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Soundproofing Information & Solutions
Soundproofing Air Vents
Air vents are often overlooked as a source of unwanted noise. Learn how to soundproof your vents effectively while still allowing proper airflow.
Understanding Sound Control
Air vents, like windows and doors, are another way for noise to enter a room. If you're already soundproofing a room, you'll want to make sure the air vents are addressed as well.
There are various approaches depending on whether you wish to completely eliminate ventilation or still maintain some airflow. The best part is that you can combine these methods with any other soundproofing strategies you're using.
Air vents are one of the biggest hidden paths for noise.
Can you soundproof vents without blocking airflow?
No. reducing noise always impacts airflow.
To answer this question succinctly, the answer is no. You can’t expect to install soundproofing materials over your air vents without disrupting the flow of air. After all, the more open that space is, the more noise will be able to infiltrate it. The more you try to seal off the room, the quieter it becomes.
Even procedures that are designed to maintain air flowing in and out of the room will impede it slightly. The majority of the noise we hear on a daily basis comes from the air. As you may expect, this means that we’re attempting to limit airflow.
Depending on your preferences and soundproofing objectives, you may choose to completely close the vent. The most crucial thing you can do, like with any other soundproofing endeavor, is to figure out exactly what you want to achieve. In an ideal situation, you’d strike a balance between your audio requirements and the room’s requirements.
For example, closing the vent hole is the ideal option if you want the room to be absolutely silent. However, if the room only has one window, the extra airflow from the vent is required. As a result, you’ll need a solution that decreases noise while still allowing air to flow through the vent. But, as you might expect, saying it is easier than doing it.
This compromise is critical, especially when it comes to airflow vs. quiet. One is not superior to the other. Obviously, I am a firm believer that a pleasant home is one that is quiet. But, because I believe in the importance of fresh air, you shouldn’t have to choose between the two.
Is your air vent allowing more noise than it should?
Before choosing a solution, inspect your vents to understand why noise is getting through. The three main reasons are:
Straight duct path
When vents in two rooms are directly across from each other, sound travels through without having to turn any corners.
Lack of internal barriers
Without enough obstacles inside the duct to bounce sound off of, noise passes through uninterrupted.
Metal materials reflect sound
Metal isn't ideal for sound absorption — it reflects noise rather than absorbing it, amplifying the problem.
Soundproofing Air Vents in 6 Steps
01
Completely Seal the Air Vent with Drywall
Best for maximum sound blocking
The first step in permanently sealing the vent is to treat it like a wall. After removing the grate, you can either completely fill the duct or just put in wooden studs at the very beginning. After that, you may either stuff it with insulation or simply cover it with drywall. Finally, use wall base adhesive to seal the area around the drywall piece so it blends in.
After everything has dried, sand the area, clean it, and paint it to match the wall. As you can see in the video below, this technique is both clean and effective, as well as rather simple to implement. If you don’t have much of a budget, however, I recommend trying one of the other suggestions.
Of course, a simpler and sloppier variant of this procedure is to flatten the grate and directly stuff it with gypsum. After you’ve plastered over the grate, smooth the plaster until it blends in, just like they did in the video. Although I’ve seen some individuals use this strategy successfully, I’d much rather do things right the first time. However, if you’d prefer get it over with quickly, there is one option.
⚠️ Note: you’ll only want to do this if the air conditioning is turned off. Condensation will form if the air conditioner is running through the ventilation system. In that scenario, you can modify this procedure by utilizing waterproof materials or by placing a waterproof cover over the studs and insulation.
02
Apply an acoustic sealant to the opening.
You can use an acoustic sealant to stop your vent if you want similar results to what you’d get with drywall and gypsum. I’m not referring to the kind of acoustic caulk you’d use to seal the cracks around your windows. Something like the Great Stuff Big Gap Filler, on the other hand, would be ideal.
Because this is a foam sealant, it expands to fill the area where it’s been applied. It will be airtight and water-resistant once it has dried. You’ll also be able to sand it to blend in with the rest of the wall and paint over it.
You can use this product to fill the entire duct if you want to. However, you should purchase enough insulating foam to completely fill the space you’re dealing with.
Make sure your gloves are on before you start working. If you plan to fill the entire gap, you can next remove the vent covers on both sides of the duct. Then you can fill the area and even replace the vent grates to restore the original appearance of your room. The entire project should take no more than a few minutes to apply, set, and cure.
On the other side, you can only fill the area close to the vent. Because the product is water-resistant, it should be able to tolerate any moisture generated by a running ventilation system. To attain the correct consistency, you can also put the foam in and mix it into the wall or even plaster over it.
03
Use soundproof curtains or blankets to cover the vent.
Of course, soundproofing your air vents is as simple as covering them with soundproof blankets or curtains. I’ve already mentioned how wonderful both of these things are. They’re basically thicker and more densely woven than normal blankets or curtains (although a regular thick blanket will work in a pinch).
