Dynamat Vs. Flex Seal – Which is Better?

Dynamat vs. Flex Seal is a topic of debate when it comes to soundproofing. Dynamat is popular for its fantastic sound deadening capabilities. On the other hand, Flex Seal is a rubber material that is actually a sealant. 

Dynamat is better for soundproofing than Flex Seal. Manufacturers created Dynamat as a sound deadener, so it serves its real purpose. Meanwhile, Flex Seal is a leak sealer, but it also works well in soundproofing since it has a rubber material.

Dynamat Vs. Flex Seal

Once you understand the difference between Dynamat and Flex Seal, you will know which one will work better for your soundproofing project. That said, you must know how to use both materials for soundproofing a space. 

Also read: MLV vs. Dynamat for Soundproofing Cars

Dynamat Vs. Flex Seal: Which Is More Soundproof?

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Soundproofing is a process of blocking or absorbing sound waves using a variety of materials. These materials can either be dense and high-mass or porous, flexible, and soft. 

However, it is crucial to note that the process of soundproofing does not eliminate noises completely. Instead, it only reduces the sound waves that can enter a space.

1. Dynamat

One of the most popular soundproofing materials right now is Dynamat. It is thin, flexible, and easy to cut, making it relatively easy to install. 

Dynamat works by stopping the sound waves that cause vibration and resonance, which results in a quieter space. 

Additionally, the primary material in Dynamat is butyl rubber installed in an aluminum alloy backing. Primarily used for soundproofing vehicles, this sound-deadening material stops vibration from creating sound waves. In addition, it can also absorb some of the exterior noises before they can even resonate within your car.

2. Flex Seal

On the other hand, Flex Seal is a liquid rubber sealant coating used for fixing leaks. You can use it for almost every type of surface, such as:

  • metal
  • fabric
  • plastic
  • glass
  • aluminum
  • cement
  • drywall

The best thing about this rubber leak sealant is that it will not deform at high temperatures or crack during the winter. It can even prevent metals from corroding.

Which Is Better Between Dynamat Vs. Flex Seal

Dynamat vs. Flex Seal, the former will work best for soundproofing. Its actual purpose is to soundproof vehicles. For this reason, all its features point towards the principles of soundproofing. 

However, you can also use it as a soundproofing material. It consists of rubber, making it a good material for reducing sound and vibration. The dense nature of the rubber in Flex Seal makes it a good material for absorbing vibrations before it can even produce sound waves. 

If you are on a tight budget and are looking for a Dynamat Alternative, Flex Seal is one of the best alternatives. 

With all that’s said and done, we can say that Dynamat is better at soundproofing than Flex Seal. 

How To Use Dynamat For Soundproofing Your Vehicle

Dynamat is a rubber material with adhesive backing. You can easily cut it, peel the paper backing and install it in your car. On the other hand, Flex Seal is a liquid material. So, Dynamat vs. Flex Seal, it is safe to conclude that the former is easier to install on your car. 

1. Remove The Front And Back Seats

To remove your car’s front and back seats, the first thing you need to do is push the seat backward and access the front bolts. These bolts have plastic covers that you need to remove before you can see the bolts. Once you remove these bolts, that is when you can push the car seats forward.

Do the same on the back seats to access the car floor freely. 

2. Take Out The Carpets

Make sure that the carpet does not have any clips or screws before removing it. Then, take it out carefully by folding it along until you access the entire car floor. 

3. Measure, Cut, And Install The Dynamat

The next step is to measure your car’s floor. After ensuring that you got the right size, cut the Dynamat to the right shape and size. 

Finally, remove the paper liner behind the sound-deadening material to access the adhesive backing. After that, carefully install the material in place, making sure that you are placing it evenly.

How To Use Flex Seal For Soundproofing

Dynamat vs. Flex Seal, the latter is more affordable. For this reason, people who are on a tight budget use it as an alternative for Dynamat when soundproofing a car.

But how do you use Dynamat for soundproofing?

1. Prepare the surface that you need to soundproof

Before using Flex Seal, make sure to open all the doors of your can for better ventilation. You can either remove the front and back seats using the step above or cover them with anything to protect them from stains. 

It ensures that you will not spray Flex Seal on unwanted areas. 

Additionally, you need to wipe off the dust from the car’s surface. If there is dirt that is hard to get off, you can use a damp cloth. 

However, make sure that the surface is completely dry if you wipe it using a damp cloth. 

If the surface has any rust, sand it off first before moving to the next step. Rust can reduce the adhesion of Flex Seal, so it is essential to remove it. 

2. Spray The Flex Seal

Make sure to shake the can of Flex Seal vigorously for approximately a minute. Next, aim the bottle’s nozzle on the surface that you want to soundproof. The distance of the can from the car surface needs to be eight to 12 inches. 

Once the Flex Seal is in the right position, spray it in a sweeping motion. Make sure that you are spraying the material evenly for a better look. 

Let the first coating dry for at least 24 hours before you apply the second coat. Finally, let the Flex Seal cure for at least 48 hours for excellent adhesion.

Dynamat vs. Flex Seal, Flex Seal, is more difficult to install. 


  1. Alternatives to Dynamat, https://www.reddit.com/r/CarAV/comments/53tkbs/alternatives_to_dynamat/,
  2. Rose Kivi, How Does Sound Proofing Work?, https://www.hunker.com/13412617/how-does-sound-proofing-work,
  3. Dynamat, https://www.dynamat.com/,
  4. Flex Seal Review – Does It Work?, https://www.consumerreports.org/cro/magazine/2012/06/flex-seal-claim-check/index.htm,
  5. Dynamat, https://www.dynamat.com/wp-content/uploads/2021/02/2010-Dynamat-Xtreme-Sell-Sheet_Web.pdf,
  6. Flex Seal Family Of Products, https://flexsealproducts.com/blogs/how-to/how-to-use-flex-seal-liquid,

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