Soundproofing has always been important for homeowners. That’s especially true today, considering we’re spending more time indoors. That makes us more susceptible to noisy neighbors or an overall noisy city.
Though exterior walls are designed and built to block or minimize sound transfer, the same can’t be said for interior walls. Why? Because they’re often hollow.
So, if you want improved noise reduction, filling your interior walls in is a good option. That’s where soundproofing spray foam, also known as acoustic spray foam, comes in.
If you’re contemplating the idea, today we will tell you all about soundproofing foam sound insulation. We will explain what it is, how it works, and everything else. This way, you can make an informed decision and enjoy the silence!
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What Is Soundproofing Spray Foam?
Spray foam is a construction material that’s meant to thermally insulate walls. It’s very common for walls and ceilings because it’s accessible. Additionally, anyone can use it.
This material is made by combining methylene diphenyl diisocyanate with a mix of surfactants, polyol resins, fire-retardants, and catalysts. When the components are blended together as they’re injected, the material expands and hardens.
Though the main goal is to provide thermal insulation, it’s an effective sound deadening material. It’s perfect for providing that extra cushion between walls. That way, they’re thicker and they can block sound a lot better.
When it’s used for these purposes, it’s known as soundproofing spray foam, acoustic spray foam, or sound deadening spray foam. It’s made out of polyurethane and there are two kinds of acoustic spray foam.
On its own, soundproofing spray foam won’t be 100% efficient. However, it’s a great way to complement soundproofing efforts, especially indoors. Not to mention it’s a great way to seal crevices and cracks, so outside noise can’t come in.
Pros of Soundproofing Spray Foam
- It can be used on ceilings, walls, crevasses, and wall cavities.
- It’s sound deadening.
- It will prevent sound from traveling into or out of rooms and buildings.
- It reduces utility bills.
- It’s an effective thermal insulator.
- It provides a barrier for air and moisture.
Cons
- It couples wall components, which can increase the transfer of sound vibration.
- It provides limited sound absorption.
- It can be expensive.
- It increases feedback, sound distortion, and reflective resonance.
- It can be messy to use and following precautions is a must.
Uses for Soundproofing Spray Foam
When you’re using soundproofing spray foam, it should be coupled with materials of greater mass and better sound absorption properties. Here are the most ideal uses for this kind of material:
- Existing Walls
- Ceilings
Soundproofing spray foam for existing walls is perfect for sealing gaps and closing leaks. Gaps on existing walls will allow the noise and air in, which is not ideal. Additionally, closing leaks around fixtures, outlets, around doors, or between drywall sheets, will also reduce noise transfer.
In case you’re interested, I wrote a detailed guide on how to soundproof your bedroom walls and door.
If you want to understand the process of soundproofing spray foam for existing walls, this video can help. In short, the insulation is injected into the closed cavity so you can enjoy the benefits. However, this must be done properly. Otherwise, the expanding foam can cause bulges.
Soundproofing spray foam can be applied to unfinished ceilings, right between the ceiling joists or the floor. This way, any crevasses or cracks will be sealed. However, keep in mind that the hardened surface won’t have enough mass, sound absorbency, or decoupling ability to block noise from dropped items, chairs, or feet.
If your ceiling is already finished, you can still inject acoustic spray foam into it. Holes need to be drilled for the job. But once you’re done, the holes can be plugged, mudded, sanded, and sealed. After that, you can repaint the ceiling and it will look good as new. If the ceiling is already insulated and it’s old, you can remove it to apply the foam. Then, you can relay the old insulation on top.
Types of Soundproofing Spray Foam
Soundproofing spray foam made out of polyurethane is available in open-cell and closed-cell spray foams. Remember, spray foam is made by combining two components; methylene diphenyl diisocyanate and a blend of surfactants, polyol resins, fire-retardants, and catalysts.
- Open-Cell Spray Foam
- Closed-Cell Spray Foam
Open-cell soundproofing spray foam uses water to deliver the two components that will turn into foam. Then, it will expand 150 times its compressed volume. It will create a hardened matrix that’s semi-permeable, which is slightly compressible and flexible.
That way, it will block and trap airflow as well as sound transmission, to a certain degree. Open-cell spray foam has a 3.6 per inch R-value, a 1/2 lb/ft³ density, and a 4.0psi tensile strength.
Closed-cell spray foam, on the other hand, uses hydrofluorocarbon instead of water. This allows the mixture to expand 35 to 50 times its compressed volume. It forms a hard barrier where 90% of the cells are close. That makes it impermeable and more rigid.
Soundproofing spray foam of the closed-cell kind has a 6.1/inch R-value, a 1-3/4 to 2 lb/ft³ density, and 28psi tensile strength. As you can see, there’s a big difference between the two, but both are very useful for different needs.
What Type of Sound deadening Spray Foam Is Better?
When you compare the two kinds of soundproofing spray foam, the open-cell kind of more porous. That means that is less rigid and some moisture and air will get through it. However, the open structure is more effective at trapping sound. That’s why it’s better for noise reduction.
