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Generator Quiet Box

Depending on the type of generator, they may make a buzzing noise inside their engines, which is carried away via the exhaust pipe. Finding out how to quiet down the exhaust sound is possible using a generator quiet box.

The generator quiet box, as the name implies is a device that goes between your portable generator and where ever you need electricity. The generator quiet box will reduce noise up to 90% depending on the unit.

Buy or Build a Quiet Box(Baffle Box) For Your Generator

There are a few different ways to make a generator quieter, one is to buy a ready-made box from someone online. The other option is to build your own generator quiet box.

The ready-made boxes(generator quiet box) can be bought from eBay or Amazon usually at a cost of around $200.00 (US Dollars).

If you don’t want to pay for a pre-made generator quiet box(baffle box), then building your own baffle box is an option.

The Requirements of a Generator Quiet BoX

The requirements for a generator quiet box(baffle box) is to provide your portable generator with:

  • A large surface area to stop the sound waves from reflecting back into the exhaust pipe.
  • The panels must be able to absorb as much sound as possible.
  • The baffle box should provide as many exit points as possible to the sound waves, therefore making them travel further away from the generator.
  • The panels should be made of heavy plywood materials like MDF (Medium Density Fiberboard) or marine grade plywood (marine ply is waterproof). Sturdy and hardwoods may also be used such as Oak, Maple, Hickory or Beech.
  • The length and width of the generator is usually around 12″ – 24″.
  • If you use marine-grade plywood then it should be around 3/4″ thick (1-1/2 inch).
  • The height for a generator impact quiet box will depend on the type of genset you have, but it should be around 4″ – 6 “.
  • The baffle box must have a solid bottom to absorb the sound waves from the generator exhaust.
  • You can mount your acoustic insulation panels via Velcro, screws or double-sided tape. The best option is to screw them in place if needed by drilling pilot holes and then screwing them into place.
  • You can now fit the generator quiet box in between your generator and where you want to use it. For example, if your generator is mounted on a trailer then near the part of the tow bar that connects to the vehicle.
  • As an option you can line up all of the panels backward and then rotate the baffle box 90 degrees so that it is now facing forward.
  • It is important that you place the generator quiet box as far away from the exhaust pipe as possible, this will stop any re-echoing or returning of sound waves to the exit point. Also, make sure you do not cover any intake points.

Making Your Own Quiet Box For A Generator

If you are making your own generator impact quiet box or baffle box, then make sure you follow these requirements above.

What will You Need to Build a Generator Quiet Box –

Here are the materials and tools you will need to build your own generator quiet box

Materials:

  • MDF – we will use it to make the box.
  • Green Glue – sandwiched between layers of MDF helps to dampen vibrational sound transmission.
  • Noise reduction is aided by acoustic caulking in seams and corners.
  • You may also put a thick layer of foam under the generator to absorb vibrations and dampness. To prevent sound from entering through the walls, cover them with foam mats.
  • Mass Loaded Vinyl (MLV) is also a great liner for the box, the thicker, the better at blocking noise.
  • A Ventilation Duct – is required to provide a sufficient air supply for the generator box.

Tools:

  • Some Pen and Paper: for notes
  • A Measuring Tape
  • Right Angular Ruler
  • Hammer and Screwdriver
  • Screw and Nails
  • Cutting Saw: Circular or Table will do

9 Steps to Build a Generator Quiet Box

Now that you have all of your items ready to build a generator quiet box, then follow these steps:

Step 1. Measurements

Now you will need two measurements to build the generator quiet box.

Generator Length: We measure from the back of the generator engine up to the exhaust pipe and add 1 ft (12 in).

Generator Height: The height we cut our MDF pieces for this example was 3 in (3/4 thick plywood) and it was 5 in high for each panel.

Step 2. Cutting Out the Box

Once you have the measurements for each panel, then you can use your cutting saw to cut them out. I recommend at least 3/4 marine plywood (marine grade ply is waterproof) and MDF for best results.

