Generator Shed Noise Abatement

[Northislander]

Going to be starting the build of my generator shed at the cabin. This will be my third gen shed build. Each time I try to reduce the noise level a little more. So the current plan is:

Walls: 2 x 6 top and bottom plate with staggered 2 x 4 studs Roxul safe and sound insulation in walls 1/2" fir sheeting with 1-1/2" Comfort Board and 3/4" rainscreen then 3/4 cedar siding 1/2" res bar and 5/8ths drywall on the inside.

Roof: 2 x 6 Handframed rafters 2 layers Roxul safe and sound in attic

Slab: 4" concrete slab with 6" curbs on top filled with 4" of sand inside 12KW Kubota diesel gen with custom built skid will sit on sand. I have found the foundation is one of the weak points for sound transmission in past builds.

A Better muffler and insulated air intake and exhaust chases

Wondering if anyone on the Garage Journal has any other tips or suggestions for sound abatement.

On this property I can't move to far from the cabin without going up the hill which I think would broadcast the noise to my neighbors. So thinking of keeping it lower but closer to me.

 

[rlitman]

5/8" drywall is good. Cement board is heavier, so it will be better at reducing sound transmission, though it's not as pretty, and it's pricey. Still, if we're talking about a box around your generator and not a garage, the material costs won't be all that bad.

Mount the generator to your skid on vibration isolators designed around it's weight. Waffle rubber maybe? That will do a lot more than the sand.

Your enclosure will still need a lot of airflow through it for cooling. Acoustic louvers are the usual answer for generators.

The hill is your friend, as it will block quite a bit of sound from reaching the other side.

 

[Robbie B]

In my friends’s recording studio he did a false wall as he calls it. Did a layer of drywall over the studs, 1” thick furring strips and another layer of drywall. He said the void kills resonant frequencies that would escape otherwise. All I know is with his doors closed you can’t hear his black metal band practicing at full volume. Like previously said. Vibration isolators from the base. Anything that has air gaps in it think foam board stuff like that should help. Go online and look up diy recording studio sound control. It’s meant more for killing frequencies but it would work for a generator also I would imagine.

 

[kaymccampbell]

I saw a generator that sat inside a 12' high, roofless concrete box. You couldn't hear it outside on the ground. If you got up high enough it was quite loud, but that required a bucket truck.

 

[kbs2244]

Can you dig into the hillside?
A root cellar style hole.
Then all you need is a heavy/thick door

 

[rsanter]

Replace with scroll compressor?

 

[nadogail]

Replace with scroll compressor?

I don't think the scroll compressor will give the OP the same output as the generator.

 

[Northislander]

5/8" drywall is good. Cement board is heavier, so it will be better at reducing sound transmission, though it's not as pretty, and it's pricey. Still, if we're talking about a box around your generator and not a garage, the material costs won't be all that bad.

Mount the generator to your skid on vibration isolators designed around it's weight. Waffle rubber maybe? That will do a lot more than the sand.

Your enclosure will still need a lot of airflow through it for cooling. Acoustic louvers are the usual answer for generators.

The hill is your friend, as it will block quite a bit of sound from reaching the other side.

Thanks did some google searches and found some Canadian suppliers of waffle rubber and acoustic louvers.

 

[Northislander]

In my friends’s recording studio he did a false wall as he calls it. Did a layer of drywall over the studs, 1” thick furring strips and another layer of drywall. He said the void kills resonant frequencies that would escape otherwise. All I know is with his doors closed you can’t hear his black metal band practicing at full volume. Like previously said. Vibration isolators from the base. Anything that has air gaps in it think foam board stuff like that should help. Go online and look up diy recording studio sound control. It’s meant more for killing frequencies but it would work for a generator also I would imagine.

Thanks for that I've been doing internet searches for Gen Sheds and finding very little used the "diy recording studio" search and blown away by the amount of info was so far down the rabbit hole reading almost forgot to come back to post some thank you's

 

[Northislander]

Can you dig into the hillside?
A root cellar style hole.
Then all you need is a heavy/thick door

Most of the hillside is rock and where it is dirt I don't want to or can't locate the generator due to possible flooding from the creek. Forgot to mention eventually I will be adding micro hydro to harvest some power from the creek. Stream Engine will be in separate compartment from generator but still inside sound proof room as they give off quite the high frequency hum when running at full capacity.

 

[zeke67]

Duct the radiator outlet up instead of straight out. Ensure the muffler outlet points up.

 

[mike93lx]

Do you own the generator already? If sound was a high priority, I'd look at marine units.

 

[nadogail]

If any of your intake or exhaust openings point up, take care to shield them from rain water incursions.

 

[Robbie B]

Thanks for that I've been doing internet searches for Gen Sheds and finding very little used the "diy recording studio" search and blown away by the amount of info was so far down the rabbit hole reading almost forgot to come back to post some thank you's

You’re welcome. Noise is noise so I figured maybe it would help.

 

[NZGarage]

Hi, after you line the interior I would mount sheets of perforated wood panel leaving an air gap between so sound waves/air can go through the holes and and expand before making contact with the interior lining.

Something like this.
https://www.architonic.com/en/products/perforated/0/3240744/1

 

[Denwood]

Just a few extra tips, based on construction of a heavily sound dampened personal theater, and a commercial film studio for my last business (30’x30’) fully sound attenuated with dedicated HVAC etc. Low frequency ground transmission is an issue..and sand with underlying mass is a good idea. You may also want to look at Sorbothane mounts like these ones: https://www.amazon.ca/dp/B00K32IGN8/?tag=atomicindus04-20

1. Metal studs staggered in place of wood dramatically reduce noise transmission over wood studs. If you use steel studs and layered drywall with green glue between, you can skip the resilient channel. Hang your ceiling drywall layers as well using steel studs.