While all of these suggestions are more easily applied to wall vents, they might also be used to ceiling air vents. You can nail a normal soundproof or moving blanket to the wall or ceiling if you’re installing it. Grommeted blankets, on the other hand, would be easier to hang as curtains.
Alternatively, you can save time and money by purchasing soundproof curtains. Install a curtain rod above the vent or along the ceiling, and hang the curtain so that it pools on the floor. This will ensure that you are completely covered, as well as thickening your walls. Still, I’d combine this idea with one of the two air vent soundproofing options below.
04
Create a sound maze within the vent.
Best for maintaining airflow
There are a variety of reasons why you might want or even want fresh air in the room. One of the most obvious reasons for the additional airflow is if the room only has a single small window. If there’s a chance of mold growing in the room, though, you’ll need to keep the vent operational. You can, of course, utilize this strategy for your own purposes as well.
If you’ve never heard of the maze method before, you might think it’s a little strange. However, bear with me. Adding absorbent materials and walls to your vent by creating a maze is an excellent way to add absorbent materials and walls for the noises to bounce off of.
These walls will be attached to the duct’s sides so that the air is forced to travel in a zig-zag pattern. Of fact, this causes the sound waves to bounce several times, causing them to lose speed and dissipate faster. Because air will still be able to pass through, this strategy will result in adequate air flow in the room. However, you’d still get a big reduction in noise.
05
Add a layer of acoustic foam for Soundproofing Air Vents.
You can use egg crate design acoustic foam to plug your air vent if you already have some on hand. Apply a small amount of 3M spray glue on the flat side of one of the acoustic foam pieces. Then, pressing that piece against another, press it back to back.
After the adhesive has dried, cut the foam to the approximate size of the duct. It’s fine if the piece you end up with is somewhat larger than the duct. The foam will bend slightly and close the gap.
Finally, there’s a third technique to make an air vent plug.
06
Keep the Vent Grate Shut
If your vent lets a lot of noise in, it’s either producing a draft or keeping your space from heating properly. Putting a temporary plug on it, on the other hand, could help with all of these problems.
Making a plug out of the grate cover itself is one technique to do this. Bring the cover to your workplace after unscrewing it. Take measurements from the inside of the grates and transfer them to a quarter-inch thick piece of plywood. Cut the piece to size and place it on the inside of the grate, then tape it in place.
If you want to make this a permanent modification, you can use liquid glue to keep it in place. Temporary solutions, on the other hand, are always preferred until the impacts are known. If AC condensation is an issue, you can even use waterproof adhesive to adhere the wood to the grate and cover the entire board.
If necessary, weatherstripping tape can be applied to the inside edges of the vent cover to ensure that no noise gets through. Finally, screw the cover back into place on the vent. This video will show you how to accomplish it if you’re more of a visual learner.
You’d still have a working air vent with this method. To reverse the situation, simply remove the board from the grate. You can even keep the tape and board on hand in case you need to close the vent again.
Materials You'll Need
Gather these tools and materials before starting your sound maze build.
A step ladder (if vent is on a high wall or ceiling)
Screwdriver or drill with appropriate bits
Jigsaw or wood saw for cutting boards
Plywood — no more than half an inch thick
Strong adhesive (e.g. Gorilla Wood Glue)
Thin acoustic foam (e.g. Silverstone, 0.15" thick)
Utility knife or scissors for cutting foam
Ruler or measuring tape
A protected workstation surface
Building the Sound Maze: Step by Step
1
Measure the duct
Determine the duct's height and width. Your maze walls should be as tall as the duct but narrower, so air can pass around each wall.
2
Cut the plywood boards
Cut the first board to size and test-fit it in the duct. Then cut remaining boards to match. More boards means more obstacles for sound.
3
Glue acoustic foam to the boards
Using wood adhesive, attach thin acoustic foam to each board. Cut the foam to size before or after gluing.
4
Open the vent cover or grill
Remove the screws and take off the grate. Use a ladder if the vent is on a high wall or ceiling.
5
Install the first maze wall
Apply glue to one side of the board and press it against the left side of the duct. Hold until the adhesive sets.
6
Create a zig-zag pattern
Attach the next board to the opposite side. Alternate left and right to create a maze. Keep at least one inch between walls.
7
Replace the vent grill
Once all walls are installed and the glue has set, screw the vent grate back into its original position.
Final Thoughts
Hopefully, one of these solutions may help you with your noisy vent issue. Finally, depending on your needs and the needs of the room, you’ll need to choose the best solution.
It’s preferable to completely cover the vent if you’re not using it anymore. If you still require airflow, one of the final few solutions can help you achieve the silent room of your dreams.
Soundproofing Products Australia
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