10 Effective DIY Ways to Soundproof Vent

The above-door air vent is an essential feature of a room ventilation system since it controls air circulation and maintains fresh air in a room.

While this may appear appealing to some, there is a major drawback to above-door vents. In addition to helping distribute fresh air, they let in a lot of noise from all sides of the door.

Many people may feel that the noise from vents overshadows any potential benefits; therefore, soundproofing these vents is necessary.

This is particularly important if you need a good night’s sleep with minimal distraction or work from home and require quiet time to do your tasks or make phone calls.

In this guide, I shall discuss some ways you can use to soundproof vent.

Soundproofing Vent Flanking Noise

Flanking noise is a sound that enters a room via an indirect channel, for example, noise from the downstairs home theater transmitting to the room above through ventilation duct work rather than through the ceiling.

Your efforts to soundproof your home may be strenuous if the sound travels through indirect media.

Another perfect example of flanking noise is sounds traveling through the air vent, which is typically designed to keep rooms cool by allowing fresh air into the room.

Flanking noise also includes sound traveling through windows, doors, HVAC system ducts, and interconnected media such as floor and walls.

Ways on How to Soundproof Vent

Build a Sound Maze

A sound maze is a series of sound-absorbing insulating layers with open ends that enable air to flow freely.

Soundproofing an above-door air vent with a sound maze is an excellent technique to achieve your goal while enjoying air conditioning benefits.

A sound maze will not obstruct airflow, so there won’t be any problems with ventilation, and it will effectively suppress undesirable noises. 

The maze makes multiple layers in the vent, so sound waves must bounce off these layers before entering your room.

Consequently, the amount of noise is substantially lowered. 

Despite its effectiveness, making a sound maze is quite tedious. 

How to Make a Sound Maze: What You Need 

• A stepping ladder
• Saw
• Measuring tape
• Acoustic foam
• Green glue
• A screwdriver
• Plywood

How to Make a Sound Maze in an Air Vent 

• Take off the air vent covers using a screwdriver. 
• Measure the interior dimensions of your air vent.
• Using a saw, cut a piece of plywood to fit the interior of your vent. After that, trim about 30% plywood on the ends to allow air to flow freely.
• Make a total of 4 equal plywood parts. 
• Use the green glue to stick equal-sized acoustic foam pieces to all surfaces of the already measured plywood parts. This will ensure sound does not reverberate off the surfaces and sound energy is used up before it travels via the vent.
• Next, use glue to stick the edges of the plywood pieces on the air vent, allowing a spacing of approximately one inch between the plywood pieces. Arrange the boards on the vent in a zigzag pattern; attach the first board on the right, followed by a board on the left.
• Use glue to stick acoustic foam at the rear end of the air vent. 
• The last step is to replace the cover on the air vent.

Soundproof Curtains / Blankets

Soundproofing curtains have several other names, including sound-absorbing, acoustic, sound deadening, and sound dampening curtains.

The name variation depends on the brand and the soundproof goal you wish to achieve.  

Such curtains, irrespective of their names, are made of thick, dense fabrics including velvety, polyester, and suede and are hung over the air vent or media you’d want to prevent sound transmission.

They often have an absorptive finish that traps sound waves, making a room quieter. A soundproof curtain and soundproof blanket is an efficient short-term measure of suppressing the noise from the air vent.

The curtains have a porous material which is an excellent sound absorber resulting in a substantially quieter space. You can also remove and fix them back when needed.

You will need a rod to hang your curtain to cover the ventilation.

Soundproofing curtains are designed to absorb noise but not block it. In simple terms, they are sound-absorbing materials and not sound-blocking materials like mass-loaded vinyl.

Make sure you get a tight woven and thick curtain long enough to run from the ceiling to the floor.

I suggest getting these curtains from NiceTown blackout curtains for both privacy and sound absorption.

Upgrade HVAC System

HVAC (Heating, Ventilation, and Air Conditioning) is the abbreviation for the systems of channeling air in and out of rooms and cooling and heating different types of buildings.

If an HVAC system has exceeded 15 years of service, the only option to deal with noise is to upgrade it to a modern model. The more your system gets old, the lesser the efficiency level.

Inefficient and old HVAC systems are sometimes the cause of unwanted noises. There could be leaks and cracks in the ducting, causing unwanted noises.

If you have enough funds, consulting a professional and renovating the entire ventilation system is the best option for reducing noise and guaranteeing appropriate air circulation within the room.

Even though it may appear to be a costly investment, it effectively reduces noise.

