Is Spray Foam Insulation Good For Soundproofing?

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How Spray Foam Insulation Works

Image of a diagram showing the application of spray foam insulation to a building.
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Spray foam insulation, also known as SPF, is a special kind of material that’s made by mixing two chemicals.

When these chemicals interact, they react super quickly and expand to create a foam that acts like a shield on your walls, around corners, and even on contoured surfaces.

This foam is not only a heat insulator but also acts as an air sealer and a moisture barrier. It means your home stays warm when it’s cold outside, cool when it’s hot, and quieter all year round!

The making of this foam needs two special liquids. They are kept in two separate containers. People call these containers “A” and “B”. The stuff in the “A” container is usually a mix of two chemicals – methylene diphenyl diisocyanate (MDI) and polymeric methylene diphenyl diisocyanate (pMDI).

The “B” side usually contains a blend of polyols, catalysts, blowing agents, flame retardants, and surfactants. Don’t worry if these names sound complicated – the important thing to remember is that when these chemicals are mixed, they react to form the spray foam insulation that we see.

Reducing Heat Loss in Winter and Heat Gain in Summer

One of the best things about spray foam insulation is that it’s great at reducing heat transfer. But what does that mean exactly? Well, heat transfer refers to how heat moves from one place to another.

This can happen through conduction (when two objects of different temperatures touch), convection (when warmer areas of a liquid or gas rise to meet cooler areas), or radiation (which doesn’t need matter to transfer heat).

Spray foam insulation is good at cutting down on this heat transfer, which helps us stay cool in the summer and warm in the winter.

Another cool thing about spray foam insulation is that it can help seal air leaks in your home. These are often tiny cracks and gaps that you wouldn’t normally see but can let unwanted air and heat in or out of your home.

Because spray foam insulation can expand up to 100 times its liquid volume, it can effectively fill these cracks and gaps, helping to control air transfer and make your home more comfortable.

Reducing Noise by Filling in Gaps and Cracks in Walls and Ceilings

While spray foam insulation is great for controlling temperature and air transfer, it’s not quite as effective when it comes to reducing noise. It doesn’t have the mass to absorb sound waves, and the hardened foam can interfere with absorption.

It also tends to increase resonance, which can distort sound quality. That said, it can still help to some extent by filling in gaps and cracks that might let sound through.

Is Spray Foam Insulation Good For Soundproofing?

Is Spray Foam Insulation Good For Soundproofing?
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Spray foam insulation can be effective at reducing noise, but it is not the best option for soundproofing.

Spray foam insulation can help to block sound waves by filling in gaps and cracks in walls and ceilings. It can also help to absorb sound waves, which can help to reduce the overall noise level in a room.

spray foam insulation is not as effective at blocking low-frequency sounds as it is at blocking high-frequency sounds. This is because low-frequency sounds have longer wavelengths, which can more easily pass through the foam.

If you are looking for a more effective way to soundproof a room, you may want to consider using other materials, such as mass-loaded vinyl (MLV) or soundproof curtains.

MLV is a heavy, vinyl sheet that is designed to block sound waves. Soundproof curtains are made of thick, heavy fabric that is also designed to block sound waves.

Here are some of the pros and cons of using spray foam insulation for soundproofing:


  • Can help to block sound waves by filling in gaps and cracks
  • Can help to absorb sound waves
  • Can be used to insulate walls, ceilings, and floors
  • Is relatively easy to install


  • Not as effective at blocking low-frequency sounds as other materials
  • Can be more expensive than other materials
  • Can release harmful chemicals into the air

Comparing Spray Foam Insulation to Other Materials for Soundproofing

When it comes to soundproofing, different materials have varying levels of effectiveness. Let’s look at spray foam insulation in comparison with other common materials.

A typical interior wall with ½” of drywall on each side has an STC (Sound Transmission Class) rating of 34. Installing fiberglass or open-cell spray foam can increase this rating to 39. This means they perform about the same in terms of soundproofing.

On the other hand, Rockwool performs exceptionally well, increasing the STC rating to 45. But it’s worth noting that Rockwool does this at double the cost of fibreglass.

