Depending on the combination of steps you take, it's possible to reduce generator noise by anywhere from 1 decibel (ineffective treatment) to over 20 decibels. These basic steps should be considered when wanting to reduce generator noise:

1. Get the right size - The more powerful the generator, the more noise it makes. Assess your power needs and stick to a generator that gives you the right amount of power. This will reduce excess noise.
2. Point the exhaust away - Make sure the exhaust is pointed away from where you’re located, or even straight up. This will help the sound dissipate.
3. Keep your distance - Put the generator as far away from you as possible, ideally a minimum of 20 feet. Invest in extra-long, heavy duty extension cords.
4. Stick to soft ground – Hard surfaces like concrete or asphalt will strengthen the reverberation and increase the noise. Placing the generator in grass or dirt will keep the vibrations down. You can use a rubber mat if you’re unable to find soft ground.
5. Build an enclosure - Or upgrade the one you have now. We've seen soundproofing materials reduce the decibel level of a generator by over 20 decibels!

Although these tips can help you reduce the noise somewhat, ultimately the generator is still exposed and will still be noisy unless you tackle #5. The best thing you can do to make your generator quieter is to add an enclosure. If you already have one, we have some advice on how to help make it quieter. If you don’t already have an enclosure and are interested in creating a generator sound box, skip ahead.

Second Skin Case Study: Generator Soundproofing

For soundproofing a generator, we recommend building a generator soundproof box, and adding sound absorption materials inside the box. The best material for getting a combination of soundproofing and sound absorption is our BlocknZorbe Sound panels featured below!

Normally when we talk about soundproofing, we suggest to completely cover and enclose the space you’re attempting to soundproof. For generator safety, it’s extremely important to account for exhaust ventilation and room for airflow. That makes it hard to do a "100% soundproofing” . While you can’t eliminate the sound completely, you absolutely can reduce it a great deal and bring the noise to a much more comfortable and enjoyable level.

1-2-3 Checklist For Soundproofing Your generator Enclosure

Soundproofing a generator box is pretty straightforward if you understand the principles of soundproofing. Start with this checklist and then keep reading to go into more detail on "why" this works.

1) What's the generator enclosure made of?

2) Do you have big air gaps where the sound can escape?

Air gaps are the mortal enemy of soundproofing. Lack of airflow is the mortal enemy of generators. We can solve for both if we plan ahead, and the smaller your enclosure - the more planning needed. Vents should face away from living spaces. A cheap box fan inside your box will move a lot of air and help keep the space cool. Building an external baffle (outside any vents) will act as a secondary noise barrier while allowing airflow. If you've never built a baffle before, contact us for questions on how to build a baffle with BlocknZorbe and 1/2" plywood. Always test the operating temperature inside the box to ensure you're at safe levels.

3) Is there sound absorption inside the box?

The easiest/quickest improvement for most generator boxes is a little sound absorption. Almost every enclosure is all hard, sound-reflecting surfaces. Sound absorption will reduce those reverberations and cut noise 5-7 decibels. Always install sound absorption on at least 2 adjacent surfaces (if you can do more, great). Covering a wall with a "checkerboard pattern" will actually add almost as much sound absorption with 50% coverage as covering 100% of the wall. For outdoor applications, BlocknZorbe will again be your best friend. We don't call it our "utility player" panel for nothing! This same process works for soundproofing a furnace closet with machinery inside.

Stopping Generator Box Vibrations on a Metal Box

If your generator box is metal (most commonly seen when attached to a vehicle), a lot of the noise is due to vibrational energy. The key to stopping this structure-borne noise is decoupling the generator from the floor (with rubber mounts) and a sound deadening material such as Damplifier Pro. Damplifier Pro is an extremely good vibration damper and heat rated to 450°F so it has no problem with generator heat. It'll knock out the structural vibrations of a metal box, and even reduce them in a fiberglass or plastic container too. Less vibration means less noise.

Blocking Sound From Escaping the Generator Enclosure

To add density to your box, apply mass loaded vinyl or another barrier material like BlocknZorbe. Our Luxury Liner MLV is an excellent noise barrier and improved the noise blocking ability of many generator boxes. The MLV comes in two densities: 1 lb per square foot and 2 lb per square foot depending on how beefy you want your barrier to be. The MLV will help to actually block the airborne sound waves, greatly reducing how loud your generator sounds. For MLV to be effective, cover 100% of either the either interior or exterior wall of your generator box. For small generator boxes, you MUST do the exterior wall. For larger generator enclosures, you can line the interior as long as you leave plenty air space or potentially add heat protection for the vinyl. Soundproof blankets are also incredibly effective and durable products that can be used to block airborne generator noise.

The only gaps should be for wires, ventilation, or exhaust (a baffle covering these gaps will help with soundproofing). Seal edges with foil tape or acoustic caulk to make the seams airtight. A good noise barrier will reduce the noise coming from your generator by 15-20 decibels. You can increase the noise reduction by another 5-7 decibels by adding sound absorption, like Mega Zorbe, inside the generator box. Mega Zorbe is temperature rated to 350°F, Class A fire rated, water resistant, and an excellent noise absorber.

Foam is not dense enough to block sound, but it can be added inside an enclosure to absorb sound waves that would otherwise reflect off hard surfaces. The graphic above shows decibel levels inside and outside a box with a 70 dB bell ringing.

