Does Spray Foam Insulation Reduce Noise?

When soundproofing my home office and my son’s band practice space, I wanted to know “does spray foam insulation reduce noise?” I checked out open and closed cell spray polyurethane foams (SPF) to see if I could use it for thermal and acoustic insulation.

Does spray foam insulation reduce noise? Based on my research, the easy answer is no. Open cell spray foam performs better than closed cell, but neither is effective at blocking sound transfer. The qualities that make it an excellent thermal barrier also create disruptive resonance and its adhesion couples the wall elements together increasing noise transfer.

Some of my friends and clients expressed an interest in what I was doing, so I figured I’d share my findings. Hope they assist you in controlling noise intrusion in your home or office.


Does spray foam insulation reduce noise

What is Spray Foam Insulation?

Spray foam is an open or closed cell polyurethane material that is made of two components that mix when sprayed onto walls or into wall cavities. It expands to cover a surface or fill a crevasse or cavity before hardening.

One part of the liquid spray is polymeric MDI (methylene diphenyl diisocyanate), and the other is a blend of polyol resins, fire-retardants, surfactants, and catalysts. The fire retardants decrease the combustibility and smoke generation.

Closed Cell

Closed cell spray foam expands between 35 and 50 times its original volume and weighs about 2 lb/ft³ when hardened. An ozone friendly hydrofluorocarbon is commonly used to deliver the mixture to the wall surface or cavity where it expands and hardens.

Over 90% of the cells are closed making the foam impermeable to moisture and vapor, and improving its thermal values. It has an R-value of 6.1 per inch of thickness. The hardened polyurethane has a tensile strength of 28psi and is much less compressible or flexible.

The greater strength offers advantages in hurricane or earthquake prone areas to help secure wall and roof components together.

Open Cell

Open cell polyurethane foam expands to 150 times its original volume and weighs about 1/2 lb/ft³. Water is used to drive the blended materials onto the wall or into a cavity where it expands to form an open-celled matrix that remains slightly compressible and flexible.

The interconnected open cells trap airflow making it a good thermal barrier. It blocks air flow and has a thermal R-value of 3.6 per inch, but is semi-permeable to moisture and vapor. It has a tensile strength of 4.0psi.

Airborne and Impact Noises

There are several types of noises we try to control in our homes or offices. Airborne and impact sounds are the two we normally attempt to control with insulation. Soundwaves are vibrations that travel through the air until they encounter an obstacle – wall, tree, window, person, etc. The frequency wave vibrates its way through the object and continues.

Some of the waves may be absorbed or reflected, so less travels onward, which can reduce the intensity of the sound. The barriers don’t usually work on all frequencies, absorbing some but not others.

Low frequency sounds from drums, and bass instruments take a lot to decrease. We’ve all felt them reverberate through walls and vehicles. Mid-range and high frequencies tend to be easier to mute.

Impact noises occur when something hits a surface inside or outside a structure. They are also known as structural sounds. Foot-falls on hardwood or concrete can echo through a building.

Bouncing a tennis ball or basketball against the wall or even on the driveway reverberates into the building the same way. The impact initiates the airborne vibration through a barrier into another space within your home or office.

What Do The Sound Ratings Mean?

The sounds we hear usually range from 20 to 20,000 Hz; age and other issues factor into the range we hear too. 0 decibels is essentially silence. The rustle of leaves is between 10 and 20 dB, a quiet home or office is 40 dB, and the average street noise or a party between 75 and 80 dB. A bass drum, jet engine or car horn can be an ear-splitting 130 dB.

Hertz (Hz) is used to measure frequencies of sound waves, and decibels the loudness heard or intensity produced by different sounds. The STC measures how different materials or barriers interact with 16 different frequencies. The NRC how much sound intensity they block.

Sound Transmission Class (STC)

The STC is a value used to rate how effective different materials or combinations of materials are at improving the sound transmission loss (TL) in decibels (dB).  It rates the movement of 16 common frequencies between 125 Hz and 4,000 Hz through the materials or assemblies. The less sound measured going through, means the greater the transmission loss, and the higher the numeric STC rating.

Noise Reduction Coefficient (NRC)

The NRC is a number system used to rate how well a tested material absorbs or reflects soundwaves. It represents the average tested absorption results of four common frequency ranges – 250 Hz, 500 Hz, 1000 Hz, and 2000 Hz.

