Generator soundproofing material: How to make one quiet?​

Generator soundproofing material: How to make one quiet?

Having a generator at home is a great tool for unprepared moments where you need an emergency power backup. Some of us have also gotten portable generators for when we hit the road for a camping trip or road trip. 

how to make a soundproof generator box pinterest

And there is one thing in common: generators are loud machines. What are the best generator soundproofing material you should use? And how do you soundproof a generator room? Or how do you soundproof a generator box?

I will aim to answer all these questions in the following sections and hopefully, you can all have a better experience the next time you bring out these bad boys.

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Tips for building a generator soundproof box

Generators make a lot of noise and its exhaust can significantly disturb your sleep, kill your plants and pollute the environment in your neighborhood. 

Many people who have generators wonder if they could soundproof their machines. 

Although there are many products claiming to do so, soundproofing generators entirely is not possible. This is because the generator needs intake air in order to run, and it needs to release exhaust. 

Generators also produce a lot of heat, so it is crucial for it to have a way to release them. This also means that there will be holes or gaps that air can travel in and out, and as you might know, sound travels through air. When that happens, it will be impossible to be 100% soundproof.

You might think that the best way to guard against your generator burning out is to ensure it’s fully sealed up. 

However, if you do this it might overheat and then start a fire! 

The good news is that carbon monoxide will escape from any unsealed gaps on its own. However, sound travels in waves that spread in straight lines so it can’t escape through round holes like the sound coming from a television.

In this case, your best bet will be to baffle the sound, effectively creating sound barriers for sound to lose its energy as it goes around them. 

The 2 main ways to achieve this is through sound absorption and blocking.

best materials to make a soundproof generator box

Materials needed for making a soundproof generator box

Like most other appliances, a generator will make some noise when in use. 

Generators are pretty big pieces of machinery after all. But soundproofing sound is always important, so it’s essential to get the best generator soundproofing materials for your project, and you’ll definitely want to keep safety in mind as well! 

For example, if you opt to go with metal for any part of the unit or box, be sure that it’s only thin layers and/or that there is an amplifying layer underneath or else you risk making matters much worse and creating excessive noise due to the vibration that metal emits. 

Medium density fiberboard is the best material to use to build walls inside your main generator box. 

The first reason behind this opinion is that medium density fiberboard provides much better soundproofing than plywood and all of its derivatives since it is harder and denser, therefore more effective at providing sound absorption. 

Secondly, the acoustic wall panels are lighter weight, easier to cut and move or transport so they’re a great choice for an on-site construction situation where you may need to reproduce your current design or move it depending on site-specific conditions.

You should use a framing method when constructing your Quiet Box enclosure. 

You can use 2×2’s or 2×4’s for this step, depending on how sturdy you require the main box to be. 

If the generator will not be placed on the ground or any other heavily used surface, it will be necessary to lay down vibration pads in order to muffle the noise being produced by the generator and to keep vibrations from traveling into the wooden subflooring beneath it.

Here are the recommended materials list:

Tools needed for this project

  • Measuring tape
  • Screwdriver
  • Pencil or marker
  • Circular saw
  • Right angle ruler

Steps to build a soundproof generator box


You must first measure your generator to determine the size of the soundproofing generator box you will need. Obtain the dimensions of the generator, allowing for soundproofing materials and ventilation ducts by adding several inches to each measurement. I recommend that you measure more than once to ensure accuracy and remember to note the measurements on a piece of paper or notebook.

Preparing the MDF

Using a table saw or circular saw, cut the MDF boards to the size of the generator. Once the pieces have been cut, label them accordingly so you know where the pieces will go during construction; the ceiling, the base, and the sides.

Ventilation holes

There are two reasons why generators need ventilation: 

Due to the fact that they run on gasoline, ventilation holes are necessary to allow exhaust fumes to escape.

It produces a good deal of heat. A good exhaust system keeps them from overheating.

The ventilation holes are created by measuring the size of the ventilation ducts that you bought and cutting two circular holes in the MDF that match the size of the ducts.

The hole should be drilled in the piece that will serve as the top of the box.

Instead of being centered, the hole should be located near the side of the piece of MDF.

Another circle should be added to the piece of MDF that will be on the side of the generator, opposite the hole on the top piece.

Installing the MLV

The importance of layers in soundproofing cannot be overstated. As more layers are applied, the more sound is blocked. 

Mass loaded vinyl are very dense and heavy, but they are also flexible and easy to work with. 

They are saturated with metal particles which makes them perfect for soundproofing projects.

While you construct the box for your generator, this should be the first layer that you install. 

Each MDF board should be measured precisely, and then a piece of MLV should be cut to the same size. To attach the MLV to its corresponding MDF board, use Green Glue. Apply green glue to the edges of each piece of MLV to ensure they are securely attached to the MDF.

Installing the acoustic foam mats

In order to install the acoustic foam mats into your generator box, you need to cut them so that they will fit into the corners of the MDF panels. These are the ceiling and walls of your generator box. To finish, position the acoustic foam carefully on top of the MLV, glued to the interior panels of the box. Adjust so that the surface is flush with the paneling. Use a second layer of Green Glue and folds in all four corners to secure the foam to the paneling.