Reducing Heat From Your Generator

If you’re worried about protecting something from the heat emitted by your generator, consider an insulating material like Heat Wave Pro or Mega Block. Remember that adding layers adds insulation linearly. Your generator still needs space and airflow for safety and efficiency. Be wary of typical foam products as they usually have low-heat resistance (less than 200 F) and can be damaged by the heat of the generator. Both Mega Block and Heat Wave Pro have high temperature ratings and are Class A fire rated. Always tape the edges of any heat insulation material you use with foil insulation tape.

A Quick Note: Quieting Generac Generator Boxes

We get quite a few questions from customers about making a Generac generator quieter. Because of the way a Generac generator is positioned inside the box, there's not a ton you can do to improve the box itself. We've seen the best success with a couple of sheets of Mega Block covering the inside lid of the box, as the extra sound absorption will cut noise 3-5 decibels.

Your best performing option is to build a soundproof fence around the box. We go into a lot more detail on what makes a good soundproof fence in our sound barrier fence article, but at a high-level, the fence needs to break the line of site with the area experiencing too much noise (fence should be tall and close to the Generac case). You also should install a fence with some density to it.

1. Build a box with enough space for proper ventilation
2. Install sound block material to the box walls
3. Optional - add sound and thermal absorbing layer facing generator

Although you can buy generator boxes, we’ve found that they can be pretty expensive for something that's not too hard to DIY. If you’ve got a few tools and a day for a project, it can be much more cost-effective to build your own. All generator enclosures are built differently, and there are some really good DIY instructions on the internet. We won't tell you exactly how to build a box for your generator, but we’ll teach you principles and strategies that will guide the soundproofing while you’re building your new generator box.

Step One: Plan for dimensions and Ventilation

Generators produce a lot of heat, so it’s important to account for adequate airflow. Be sure to add extra height and width, you don’t want the generator too close to the walls of the box as it can damage it and your generator. Consider the additional insulation and soundproofing layers you’ll be adding, as they will add thickness to your box. Finally, be sure to measure cutouts for the exhaust, and to run cables from your generator.

Not creating adequate ventilation for your generator is dangerous, and will ruin both your brand new generator box, and your generator. If you want to have a smaller box, you’ll need to add an extended exhaust pipe that can run outside of your box. Some people add a fan to their generator box to help with airflow and cooling their generator. If it’s a bigger box with more airspace, you can get by without one. You may be able to purchase an exhaust pipe specifically for your generator. If not, measure the size of your exhaust and use a material like copper piping that can endure the heat from the exhaust. Ensure that the pipe seals completely at the generator exhaust, as you don’t want fumes leaking and circulating in the box. Depending on the size and heat coming off your generator, you may want to consider cutting out additional ventilation windows.

Step Two: Add Sound Blocking Material

Choose a noise barrier like our Luxury Liner on the interior of the box to stop sound from transferring through the box. Another sound blocking material we highly recommend for generator boxes, especially smaller generator boxes is our BlocknZorbe Multi Purpose Sound Panels. These panels are great because they block sound and absorb sound, while also being very durable in any condition. For small at home generator, these things are sound killers!

Step Three: Optional - Add Sound and Thermal Absorbing Layer

Well, if you used BlocknZorbe in step two then you are all good! If not, it can be helpful for sound purposes to have an absorptive material facing the generator inside the box to help absorb some of the sound that is bouncing around the box. Another product that is a do it all - sound absorbing and sound blocking material is our Quiet Quilt Soundproof Blankets!

Choosing the right insulation and soundproofing material for your generator box is crucial. The main products we recommend are:

• BlocknZorbe - Multi Purpose Sound Panels
• Mega Zorbe - Open Cell Foam
• Heat Wave Pro - Jute Insulation
• Luxury Liner - Mass Loaded Vinyl

Insulation

If you’re concerned about the amount of heat coming off your generator, you can try insulating your generator box. The best way to do this is to create panels with a space between them as your walls. In this space you can insert a Class A fire rated insulating material like Heat Wave Pro (jute) or Mega Zorbe (high heat open cell foam), which are also great products for a quiet bitcoin mining rig.

Soundproofing a Generator Box

Generators are engines - loud, rattling, mean machines designed to do one job really well. Adding a mass loaded vinyl material will do wonders to block the sound from your generator and keep your area quiet. Our Luxury Liner is only 1/8th in thick and comes in easy to manage sheets for you to cut to size. We recommend installing the material to the exterior walls of your generator box or to combine MLV with the fence or other structure you're surround the box with. Be sure to cover the walls edge-to-edge and adhere it firmly with a vinyl contact cement, nails, screws, or staples. Tape the edges with foil tape or use an acoustic caulk to ensure the seams are airtight. This process is similar to building a soundproof pool pump box.

Frame your box with wood, simple 2x2’s or 2x4’s will work fine. For the paneling consider a lighter, flexible material such as fiberboard (MDF). You can use plywood if you’d like but it is heavier and stiffer, so it will make the box harder to move around. Absolutely stay away from metal for the walls or frames as it will rattle and create more noise. If you do use metal, plywood, or a stiffer material, couple it with Damplifier Pro or Spectrum to reduce rattling.

Ultimately generators are incredibly useful, but come with the cost of a constant loud, low rumble whenever they are in use. With some cheap construction materials, and a few soundproofing products from us, this is one DIY project you won't regret. Now you can make your generator more people-friendly and finally finish telling that story about the giant fish you caught around the campsite.