Will Soundproof Expanding Foam Help Reduce Noise?

soundproof expanding foam ceiling install

Last updated: November 8, 2021 at 14:30 pm

Expanding foam is commonly used to insulate walls and ceilings. However, there is expanding foam which claims to have soundproof qualities.

In this article:

Let’s look at what soundproof foam actually is, and whether it’s worth it if you’re trying to soundproof a wall, or even a whole room.

What Is Soundproof Expanding Foam?

Soundproof expanding foam is a closed or open-cell polyurethane material that expands to fill a cavity or cover a surface before hardening. Sprayed into wall cavities or onto walls, spray foam is a construction material used (mainly) for wall thermal insulation.

It’s commonly used amongst builders because of its ultra-accessibility and comparative ease of use. Despite primarily serving as a insulation, soundproof expanding foam is also used to eliminate unwanted sound, especially because of the additional barrier it creates between connecting walls… enhancing their thickness and sound resistivity.

Spray foam, as mentioned earlier comes in two variations; closed-cell and open-cell spray.

Closed-Cell

Made from closed cells polyurethane, this type of spray foam is denser, heavier, and more rigid as its cells are compact. Therefore, allowing little or zero flow of heat and air.

It is also water-resistant, preventing humidity and water from entering the space. However, its expansion is relatively smaller than open-cell spray foams, making it a solid option for major construction.

Open-Cell

open cell foam

Open-Cell foam is lighter and less dense than closed-cell foam. Technically, they are direct opposites of each other. Open-cell spray foam is very light due to the open cells in the polyurethane, making them expand up to 3 inches more.

It’s also flexible, ideal for sealing little cracks in windows and walls. While they have excellent heat resistivity, open-cell foams aren’t great at repelling vapor and water.

Will Soundproof Expanding Foam Help to Reduce Noise?

Does spray foam soundproofing reduce noise? Technically, no. Although open-cell spray foams perform better, neither offers maximum effectiveness for sound deadening. The qualities that make soundproof expanding foam an excellent thermal barrier significantly contribute to its inefficiencies in reducing noise transfer.

The weight and structure of the materials to use are essential factors to consider when soundproofing. Typically, useable materials must absorb, block, and dampen soundwaves to prevent sound transfers through walls or ceilings.

Applying this knowledge alongside that of closed and open-cell polyurethane is instrumental in comprehensively understanding why soundproof expanding foam may not be the best soundproofing option.

This also cuts across understanding the type of noise we typically deal with daily: impact and airborne sounds. These sound types travel in varying frequencies, determining their encounters with obstacles, such as walls, ceilings, etc.

Typically, sounds consist of vibrations that travel through the air. To achieve effective soundproofing, you must adequately dampen and absorb such vibrations to reduce their impacts. Objects with hard surfaces, such as walls, aid the easy passage of sounds and vibrations. This is why spongy, soft materials are often recommended for soundproofing.

However, although spray foams do not reduce noise to desirable levels, it still remains an essential foundation for other effective soundproofing materials. For instance, you can use soundproof expanding foam to fill wall crevices, ensuring sound doesn’t infiltrate through any gaps.

How Much Does Expanding Foam Cost?

Generally, open-cell spray foams aren’t as expensive as closed-cell spray foams. The costs of soundproof expanding foams depend on various factors, including where you reside, the location the spray foam is used, if you want to DIY or hire professionals, cost of labor, etc.

While some areas need 4 to 5 inches of foam, some may need more than 10 inches. Sometimes, also, some space may require a combination of both closed-cell and open-cell spray foam. Labor costs also vary, depending on location, amount of insulation, accessibility, material costs, etc.
Generally, the costs of soundproofing your space with expanding foam may be high, depending on the factors briefly outlined above. However, to get the most approximate price for your home soundproofing, contact an installer for an assessment.

As mentioned earlier, location of use also plays a significant role in determining the cost of spray foam soundproofing. We have carefully explained this below:

Loft/Ceilings

Installing soundproof expanding foam, whether open-cell or closed-cell, on your ceiling averagely costs £2,400 to £8,000. However, understand that spray foam isn’t ideal for such a location due to the risk of moisture infiltration. If you must spray foam your roof, ensure you use closed-cell expanding foam.

Walls

Installing soundproof expanding foam on walls averagely costs £2 to £8 per square foot. This applies to both insulating an existing home or a newly constructed space. Factors that may influence price discrepancies between both cases include location and accessibility. Also, some installers may need to open existing walls which may also add to the insulation costs.

Better Alternatives to Soundproofing Walls/Ceilings

There are better alternatives to soundproofing your walls and ceilings than using the soundproof expanding foams. Interestingly, these alternative solutions also have excellent thermal properties like expanding foam… but possess better soundproofing capabilities.

Soundproof Panels

Soundproof panels are arguably the best way to enhance your space’s sound quality. These panels are also made of polyurethane foam and available in square shapes, hangable on walls to reduce echo, reduce noise infiltration, and significantly improve sound quality.

They typically possess pyramidal or wedged textures that contribute to their effectiveness in dissipating sound waves. Apart from its noise cancellation properties, soundproof panels are also safety materials, thanks to their fire-retardant capabilities.

Soundproof Plasterboard

Soundproof plasterboard is paper-backed mixes of paper nailed to wall frames to reduce echo and noise. Builders achieve this by varying the density of the core compared to the facing material. This makes the plasterboard tougher, consequently reducing sound transmission and impact damage.

How effective are soundproof plasterboards? Very effective! Due to their higher density, they can excellently absorb airborne sounds, echo, and vibrations. The higher the mass of soundproof plasterboards, the better their level of sound insulation. They’re most recommended for ceilings and thin walls.

Plants

Plants have several “known” benefits and numberless less-known ones. One of the less-known benefits of plants is their noise reduction capabilities. Used in various ways to reduce noise, plantings along freeways to reduce distributed noise to the adjacent communities.

Plants reduce noise majorly through sound absorption, thanks to parts, such as leaves, stems, wood, branches, rough bark, etc., with high sound-absorption properties because of their unique surface area. Plants also reduce through deflection.

Sound waves reflect back to their source when they hit a masonry wall due to the wall’s rigidity. However, when the same wave hits a flexible material, it causes the material to vibrate, converting the sound into other energy forms and deflecting it in other directions. This deflection effect significantly aids noise reduction.

Plants also cause the refraction of sound waves: this follows the working principle of carpets and rugs. Carpeting prevents sound from bouncing around rooms, eliminating echoes. Covering surface areas also create the same effects. Perfect examples of such applications include ground cover plantings, lawns, green walls, etc.

The sound deadening capabilities of plants depend on several points. This includes:

  • The number of plants – the more the plants, the better its ability to reduce noise.
  • Size of plants – plants with a larger surface area would absorb sound better than others. Besides, the soil is an excellent absorber of sound; therefore, the bigger the container, the more soil containable, and the better its sound reduction quality.
  • Plant placement – where you place the plant also matters. They should be placed around the space’s perimeter instead of the center. This way, sound reflecting off the walls bounces straight unto the leaves of such plants.

Conclusion

Answering the question again, soundproof expanding foam isn’t the best insulation method to soundproof your room or building. Soundproof expanding foams are ideal for thermal insulation; of course, there are better alternatives to soundproofing your home.

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About the Author: AJ

AJ writes about living a quieter life, soundproofing tips and recommending the best quiet products here on Quiet Living.

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