Closed-cell foam is a lot more rigid and solid, so it’s a lot more durable. The air in the cells creates thermal voids and the closed structure keeps moisture and air out. The hard surface can block, reflect or even resonate sound. So, the best one for soundproofing purposes is open-cell acoustic spray foam. If you want to browse both options, this list of options can be helpful.
- FROTH-PAK 620 Sealant – 2 Component Foam Insulation Kit -Our best choice
- Dow Froth Pak 650, Spray Foam Insulation Kit
- Spray Foam Kit II-205 Class 1
What Are Spray Foam Sound Ratings?
Acoustic spray foam sound ratings are important to understand. When you measure sound intensity, there are certain values and metrics you have to follow. This is essential to soundproofing because it will allow you to make the right choices for your needs.
Hertz and decibels are the two essential measurements when it comes to sound. Hertz measures the frequency and decibels measure the intensity of sounds. When you’re trying to dampen sound and prevent it from going through the walls, these are the two things you need to determine.
As you can imagine, certain materials are better at soundproofing than others. For instance, fiberglass will deal with most noises and vibrations, while closed-cell foam spray will barely make any difference. As opposed to open-cell spray foam, which is a bit more effective.
Aside from hertz and decibels, you also want to measure STC and NRC. Sound Transmission Class will measure how effective a material is at blocking or reducing sound. The higher the STC, the less noise will get through. So, that’s a big indicator of a good sound dampening material.
On the other hand, Noise Reduction Coefficient measures how effective a material is at reflecting or absorbing sound waves. This measurement works in Hertz and the greater the number, the better soundproofing properties. This is another way to identify an effective soundproofing method.
Open-cell soundproofing spray foam will expand 3 inches once it’s applied. It has an STC of up to 39 and an NRC of 0.70. Close-cell spray foam only expands an inch when applied. It has an STC of 36 and an NRC of 0.70. So, both kinds of acoustic spray foam have the same level of NRC. However, open-cell spray foam has slightly better STC levels.
Does Spray Foam Sound Insulation Reduce Noise?
When you want to stop noise from penetrating through walls, you need a lot of mass. That’s what will dampen, block, and absorb sound waves so they can go through. Additionally, you’ll need to decouple the wall components to prevent vibration from going through.
As we just discussed, open-cell soundproofing spray foam works better for this. However, you have to keep in mind that spray foam can only go so far. It’s meant to provide thermal insulation above all.
That means that the sound dampening properties are not as strong. However, using acoustic spray foam can serve as a complement to other soundproofing efforts. Spray foam reflects some noise which reduces its transmission. Unfortunately, it usually increases resonance.
In other words, vibration transfer will still be possible. In fact, the spray foam creates an easy path for vibrations to travel. Why? Because it connects all the wall components once it expands and hardens. To understand how effective spray foam is at soundproofing, we need to look at the types of noises.
In our daily life, we commonly hear the impact and airborne sounds. These noises travel in different frequencies, so they encounter obstacles in different ways. Remember that sounds are vibrations, which travel through the air until they find our walls or other surfaces.
If you want to soundproof your walls, you need to dampen those vibrations so you can’t perceive sound. The hardness and density of surfaces will determine how easily sound will travel through them. That’s why spongy materials are often so effective at soundproofing.
Sound dampening panels are a common soundproofing method. They’re made of spongy polyurethane, which absorbs sounds and reduces echo and interference. That’s why spray foam, particularly open-cell spray foam, provides certain soundproofing properties.
They have a limited soundproofing effect, though, and it’s important to be aware of that. Open-cell spray foam will reduce incoming noise. However, it doesn’t do it in a big way. The difference is not huge. That doesn’t mean it’s not an essential foundation to soundproofing.
For instance, spray foam sound insulation can be applied to all the crevices and cracks in the wall. That means the sound won’t come in through fissures. Combine that with three layers of soundproofing paint, and the results will be even better.
If you haven’t seen it before, soundproofing paint is super thick. So, by applying a few layers, it can make a small difference. Once the paint is dry, you can install acoustic panels on the walls that receive the most noise.
All this is just an example of how combining different methods can meet your soundproofing needs. If you want to know the difference that soundproofing spray foam makes, go two minutes before the end of this video. They do a demonstration that will give you a good idea.
The Process of Using Soundproofing Spray Foam
Unless you have experience as a contractor, we don’t recommend you do this on your own. Especially not if you want soundproofing spray foam for existing walls. What you should do is find an expert contractor in your area and get a quote from them.
Once you do that, the process of spray foam insulation can begin. We will explain it here, so you know what to expect. The first thing contractors will do is remove the existing insulation in the area you want to soundproof. If you have a new build property, nothing will have to be removed.
When they’re done removing the insulation, if applicable, the crew will have to prep the area for the soundproofing spray foam. The kind of preparation will depend on the area. For example, if you’re soundproofing the basement rim joist, the crew will have to move any items you may be storing. They will also cover them with plastic.
After contractors are done preparing, they will run a hose to the area. When you see trailers and trucks coming to your home, the real work is about to begin. They will start insulating the walls with the soundproofing spray foam and when they’re done, they will clean the area.
Though we don’t recommend you insulate walls, ceilings, and other large surfaces yourself, there’s something you can indeed DIY. You can use soundproofing spray foam to get all the cracks and crevices on walls, etc.