The closed-cell foam also increases the STC rating, but only to 37, and at a higher cost than open-cell foam or fibreglass.

Potential Risks with Spray Foam Insulation

A person is spraying foam insulation on a wall. The foam is expanding and filling in the gaps between the studs. The person is wearing safety glasses and a respirator to protect themselves from the fumes.
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While spray foam insulation can be effective, it’s important to be aware of potential risks. Spray foam can ignite and burn if exposed to a sufficient heat source, making it combustible.

This type of foam has chemical properties that produce smoke when ignited, which could potentially render occupants of a house unconscious and even lead to temporary blindness.

It’s also important to know that both open-cell and closed-cell spray foam have a Flame Spread rating of 75, which means that it can spread fire to nearby combustibles much quicker than Rockwool or fibreglass, both of which have a Flame Spread rating of 25.

Other Soundproofing Techniques

Apart from using soundproofing materials, there are other techniques to further enhance soundproofing.

One such method is installing two layers of drywall. This adds more mass to the wall, effectively creating an additional barrier that prevents sound from getting through.

One sheet of drywall can already provide a significant reduction in noise, but installing two layers of 5/8 drywall with a noiseproofing compound between them can further increase the insulation.

This can give you an approximate STC of 35 or 40, reducing the noise that’s allowed through the wall by about 35dB-40dB.

Another technique is building a decoupled 2-layer drywall. This involves building a second wall and leaving an air gap between it and the previous wall, which is then filled with fibreglass or Rockwool.

Two sheets of drywall are then installed, with a noise-proofing compound between them. This method effectively decouples the new wall from the original studs, reducing the transmission of sound and vibration to the drywall.

Great! Let’s dive into each of these soundproofing methods in detail, and I’ll share some of my experiences along the way.

Other Options For Soundproofing

Mass Loaded Vinyl

Mass-loaded vinyl, or MLV, is an excellent soundproofing material. It’s a flexible, heavy sheet that you can add to walls, ceilings, or floors to reduce noise transmission. I’ve used MLV in my own home studio, and it made a huge difference.

This soundproofing method is versatile and works great, especially when you’re dealing with low-frequency noises like the rumble of traffic or machinery.

Soundproof Drywall

Another reliable method is soundproof drywall. It’s denser than regular drywall and contains layers that are designed to absorb and dissipate sound waves.

When I renovated my basement into a quiet workspace, soundproof drywall was a game changer. It’s perfect if you’re starting a construction project or if you’re ready to replace existing walls.

Acoustic Panels

Acoustic panels are another one of my favourites. They’re designed to absorb sound, reducing echo and background noise. These panels can be installed on walls or ceilings, and come in various sizes and colors. I’ve found them particularly useful in my home theater where they helped create a clearer, more focused sound.


Carpeting might seem like an old-school solution, but it’s surprisingly effective. Carpets, especially with padding underneath, can absorb sound and reduce echo. I’ve noticed a significant difference in my upstairs bedroom after laying down a plush carpet. It’s an easy and stylish way to soundproof a room while adding comfort underfoot.

Heavy Curtains

let’s talk about heavy curtains. These are great for soundproofing windows, and they’re also useful for reducing noise from outside. I’ve hung heavy, thermal curtains in my living room, and they’ve made my space much quieter, besides helping with temperature control.

FAQs for spray foam insulation

How much does spray foam insulation cost?

In general, open-cell foam is less expensive than closed-cell foam. The cost of spray foam insulation can range from $1 to $3 per square foot.

How long does spray foam insulation last?

Foam insulation stays good for a long time. How long? It depends. If it’s open-cell foam, you’re looking at 10 to 20 years. But with closed-cell foam, it might stick around for 20 to 30 years. The type of foam matters, and so does how you put it in.

Is spray foam insulation safe?

Spray foam, if put in right, is not a danger. Still, it gives off some chemicals for a bit after it’s put in. These chemicals float into the air. This time lasts a few days usually. It’s key to let fresh air in during this time.


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About Author

this is john Andrew from Australia, I am an architect I have worked for the home improvement company Bunnings. I am a home improvement specialist as well as a part-time blogger. Where I will keep giving you tips on soundproofing, you follow our blog.

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