How To Build A DIY Soundproof Generator Enclosure

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How to Build a DIY Soundproof Generator Enclosure

If you can’t take the grunt of your generator much longer, you’re among friends, and you’re in the right place.

Welcome to your one-stop guide on building a new soundproof home for your noisy nuisance.

We’re going to cover the main objectives of the build, the materials you’re going to need to build it, and an easy-to-follow step-by-step guide on how to get the job done. Are you ready to hear yourself think again?

What is a Generator Quiet Box?

A generator quiet box is exactly what it sounds like. It’s a box that you place over your generator to partially dampen the racket from reaching yours and other people’s ears.

They’re especially handy if you’re running a generator in a shared area, as there’s no faster way to tick off your neighbors than to fire up an extremely loud motor for extended periods of time.

Once you’ve crafted your generator box, you can also employ it to mute noisy air compressors and pool pumps too...the principles are the same.

Why Use This Generator Quiet Box Plan?

There are a ton of YouTube videos on the topic of generator boxes, and there are definitely some good ones out there, but many of them overcomplicate things.

Likewise, there are other DIY plans elsewhere on the internet, but we feel none of them really hit the spot for us.

The plan we’ve devised arrives at an intersection between functionality and ease of construction.

With one of these boxes at your disposal, your decibel dilemma will truly be a thing of the past...unless of course, you buy a bigger generator at some point. Then you’ll need to build a bigger one.

Objectives of the Build

Now let’s have a glance over the primary objectives we wish to achieve with our generator quiet box. These are the main criteria that we based all aspects of the design on.

  • A 50% Noise Reduction - As your generator needs to be able to breathe in order to remain cool under load, we’re never going to be able to fully silence it. Our goal then becomes to reduce as much noise as is feasible, and 50% is an attainable reduction - one that makes the effort of a DIY build worthwhile.
  • Storage Friendly - You may be running a monster generator, which means you’ll need a monster box to match, but what about when it’s not in use? It needs to be somewhat collapsible for easy storage.
  • Easily Assembled - We’re all busy enough as it is. Building a box that relies on a complex assembly procedure involving tons of tools and screws is out of the question. You need something efficient.
  • Airtight Mating Surfaces - Mating surfaces are any areas that our chosen materials make contact. We need them to be completely airtight to prevent sound waves from escaping.
  • Non-Restrictive - It’s absolutely fundamental that the quiet box allows your generator to take in and exhaust air as usual. If the box isn’t breathable, you’ll kill your generator, which will certainly silence it, but leave you with a bunch of bigger, more expensive problems.
  • Safety - The quiet box should not cause any sort of hazard. You and others should never be at risk of overexposure to carbon monoxide.
  • Modularity - This means we need the box to be expandable. We want to have the freedom to bring new sound baffles or fans into the equation without having to build a whole new box.

Materials You Need To Build Your Generator Quiet Box

Before you get started, you’ll need to amass these key components.

  1. Medium Density Fiberboard (MDF) - This is the bones of our box, folks. If you’re not sure what you’d be looking for in the hardware store, just buy some here: Grafix Medium Weight Acid-Free 0.057” Chipboard Sheets.
  1. Foam Mats - Extra layers of sound dampening magic! These Prosource Fit Extra Thick Puzzle Exercise Mat 3/4" or 1”, EVA Foam Interlocking Tiles are perfect for the job.
  1. Mass Loaded Vinyl - This is our first line of defense against those monstrous soundwaves. One of the best things about vinyl flooring is that it has excellent sound dampening qualities. We’re going to apply that to our generator box. We recommend this soundsulate 1 lb Mass Loaded Vinyl MLV, Soundproofing Barrier.
  1. Green Glue Compound - To prevent reverberation between our soundproofing components, they need to be held firmly together, and what better way to achieve this than with a glue that is itself a sound-dampening compound. There’s no doubt about it, Green Glue Noiseproofing Compound is a miracle creation.
  1. Green Glue Sealant - We’re going to use this stuff to seal the edges of our soundproofing materials. Snag some here: Green Glue Noiseproofing Sealant pack of 6 Tubes (29 oz each) - With Cleanup Wipes.
  2. Ventilation Duct - iPower GLDUCT4X8C 4 Inch 8 Feet Non-Insulated Flex Air Aluminum Foil Ducting Dryer Vent. This silver snake is how we create much-needed airflow in our box.

Tools You Need to Build Your Generator Quiet Box

  1. A Measuring Tape (Retractable is best)
  1. An L Square - Mr. Pen- Carpenter Square, Framing Square, 8 inch x 12 inch, L Square Ruler
  1. A Notepad, Pen, and Pencil
  1. A Box Cutter or Craft Knife
  1. Nails and Screws
  1. Screwdriver and a Hammer
  1. Saw (Table or circular...dealers choice)

How To Build Your Generator Quiet Box - Step-By-Step Guide

Without further ado, let’s build a dog house for your generator to bark in.

