Soundproofing Spray Foam For Existing Walls

by Matthew David | Updated: 09/15/2023

Soundproofing Spray Foam For Existing Walls

Have you ever been frustrated by hearing your neighbor’s music, kids, or barking dogs through the walls? Or do you wish you could watch a movie without disturbances from outside noises? If so, you’re not alone. Many homeowners deal with unwanted sounds transferring between walls and into living spaces.

Luckily, there’s an easy and affordable solution to soundproof existing walls – spray foam insulation! In this guide, we’ll explore using spray foam to block noise and transform those thin, hollow walls into noise-blocking barriers. Let’s dive in!

Benefits of Using Spray Foam for Soundproofing

Spray foam insulation offers a bunch of excellent benefits for soundproofing:

It Creates an Airtight Seal

When sprayed into cracks, gaps, and cavities, the foam expands and hardens to form an airtight barrier. This prevents sound waves and noise from penetrating through openings in the walls. The airtight seal locks out exterior noise pollution.

It Fills Cracks and Gaps

All those small cracks around outlets, windows, and baseboards become pathways for noise to enter. Spray foam insulation expands and finds its way into even the tiniest crevices, sealing all potential holes. No more audio leakage!

It Acts as a Sound Barrier

In addition to sealing gaps, the hardened foam forms a physical barrier that helps block sound transmission. The dense foam dampens vibrations and absorbs some of the sound energy. The more layers added, the better the noise reduction.

It’s Easy to Apply in Existing Walls

A major perk of spray foam is that you can apply it without removing drywall or doing major renovations. Just drill some small holes, insert the applicator nozzle, and fill the cavity. It’s that simple to upgrade your walls for noise control.

It Provides Insulating Qualities

The foam offers thermal insulation too. By keeping your home well-insulated, you won’t have to crank up fans and air conditioning units that can make ambient noise. It’s a two-for-one deal!

It Adds Moisture Resistance

Spray foam is water-resistant, preventing moisture accumulation within the walls that could lead to mold growth. Bonus points for added insulation against outdoor humidity.

It’s Cost Effective

Compared to fully soundproofing a room or rebuilt insulated walls, spray foam is budget-friendly. The foam itself is relatively inexpensive and it only takes a few simple tools to get a noise-reducing solution installed in your existing walls.

Types of Soundproofing Spray Foam

There are two main types of spray foam to choose from: open-cell and closed-cell. Both work well for soundproofing but have some differences.

Open-Cell Spray Foam

Open-cell spray foam has a sponge-like texture with tiny open air pockets throughout its structure. It’s flexible and soft. When sprayed into a cavity, open-cell foam expands rapidly, sometimes tripling in size! This helps it push into cracks easily and adhere well to odd shaped spaces.

The open structure gives open-cell foam effective sound absorbing capabilities. Noise is able to enter the foam but then gets trapped and muffled within the material. Open-cell provides noise reduction across a broad spectrum of frequencies.

Open-cell foam is also lighter, cheaper, and requires less material to fill a space compared to closed-cell alternatives. The only downside is it has a lower R-value, so the insulating properties are a bit weaker.

Closed-Cell Spray Foam

Closed-cell spray foam has a very dense, rigid structure. The foam cells are completely closed and filled with gas, limiting air movement. Closed-cell foam expands much less than open-cell, only around 1 inch max.

The compact structure makes closed-cell foam resistant to moisture and vapor intrusion. The stiffness helps reinforce structural integrity too. Closed-cell foam has superior insulating R-values than open-cell.

For soundproofing, the rigidity and density allow closed-cell foam to block noise effectively. However, it does not absorb as much ambient sound due to the lack of open air pockets within it. Closed-cell foam works best as a sound barrier.

Overall, open-cell spray foam may have a slight edge for noise reduction given its sound absorption capacities. But combining layers of open-cell and closed-cell foams can provide the best of both worlds!

How to Apply Spray Foam for Soundproofing

Ready to soundproof your existing walls with spray foam? Here’s a step-by-step guide:

Safety First!

Gather Your Materials

Step 1: Identify Problem Areas

Step 2: Prepare the Wall

Step 3: Apply the Foam

Step 4: Smooth and Trim Excess Foam

Tips for Best Results

And that’s it – you’ve now transformed those hollow, echo-prone walls into sound-dampening barriers!

Real World Examples

Wondering how spray foam can be used for soundproofing in real home projects? Here are some examples:

Soundproofing a Home Theater

Installing home theater surround sound? Noise leakage can be an issue. Apply closed-cell spray foam between the studs before drywalling to create mass loaded noise-blocking partitions between the theater and rest of home.

Soundproofing a Bedroom

Bedrooms often share walls with kitchens, bathrooms, and noisy pipes. Fill the cavities with open-cell spray foam to prevent ambient noise transfer for better sleep. Closed-cell foam around windows helps block exterior sounds from traffic.

Soundproofing a Basement Music Studio

Building a basement jam space? Use layers of open and closed cell foam between the studs for maximum noise isolation. Prevent sound from disturbing housemates by creating a fully insulated sound cage around the studio.

Choosing the Right Spray Foam Product

With all the brands of spray foam products out there, how do you pick the right one for soundproofing? Here are key factors to consider:

Combining Spray Foam with Other Soundproofing Methods

While spray foam insulation alone can make a notable difference, combining it with additional soundproofing techniques can take noise reduction to the next level:

Soundproof Drywall

Use special soundproofing drywall like QuietRock over the cured foam. The laminated mass loaded vinyl barrier helps block additional noise.

Acoustic Panels

Strategically place acoustic foam panels over the spray foam to absorb any residual sound waves penetrating the insulation.

Insulation Blankets

Adding insulation blankets like Roxul Safe’n’Sound before installing drywall boosts the wall’s noise blocking capacity.

Soundproof Curtains

Install dense, multilayer soundproof curtains over windows and doors to prevent noise entry from outside your home.

Isolate Vibrations

Use rubber isolation pads under any vibrating equipment or appliances to prevent transfer of vibrations through walls.

Noise Canceling Devices

Add white noise machines or noise cancelling speakers to mask ambient noises that make it through the insulating foam barrier.

Layering these soundproofing techniques with spray foam can significantly improve noise reduction and provide auditory privacy.

Limitations of Spray Foam Soundproofing

While spray foam is an accessible and affordable noise reduction solution, it’s good to be aware of a few limitations:

Even with these limitations, spray foam remains one of the most convenient ways to dampen noise penetration through existing walls. Just supplement with other methods like mass loaded vinyl barriers for low frequency sound control.


After learning all about using spray foam insulation for soundproofing, are you ready to transform those echoey, noise-leaking walls?

This simple yet effective method lets you seal air gaps, absorb vibrations, and create an interior sound barrier without major renovation work. Just spray it into the cavities and let chemistry do the rest – noise-blocking foam in a can!

Armed with the right techniques and products, you can control noise transfer through walls for peace and privacy. So don’t tolerate unwanted racket from next door or outside any longer – fight back with sound-smothering spray foam!