Do you want to be able to relax in peace and quiet while still using your generator to keep the lights on?
Generators can be so loud that they can even be heard over a bunch of speakers and a subwoofer blasting music right next to the device.
The good news is that you can learn how to soundproof a generator by building a soundproof generator box to enclose the generator in. It won’t stop all the sound, but it can significantly reduce the amount of sound that comes from the device. Quiet enough is alright, right?
How to Build a Soundproof Generator Box
If you want to make your portable generator quieter by making a soundproof box, then these materials below will be all you need. You may have some extra plywood lying around your garage, or you can head to Lowe’s or Home Depot and pick some up.
- 1/4″ thick plywood
- 1/2″ thick plywood
- A pencil
- A measuring tape
- A circle saw
- Three to four 1″ thick foam sheets
- A drill (optional)
- A 7/8″ spade bit (optional)
- A sanding file
- A dual-action sander (optional)
- Wood glue
- 1 and 1/2″ galvanized nails (8-24 of these)
- A hammer
- 1/4″ acrylic/plexiglass sheets (optional)
- 1/8″ drill bit (optional)
- 1/8″ screws (optional)
How to Build the Outline
Let’s start out by making the outline of the box. Be really careful with this part, to ensure that you don’t make it too big or too small. The sides of your soundproofing box must also meet in such a way that you can glue and nail them together without letting any sound leak out.
Measure your generator and find out how long and how wide you need your box to be. You want to use quarter-inch thick wood for the sides and half-inch thick wood for the top. Make sure that you’ll have about 1 inch of space between your generator and the box at the sides and 2 inches of space at the top. That way, the foam you’ll use for soundproofing will fit inside the box along with the generator. You’ll want to leave enough space at the top for the gas cap as well.
On your plywood, draw out the measurements for each section of the soundproofing box. You’ll have to cut individual pieces for each section, including the top, the bottom and the three sides. It’s necessary that you cut the piece that you’ll use for the front about half an inch longer than the other pieces. This will make it easier to put the box together when you get to that step. It’s better if this piece is too long, rather than too short, as you can just cut it shorter later if you need to. Keep in mind that you’ll be leaving one of the sides open to allow the generator to breathe.
Next, grab your circular saw and cut the pieces of your plywood in accordance with the measurements that you just drew.
Test the dimensions
After you make the necessary cuts to the plywood, set your bottom piece on the ground. Set your generator on top of the bottom piece. Place one of the two side pieces you cut on each side of the generator.
Next, place your top piece on top of the generator. Determine that your generator has been placed in the box in such a way that the exhaust is facing towards the open part of the box, and leave the whole backside part of the box completely open.
Grab your 1-inch thick foam sheets and cut them so they’re the same length and width as your generator. The foam is going to absorb soundwaves from the generator to help soundproof the inside of the box. Insert the foam sheets inside the box, with two on the sides and one on top.
Finally, ensure that your generator is going to fully fit within the pieces that you cut, and that it’s in there snug and tight, before we make the box permanent.
Adding the Windows
When you can see that your generator will fit inside your soundproof box, you’re going to want to figure out what part of your generator is pulling in fresh air. Once you find out, draw a shape on your plywood that will allow just enough space for the generator to pull in the air, and then cut that shape out of the plywood.
This window can also be used for the extension cord, so it can drop down and plug into whatever electrical devices you need. If your generator has a control panel, measure out a small window you can cut out for that as well, so you can view your control panel while the generator is in the box. Additional windows are going to affect how much sound can leak out of the box, so be careful to only add windows that are absolutely necessary.
We’re going to craft the box so you can just lift it up and put gas in the generator without taking it out every time, so you may find that having as few windows as possible is the best solution, since you can just lift up the soundproofing box if you need to do maintenance while the generator is running.
We don’t need to cut a hole for the gas top because we may already have too many windows that are going to leak sound from the unit. The main thing is making sure there’s enough room for the generator to breathe (so it can receive clean air) and for an extension cord to be able to come out of the unit. Adding any other holes is going to reduce the efficiency of your soundproofing.
For the windows, you’ll want to use a 7/8-inch spade bit to drill a hole into each corner of each outline you’ve drawn before you use the circular saw to cut it out.
The 8-Step Assembly Process
- Use a file to clean up all your rough cuts in the plywood so you don’t get any splinters. If you’d like, you can go over the plywood again with a dual-action sander to make sure the edges are super-smooth. This will also make the wood glue much more effective, because it’ll have a smooth surface to attach to.
- Next, we’ll put together the sides. We’ll do the sides first to make sure we have a sturdy foundation around the generator (including the part that leaks out the most noise). We must also make sure the sides are even and snug before putting the top of the box on. To start putting the sides together, take your wood glue and glue the two side pieces of the soundproofing box to the front piece.
- Take your galvanized exterior nails and your hammer and add four nails, one in each corner, to the front of the soundproofing box.
- Pick up the top piece and use your wood glue to glue it on top of the sides, using as much glue as you need to. Ensure that there are absolutely no holes in the top or on the sides, besides the necessary ones. The fewer holes you have, the more noise reduction you’ll have.
- Nail in eight nails along the top of the box, adding four to the corners and four to the edges.
- Use your wood glue to glue your foam pieces to the inside the soundproofing box. They must be glued onto the side pieces and the top of the box.
- If you cut a window for a control panel, pick up your sheet of acrylic and cut it about a half-inch wider and taller than your window. This is going to provide a little extra soundproofing while allowing you to monitor the important signals of your generator. Use your 1/8-inch drill bit to drill six holes in your acrylic, including one in each corner, one on the top and one on the bottom. Take your 1/8-inch screws and use a screwdriver to screw the acrylic piece into the inside of your box.
- To finish, sit your generator on the bottom piece and place the soundproof box on top of it.
This entire process should give you about five decibels of base noise reduction.
How to Soundproof a Generator Room
If your little soundproof box just isn’t cutting it, you might want to look at building an entire generator room. There are a variety of ways you can go about this, but you’ll want to build it in a way that’s similar to how the recording studios do it.
For example, you can get foam padding that people use to soundproof recording studios in place of the cheap foam sheets we used in the guide above, but these can get pricey.
Alternatively, you can use metal to reinforce the plywood on the outside of the soundproofing room to provide an added layer of soundproofing to the whole room. The sound that’s not absorbed by the padding will reflect off the metal and back into the box for significant noise reduction.
Bookmark This Guide
Pretty simple, right? This isn’t going to make your generator as quiet as a mouse, but it’ll lead to a significant reduction in its noise level.
Make sure you bookmark this guide and send it to your friends so they can learn how to build a soundproof generator box, too. You can also refer back to the instructions whenever you need to.
By using the tips from this guide, you’ll be able to create your own soundproof box for your generator without spending money on an expensive unit that might only do half the job you can do by making your own.