The average is the NRC value and is rounded to the nearest 0.05 between 0 and 1.0. The greater the value, the better the material is at absorbing or reflecting sound.

Does Spray Foam Insulation Reduce Noise?

To soundproof a partition wall, consider the structure and weight of the material you want to use. We know we need to absorb, block, and damp the sound waves, plus decouple the layers to stop sound transfer through the wall. Some materials have NRC and STC ratings that help us out, and you can read about it in my post about soundproofing insulation options.

When we apply what we know about open and closed cell polyurethane we can also understand why it may not be good for soundproofing. Although it has good thermal properties, it doesn’t have the mass to absorb soundwaves.

The hardened foam forms a rigid material that also interferes with absorption. Couple the harder material with open or closed cells, and you get increased resonance whereas a softer more airy substance will damp it.

The property that makes the spray foam good for hurricane and earthquake zones is also what makes it bad for decoupling. It secures wall components together, so that sound vibrations can move through more easily. The wall construction, the thickness of the foam, and wall sheathing influence performance too.

Comparison of How Insulation Improves the STC Rating of a 2”x4” partition wall with 1/2″ drywall on both sides and an initial STC between 33 and 35

Insulation Thickness NRC STC
Open Cell Polyurethane 3” 0.70 37-39
Closed Cell Polyurethane 2.75” 0.70 36
Rockwool Safe’n’Sound Batten 3” 1.05 45
Rockboard 60 3” 1.10 52
Owen-Corning R-11 Batten 3.5” 0.95 39
Owen-Corning Fiberglass 703 3” 1.10 52

As you can see from the comparison table, spray foam is not the best material for sound insulation. Closed cell spray foam insulation has the lowest noise deadening ratings.

Open cell polyurethane spray foam performs better with noise reduction and comparable to fiberglass batten insulation. Both types of foam largely underperform compared to Rockwool and fiberglass rigid insulation.

Although the values should indicate an improvement in the sound attenuation of a standard 2×4 partition wall, the adhesion of the foam to the components allows soundwaves to pass through easily.

Additionally, the open and closed cells in the hardened foam increase mid-range frequency resonance distorting the sound quality. It has excellent thermal performance, but comparatively not a good soundproofing material.

Spray Foam Insulation Cost

Open cell polyurethane spray foam is less expensive than closed cell. The cost of the material depends on where you live, and if you plan to install it or have the pros. Some places give the cost per board foot and others by square foot at R-1. However, I prefer a 1-inch thick square foot price.

Polyurethane Foam Insulation Cost

(Not including labor)

Insulation Cost per Board Foot Cost per Square Foot at R-1 Cost by Square Foot 1”x12”x12”
Open Cell Polyurethane Foam $0.40 – $0.75 $0.12 $1.00 – $1.20
Closed Cell Polyurethane Foam $1.00 – $1.50 $0.20 $1.25 – $1.50


Better Alternatives for Soundproofing

There are alternative insulation products that can be used instead of polyurethane spray foams. They have excellent thermal properties like the foam but have even better soundproofing abilities.


U.S. Greenfiller LLC Fiber InsulationTrying to improve the soundproofing of existing walls can be a challenge. Blown in cellulose insulation is 75-85% recycled material and is an excellent sound absorbing material that reduces feedback, and mutes echo.

It comes in two formats – loose fill which is less expensive, and dense fill. Loose fill has an STC of 44 and an NRC of 0.80, while the dense fill has an NRC of 0.90 and STC between 44 and 68 depending on how dense it’s packed.

New Construction:

New construction offers a blank slate for soundproofing. Metal or wood studs, isolation clips and channels to decouple layers, mass loaded vinyl, Green Glue for damping, newer construction techniques, and your choice of insulation.

It’s easier to soundproof from the start than to retrofit sound control in later. Two helpful articles you may find interesting are How to Soundproof Walls and Soundproof a Basement Ceiling.