Acoustic Foam Panels

Acoustic foam panel is an open-celled foam commonly used in acoustical treatments. It works by significantly reducing the amplitude of airborne sound waves and converting the resulting sound energy into heat.

Acoustic foams are available in a wide range of colors, shapes, and thicknesses allowing you to choose one that complements the aesthetics of your room. 

Mainly, acoustic foam is applied to walls, roofs, doorways, and other room areas to reduce noise, vibrations, and echoing and improve sound insulation.

Acoustic is meant to enhance overall sound quality in an enclosed environment by absorbing echo, for example, in theaters, cinema halls, and studios. I’m sure you’ve seen most gamers or YouTubers hang these wedged-like materials on the walls.

Since the surfaces of ventilation ducts are often composed of metal, lining the ventilation ducts with acoustic foam will significantly help reduce the noise problem. 

Acoustic foam costs approximately $1.5 per square foot and is available in various types at any hardware shop and online store. 

Acoustic Foam Panels Installation Process:

• Take off the ventilation covers and measure them. 
• Trim the acoustic material to the exact dimensions of the ventilation covers. 
• Apply glue to the inner side of the coverings’ edges. 
• Stick the acoustic to the coverings, ensuring no gaps are left uncovered.
• Put the cover back on the ventilation.
• You have to line the acoustic panels on the air vent duct to reduce noise and echo. The acoustic foam panels will minimize noise without limiting air circulation.

Soundproofing Sealant

Soundproofing sealants such as green glue are specially designed to absorb noise and may be applied to various construction materials, including wooden, metallic, and even gypsum materials.

Most acoustic sealants are water-based, flammable-free, non-toxic, have a low odor, and are freeze-thaw-resistant.

The rubbery substance in the sealant can handle all seasonal variations in materials. The caulk maintains its flexibility and guarantees a lasting sealing over sound wave transmission.

A standard sealant will dry out and harden over time, shrink, and separate from its surroundings which does not happen to acoustic sealants. Acoustic sealants won’t entirely dry off or shrink, making them perfect for sound insulation.

In addition to being painted, acoustic sealant can be spackled and taped. 

Foam-based sealants are mostly recommended because they are long-lasting, stick well on air vents, and are simple to clean. Additionally, they are water-resistant and airtight when they dry up.

When using this method, you only need to apply an adequate amount of the sealant to the air vent; it will expand to fill the accessible space.

You need to take off the vent cover, apply the sealant on the vent, then put back the cover. The entire procedure takes only a few minutes. 

Acoustic sealants will help block sound and airflow from getting into your house. This will not only help with noise reduction but also heat insulation.

The good thing is that you can easily remove your foam-based sealants if you wish to have your air vent back.

Block the Vent with Drywall

Drywall is a board mainly built of gypsum used for construction purposes as a cheaper alternative to wood and concrete. Drywall is an ideal option if you want to block your air vent.

With this method, you have two options for permanent blockage. You can either build drywall around the air vent or seal the duct.

Fill the vent duct with sound absorbents such as foam or wood to accomplish this.

After sealing the vent duct, install a properly measured drywall with an adhesive to completely block the vent. No air or sound will get through after this is done.

You can use soundproofing or regular drywall to achieve the desired sound absorption.

Using soundproofing drywall provides better sound insulation without taking up too much space compared to standard soundproofing methods.

You can reach an STC (Sound Transmission Class) score of 68 with two layers of standard drywall on every side. (Source)

Remove the Vent Completely

Completely removing an air vent is often the best solution if you wish to get rid of the noise. The method is quite laborious and may require a professional.

Before removing the air vent, make sure you have the right tools for the operation.

Tools Required to Remove an Air Vent

• Safety goggles
• Screwdriver
• Stepladder
• Dust cloth

How to Remove Air Vent: Step-by-Step Guide

• Protect your floors from dust by placing a dust cloth under the vent. 
• Position your ladder on top of your dust cloth and cautiously climb up with a screwdriver in your hand. 
•  Using your screwdriver, take off the screws while keeping one hand on the vent to prevent it from falling. 
• Remove the vent slowly and cautiously to avoid possible injuries.

After the vent is removed, you need to fix the hole with gap fillers. Gap fillers are used to fill spaces between or within construction materials.

Fillers can be applied with various construction materials and repainted to match the wall color.

Fillers are applied to various construction materials such as gypsum, wood, cement plaster, bricks, or blocks, and other types of materials such as aluminum and so on.