Step 1 - Measurements

The first port of call is to measure your generator. Bear in mind that you won’t be making your box to fit around the exact dimensions of your generator.

You’ll need to add at least a couple of inches on every side to accommodate the soundproofing and ventilation systems. If you’re anything like us, you’ll want to write your measurements down in a notepad to make sure you don’t forget.

If you plan on crafting a multipurpose enclosure for all your noisy gear, make sure you’re taking the measurements of the largest one, otherwise, it’ll be more of a quiet hat than a quiet box.

Step 2 - Chopping up Your MDF

Having taken some super accurate measurements of your noisy generator, you’re now ready to get cutting.

Before you mark up your MDF, double-check that you’ve got the right sized boards. The last thing you want is a last-minute trip to the hardware store and to invest even more money in the project.

We know you’re itching to fire up your saw, but first, take your L-square and a pencil, markup your boards with the cutting lines, and label them, so as you move on to assembly, you know exactly which pieces are which.

Once you’ve finished tattooing your boards, you're free to slice them up!

Step 3 - Cutting Out Ventilation Ports

Next on the agenda is measuring your ventilation ducts. It can be hard to measure circles, so now might be a good time to switch that rigid retractable tape measure for a fabric one.

Once you’ve noted down the circumference of your tubing, it’s time to pencil them onto your MDF boards.

The intake of a generator is usually situated high up, so that’s where you’ll need to mark your first ventilation hole.

Take the board you’ve labeled as the ‘top’ or ‘roof’ piece and draw your cutting circle at one end rather than the middle.

Your second ventilation port should be cut in the wall that will stand opposite the ventilation port on your roof board.

To wrap up this section of the tutorial, cut the holes using your saw, and voilà! You’re done.

Step 4 - Gluing and Caulking Vinyl to Boards

Now we’re getting crafty! Apply generous amounts of Green Glue Compound to the inner sides of your MDF walls and roof.

Even if you’re using another type of glue as the primary adhesive or the vinyl has its own adhesive layer, we highly recommend a layer of Green Glue as well. It’s really going to help kill off some sound waves.

Now you can apply your mass loaded vinyl sheets to the boards. Using your box cutter or craft knife, you can either precut your MLV or simply trim the edges down once it’s firmly glued in place.

Now the vinyl’s secure and trim, switch up that Green Glue Compound for your Green Glue Sealant, and use it on the edges of the vinyl, working slowly to ensure accurate application.

This means no pesky sound waves escape through the open pores of the cut vinyl.

Step 5 - More Soundproofing

You can use pretty much any sort of foam matting for this layer, but if you want the best of the best, hit up your local hardware store and ask for some closed cell vinyl nitrile.

First, we’re going to trim the foam paneling down to size. Want a top tip?

If you’re struggling to get a clean cut with your box cutter or craft knife, electric kitchen knives are surprisingly amazing for slicing up foam.

Now it’s just a rinse and repeat scenario. Give the vinyl a good helping of Green Glue Compound, then stick your sound-absorbing foam mats into place.

Caulk the edges as you did with the vinyl, and give yourself a pat on the back because that’s the soundproofing aspect of this project complete.

Step 6 - Assembly

It’s the moment you’ve all been waiting for, folks - assembly time.

As we want to be able to make adjustments to this quiet box at a later date, we recommend using screws rather than nails.

Focusing on two walls at a time, screw them together, but be conservative with the number of screws you use.

Use the absolute minimum required for structural integrity. The less hardware used, the easier the box will be to disassemble and place into storage.

Once all your walls are standing strong, you can pop the roof on and screw that in place too. If you’d prefer a hinged roof, so you can keep a closer eye on proceedings without lifting the whole box, go ahead. It’s a great idea.

If you don’t plan on fully disassembling your quiet box, why not do some more caulking around the edges.

Fully sealing the mating points of your enclosure means as much sound as possible will be trapped inside.

Step 7 - Installing the Ventilation Ducts

Without these key components, your generator is sure to overheat, so it’s important that they’re installed just right.

Thread each duct into their respective port, and secure them in place. You may even want to add some sort of vent to the openings of the ducts to act as both a filter and a final soundproofing stage.

Want another top tip? The longer and windier the ventilation ducts are, the more sound they’ll kill.

Peace and Quiet

What’s that noise? Well, it’s your thoughts of course.

Now you can finally hear yourself think! Building this DIY quiet box for your generator is an enjoyable and easy project even for the novice woodworker or craftsperson. 

What’s more, avoiding professionally built quiet boxes is going to save you a ton of money - money you can then invest in more tools, or perhaps another generator. Enjoy!