Does Spray Foam Insulation Reduce Noise?

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Home is where the heart is, they say. But what if your beloved home comes with a side of unwanted noise? Whether it’s the traffic outside, the neighbor’s blaring stereo, or even the pitter-patter of raindrops turning into a thunderous downpour, noise can be a relentless intruder, disrupting your peace and serenity. If you’ve ever wished for a magic solution to hush those unwelcome sounds and turn your house into a sanctuary of tranquility, you’re in for a treat.

One of the most popular products people hype for is spray foam insulation. While it does exemplary well in thermal insulation, does this product reduce noise?

Spray foam, or spray polyurethane foam, does provide a degree of sound reduction, but it falls considerably short compared to alternative insulation materials like fiberglass insulation and mineral wool. Furthermore, fiberglass and rock wool exhibit superior fire-retardant properties compared to spray foam insulation.

Does Spray Foam Insulation Reduce Noise?

What is Spray Foam Insulation?

Spray foam, also known as expanding foam in the UK, is a chemical compound formed by combining two substances: isocyanate and polyol resin. When these components are mixed and applied, they undergo a reaction that causes the foam to expand dramatically, increasing in volume by 30-60 times its original liquid state.

Spray foam is versatile and can be applied in various settings, such as new construction, attics, crawl spaces, and rim joists, where open cavities are present. Additionally, it’s suitable for use in existing homes, commercial buildings, and pole barns, provided there is access to the cavities.

One outstanding feature of spray foam is its ability to maintain its original shape indefinitely. Unlike traditional insulation materials, spray foam adeptly seals cracks, gaps, and crevices during installation, ensuring it won’t undergo compression, sagging, or settling over time.

Types of Spray Foam Insulation

There are two primary types of spray foam insulation: open-cell and closed-cell. Let’s explore these two types in more detail:

  • Open-Cell Spray Foam Insulation
  • Closed-Cell Spray Foam Insulation

Light Density Open-Cell Spray Foam Insulation

Open-cell spray foam is a lightweight, flexible insulation material. It gets its name because the tiny cells within the foam are not completely sealed; instead, they remain open, filled with air.

Commonly referred to as “half-pound foam,” light-density open-cell SPF (Spray Polyurethane Foam), or ocSPF for short, exhibits a semi-rigid texture resembling a sponge. During installation, ocSPF expands to generate small, open cells that become infused with carbon dioxide. This unique expansion property enables it to effectively conform to various cracks and crevices. This product adheres to irregular surfaces when applied, creating a reliable air-sealing insulation layer.

What sets ocSPF apart is its pliability. Buildings naturally undergo contraction and expansion due to changing weather conditions. Thanks to its flexibility, ocSPF can adapt to these structural shifts, minimizing the need for frequent reinstallation.

While it may not be a vapor barrier, ocSPF excels in acting as an effective air and sound barrier. Consequently, applications within interior walls and various indoor settings are often recommended where these specific insulation properties are desirable.

Medium-Density Closed-Cell Spray Foam (ccSPF)

Closed-cell spray foam is denser and more rigid compared to open-cell foam. The cells within closed-cell foam are completely sealed and filled with gas. Density: Closed-cell foam boasts a significant thickness, imparting it with structural strength and the ability to resist compression.

  • Thermal Insulation: It boasts impressive thermal insulation characteristics, boasting a higher R-value than open-cell foam, rendering it more efficient in extreme climate conditions.
  • Moisture Resistance: Closed-cell foam functions as a formidable moisture barrier, displaying exceptional resistance to water. This makes it particularly suitable for areas susceptible to moisture infiltration.
  • Air Sealing: It provides top-notch air sealing capabilities, effectively reducing air leakage and draft issues within a structure.
  • Strength: Thanks to its inflexible composition, closed-cell foam has the potential to enhance a building’s structural integrity.

Closed-cell spray foam insulation is often used in exterior wall insulation, roofing systems, basements, and foundations, where moisture resistance and enhanced structural integrity are essential. It is favored in areas with high humidity or a risk of flooding.

Spray Foam Insulation vs. Other Insulation STC Ratings

An average interior wall, comprising 1/2-inch-thick drywall on both sides, naturally comes with an STC rating of 34.

Adding fiberglass increases its STC rating to 39, and the same enhancement is achievable with open-cell spray foam. This implies that fiberglass and open-cell foam deliver similar soundproofing performance, distinguishing them from closed-cell foam.

On the other hand, Rockwool stands out as an exceptional performer, elevating the STC rating significantly to 45, marking a substantial improvement.

