Does Spray Foam Insulation Reduce Noise?

Spray foam insulation is an excellent product that solves a multitude of issues. It can reduce air leaks, provide thermal insulation, and save energy for your property. However, a lot of people wonder if it can also reduce noise levels.

The answer is no. Spray foam insulation will not reduce noise levels since it is not an acoustic insulation material. However, it may help to prevent the sound of air leaks from entering your home through the walls and ceilings.

Air leaks are a common cause of noise pollution, so by plugging them up with spray foam insulation, you could see a reduction in noise levels. However, if you have an active source of noise, such as a noisy appliance or other problem inside your home, spray foam insulation will not be able to help.

What is Spray Foam Insulation?

Spray foam insulation is a spray-applied material used to insulate buildings and cover cracks and gaps in walls, ceilings, and floors. It is made from two components: a polymer resin and a foaming agent. When the two are mixed together, they create a spray foam that expands up to 60 times its original size.

Spraying Foam Insulation

The spray-foam insulation is applied via special equipment, which coats the area evenly and quickly. It dries to a hard white finish to form thermal insulation and an air barrier.

There are mainly two types of spray foam insulation: open-cell and closed-cell. Although both types of insulation have their own unique properties, closed-cell insulation is generally considered to be better at preventing air leakage and providing a more effective thermal insulation.

The R-value of closed-cell spray foam is R-7 per inch while the R-value of open-cell spray foam is R-3.8 per inch. Also, the material densities of open-cell and closed-cell spray foam are significantly different. The density of open-cell spray foam is about 0.5lb/ft3, while the density of closed-cell spray foam is 2lbs/ft3.

While both materials work blocking air infiltration, closed-cell insulation does a better job by forming an airtight seal. This is why it is the preferred type of insulation for commercial and industrial buildings.

Having said that, the porous nature of open-cell spray foam provides better acoustic insulation properties than closed-cell insulation. This is mainly because the tiny air bubbles in open-cell foam absorb sound waves, preventing them from passing through the insulation and into the adjacent rooms.

How much does spray foam insulation reduce noise?

Although spray foam insulation is not an acoustic insulation material, it will still reduce noise levels as an insulation material. Before we can figure out how much noise it will reduce, let’s take a look at two ratings used by building professionals when discussing noise:

Sound Transmission Class (STC)

Sound Transmission Class (STC) is a rating that measures how well a material stops the transmission of sound. It is used to rate the sound insulation of walls, ceilings, floors, and windows.

STC values range from 0 to 100, with higher numbers signifying better performance. For example, a house with an STC of 50 indicates that noise levels on one side of the wall are 50 decibels higher than on the other.

Noise Reduction Coefficient (NRC)

Noise Reduction Coefficient (NRC) is a rating used to measure how well a material absorbs sound. It can range from 0 to 1. NRC of 0 means that the material absorbs no sound, while an NRC of 1 means that the material absorbs all sound.

NRC is often confused with STC, but they are different in the sense that NRC measures the absorption of sound while STC measures the transmission of sound. The higher the NRC rating, the better the material is at absorbing sound.

Now that we know what these ratings are, let’s see how they can be used to figure out how much noise spray foam insulation reduces.

Sprayed polyurethane foam insulation at 3-inch thickness has an NRC rating of 0.70 and an STC rating of 35. This means that noise levels will be reduced by 35 decibels when the insulation is applied.

To give you a better picture, standard glass doors can have an STC of 28 to 35, laminated glass doors can have an STC of 35 to 40, and soundproof glass doors can have an STC of 48 to 55 or more.

This tells us a 3-inch thick layer of spray foam insulation will acoustically perform somewhere between the standard glass door and laminated glass door while it will not perform at all like a soundproof glass door.

How to improve the noise reduction properties of spray foam application?

Use low-density spray foam

Low-density spray foam means it has more air space and less foam. This creates an air gap that can absorb more sound waves. Open-cell foam has a lower density than closed-cell foam, and as a result, it will provide better sound insulation.

Add a sound-barrier material

If the surface you are applying the insulation is a wall, you can add a sound-barrier material to the surface before/after the insulation is applied. This will help to improve the noise reduction properties of the foam insulation. You can use a variety of sound-barrier materials, such as acoustic paints, a dedicated membrane, acoustical tiles, or soundproofing blankets.

Leave a gap between the insulation and the surface

If you can, leave a gap of at least ½ inch between the insulation and the surface. This will allow the sound waves to be absorbed by the air space you have created.

You can achieve this by creating a furring strip and placing a vulcanized fiber sheet on top of it. By doing so you reserve air the gap between the insulation and wall surface to absorb sound.

Mix the insulation with a sound-absorbing material

Another way to improve the noise reduction properties of spray foam is by mixing it with materials that are known to absorb sound. This can be granulated cork or wood wool but fine enough to pass through the hole that is created by your spray nozzle.

You can also apply these materials as a finishing layer over the foam insulation. However, this will not add much to the noise reduction properties of your insulation because a very thin layer of material is applied on top.

Use Acoustic Sealants

Acoustic Sealants are products that are specifically designed to seal the gaps and cracks around doors, windows, and other openings where sound can escape. They are applied similar to architectural sealants. However, they serve primarily serve as an acoustic sealant and not as a thermal barrier.

Since acoustic sealants are also initially applied in liquid form, you can easily use them in conjunction with spray foam insulation. This will create a continuous seal and improve the noise reduction properties of your insulation.

Use Acoustic Caulk

Another great way to improve the noise reduction properties of spray foam insulation is using acoustic caulk. Acoustic caulks are applied in much the same way as regular caulks using a caulking gun.

Therefore, you can easily use acoustic caulk in conjunction with spray foam insulation to create a continuous seal. You can try multiple coats of foam insulation followed by acoustic caulk or you can even try mixing the two together.

Try a Soundproofing Primer

If you are not happy with the results of your noise reduction efforts, you can always try a soundproofing primer. A soundproofing primer is a special type of paint that is designed to improve the noise reduction properties of surfaces.

Once your foam insulation has dried, you can try applying a layer of soundproofing primer. This will help to reduce the amount of sound that is able to travel through the surface.


Spray foam insulation is an excellent choice for filling cracks and gaps in your home’s walls. However, it is not intended to be a noise barrier. To reduce the amount of sound that travels through your walls, you must look for dedicated solutions, some of which are mentioned in this article.

There is no one-size-fits-all solution, so try a variety of methods to see what works best for your home. With a little bit of experimentation, you can make your home significantly quieter.