Is Cork a Good Soundproofing Material? (Underlayment Use)

An older man with gray hair, a mustache wearing glasses, a blue hard hat, and red ear defenders wincing in pain due to loud noise. The image's background is a cork board and the words "Is Cork a Good Soundproofing Material? (Underlayment Use)" are written across the top of the image.

Are you tired of hearing your neighbor practicing their tap dancing routine at 11 PM? Or maybe you want to create a home recording studio without disturbing your roommates?

Whatever the reason for wanting to create a barrier for sound, you must start by looking for excellent soundproofing material.

This brings us to the question answered in this article, “Is cork a good soundproofing material?”

Cork is a good soundproofing material due to its air-filled cells. The air helps block and absorb most sound waves. Moreover, cork has a high noise reduction coefficient of 0.7 that absorbs up to 70% of the sound, bringing calm and tranquility to any room.

In the rest of this article, I’ll discuss the properties that make cork good for soundproofing and underlayment. I’ll also compare cork with other soundproofing materials to help you make an informed decision on what to buy.

Let’s dive right in!

Properties That Make Cork a Good Soundproofing Material

A woman with long brown hair making the "OK" sign with her left hand and smiling against a cork background.
Cork has several properties that combine to make it an excellent soundproofing material.

Before discussing the properties that make cork a good soundproofing material, let’s discuss what makes soundproofing materials like cork effective.

Soundproofing materials are designed to absorb or block sound waves from entering or exiting a room. This is done using thick walls and special acoustic panels that reduce reverberation.

Cork is an ideal soundproofing material because it possesses the following properties:

High Noise Reduction Coefficient (NRC)

NRC is the standard rating for how well a material reflects or absorbs sound. It’s a single-number value ranging from 0.0 (perfectly reflective) to 1.0 (perfectly absorptive).

The above definition means that the closer a material’s NRC is to 1.0, the better it absorbs sound. High sound absorption prevents sound from being reflected into the room to cause noise.

On the contrary, the closer a material’s NRC is to 0.0, the higher its sound reflection capability and poor absorption.

Cork has an NRC rating of 0.7, making it perfect for soundproofing. With such an NRC, cork absorbs up to 70% of sound, meaning only 30% is reflected into the room. Consequently, you get a perfect ambiance for your activities.

Cell Structure and Composition

A microscope image showing the structure of cork cells. They are a honeycomb structure.
Viewing cork under a microscope reveals its honeycomb structure. Image courtesy of Macmillan Learning.

Cork has a honeycomb-like structure that’s made up of millions of air-filled pockets. This structure and its composition (suberin, lignin, and lactic acid) allow it to absorb and dampen sound.

Since air molecules are not in continuous contact, they can’t transmit sound waves efficiently. Therefore, the pockets help break down sound waves before they reach the opposite end of the room.

The honeycomb-like structure also makes cork light yet durable enough to withstand pressure, making it a fantastic choice for underlayment.

Low Density

Density plays a crucial role in a material’s soundproofing ability.

According to Scientific Research Publishing, it’s hard for sound to penetrate the pores and voids of higher-density materials, resulting in more reflection.

On the other hand, sound penetrates easily through low-density materials, increasing their soundproofing capacity.

Cork has a low density of 0.25g/cm3, making it easier for sound to penetrate. Once the sound gets into the cork’s fibers, it’s absorbed and prevented from reflecting into the room.

Excellent Compressibility

Cork is highly compressible, thanks to its low density and relatively compliant cell wall material.

It’s worth noting that sound travels faster in more rigid materials because their molecules are closer together and more tightly bonded.

The fact that cork is highly compressible means its molecules are farther apart and less rigid, thus slowing down the sound waves and allowing for better absorption.

In addition, this compressibility allows cork to recover to its original form after compression.

High Flexibility

Cork is highly flexible – you can easily mold it into different shapes and spaces. This property is ideal for soundproofing as it allows for optimum sound absorption.

Furthermore, due to its flexibility and compressibility, cork can fit into tight spaces that are usually hard to reach with other materials.

With this kind of flexibility, you can easily create a soundproof space, no matter your room’s size and shape.

Highly Sustainable

A cork oak tree with the bark removed. A green footprint is overlain across the image.
Cork harvested from cork oak trees has a low environmental footprint, making it highly sustainable.

