How to Make a Silencer for a Generator

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How to Make a Silencer for a Generator

A noise-free environment is highly desirable in any part of the world. Since generators are one of the main contributors to noise and environmental pollution, with the biggest risk occurring at night when ambient noise is lower, finding practical solutions to deal with their loud motor noise is important. So, how can a generator owner devise a silencer to mitigate noise?

To make a silencer for a generator, you’ll need to get the correct dimensions of your generator, construct a wooden frame, and attach an appropriate form of insulation to muffle the sound. Then proceed to also build and attach a homemade silencer directly to the exhaust tubing.

Also read: How to Make a Soundproof Generator Box (DIY)

In this blog, we shall discuss two combined approaches to creating a highly effective silencer for a generator. Silencers play a vital role in engine sound attenuation or reducing noise, and the idea is to design your silencer box in a modular manner for flexibility to install your supplementary silencer. Let’s get started, shall we?

How to Make a Silencer for a Generator

As we commence, it is important to understand the core noise sources on generators, such as radiator fan noise, structural-borne noise, generator exhaust system noise, and noise emitted from the engine.

These noise sources can be treated differently with fan discharge silencers or louvers, intake silencers, exhaust air mufflers, and acoustical enclosures or boxes.

Generally, our first approach is to contain the sound waves and dramatically lower the noise decibels from the generator motor. Specifically, the beauty of such an acoustic silencer is that you can purchase one or make your own. However, the latter does necessitate a few woodworking skills.

Here is the step by step process on how to make a silencer box for a generator:

1. Measure the Dimensions of the Silencer Box

To achieve the silencer box, you need to measure the space your generator silencer box will occupy accurately. Be sure to leave a few inches on each side of the box to cater to the insulation thickness and the ventilation aspects.

2. Create Provisions for Ventilation

Generally, adequate air circulation and airflow are critical for the overall health and functioning of your generator. Implement the first ventilation duct on the roof of your enclosure with the second ventilation duct on a side piece that will be on the opposite side from the top duct.

3. Set Up an Isolating or Mating Surface

A mating surface will help prevent sound leakage, so it should be airtight to an extent. Ordinarily, the sound results from air pressure changes caused by vibrations, so an isolating surface can help reduce this.

Your isolating layer should be between the ground and floor for your silencer box, and you can use thick rubber sheeting for this task.

4. Construct a Wooden Frame That Fits the Generator

Next, you will need to construct an appropriate wooden frame that fits over your generator. The frame can either have an inner and outer box.

5. Apply Sound Insulation

The trick with sound insulation is to add layers of free space that enables sound to dissipate, which is achieved with a layer of sound mitigating material such as TMS Mass Loaded Vinyl (Amazon).

Your next step will be to apply either foam backing, plywood, or any other insulation material suitable for containing sound. This insulation approach should help reduce noise while keeping the box lightweight. Also, utilize good quality glue to apply the vinyl pieces directly to the box’s inner walls.

Furthermore, ensure to leave some free space to allow sound to scatter inside the box, so it is entirely absorbed by the sound dampening material.

However, as you implement this technique, there a few things to note:

  • Be sure to nail on a handle for easy portability. Furthermore, the box must be easy to assemble and disassemble.
  • Cater to an adequate airflow to reduce the risk of overheating. Essentially, air intake and output ports must allow for sufficient cooling too. This can be achieved by provisioning a cutout for an exhaust extension to enable sufficient exhaust flow from the generator.

6. Add Extra Insulation

You can consider introducing more insulation layers on the walls of the silencer box for enhanced sound reduction. For example, you can add some of these Anti-Vibration Pads (Amazon) to absorb all the vibrations and eliminate reverberations inside the box.

Notably, ensure to glue all the components properly to the box’s surface as exposed gaps and crevices will hinder the desired output of your silencer box.

7. Assemble Your Silencer Box

Since you’ve done the groundwork, it’s now time to assemble your silencer enclosure. Lastly, carefully attach the top of the enclosure and securely screw it down.

Making a DIY Silencer for a Generator

Making Silencer for a Generator

If you want to silence a generator further, you can combine a DIY Silencer with your silencer box or enclosure. These two methods can effectively reduce over 20 decibels of noise from your generator’s original noise level.

Your next approach will be to add a DIY silencer to complement your generator. Though most engine equipment is typically fitted with a factory silencer to dampen the noise output, these factory-installed mufflers aren’t usually as effective.

To make your generator quieter, you can consider building a supplementary silencer to muffle better the sound coming out of the exhaust pipes attached to the generator’s motor.

The idea with your silencer is to deflect the sound waves from the engine to reduce the noise that eventually leaves the exhaust pipe, as it is one of the loudest parts on the generator.

As you proceed, it’s noteworthy to have some welding skills to attach the silencer. So, here are the steps we shall take to make our DIY silencer for a generator:

  1. Measure your generator output for your exhaust outlet.
  2. Proceed to construct an appropriate casing that will surround your exhaust outlet. Depending on the size, you can build a metallic enclosure or use materials that seem adaptable to fit this generator’s endpoint.
  3. Apply duct insulation (Amazon) or any relevant type of insulation inside your silencer device. Ensure that the form is effective and put in within your enclosure on the inside with spray glue for reinforcement. Watch out for your insulation expanding, and be careful in creating an outlet for the carbon monoxide to prevent indoor poisoning.
  4. Assemble or weld the silencer onto the generator. You can still achieve reduced noise levels by bolting the silencer on with some clamps and exhaust flex tubing. However, this is not as effective as welding the correct piping together.
  5. Start the generator and check for any leaks around the silencer. This silencer should mitigate a huge percentage of the noise from the exhaust pipe, leaving mainly noise from the engine. Here is a video demonstrating how to make a simple DIY Generator Muffler/Silencer out of sheet metal and a roll of fiberglass insulation:
How to Make a Generator Muffler
Watch this video on YouTube.


With all things considered, these techniques don’t work on soundproofing your generator fully. You cannot completely get rid of the motor noise as there will always be a requirement for provisions for air to get in and out for ventilation.

This consequently allows noise to fluke out somehow. So, these methods only help to make the sound a bit less disturbing and more manageable.

Noise is highly subjective. What is irritating to one can be bearable for another. However, most generator noise generally warrants some form of reduction for residential neighborhoods.

That said, most noise reduction methods depend on the generator room, exhaust, and type of structure, and these same principles can be considered when making a silencer for a generator.

By combining these two approaches to make a silencer for a generator, you can significantly lower your generator’s overall noise level and peacefully coexist with your neighbors.