Putting together the soundproof generator box

Make sure the Green Glue has fully dried. Once dry, assemble the panels and put them in place. Put the sides together around the ceiling panel. Ensure that the walls are positioned properly. Screw in the panels. Additionally, hinges can be installed to make it easier to access the generator. Green Glue should be applied along the edges of each piece of MDF before screwing it in place in order to prevent gaps between the top and sides of the generator box. In addition to being a soundproofing medium, Green Glue will help to block any gaps from which sound could escape, thereby improving the soundproofing capabilities of your generator box.

Adding vent ducts

Remember earlier we mentioned that a generator needs to have ventilation? This is where the vent ducts come into the picture. This step is critical. If you do not do this, you run a high risk of letting the generator overheat, resulting in a fire and possibly something worse. 

Using the ventilation holes in the top and sides of the box, position the vent ducts into them. It is important to ensure that the ventilation ducts are securely fastened, otherwise they might move when the generator is running, which might prevent proper ventilation and reduce the soundproofing capabilities of the box. 

It is helpful to keep in mind that soundwaves that have a straight, linear path can easily travel out of the air ducts of a box and reduce its soundproofing capabilities. Which is why you should add in bends and turns where possible to further reduce the impact of noise.

Getting a ready made soundproof generator box instead

Obviously if you prefer to get something ready made, there are always options available.

Depending on your personal situation, you may choose to invest in a more permanent solution like a generator noise reduction enclosure or you might just need a temporary one such as when you go camping. For a longer term solution, it is best to build one with the good materials as described above, or if you do have the budget, you can consider the ZombieBox, regarded as the world’s first and only patented portable noise reduction system.

For one that is temporary, I highly recommend the GenTent cover. Although it is not perfectly soundproof, it still does a great job at reducing noise and is particularly effective at protecting your machine from the elements. Perfect for outdoor use. This portable generator sound enclosure has done wonders for our RV trips and I love how durable it has been.

GenTent Generator Running Cover - Inverter Kit (Standard, Tan) - for Fully Encased Inverter Generators
  • Safely run your portable generator outside in any wet weather - rain, snow, ice, sleet, and wind.
  • Waterproof and sheds water away, protecting sensitive electrical areas, large door for easy refuel.
  • Running cover for fully encased inverter generators with perimeters ranging from 40"-120".
  • Patented design maintains generator natural cooling air flow, does not impede generator operation.
  • Uses GenTent strap mounting system to attach to the generator case.

How to Reduce Generator Noise without Building a Soundproof Box?

I totally understand that some might not want to build a soundproof generator box nor do they want to invest additional money after spending a fair amount on the machine. There are some tips I would like to share where you can reduce the amount of noise a generator makes without using a soundproof box.

Adjust the position of the exhaust

Most of the time, exhaust pipes are positioned horizontally. If you can change them to point vertically, it makes the dispersion of noise more effectively and thus reducing the impact. Also, be sure that the exhaust points away from the house to further lower the volume.

Deflect the noise

Deflecting the sound is one of the best ways to reduce it. You can either build something or simply place objects around it to achieve this effect.

Make a list of materials you can use for barriers. Objects such as hollow boxes, sacks filled with sand are free and readily available. You should definitely check out your garage for some ideas. 

Just make sure the items you use are fire resistant and you have no problem placing them outdoors under the weather.

Change the muffler

Just like a vehicle, a muffler can have a significant impact on the amount of noise it emits. Check with the manufacturer or on Amazon to see if there are any suitable mufflers you can use.

Alternatives to building a wooden soundproof generator box

Using MDF to build your box is not the only way to go. If you have the right materials in place, you can replace the wood with metal, or you can simply fence it up and drape a soundproof blanket (moving blanket) over it. I have seen some people using concrete as well, but that will likely be a much more complicated and pricey project.

Always be sure to allow for ventilation to prevent any overheating.

Read this too: Does Vinyl Fence Block Sound?

Frequently Asked Questions (FAQ)

How Much Does It Cost To Soundproof A Generator Enclosure?

As you might imagine, the cost depends a lot on what you want to achieve, but as an estimate, you can budget close to $200 for making a decent one using MLV (this is the most expensive item). The other materials you need such as MDF boards are quite cheap. If you wish to lower the budget, consider using moving blankets in place of MLV. 

How Much Noise A Soundproof Generator Box Can Reduce?

Typically, a well constructed box (following the steps above) can help you to reduce the noise levels by about half. This of course depends on how well the box is constructed and the materials chosen.

What Are the Most Effective Soundproofing Materials?

The thing you should understand about soundproofing is that there are actually several aspects to it, for example sound absorption and blocking. Each aspect uses different materials. Check out this article to learn more about the best material you can use.

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Bryant Littlewood is the Chief Editor behind SoundproofingHacks. He shares all the lessons he has learned in turning his home and office into quiet sanctuaries across the blog posts here. Bryant is also a part-time audiophile, and some of the posts here will reflect that passion of his too. Connect with him on LinkedIn or read more on the about page.