This post contains affiliate links for which we may make a small commission at no extra cost to you should you make a purchase. We're passionate about DIY soundproofing and our recommendations are genuine.
Does spray foam insulation reduce noise? The answer is YES, spray foam insulation does work.
Even though this product is specially designed for thermal insulation purposes, it does offer some soundproofing capabilities.
Soundproof spray foam is an open/closed polyurethane material is made up of polymeric MDI and a blend of polyol resins, fire retardants, catalysts, and surfactants.
The fire retardants help in reducing smoke generation and combustibility. (Source)
Does Spray Foam Insulation Reduce Noise
Spray Foam insulation is a type of seal used to make a room more comfortable by sealing all the cracks, cavities, or gaps. Once applied, the seal prevents entry of unwanted air into a room.
The foam is also effective at reducing heat transfer between two surfaces.
Most homeowners prefer spray foam insulation because, unlike other types of insulation, it does not sag over a while. Apart from heat insulation, the foam reduces mold growth, and also sound transmission.
The foam keeps your home warmer during the winter. When sprayed, the foam expands to fill up the spaces, thereby creating an airtight seal against air infiltration.
Spray foam is either open-celled or closed-cell foam. Open-cell foam insulation is light and pretty flexible because when drying up, it dispels heat through its openings.
Open-cell expands up to 150times more than its volume to achieve a weight of 1/2 lb/ft³
Closed-cell foam, on the other hand, is much denser. It provides a thicker surface that is much resistant to heat and air transfer.
When applied, closed-cell can expand up to 50 times more than its original form. It also gains a weight of 2 lb/ft³.
Due to its thickness and strength, the closed-cell can withstand harsh weather conditions such as a hurricane.
Both of the materials effectively reduce heat transfers, but homeowners are also using them to reduce noise transfers. However, does it really reduce noise?
Before you know whether it does reduce noise, you need to understand more about noise transmission.
As you may know, noise is transmitted through waves in the air. What you don’t know is that those waves travel through vibrations.
Since noise travel through vibrations, it means it can also travel through solid objects such as walls.
If the sound encounters a soundproofed object, the noise will be reduced significantly. Some soundproof materials will absorb noise, others will block, but this will depend on the noise frequencies.
Noise with high frequencies is generally easy to minimize, unlike low frequencies. Low-frequency noise includes drum noise.
The sound coming from its source will travel until it encounters an object. From there, it will vibrate through it as it continues.
For something to be considered a noise reduction material, it must address both airborne and impact noise.
Airborne noise is transmitted through the air. They come from people having a conversation, TV, radio, cars, etc.
Impact noise also referred to as structural noise, is transmitted when something hits a surface or structure—for instance, footsteps or an object falling on the floor.
Before any product is used to soundproof noise, the level of noise must first be rated. The intensity of noise is measured in decibels, while Hertz (Hz) measures the frequency of a soundwave.
When a room is quiet, the level of noise is considered to be 40 decibels. Total silence, on the other hand, is 0 decibels.
An average noise is 75 decibels, while loud bass is 150 decibels.
A high level of noise requires more effective noise reduction materials. But to understand what material is effective, you need to check their SRC and NRC ratings.
Sound Transmission Class (STC)
SRC stands for sound transmission class, and it rates how different materials effectively transmit noise loss.
A higher SRC testing means that there is greater transmission loss, and the material is transmitting less noise.
It tests 16 similar frequencies that range from 125 Hz and 4,000 Hz of different materials.
Noise Reduction Coefficient (NRC)
Noise Reduction Coefficient (NRC), on the other hand, tests how materials absorb and reflect sound waves.
When a material has a greater NRC rating, it means it is much better at absorbing noise.
A material that has an NRC of 0 means it highly reflects noise, while those with 1 have a high absorption rate.
How Does Spray Foam Insulation Reduce Noise?
To understand whether spray foam can reduce the noise, you need to check both their NRC and STC ratings when compared to other materials.
This comparison is made against a 2″x4″ wall partition covered with drywall on both sides.
For a material to reduce noise effectively, it must have mass. However, in this case, spray foam does not have enough mass to effectively reduce noise.
Open-cell has a thickness of 3 inches while the closed-cell has 2.75 inches. Other materials like fiberglass also have 3 inches but have both a high NRC and STC.
Open-cell foam has an NRC of 0.70 and an STC of between 37-39; this shows that it is better at reducing noise through absorption.
It is more porous, making it easy to dissipate noise.
The closed-cell foam has a low noise reduction coefficient of 0.70 and an STC of 36.
This shows that like open-cell insulation, it is effective at thermal performance but a low performer in noise reduction.
However, compared to the two, a closed-cell has the lowest noise reduction rating.
Compared to Fiberglass 703, which has a thickness of 3 inches similar to open cell, it has a low-performance rating.
The fiberglass has an NRC of 1.10 and STC of 52, which is much higher than an open-cell.
Better Alternatives to Spray Foam Insulation
Even though spray foam insulation has better thermal insulation properties, its sound insulation properties are not admirable.
However, there are other materials with better noise reduction properties.
Owen-Corning Fiberglass 703
As mentioned before, fiberglass 703 is much effective at noise reduction compared to spray foam. Its higher STC and NRC means that noise passing though it is minimal.
Fiberglass panels are installed on the walls, but they can also be used on the cavities of any building including your home.
Rockwool Acoustic Mineral Wool Insulation
Rockboard 60 is another material that is also effective at noise reduction compared to spray foam insulation. It has a thickness of 3 inches, an STC of 52, and an NRC of 1.10.
This shows that is can reduce noise much easily. It is also more capable of absorbing and reducing reverberations.
On Does Spray Foam Insulation Reduce Noise
The answer to the question does spray foam insulation reduce noise is YES. This material is highly effective in both soundproofing and thermal proofing.
However, it’s unfortunate that the features that make spray foam insulation trap noise waves also help contribute to resonating chambers that increase mid-range sound frequencies.