  • Fiberglass
    Fiber glass insulation for soundproofingFiberglass battens and panels insulate and also soundproof more effectively than foam. Owens Corning 703 Fiberglass Panels are 2-inches thick and have an NRC of 1.10 and an STC of 52. The panels can be used on the wall or inside the cavities. It absorbs sound, reduces echo, and control reverberation.
  • Stone Wool
    Roxul Rockwool Acoustic Mineral WoolStone wool is available in insulating boards and battens too and is also better for controlling sound than the spray foams. mineral wool insulation is 2-inches thick, has an STC of 52, and an NRC of 1.10. Like fiberglass, it reduces echo, controls reverberation, and absorbs sound.



Polyurethane spray foam is great thermal insulation and it does have some soundproofing potential. Unfortunately, the characteristics that allow it to trap soundwaves also create a resonating chamber that seems to amplify mid-range frequencies which are disruptive.

Additionally, the hardened foam also binds layers together which couples the wall elements and can increase sound transfer. If you found this article of interest and you know someone who might appreciate it, pass it on. Your comments and suggestions are appreciated too.

Eugene Sokol

Hi, I’m Eugene. I work with noise all day, so I enjoy any peace and quiet I can find. I began looking at ways to improve the sound quality of my home and to make a soundproof office for myself. As a DIY enthusiast, I looked for solutions I could do. I created this blog to share what I learned and to make it easier for you to improve your quiet space too.

18 thoughts on “Does Spray Foam Insulation Reduce Noise?”

  1. The paragraph about NRC uses the unit dB. I think you meant to use Hz (abbreviation for Hertz, 1 cycle per second).

    Noise Reduction Coefficient (NRC)

    The NRC is a number system used to rate how well a tested material absorbs or reflects soundwaves. It represents the average tested absorption results of four common frequency ranges – 250 Hz, 500 Hz, 1000 Hz, and 2000 Hz.

  2. Good explanation. Needs to add the reduction potential by 1/3 octave bands because there might be an application for a select band of frequencies of interest for noise reduction.

  3. I can’t believe there isn’t paneling or something you can put on wall that would look nice and provide some insulation from thin cheap construction walls in a condo. It seems so simple but all you see are ugly panels to hang on your wall, who wants that… one.

  4. I have a 4″ drain in a closet, and I’ve wrapped it with some sound deadening mass vinyl, but it has some branches in the line, so it’s hard to completely wrap it.

    I’m putting in a new interior in the existing closet, and was planning on just filling the space around the pipe and the wrapping with some Great Stuff foam, as I build in the closet.

    I think your article is suggesting that instead I should get and use that instead? It’s pretty darn tight, so I’m concerned there won’t be much space to get it in. It might be easier to work with though…!


    • Hi Eric,

      Spray foam is not your friend when it comes to soundproofing. It will help some when filling holes where pipes penetrate walls. Here a few space-saving ideas:
      1) Install as much Rockwool as possible in the cavity. Do not pack it tight. (Tighter will reduce soundproofing.)
      2) Install a sheet of Mass Loaded Vinyl over the studs before drywalling.
      3) Hang a soundproofing blanket either inside on the studs before drywalling, or over the wall after it is finished.
      4) Double 5/8″ drywall with Green Glue sandwiched between is probably the best choice because of the extra mass and lack of space you have to work with. You can still install rockwool before drywalling for a bit more.

      Hope one of these will work for you,


  5. My bedroom shares an existing wall with some noisy neighbors. In addition to hanging MVL sheets and sound blankets like a giant curtain in front of an exiting shared wall, I was thinking of filling any gaps between the drywall and the electrical boxes on that wall (and whatever I could reach behind the boxes using the straw) with low-expansion spray foam. Now I’m not sure that is a good idea. Any suggestions on how to retrofit to help soundproof around the existing electrical boxes?

    • Hi Lisa,

      Foam is not the greatest soundproofing product, but anything that fills the holes is better than nothing. You will probably not be able to fill behind the boxes. Any foam you spray into the wall cavity will hit the opposite drywall and slide to the bottom. My preference would be to caulk around the box with acoustic caulking (assuming the drywallers were any good and the gap is less than 1/4″). Then install a Trade Gear Wall Plate Insulation Gasket (Amazon) before putting the cover back on. You can put a small bead of paintable caulking around the plate if it does not fit tight.

      You will get way more gaskets than you think you need, but acoustic caulking never dries so if you ever remove them, you are going to throw the old one away. They are universal and will fit regular duplex outlets, GFI outlets, and switches.

