How to Soundproof a Wall Already Built: Tips and Tricks for a Quieter Space

If you live in an apartment complex or a house with thin walls, you might be familiar with the problem of noise pollution. Whether it’s the sound of your neighbor’s TV or the traffic noise outside, it can be challenging to relax and enjoy your living space.

Fortunately, there are ways to soundproof your walls without removing drywall.

One of the first steps in soundproofing your walls is to identify the source of the noise. Is it coming from outside or inside your home?

Once you have identified the source of the noise, you can start implementing soundproofing techniques.

There are several methods to soundproof a wall already built, and the best one for you will depend on your specific situation.

Some of the most effective soundproofing methods for existing walls include adding insulation, creating more mass, and using acoustic absorption materials.

These techniques can help reduce the transmission of sound through your walls, creating a more peaceful and relaxing living environment.

In the following sections, I will explore these methods in more detail and provide step-by-step instructions on how to implement them.

Understanding Soundproofing

When it comes to soundproofing a wall that’s already built, it’s important to understand the basics of soundproofing.

Soundproofing is the process of reducing or eliminating sound transmission between two spaces. This can be achieved by adding mass, damping, decoupling, or a combination of these techniques.


Mass is one of the most important factors in soundproofing. The more mass a wall has, the more difficult it is for sound to pass through it.

Adding mass to a wall can be done by adding additional layers of drywall, mass loaded vinyl, or other heavy materials.


Damping is the process of reducing vibrations in a wall. Vibrations can be caused by sound waves hitting the wall, and can cause the wall to vibrate and transmit sound.

Damping materials, such as acoustic foam, can be added to a wall to absorb these vibrations and reduce the amount of sound that is transmitted.


Decoupling is the process of separating two surfaces to prevent sound from passing through them.

This can be achieved by adding a resilient channel or using sound isolation clips. These techniques create a gap between the wall and the structure, which reduces the amount of sound that is transmitted.

Choosing the Right Materials

When it comes to soundproofing an already-built wall, choosing the right materials is crucial.

In this section, I will discuss the two main categories of materials that you will need to consider: insulation materials and sealants and adhesives.

Insulation Materials

Insulation materials are designed to absorb sound waves and reduce the amount of noise that passes through walls. There are several types of insulation materials available, each with its own set of pros and cons.

One of the most popular insulation materials is fiberglass insulation.

Fiberglass insulation is made of tiny glass fibers that are woven together to create a fluffy material that is easy to work with. It is also very effective at absorbing sound waves, making it a great choice for soundproofing walls.

Another popular insulation material is mineral wool insulation.

Mineral wool insulation is made of rock or slag fibers that are compressed and formed into batts or rolls. It is denser than fiberglass insulation, which makes it more effective at blocking sound waves.

Sealants and Adhesives

Sealants and adhesives are used to seal gaps and cracks in walls, which can help to reduce the amount of noise that passes through. There are several types of sealants and adhesives available, each with its own set of pros and cons.

One of the most popular sealants for soundproofing walls is acoustic sealant.

Acoustic sealant is a specially formulated sealant that is designed to be flexible and to absorb sound waves. It is also very easy to apply and can be used to seal gaps and cracks in walls, floors, and ceilings.

Another popular sealant for soundproofing walls is green glue.

Green glue is a viscoelastic compound that is applied between two layers of drywall. It is very effective at reducing the amount of noise that passes through walls and is also very easy to apply.

Preparation Before Installation

Before starting the installation process, it is important to prepare the wall surface properly. This ensures that the soundproofing materials adhere properly and create a tight seal. Here are a few things to keep in mind when preparing the wall surface:

  1. Clean the surface: Clean the wall surface thoroughly with soap and water to remove any dirt, grime, or residue. This will ensure that the soundproofing materials adhere properly.

  2. Fill in gaps and cracks: Fill in any gaps or cracks with acoustic sealant. This will prevent any sound from leaking through the wall. Make sure to use a high-quality acoustic sealant specifically designed for soundproofing purposes.

  3. Evaluate the wall composition: Evaluate the composition of the existing wall to determine the best soundproofing method.

    Blown-in insulation is most effective at reducing airborne noises such as voices, television sounds, or general background noise. However, it may not be as effective at blocking low-frequency vibrations caused by heavy machinery or loud music.

  4. Choose the right soundproofing materials: Choose the right soundproofing materials based on the type of noise you want to block.

    For example, acoustic foam panels are effective at reducing echo and reverberation, while mass loaded vinyl is effective at blocking low-frequency noise.

Installation Process

When it comes to soundproofing an already-built wall, there are two main steps you need to follow: installing insulation and applying sealants. Here’s how to do it:

Installing Insulation

The first step in soundproofing an existing wall is to install insulation. This will help to absorb the sound and prevent it from traveling through the wall.

There are a few different types of insulation that you can use, including fiberglass, cellulose, and foam.

To install insulation, you will need to cut it to size and then place it between the studs in the wall.

Make sure that the insulation is snugly in place and that there are no gaps. If there are any gaps, sound will be able to travel through them and the insulation will be less effective.

Applying Sealants

The second step in soundproofing an existing wall is to apply sealants. This will help to seal any gaps in the wall and prevent sound from traveling through them.

There are a few different types of sealants that you can use, including acoustic sealant and silicone caulk.

To apply sealant, first, identify any gaps or cracks in the wall. Then, apply the sealant to the gaps using a caulking gun.

Make sure that the sealant is applied evenly and that there are no gaps or air pockets. Once the sealant is dry, you can paint over it to match the color of the wall.

Post-Installation Tips

Now that you have successfully soundproofed your wall, there are a few things you can do to ensure that it remains effective for years to come. Here are some post-installation tips to keep in mind:

1. Regularly Inspect the Soundproofing Materials

It is important to regularly inspect the soundproofing materials that you have installed to ensure that they are still in good condition.

Over time, the materials may wear down or become damaged, which can reduce their effectiveness.

By inspecting the materials on a regular basis, you can identify any issues early on and address them before they become bigger problems.

2. Seal Any Gaps or Cracks

Even the smallest gaps or cracks in your soundproofing materials can allow sound to leak through. To prevent this from happening, make sure to seal any gaps or cracks that you find.

You can use a variety of materials for this, including acoustic sealant, weatherstripping, or foam tape.

3. Use Sound-Absorbing Materials in Your Room

While soundproofing materials are designed to block sound from entering or leaving a room, they do not necessarily absorb sound within the room.

To reduce the amount of echo and reverberation in your space, consider using sound-absorbing materials like acoustic panels, rugs, and curtains.

4. Consider Upgrading Your Doors and Windows

If you are still experiencing sound issues after soundproofing your walls, it may be time to upgrade your doors and windows.

Sound can easily pass through these areas, so upgrading to thicker, more sound-resistant materials can make a big difference.

By following these post-installation tips, you can ensure that your soundproofing materials remain effective and that your space stays quiet and peaceful.

Leave a Comment