Filling the Air Vent Gap: What You Need

• Concrete blocks
• Masonry spoon
• Filler
• Cement and sand
• Stepladder

How to Fill the Vent Gap: Step-by-Step Guide

• Mix cement and sand to make a mortar. The amount of mortar to make depends on the size of the gap.
• Ensure your blocks are measured and cut accordingly to fit the gap.
• Using the masonry spoon, lay an adequate amount of mortar on the gap and put the concrete block on top. The mortar acts as glue.
• Keep laying the blocks with mortar until the whole gap is covered.
• Plaster the interior and exterior of the vent with mortar and lay it evenly to match the rest of the wall.
• Use a filler such as the easy fill (available in hardware and online stores) to even out the plastering and make it smooth.
• Wait for it to dry and paint the surface to match the rest of the wall. You can use soundproofing paint for even much better sound reduction. 

Only use this method if you’re sure you won’t use the vent again.

Install Duct Liners

A duct liner is a substance used in lining the inner surface of a duct. Using elastomer foam to line a duct effectively absorbs noise and dampens vibrations from HVAC systems.

To achieve the best possible acoustic performance, use an insulating material with a high noise reduction coefficient (NRC) that can absorb various sound frequencies.

The greater the acoustic properties and sound insulation, the greater the NRC score. One of such products is the Acoustic Duct Liner sold by Sound Acoustic Solutions. It has an NRC rating of 0.7 and 0.8 for 1inch and 2 inches sizes, respectively.

How to Install Duct Liners: What You Need

• A sharp blade, or scissors.
• Glue
• Tape measure

Installation Procedure: Step-by-Step

• Measure the interior of your ductwork and use the exact dimensions to measure the duct liner.
• Using scissors or a blade, cut the duct liner with the exact measurements as the ductwork.
• Apply an adhesive or glue on all the edges and attach it to the inner side of the duct.
• Ensure the metallic duct surfaces are entirely covered.

It is important to note that all the duct liners are not the same, meaning the installation mode may differ. Fortunately, most manufacturers issue user manuals with installation instructions.

Install Soffit Mufflers

Soffit mufflers are meant to suppress sound at the entrance of the HVAC system to prevent it from spreading.

Soffits are constructed to safeguard the building from natural features such as dampness and mold. Soffits are further known as false ceilings in some instances.

Building a soffit is an excellent way of dampening sound.

A standard soffit for soundproof is mainly composed of an MDF (medium-density fiberboard) inside an insulating material.

These soffits are also highly popular in audio system installations since they are excellent at minimizing noise.

The use of soffits is quite efficient, and it’s more appropriate in spaces that need a lot of soundproofing.

If you are on a low budget and need to make a soffit, you will use around 7 inches of flex duct, adhesive, silencer, insulation, and drywall.

A flex duct should be installed and stretched from the ventilation to the HVAC system. Next, inside the space, make a tiny box using adhesive and drywall to enclose the flex duct completely.

You can also add fiberglass coating on the box’s edges to improve soundproof capabilities.

When installing a flexible duct in the soffit, you’ll get lots of bends that will help soundproof the air vent more.

Get a Duct Silencer

A duct silencer is a feature of a vent system that reduces sound transmission through the duct work.

They are also known as sound attenuators, mufflers, and sound traps.

Duct silencers are fitted in vent ducts close to where the sound originates from – for example, air vent.

Duct silencers can be installed directly on the vent to absorb sound coming in through the vent.

There are several examples of silencers that include;

·         Sound Traps- Decrease the amount of noise from noisy production machinery.

·         Gen-Set Silencers- Regulate sound from generators and engines.

·         HVAC Silencers- Noise silencers for an air vent in buildings.

·         Acoustical Silencers- Reduces sound reverberation.

HVAC silencers are the best fit for an above-door air vent.

Most HVAC silencers have baffles, which have acoustic material consisting of many air pockets.

When sound waves collide with the molecules in such air pockets, the sound energy is converted from noise to heat. This efficiently minimizes noise while also lowering airflow pressure.

On Soundproof Vent

If you only want to reduce soundproof vent, I propose assessing all the available solutions and deciding which one is best for you.

The ideal soundproofing solution is to remove the air vent entirely or seal up the vents with insulation foam.

The negative aspect is that there will be no free airflow, and it is also not ideal for rented apartments.

If you wish to maintain airflow while reducing noise, creating a sound maze or fixing soundproofing curtains or blankets is the best option. Such options are ideal if you live in a rented apartment.

Nonetheless, you need to do a need assessment and consider your budget when choosing the best soundproofing method from the ten listed options.