It’s important to mention that closed-cell foam also raises its STC rating, but the increase is limited to 37.

Material Sound Transmission Class (STC Ratings)
Typical inside wall with ½ “of drywall on either side 34
Open Cell Spray Foam 39
Closed-cell spray foam 37
Fiberglass 39
Rockwool 45

Spray Foam vs. Other Insulation Noise Reduction Coefficient (NRC)

The Noise Reduction Coefficient (NRC) is a measure used to quantify the sound-absorbing properties of a material or surface. It is commonly used in architecture, interior design, and acoustics to assess how effectively a material or surface reduces or absorbs sound within a specific environment.

The NRC is a number between 0 and 1, typically expressed as a decimal or percentage. The higher the NRC value, the better the material or surface absorbs sound. Here’s what the NRC values usually mean:

  • An NRC of 0 indicates perfect sound reflection, meaning the material or surface does not absorb any sound but reflects it entirely.
  • An NRC of 1 (or 100%) indicates perfect sound absorption, meaning the material or surface absorbs all incident sound.

Sound absorption tests are conducted according to standardized procedures to determine the NRC of a material or surface. These tests measure the material’s ability to absorb sound at different frequencies. The NRC is then calculated based on the average absorption coefficients across these frequencies.

Insulation Type Thickness NRC
Closed Cell Polyurethane 2.75” 0.70
Open Cell Polyurethane 3” 0.70
Rockwool Safe ‘n’ Sound Batt 3” 1.05
Rockboard 60 3” 1.10
Owens Corning Fiberglass 703 3” 1.10
Owens Corning Fiberglass 703 3” 1.10

Does Spray Foam Insulation Help with Soundproofing?

Does Spray Foam Insulation Reduce Noise?

Spray foam insulation can help with soundproofing to some extent, but its effectiveness in reducing sound transmission depends on the type of spray foam used and its application method.

Open-cell foam is porous with interconnected, open cells. It is less rigid than closed-cell foam, allowing some air and moisture to permeate. Due to its open structure, open-cell foam excels at sound absorption, making it a superior choice for noise reduction compared to closed-cell spray foam insulation.

The hard surfaces of closed-cell spray foam won’t absorb sound waves and will reflect, resonate, and bounce more sound waves.

What type of insulation is the best for soundproofing?

From the sound transmission class STC rating table above, there isn’t a noteworthy difference between fiberglass insulation and spray foam. Open-cell spray foam might be the preferred option since it simplifies sealing all the nooks and crannies. You won’t have concerns about it shifting over time like Rockwool or Fiberglass might, potentially creating openings that permit sound to penetrate.

But Rockwool does exemplary well in blocking and absorbing sound waves. Let’s see how they compare now that we have only two contenders.

  • Locations for Installation: Rockwool is versatile and can be used in various locations, including unfinished walls, floors, ceilings, ducts in unconditioned spaces, unvented low-slope roofs, new cavities, and unfinished attic floors. In contrast, Spray Foam is primarily used for insulating floors and ceilings, creating a tight air barrier.
  • Effectiveness in Blocking Air: Rockwool does not provide an air barrier, allowing air to pass through. In contrast, Spray Foam (closed-cell) creates a tight air barrier, making it more effective in preserving energy efficiency.
  • Longevity: Rockwool insulation has a limited lifespan, whereas Spray Foam insulation is more permanent.
  • Extreme Weather Temperatures: Rockwool allows heat to escape rapidly in cold temperatures but is less effective in extremely hot or humid climates. On the other hand, Spray Foam is suitable for both hot and cold environments.
  • Cost: Rockwool has a lower initial cost compared to Spray Foam, which comes with a higher upfront expense.
  • Installation Process: Rockwool can be installed as a DIY project, but it requires anchoring of the insulation. In contrast, Spray Foam typically necessitates professional installation, although cautious DIY installation is possible.
  • Health Hazards: Rockwool is considered safe with no known health hazards. In contrast, Spray Foam can be carcinogenic with long-term exposure, posing potential health risks.
  • Does Spray Foam Insulation Reduce Noise?

 Final thoughts

In conclusion, the question of whether spray foam insulation reduces noise can be answered with a resounding “yes.” Spray foam insulation, known for its exceptional thermal insulation properties, also acts as an effective sound barrier. By sealing gaps, cracks, and crevices in your walls and ceilings, it minimizes the transmission of airborne noises, making your living spaces quieter and more comfortable.

However, it’s essential to note that while spray foam can significantly reduce noise, it may not eliminate all sound sources. A combination of insulation materials and soundproofing techniques may be necessary for complete noise control, especially for impact or structural sounds.


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