent is to take the vent cover off and then put a piece of plywood behind that layer to fill everything up. To close up some of the gap, use weatherstripping or some other type of tape along the edges so that everything creates a nice seal.

The downside to going in this direction is the fact that the vent is no longer in use. It looks a bit better when it is covered up underneath the cover, simply because it still looks like it is entirely in use.

Other people will decide to use a cover instead, which is quicker but might not look aesthetically pleasing.

When covering up a vent on the outside, there is the option of taking it down quickly if it needs to be for any reason. Some people will change whether or not the vents are open depending on the time of year, which is one thing to keep in mind if the sound is just a little too problematic.

5. Flexible Ducts

Flexible air ducts

Instead of making a sound maze, there is also the opportunity of using Flexible Ducts (Amazon) to help with breaking up the sound. This works in a lot of similar ways, but instead of having to put anything inside the vents, it just needs to be bent around a bit so that it does not have any straightaway spots.

It might not look as aesthetically pleasing if the air ducts are exposed, which is why not everyone goes this route. However, if there is a way to use some of the flexibility to advantage, it is definitely one way to go.

6. Is the HVAC System to Blame?

An HVAC system can cause some issues with the air vents, although they should be looked at as a separate issue altogether. It is true that if their system is making a lot of noise, it is only going to be amplified by vents that might not be properly soundproofed.

If the source of the noise is coming from the HVAC system, look into repairing the system itself before also doing something with the ducts and vents. In some cases, a person might only need to touch one or the other.

The good news about fixing the HVAC system is that there could be some other issues that people do not even really realize until they really dig deep into everything.

For example, maybe the HVAC system is making noise because it is not functioning properly, and therefore utility bills are jumping up as well. It might cost a little initially to repair, but it could be better long-term to help out.

7. Full Air Ducts and Vents Replacement

Ducts and vents are meant to last a long time, but sometimes things happen that they need to be replaced. Maybe they were accidentally damaged, or there are other factors that have worn everything down to the point of no repair.

As long as a person takes measurements on exactly how big the air ducts and vents are, it is relatively easy to replace them if a person wants to go that direction.

Some do not trust themselves, so they will get a professional to handle all the replacement pretty quickly as well.

Is it ultimately worth soundproofing air vents in a home?

Other than windows and doors, air vents can cause some of the most troubling issues when it comes to sound inside a room. When someone stops and thinks about it, this is basically a pathway for sounds to come in, even if the rest of the room is very well soundproofed.

Most of the solutions are pretty inexpensive, and there is no harm in trying a few out before investing in something better. In many cases, creating a sound maze is going to do enough to help out the vast majority of people.

Do not be intimidated by opening up the vents and putting in some work, because, in the end, it should work out just fine.

No one likes feeling forced to replace air vents or even the HVAC system, but keep in mind that in some scenarios, that is the only way to get things back on track.

Trying to patch up everything and come up with a different solution instead of addressing the major problem is just going to frustrate people.

What Purpose Do Air Fans Serve?

The goal of any vent in a home is to control the temperature inside. Hot air in a room rises, which means that the ventilation air ducts can handle everything efficiently.

Most of the time, these vents and ducts are placed where temperature jumps up a bit, so look for them above doors and other warmer locations.

Of course, there are also air ducts and vents pumping in air conditioning and heat throughout the year. Some feel like these are noisier since it can amplify the sounds coming from a noisy HVAC system.

Why Do Air Ducts Become A Noise Problem?

There are a few different reasons why air ducts might be a source of noise problems inside at home. To start with, there are a lot of flat surfaces for sound to reflect off of that can cause some problems leading up to the vent.

If the vent is doing its job, there is going to be quite a bit of air passing through. That is always going to make a little bit of noise, and how the vents are set up at the end of the air ducts initially will determine just how noisy it can be.

There is also the case of an air duct needing some repair, or a full replacement for that matter. There is only so much a person can do if the ducts are just not operating correctly. Sometimes some simple fixes might be able to help initially, but it is going to require a little more effort than that later on.

Finally, materials do play a pretty big role in how noisy air ducts and vents might be. There are some instances where people who have a little bit more money to spend on air ducts and vents initially will do that to avoid needing more help later on. That helps a lot with overall headaches, but not everyone has that luxury or new construction.

To sum it up, air ducts and vents are very susceptible to making flaking noises. This is any type of noise that enters a room in unconventional ways. It falls in the same category as noises coming from HVAC systems, indirectly through doors and windows, and other small areas.

Martin Poirier

For the last number of years, I've Been dedicating a lot of time in soundproofing and helping people be able to soundproof their home, business, and vehicles. I also have a YouTube channel by the same name Soundproof Guide.

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