In some rooms, soundproofing air vents could be the solution to unwanted noise.
So, how to soundproof vents?
In this article, we’ll discuss different solutions for eliminating the noise entering your room through air vents. You’ll develop an understanding of the different options available to you – from covering them to blocking them or replacing them.
If you’ve already soundproofed your walls, soundproofed your windows and find noise is still infiltrating your room, turn your attention to your air vent.
This guide will focus on standalone air vents that are not connected to a larger heating, ventilation, and air conditioning (HVAC) system. They are typically located high up on the wall, often above a door, or on a ceiling. They do the job of allowing fresh air to enter your room from outside and can be common in bedrooms, kitchens, and bathrooms.
Just to reiterate – we are not covering vents that are part of HVAC systems here. This article only applies to soundproofing a vent itself.
Why do vents let in noise?
Because air vents supply your room with cool air from outside, they leave a gap through which noise can enter.
If your room is next to an external wall, you may have an air vent that lets air through directly from outside. In other cases, air can be supplied to your air vent via a duct (a passageway or tube). Whether the noise comes directly from outside, or via a duct (flanking noise), there are several solutions you can look at:
Skip to:
- Cover an air vent
- Block an air vent
- Create an air vent sound maze
- How to soundproof vents: The best solution
Now let’s dive into the best options for how to soundproof a vent.
Cover an air vent
You might see this as the low-hassle, low-cost option.
Ventilation backup plan
Before we go any further, we should note that any method of covering or blocking your air vent will impact the airflow itself. For this reason, you should have a backup plan for ventilation. This ensures you can regulate temperature and avoid condensation that can lead to rotten surfaces.
If you already have windows in the room or an HVAC system that allows you to control temperature, you should be able to cover or block your air vent without making your room uncomfortable or unhealthy.
Now let’s move on to the various options you have for covering your air vents for soundproofing.
Acoustic foam
We usually advise against acoustic foam as a total method of soundproofing, as it does a better job of absorbing sound, rather than blocking it.
However, using acoustic foam to cover your air vent can certainly help to take the edge off noise coming through the vent.
You can do this by taking off the covers of the air vent and gluing acoustic foam to the vent cover. Stick the foam to the inside of the vent cover, making sure you cover all the gaps.
Here are some acoustic foam panels we found on Amazon. You can cut them down to the size of your air vents.
Soundproof curtain or blanket
You may want a temporary solution for covering the vent that you can easily take on and off as you please. Why not go for a soundproof curtain; made of insulating material like linen, cotton, or polyester? They may not eliminate 100 percent of the noise coming through your vent, but they can make a significant difference.
Here are some short soundproof curtains we found on Amazon
Soundproof blankets – usually manufactured from fiberglass – are another option. Both soundproof curtains or blankets can be hung from grommets over the vent or stuck with Velcro. Ensure you have as tight a fit as possible over the vent.
Here is a suitable soundproof blanket we found on Amazon
Note – soundproof curtains are suitable for covering vents on walls. If your vent is on the floor, a soundproof blanket or a piece of furniture is a better option for covering it. If you use furniture, a soft sofa or armchair will work better than a hard item such as a wardrobe.
Magnetic vent cover
Magnetic vent covers form a tight seal over the top of your vent. They can be an effective sound blocker, and have the advantage of being removable for when you want your cold draft back (in summer, for example).
Because they attach to your metal vent magnetically, you can guarantee a tight seal. There are also other advantages to purpose-made vent covers, such as; cooling your room quicker when you turn on a separate HVAC system; and helping you save on your heating bills during the cold times of the year.
Block an air vent
You may not rely on your air vent for ventilation if you also have an HVAC system or windows in the room. That means you could block the air vent entirely, without heat becoming a problem.
We should stress – blocking an air vent shouldn’t be done if the vent is attached to an HVAC system. Standalone vents are what we are talking about in this guide. You should also be wary of blocking a vent in your kitchen or bathroom, as these areas need sufficient ventilation.
There are various ways you could set about blocking the vent. Let’s cover some of them:
Using plywood to block the vent
You could use plywood to block your vent. This involves taking off the vent covers on either side of your wall, before measuring them. After you have an accurate measurement for the covers, you can cut a section of plywood that is a little smaller than the cover, allowing it to fit snugly inside the vent.
You can supplement your two pieces of plywood in the vent with Green Glue. Green Glue is a versatile compound used in construction. It offers a nice advantage for soundproofing, helping walls to dampen sound.
We recommend this Green Glue on Amazon. It’s a popular damping compound that acts as a sound deadener, enhancing your soundproofing.
Once you’ve put in the plywood, you could pop the covers back on if you think that the plywood looks unsightly.
Want some backup? An extra soundproofing edge can be provided by weather stripping. Find yourself some weather stripping with adhesive – and stick it down along the cover’s inside edge. After you’ve reattached the cover, the stripping will be pushed against the wall, giving a nice tight fit and offering more sound insulation.