Step 3. Cutting Out Ventilation Duct Holes

Using the measurements you have made, you can now use your cutting saw to cut out two ventilation holes on either top corner of the generator quiet box.

Step 4. Make a baffle box

Now that you have your measurements, you can now build the box to dampen any sound waves produced by the generator running. You may use 3/4″ MDF sheets or plywood to build the foundation for all of the panels. We used 1/2 inch thick MDF panels on the bottom of our quiet box.

To absorb the sound waves from the generator exhaust, the baffle box must have a solid foundation. To do this, place a layer of 3/4″ thick MDF on any flat surface and then use some noise reduction material. Acoustic insulation can be easily attached with Velcro, screws or adhesive pads.

We used screws that are 1/2″ long to attach the insulation board to the bottom of our quiet box. You can use glue, bolts or screws but make sure you do not drill any holes in the generator!

Step 5. Seal All Seams with Acoustic Caulk or Green Glue

Once you have all of your panels cut out, then you will need to seal all of the seams with acoustic caulk or Green Glue. Green Glue is a professional product and it works great for most applications, but if you do not have access to it then use the acoustic caulk.

Step 6. Add the Second Layer of Soundproofing Inside the Quiet Enclosure

Now that you have your baffle box built, then it is time to add the panels on the inside of the box. This is where you will need some acoustic insulation and Green Glue sandwiched between 2 layers of MDF board (or plywood) as seen below.

We used 1/2″ thick MDF boards and put a layer of noise reduction insulation between each panel. We used 3/8″ thick acoustic insulation as seen below.

Step 7. Screw on the Final Panel

Now that you have the inside soundproofed with Green Glue and acoustic material, it is time to attach one more final panel on the front of your quiet generator box.

We used 1/2″ thick MDF panels that were cut to fit perfectly inside our quiet box. The final step is to seal all seams and screw the front panel on.

Step 8. Attach a Vented Lid

Now you can attach a vented lid for easy access to your generator later if needed.

We used a 2″ x 12″ vent on our generator boxes as seen below which allows the air to flow freely to the inside of the enclosure.

Step 9. Test It Out

Once you have assembled your generator quiet box, it’s time for a test run. Make sure all screws are tight and go enjoy your generator in its new quiet box.

Frequently Asked Questions

Why are generators so loud?

There are a number of reasons why generators seem to be so loud. One of the main reasons is that most residential homes have been built with insulation and air-tight windows which means more sound is being reflected back into the generator quiet box.

What types of materials should I use for my generator quiet box?

Marine plywood or MDF board would be the best to use for this project as you need something that is waterproof. If not, then any type of plywood or MDF will work as long as it is sealed properly with acoustic caulk or Green Glue.

How can I make a generator quiet for camping?

Having a generator quiet box is great for camping as well. Just make sure that it is portable and can be easily moved into or out of your tent, RV or cabin. No one wants to deal with the noise of a generator while trying to enjoy their camping trip!

How much airflow does a generator need?

It is important to have the generator in a well-ventilated area so you do not produce any carbon monoxide fumes that can be dangerous if not vented properly. You want your generator quiet box to have at least 1″ of open space on each side for airflow, but it does depend on the size of the generator you are using.

What’s the best technique to keep noise from your generator at a minimum?

The best way to keep your generator quiet is by putting it in a generator box. It’s also great for containing the noise when you are traveling with it in an RV, cabin or tent. If you cannot afford to purchase one of these boxes, then make sure you find a flat surface inside your home or building and lay some acoustic insulation on the floor. Also make sure that when you are traveling with it, that you keep the generator at least 50 feet away from your tent or cabin.

Conclusion

Soundproofing your generator is so important when you are camping at a campground with other people, or if you live in an area that has close neighbors. If you have ever had to listen to the noise of a generator all night while trying to sleep, then you know exactly what we are talking about! Whether it’s for work or play, it’s wise to invest in a quiet generator box so you can enjoy the low noise level instead of dealing with all that annoying sound.