      Hope that helps,


  6. Rather than hanging whole sheets of sound deadening material i was thinking of facing the metal studs with strips of it before the dry wall goes on. And then use green glue with another layer of dry wall board. Or am i wasting my time?
    It is a cargo trailor conversion to be used for camping/ sleeping and for work at a desk. So the quieter the better! (Even white noise machines are very irratating for me! Unfortunately!!!)

    Thanks for your time!

    • Hi Paul,

      Unfortunately you will be wasting your time and money. Sound travels through gaps. If you are going to use something like Mass Loaded Vinyl cover the entire wall or don’t bother. Double drywall will Green Glue will help a lot because of the added mass. Spray foam on the metal walls should help with the vibration effect and it will act as a vapor barrier on the steel skin. Not sure where you live but up here in the frozen north, condensation is a real problem with steel shells.

      Hope that helps,


  7. would foam injection into masonry blocks help reduce noise?
    I was planning on injecting foam into the blocks on a new construction house then insulate with, either spray foam or insulating panels, in between the block and the sheetrock from the inside.

    • Hi Esteban,

      Injecting foam into the concrete block will not help very much (STC rating of 36 – 39). If I were doing it, I would use cellulose blow-in insulation (STC rating of up to 70). I am assuming you are going to either strap the inside of the block or build a 2 x 4 wall on the inside to accommodate insulation and drywall. 2″ Rockwool batts between the strapping will give you the best soundproofing option. Spray foam on the inside of the wall will be less effective for soundproofing, but will provide good insulation value.

      Hope that was helpful,


  8. Cellulose blow in insulation blown in between nyc noisy neighbor shared wall would have STC up to 70 and what would the NRC be? Am I reading that to reduce noise, cellulose blown in insulation would be best bet? With the insulation now in the wall would the noise vibrate off the material and transfer sound in? Looking to mitigate in apt shared wall and best material without adding mass or draping MLV entire wall. Some helpful and economic Suggestions Questions for a contractor coming to give estimate

    • Hi Maura,

      According to the Cellulose Insulation Manufacturers Association NRC can be upwards of 0.80. Cellulose is way better than foam, and better than many other products. Cellulose cuts down vibration and sound transfer. Your contractor should have some experience doing this. Not just someone who rents a machine and blows stuff in. He needs to cut about a 2″ x 4″ hole at the top of the wall between every two studs, drop the hose to the bottom of the cavity, and pull it out slowly as he is blowing to get a good job. And turn the air down on the blower unless you want the stuff blasting back through the hole and filling your place with a whack of dust. If it is just blown in at the top, the cellulose will get hung up on electrical boxes, wires, plumbing, and even nails that missed the studs giving you areas in the wall that have thin insulation. Then he should have the talent to patch the holes.

      Hope that is helpful,


  9. I wish I had known this sooner. We peeled off a layer of fibreboard and a layer of shiplap board in order to spray foam between the studs from the outside. Now our place is an enormous sound attractor. Outside footsteps, coughs, car doors, everything is audible.

    Any idea on what we can do to remedy the situation? Peel off the siding, frame an extra layer of studs with Rockwool? MLV inside or outside? An extra layer of drywall inside with green glue? An extra layer of OSB outside?

    Thanks for your help.

    • Hi Fred,

      Sounds ugly. Like living inside a bass drum. But you probably get good insulation R-Value, so tearing it all out again to replace it with Roxul rockwool soundproofing batts (although and option) is probably not very attractive. I think you need to decouple the wall by using sound isolation clips c/w hat channel. Then dry wall with either 5/8″ soundproofing drywall like QuietRock or Certainteed, or double 5/8″ standard drywall with Green Glue sandwiched between. Another option is to build a room-within-a-room that is not connected to the existing walls in any way. You can take a look at our article ‘How to Build a Room-Within-a-Room‘ for more information on that type of a project.

      You could add plywood or OSB to the exterior. But if I were considering that, I would put a layer of QuietRock on the existing sheathing first to add soundproofing mass, then sheathing, then re-installing the siding. This does not provide the decoupling but the added mass may be sufficient. And you do not need to tape and mud and paint, or extend electrical boxes and window and door jambs.

      Hope that helps,



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