2. Consider two (or three) layers of 5/8 drywall inside with green glue separating them. Treat the door the same with full air sealing including the door stop. Your typical cineplex uses 4-5 layers of drywall on each side to isolate. Caulk the floor, wall and ceiling seams with green glue acoustic caulk. HD carries this stuff.

3. Construct dead vents, or DIY duct mufflers for your intake and exhaust. Longer is better. Duct mufflers are cheap to make and very effective. Here’s a link to my theatre build where my 94db source signal (in a bare room) was knocked down to 42db using essentially steel studs, drywall, green glue and duct mufflers.

If you follow the above build advise, your air vents and door will be the only weak points.

The core is just wire mesh wrapped with fiberglass acoustic duct liner.

You want the outer pipe 3-4” larger than your wire mesh core. Longer is better! Use duct sealer on all your joints.

You can build a virtually sound proof shed this way for just the incremental added cost of drywall, green glue, door seals, some ducting and acoustic duct liner.

 

[Stuart in MN]

Thanks for that I've been doing internet searches for Gen Sheds and finding very little used the "diy recording studio" search and blown away by the amount of info was so far down the rabbit hole reading almost forgot to come back to post some thank you's

I had a next door neighbor who ran a commercial recording studio out of his house. The studio was essentially a separate room framed up inside another room, with the space between the walls filled with sand. It worked really well for soundproofing.

 

[ItsNemo]

Seems like a lot of building for a generator...why does the noise matter so much? how much is this thing going to run? 12kw isn't much, so is this just a backup? Could you run a little inverter gen for most of the loads and only fire up the big one when you need it?

 

[Denwood]

Vancouver Island...not cool to make noise

You don't need the room in a room concept as this is a standalone structure. Just build in the isolation.

 

[Northislander]

Thanks everybody for your help. I will post a pic. of my plans in a day or two hope to get something drawn.

 

[haugy]

I'm no help, but I'm definitely paying attention as I'll need to do this for my compressor and back-up genny as well. Great info in here.

 

[theoldwizard1]

Roof: 2 x 6 Handframed rafters 2 layers Roxul safe and sound in attic

Slab: 4" concrete slab with 6" curbs on top filled with 4" of sand inside 12KW Kubota diesel gen with custom built skid will sit on sand. I have found the foundation is one of the weak points for sound transmission in past builds.

A Better muffler and insulated air intake and exhaust chases.

Air should come in at the bottom (well screened to prevent rodents) and go out the roof. Noise does with the air and straight up is the best ! (The taller the shed, the better.)

Intake and exhaust are NOT major contributors to overall noise.

 

[Jacko264]

Many years ago I had a race car put on a rolling road .
The walls of the building had fibre rock wool on them then peg boarding it stoped the sound by socking up the noise into the rock wool
Graham

 

[Showkey]

Eu2200 Honda for low power would be very quiet with out building a building.

Eu2200 noise level of 57 decibels at a rated load, and 48 decibels at a quarter load.

More power required buy Eu7000............it less money in the long run.

The EU7000iS operates at 52 to 58 dB(A), which is less noise than a normal conversation. This makes it ideal for supplemental RV power, powering outdoor events, and any other activity that requires quiet operation.

Any generator shelter sufficient cooling is going to be a major hurdle.

 

[Northislander]

Eu2200 Honda for low power would be very quiet with out building a building.

Eu2200 noise level of 57 decibels at a rated load, and 48 decibels at a quarter load.

More power required buy Eu7000............it less money in the long run.

The EU7000iS operates at 52 to 58 dB(A), which is less noise than a normal conversation. This makes it ideal for supplemental RV power, powering outdoor events, and any other activity that requires quiet operation.

Any generator shelter sufficient cooling is going to be a major hurdle.

Showkey the property is eventually going to have 4 cabins on it so the diesel is the way to go for load and longevity. And i already have the Genny on site presently running out of a cargo trailer.

As for cooling we've done this several times in the past. As well as almost every fishing resort and logging camp i work at has much larger gennys in gen sheds with no problems with cooling

 

[rayra]

Look at home theater building forums for tips on sound-deadening with double layer drywall and that caulking goop that creates a small air gap between the drywall layers. The goop will cost more than the drywall will.

Also, rubber feet / isolation mounts, to minimize sound conveyance thru the shed floor / structure.

---

About to move into a new house and build a new sound-obscuring corner cabinet in the garage. Was just thinking about decoupling strategies, sound absorption. Have a noisy craftsman standup oil-less compressor. I was using a small / short confining cabinet, with a pegboard roof and low skirts, so it got a little airflow. And the front door was storage shelves and lined with eggcrate-style foam and all the air tools, so a good bit of the noise was blocked.

 

[Bretny]

By far the best way to quiet a generator is to get a 1800rpm one over a 3200-3600rpm.

 

[rlitman]

By far the best way to quiet a generator is to get a 1800rpm one over a 3200-3600rpm.

That is very true. It's also what you want for "prime" power for a site.

 

[Stuart in MN]

You mentioned in the first post you were going to use a 12kW Kubota. If it's this model, it already comes with its own enclosure and the sound ratings are pretty good - 67dB. https://www.kubotaengine.com/generators-listing/gl14000/ For something like that I think you just need a shed with louvered panels in the walls, that will keep out the weather but allow for cooling air and combustion air. Below is a screen shot from Google Maps Street View of a similar shed for a generator I did some years ago for a municipal wastewater lift station.

 

[rlitman]

Why would you put a lamp post in the middle of a carriage door?