Construction material for portable generator sound-deadening box

[joshuabardwell]

I am planning on building a sound-deadening box for a portable generator. I'm curious if y'all could suggest some hardware-store material that would be a good choice, that might not be obvious. As I understand it, the best material would be MDF, because of its density, but that's a no-go because it disintegrates as soon as it gets wet. I have heard that plywood is a poor choice because it basically just resonates like a drum and doesn't really baffle the sound much. One person on the Internet suggested the silver insulation panels, but I'm skeptical; they contain air, for thermal insulation, so it seems like they would have too low a mass to be effective at sound deadening. Another person put fiberglass batting on the inside of his box, which I'm skeptical of for the same reasons.

Any input y'all might have would be welcome.

 

[aczlan]

3/4" plywood with sprayfoam on the inside, then tin inside that.

Aaron Z

 

[wyeguy]

Don't know about sound deadening, sorry, but if I was doing this I'd also consider fresh air for engine operation & venting the exhaust. Maybe you've already got this covered. Good luck!

 

[joshuabardwell]

Don't know about sound deadening, sorry, but if I was doing this I'd also consider fresh air for engine operation & venting the exhaust. Maybe you've already got this covered. Good luck!

Yup. I've done a lot of research into various construction techniques. It's tricky to keep the generator from overheating while not opening up big holes that let the noise out. I don't have any solid answers there. I'm just going to try stuff and see what happens.

 

[joshuabardwell]

3/4" plywood with sprayfoam on the inside, then tin inside that.

What's the purpose of the tin? To keep the spray foam insulation from being knocked off?

 

[aczlan]

What's the purpose of the tin? To keep the spray foam insulation from being knocked off?

That and spreading the heat around enough that you don't get hot spots that light the foam on fire.

Aaron Z

 

[joshuabardwell]

I have done some looking into spray foam insulation, but I think I must be looking at a different product than you're suggesting. Everything I'm seeing is way expensive, and requires specialized equipment. Can you point me at a specific foam product?

What's the benefit of the spray foam over, for example, the silver insulation board?

 

[pwright]

You might look into the sound deadening and thermal barrier stuff they sell for vehicles.

 

[ericb2400]

short stroy from many years ago when i was not as smart as i am now I was chosen to drive the truck to pull the tlr in a Christmas parade. we put christmas lights on the tlr + flood lights etc etc. Generator in bed of my truck. It is a chrismas parade so we wanted the generator to be quiet. Made a temporaroy box out of blue foam inslulating board. Had 1.5ft clearance all arouind for air space and brathing holes cut in the box also. long story short. It got hot in the box. the gas tank swelled becaous of the heat, when i uncovered the generator, gas was shooting 20+ft out of the vent hole in the gas cap. :shocked: Once it cooled down etc, the gas tank was still distorted. I will never box a generator again. I would rather listen to it than risk what could have happened that day.

 

[PILOON]

Staple old carpeting on the inside of a plywood housing, that will help a lot.
Felt is also good.
For cooling, a computer type muffin fan while quiet will move lots of air. You can get them in 12 VDC as well as 110AC (and barely draw 1 amp).
Make the exit opening the same size as the fan you select and orient inlet and outlet in opposite sides/corners.