Using MDF to block the vent
Like plywood, MDF is another engineered type of wood. It’s a simple option for blocking your standalone vent that isn’t attached to HVAC.
You can install pieces of MDF in the same way we’ve advised fitting plywood in the section above, using green glue to add an extra soundproofing element.
Using drywall to block vent
Drywall has more mass than either plywood or MDF, so I think it is fair to say it will do a better job of soundproofing your vent.
In general, you’ll find that drywall is also cheaper than plywood or MDF, too: Wood is typically more expensive than drywall.
Measure the pieces of drywall you need in the same way described in the sections above; making them slightly smaller than your vent covers.
You can fix the drywall in place using drywall nails or screws, then use green glue or another acoustic caulk to add even more soundproofing ability.
Create an air vent sound maze
You might not want to cover or block your air vent. Heat could be a reason for this. If your room heats up quickly and you don’t have an HVAC system that does the job of cooling it sufficiently, then you might not want to obstruct the air passage offered by your vent.
A good way of getting around this problem is to create a sound maze. Don’t get discouraged by the word ‘maze’! You needn’t get lost making a sound maze. They are quite simple. You could have a builder install one, or you might like to give it a go yourself.
What is a sound maze?
A sound maze consists of some simple components within your air vent which change the path of sound, reducing noise levels. It’s a system of barriers that alters the direction of sound propagation. By sound propagation, we mean the traveling of sound from its source to the surrounding area. Make sense?
Design can vary, but in general, a sound maze is not an expensive installation. You’ll be able to make one with some plywood and acoustic foam.
How do sound mazes work?
Sound mazes deaden sound coming through an air vent while allowing hot air to escape and cooling your room.
As you can see from our no-frills infographic (!), sound mazes work by making sound waves travel further to get into your room. That’s because adding the various components forces the sound waves to deflect off more surfaces.
The end result of a sound maze is to use up the energy of sound waves inside the air vent so that the noise which gets through to your room is decreased.
The benefits of a sound maze
So why should you consider getting a sound maze made? There are a few reasons a sound maze could be a good option for how to soundproof vents:
- They can control noise coming through an air vent without blocking or covering, allowing air to circulate
- Arranged in the right way, with the right materials, sound mazes can block and absorb sound waves, doing a good job of reducing noise
- They are inexpensive
- They are simple to make
How to make a sound maze
As we’ve seen from the beautiful infographic further up the page, sound mazes aren’t all that complicated. If you fancy a bit of DIY, why not have a go yourself?
First, you’ll need to get your materials and equipment together. You require the following:
Materials
- Acoustic foam – try this one from Amazon
- Some basic plywood (anything from ¼” to ½” thickness will do)
- A strong glue – we recommend XX from Amazon
Equipment
- Step ladder
- Saw
- Tape measure
- Screwdriver
- Stanley knife
Using the materials and equipment above, you can make your sound maze as follows:
1. Note the dimensions of your air vent
Get up on the step ladder and unscrew the air vent covers on either side. Measure the height, width, and length of the air vent with your measuring tape. How long your air vent is will dictate how many plywood barriers you can install.
2. Cut your plywood
You can use the width and height measurements you have just taken to cut your plywood. Mark these measurements on your plywood sheet. Make the plywood piece about 25% shorter than the width of the vent, and the height the same as the height of the vent.
3. Check your plywood fits satisfactorily
Still with us? Good. Now cut your first piece and check it fits OK, before cutting the rest of your pieces. Four pieces will usually do.
4. Attach acoustic foam to the plywood
Acoustic foam can be stuck to either side of the plywood pieces with your glue. While plywood will be a good sound blocker, the acoustic foam will absorb sound coming through your air vent and decrease echo.
5. Install your sound maze
Now install your foam-covered plywood pieces inside the air vent, evenly spaced. Stick them to the base and sides of the vent. Remember, you are fitting them in a maze formation on alternate sides of the air vent.
Want an alternative method? Another way of building a sound maze is to attach the plywood pieces to plywood sections that are designed to slide down either side of the vents, next to the wall. This method involves building and gluing the sound maze outside the air vent, and then slotting it in without having to glue directly to your wall.
*You should note – you can expect a sound maze to significantly reduce noise coming through your air vent. However, in terms of pure sound reduction, a method such as blocking the vent with drywall will be more effective.
How to soundproof vents: The best solution
Ultimately, which method you go for will depend on how much you need the airflow from your air vent:
Does your HVAC system do a sufficient job of cooling your room? If yes, you should be OK to cover or block your air vent.
Do you get enough ventilation through your windows or other openings? If yes, covering or blocking your air vent may be a good option.
However, if you rely on your air vent to cool your room, blocking or covering your air vent might make heat an issue. In this case, consider a sound maze.
Is unwanted noise still infiltrating your room? Read our article on how to make a room soundproof
