How To Build A Soundproof Box For Inline Fan (8 Steps)

No one can deny how big of an irritant fan noises are. What is even worse is when the fan making noises is the inline fan in your grow room. Fortunately, you do not have to live with such a noise forever if you know how to make a soundproof box for the inline fan. 

To build a soundproof box for an inline fan, you will need materials with a rigid surface like wood or cardboard. You need to attach each wall of the box to its corresponding place until you form a box. Additionally, you have to seal the gaps on each corner to ensure that the sound the inline fan makes will not leak out.

How To Build A Soundproof Box For Inline Fan

 A soundproof box is an excellent solution for noisy inline fans if you know how to make one correctly. But you need to know what sound-absorbing materials you can use for the box to ensure that it will dampen as many sound waves as possible. 

Check out my guide on How To Soundproof A Cardboard Box At Home.

How to Build A Soundproof Box For Inline Fan

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Every homeowner wants a quiet environment. However, there are many factors at home that make it almost impossible to have a quiet environment. One example is an inline fan.

An inline fan is mounted in line with the ductwork to suck air from the inside to the outside. It is helpful for different home applications. That includes ventilation for grow rooms and wet spaces, including bathrooms, laundry rooms, and kitchens.

No one can ignore the noise that inline fans make because it is bothersome. Fortunately, there are several soundproofing options that you can use to manage loud noises created by your inline fan. But the most effective of them all is a soundproof box.

To create a soundproof box for your inline fan, you will need:

  • wood or cardboard
  • mass-loaded vinyl
  • pencil and paper
  • measuring tape
  • insulation wool
  • screws
  • adhesive spray
  • ventilation duct
  • caulking

Step-1. Take your measurements

Get your measuring tape and a piece of paper and pen to record the measurements you will get. You need to measure the space that your inline fan will take accurately. 

Additionally, make sure that you leave a few inches of space on each side. This extra space will cater to the insulation materials and ventilation duct you will need to add later. 

Step-2. Cut your wood or cardboard in equal sizes.

You will need two sets of planks, with five wood or cardboard planks for each set to make a soundproof box.

The first set should be a little bigger than the other set. Make sure that when you assemble the inner and outer box, there should be at least one and a half inches gap in between.

Remember that you need to leave the top completely open as you will attach that part to the surface where your inline fan is located. 

Step-3. Prepare the mass loaded vinyl and insulation wool

The mass-loaded vinyl will help prevent sound waves from leaking out of your soundproof box. On the other hand, the insulation wool will absorb some of the sound and vibrations. For this reason, you will hear less noise once you install the soundproof box.

You will use adhesive spray to install the mass-loaded vinyl into the box. 

Step-4. Make a frame for the soundproof box.

After preparing the soundproofing materials, you need to construct a frame that fits on your inline fan. You will attach the wood or cardboard boards you cut earlier on this frame during the assembly process.

Step-5. Apply sound insulation materials

One trick for sound insulation is to add layers of free space. Such will let sound waves dissipate, which you can achieve using the mass-loaded vinyl. 

Before assembling the outer box, you first need to adhere to the mass-loaded vinyl on the inner side of the box. Wait for the spray adhesive to dry completely before assembling the box.

Step-6. Apply additional soundproofing materials

Now that you successfully installed the mass-loaded vinyl, the next thing you need to do is to add additional soundproofing materials, like wool insulation.

Step-7. Assemble the box

Take the boards that you prepared earlier. Assemble the inner box first by screwing each piece together. After ensuring that you secured the inner box, you can make the outer box using the same process you did for the inner one. 

Additionally, make sure that you add a ventilation duct on one side of the box to maintain airflow within the compartment.

Step-8. Apply caulking on edges

Your box is almost ready. But you need to apply caulk to seal the edges to improve the box’s soundproofing capabilities further. 

There are caulk varieties that you can choose from, including:

  • Silicone
  • Latex
  • Butyl rubber
  • Polyurethane

Regardless of your choice, the caulk will work by sealing even the most minor gaps on your box. 

When the caulk dries out, your soundproof box is ready for use.

Noise-Absorbing Materials for a Soundproof Box

Apart from mass-loaded vinyl and wool insulation, there are more sound-absorbing materials that you can use for your soundproof box.

Soundproof paint

Applying a few coats of soundproof paint to your soundproof box will help you contain mid-range sound. Soundproof paint works by blocking noise and absorbing vibrations. Such is an important role to play if you want to get rid of unwanted noise.

Acoustic foam

Hard surfaces like wood reflect and amplify sound waves. For this reason, you need to attach soft materials that can absorb sounds and make them less noisy. One good sound-absorbing material is acoustic foam.

Acoustic foam will prevent sound waves from bouncing through surfaces. As a result, your soundproof box will be able to contain the noise that your inline fan makes effectively.


You can use rugs as an alternative for mass-loaded vinyl. You can install it the same way that you did with MLV, but it will cost you less.

However, make sure that you will buy an extra-thick rug for more effective sound protection.


  1. John Terry, Inline fan Noise Reduction: The Best Guide so Far, What For Me,
  2. Morgan Adams, How To Make a Sound Proof Box, Hunker,
  3. Joseph Truini, How to Soundproof a Room, Popular Mechanics,

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