However, you have to find a good kit, like the GREAT STUFF PRO foam insulation kit. Additionally, you need to get familiar with the process. This video provides many helpful tips that will make things a bit easier.
Cost of Acoustic Spray Foam
On average, open-cell soundproofing spray foam costs between $0.44 and $0.65 per board foot. On the other hand, closed-cell soundproofing spray foam goes for $1 to $1.50 per board foot.
It’s important to note that insulation costs may vary depending on where you live, the required R-value, and the kind of insulation. So, these numbers are just to give you a general idea of spray foam costs.
Hiring a professional to install your soundproofing spray foam will cost you between $1,294 and $3,836. We don’t recommend DIY for big surfaces unless you have experience. However, if you feel up for it, you will spend less on installation. The downside is that there’s no warranty.
Here’s a list of average costs for spray foam insulation based on square feet:
| Square Feet | Average Price |
| 100 | $44 to $150 |
| 200 | $88 to $300 |
| 500 | $220 to $750 |
| 1,000 | $440 to $1,500 |
| 1,500 | $660 to $2,250 |
| 2,000 | $880 to $3,000 |
| 3,000 | $1,320 to $4,500 |
Measure the area you want to insulate and decide whether you want open-cell or closed-cell spray foam. Then, you can easily calculate an estimate. Remember, prices may vary depending on different factors, but this will give you a general idea.
Soundproofing spray foam insulation kits to take care of cracks and crevices cost between $100 or less and $2,000 or higher. That depends on the amount of spray foam, the kind of material, and the equipment they provide.
Alternatives to Acoustic Spray Foam
Now that you fully understand what soundproofing spray foam is, it’s time to discuss a few alternatives. As discussed before, acoustic spray foam can only go so far. If you want to do the job well, you’ll need to combine it with other soundproofing methods. Here’s a list of the most common options and why they work well:
- Soundproofing Panels
- Soundproofing Curtains
- Soundproofing Paint
- Fiberglass Panels
- Mass Loaded Vinyl
Soundproofing panels are one of the most common methods because they’re really good. They can improve the sound quality in any area you decide to install them. They are made of polyurethane foam and they come in squares that you can hang on the walls.
Usually, they feature a pyramidal or wedged texture, which contributes to their soundproofing properties. They are 1-inch thick and that works very well when it comes to blocking sound waves.
Using soundproofing panels is an effective way to reduce noise in any room and they’re fire retardant, which is a good plus. They’re not difficult to find and the average cost ranges from $1 to $10 per square foot.
Soundproofing curtains are another great option! They are thick and soft, but they are effective at reducing noise and absorbing vibrations. Additionally, they can black out the room, which is great for bedrooms.
These special curtains are made with thick fabrics and they are stylish, so you won’t have to sacrifice your décor. They will improve the room’s acoustics, which makes them worthwhile.
Curtains are very easy to install and you can hang them anywhere. If you’re planning on soundproofing your home little by little, this is a great way to accomplish that. Soundproofing curtains will cost $50 or less to $500. We recommend investing in high-quality ones!
This is another great way to soundproof your home step by step. Soundproofing paint can make a nice difference. It’s thicker than regular paint and it’s recommended you apply at least 3 coats of it.
The only drawback is that it’s not easy to apply and it will take time, so get ready for some work. Or you can hire someone to do paint the area for you! Its sound dampening effect is enough to make it worth your time.
A soundproofing paint job costs around $2 and $3 per square foot. You can expect to pay $10 to $25 per wall, depending on the size. The gallon of soundproofing paint can cost between $50 and $70, to give you an idea.
Fiberglass panels are a great option as well. As far as soundproofing methods go, this is one of the most popular. It’s a great noise and temperature insulator, so it’s commonly used in the construction of homes and buildings.
If you want to soundproof your home with these panels, you can get them in square shapes or the shape of food panels. Do keep in mind that fiberglass panels are expensive, but they’re very effective.
On average, fiberglass panels can cost from $1,000 to $1,300. That’s a big investment, so you’ll have to think about it. One thing’s for sure, you can be certain these panels will block high and low-frequency sounds.
Last but not least, we have mass-loaded vinyl. It can absorb sound very well and also reduce vibrations. It has many different applications, so you can use it in your home or your car.
It’s one of the most common options when it comes to soundproofing music studios, home theaters, and offices. That means it’s very effective! On average, it costs between $2.50 and $5 per square foot.
Mass-loaded vinyl is durable and it’s versatile because it’s available in different thicknesses and weights. Additionally, installation won’t take much time and the material is very easy to find.
Here’s an interesting comparison between Rockwool and Fiberglass insulation, if you want to check.
Final Words
When it comes to soundproofing, there are many ways to reach your goals. What we can take from all this information is that soundproofing spray foam has useful applications. Combined with other soundproofing methods, it will provide exactly what you’re looking for; peace and quiet!
On its own, acoustic spray foam won’t provide the results you need. However, we encourage you to pair it with soundproofing paint and soundproofing curtains. If you want to go the extra mile, consider getting soundproofing panels. Either way, it will do the trick!