In the modern era, we are after sustainable construction to reduce our carbon footprint and mitigate climate change. In this regard, cork is the ideal choice for soundproofing as it’s highly sustainable and eco-friendly.

Cork is sustainably harvested from cork oak trees every nine to twelve years without causing damage to the environment or harming animals. Therefore, when you opt for cork as your soundproofing material, you’re also doing your bit for the environment.

Cork Soundproofing Underlayment

Soundproofing underlayment involves adding some give to a hard floor surface to reduce the vibrations passing into the floor. The primary aim is to reduce the amount of impact sound.

An easier way to think about soundproofing underlayment is like reducing the volume knob on your footsteps instead of just absorbing the noise after the impact.

Cork is excellent at reducing vibrations and decreasing noise transfer within the floor. However, this depends on the thickness.

It’s advisable to use half-inch cork panels as an underlayment attached to concrete with an underlay adhesive.

The panels should be placed on top of the subfloor and then covered with another layer of laminate, hardwood, cork tile, or carpet padding for added comfort.

Besides noise reduction, cork underlayment acts as a thermal barrier, improving comfort if you pad around barefoot.

Comparison Between Cork And Other Soundproofing Materials

Before leaping to buy, we all want to be sure we’re going for the best construction material to provide good soundproofing.

In the next section, we shall look at how cork stacks up with other soundproofing materials to help you choose the best.

Acoustic Foam

A wall covered in blue acoustic foam that is shaped like small pyramids.
Acoustic foam is great for reducing echoes in a room because it absorbs sound well. Unfortunately, it is less good at deadening sound from outside the room.

While cork is both a sound deadener and absorber, foam is only a sound absorber. Therefore, while the latter is essential in reducing echo, the former boasts double soundproofing properties.

It’s worth mentioning that acoustic foam panels are designed to absorb sound instead of soundproofing. Soundproofing entails blocking sound from leaving or entering a given space.

While sound absorption is part of soundproofing, it doesn’t block sound on its own, making it a less effective choice.

On the other hand, cork is both an absorber and deadener, making it more effective in soundproofing any space.

Rubber Mats

Rubber mats have higher moisture resistance than cork underlayments.

However, rubber mats have drawbacks, like being less durable. They become softer over time after compression. When this happens, rubber mats become less effective in soundproofing the space.

Cork is an ideal option that recovers its original shape after being compressed, making it a more reliable choice for soundproofing.

However, cork must be at least 30% thicker than rubber underlay for efficient sound insulation.

Mineral Wool

A worker wearing protective gloves installs mineral wood in a wall and floor space.
Mineral wool is great at soundproofing and thermal insulation. However, it is harder to install than cork and messier.

This is a heavy material, highly resistant to fungi, mold, and bacteria. It offers excellent sound insulation due to its low-density, lightweight, and compressible nature.

However, mineral wool is a little harder to install and may require a professional. It’s also labor-intensive and messier, which adds to its installation cost.

While cork is easy to install, it’s more expensive than mineral wool.

Mass Loaded Vinyl (MLV)

MLV is a limp vinyl sheeting impregnated with metal particles to increase its mass. It’s used as part of a sound control scheme in walls, ceilings, and floors.

It’s highly effective at blocking sound transmission. However, MLV doesn’t absorb sound due to its rigid nature. Therefore, it’s less effective than cork in dampening noise within a space.

The table below compares cork with other soundproofing materials in terms of cost and NRC:

MaterialCost Per Foot in USDNRC
Cork3-60.7
Acoustic foam1-30.4
Rubber mats3-80.015
Mineral wool1.40-2.100.8-0.9
Mass loaded vinyl3-40.5

Table 1: Comparison between cork and other soundproofing materials

Final Thoughts

When it comes to soundproofing your space, the ideal material should have both sound-deadening and absorption properties.

Cork is among the best materials for improving your home or workplace acoustics. Its high NRC rating makes it an excellent choice for soundproofing any space.

Besides being sustainable, cork’s lightweight nature makes it easy to transport and install.

Now that you know cork is a good soundproofing material, check out this ultimate guide to cork insulation. It discusses the quality of cork insulation and why you should use it.

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2 Comments

  1. Thanks for your interesting article. What are your thoughts about sound-proofing a newly installed undercounter refrigerator with a loud compressor and fan hummm. There is enough space for 1/2 to 1” insulation. I was thinking to use cork-underlay, which could be doubled up where space allows, perhaps in combo with some other material if needed. Thanks.

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