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Sound Insulation for a dishwasher

MEPTMoore's picture

I have a new house that has a fairly noisy dishwasher.  Guess I should have spent a few more bucks on it.  It does have the standard thin fiberglas insulating blanket on it.  There is a bit of room inside the cabinet and around the dishwasher, so I was wondering if it would do any good to add some material in there.  I was thinking about trying acoustical ceiling tile (for a dropped ceiling) or maybe Homasote.  One side has about 4" of space between it and the cabinet, so I thought I'd try fiberglass or something else in there.  Anyone have any suggestions?  Thanks

(post #110767, reply #1 of 14)

Fiberglass is what dishwasher manufacturers use to insulate their machines, and in the better models it works really well.  Yea, the pricier models really are quite a bit quieter.  I'd recommend fiberglass over the Homosote or ceiling tiles.  Unlike for thermal insulation, it works best for sound insulation when it's packed quite tightly.  The fiberglass blankets made for noise control are much more densly packed than those for thermal control.

(post #110767, reply #8 of 14)

Thanks a lot to everyone for all the good ideas.  I'll probably try a combination of them.  I just need to make my wife happy and quiet down "her" dishwasher so I can move on to all my other projects.  Thanks again.

(post #110767, reply #9 of 14)

My wife and I just replaced out 12 year old Maytag with a new mid-range Kitchenaid last week.  The Maytag was giving out, but it had been so noisy since new that we had to run to dw and shut it off if the phone rang.  The new one is SO quiet that once you are about 8 feet away in any cycle, you can barely hear it.  I'm afraid that you are beating a dead horse by trying to insulate the old unit.  In the older machines, almost all the noise comes either through the door or from the motor directrly underneith or both.  Don't close off the vent in the door....all  the dw vent steam out of there.

(post #110767, reply #2 of 14)

Our new washer came with a gasket that fits tightly around top and sides. If your washer does not have those, you could probably make some with adhesive backed foam or rubber insulation.

If sound is rediating out front into the room,then the acoustic batts will help and rim gasket will help. If sound going through wall behind the washer, you could glue(silicone caulk) some tile backer board. The heavy density board cushioned with the caulk, will stop a lot of sound transmission.

Some high end washers have a sound deadening material that is used in the auto world. It is black and looks like rubberised tar paper. You could remove the fg blanket, put on the deadening layer, and then replace the fg.

Also check to see how easy to get behind the front panel. I was able to quiet a washer by putting a layer of deadening mat behind the door. I then had to move the springs up one notch to properly counter balance the door. Hope this helps. Paul

Energy Consultant and author of Practical Energy Cost Reduction for the Home

Energy Consultant and author of Practical Energy Cost Reduction for the Home

(post #110767, reply #14 of 14)

re - Some high end washers have a sound deadening material that is used in the auto world. It is black and looks like rubberised tar paper. You could remove the fg blanket, put on the deadening layer, and then replace the fg

--------

The roofing ice-dam shield is pretty much the same thing.

I'm planning on getting a roll for several sound deadening applications, especailly in an old VW bus.

(post #110767, reply #3 of 14)

Most of the noise from ours (lowest priced GE) came thru the front.  Easy to disassemble the front and cut a slab of closed cell poly foam to fit around whatever is in there.  Quite a bit quieter. Plain old rock wool batting* around the rest of it inside the cabinet, lots cheaper than paying the $100 or so for 'quieter' model. Dont forget a piece of batting inside the bottom kick panel to deaden pump noise.


* Used to be the local aerospace store sold surplus insulation batts used in aircraft walls, these were essentially lead coated insulation batts.  After Pb lawsuit scares, no more surplus of those available.

(post #110767, reply #4 of 14)

Not sure how sound this technique actually is but a GC I have worked with when faced with a noisy DW took the mastic backed sheeting used as ice barrier under shingles, the stuff that seals around the nails and is sticky as the IRS.


He cut it into pieces and plastered, in several layers in spots, it on the body under the fiberglass, under the countertop and the sides of the cabinets on either side of the DW. Seemed to deaden the vibrations and noise quite a bit. Cost him nothing as it was scrap


He said he had previously used it to deaden the sheet metal in his car after installing speakers.

(post #110767, reply #5 of 14)

I am like Junkhound. I bought the cheapest dishwasher that GE makes as a replacement for a wornout high end model in my last house. I took the insulation blanket off of the old dw and added it to the el cheapo. With two f/g blankets, the new dw was less noisie than the older , more expensive model.


Dave

(post #110767, reply #10 of 14)

'the new dw was less noisie than the older , more expensive model' Gotta laugh at that. I keep thinking you are refering to the dear wife instead of dishwasher.

(post #110767, reply #13 of 14)

ROF, but after a little refection, you are right. Don't think the first dw was a more expensive model....., she just thought she was.

(post #110767, reply #6 of 14)

"...ice barrier under shingles, the stuff that seals around the nails and is sticky as the IRS. "


I've used that material for sound deadening as well.  Works quite well.  Dense materials like this block low frequency sounds.  A couple hundred dollars worth of lead flashing would work too...

(post #110767, reply #7 of 14)

most DW like GEs have an air vent in the bottom front where the noise comes out. I am afraid to cover it up.

consumer reports magazine sez all DW are noisy even the "quiet" ones - some less so.


Edited 1/15/2004 10:12:24 PM ET by wain

(post #110767, reply #11 of 14)

Fiberglass is a poor sound insulator. Sound is mechanical energy, and to reduce the sound you need a substance that can absorb and disipate the vibrations as heat. Fiberglass is poor because the strands are rigid and smooth, so they don't pick up vibrations, and those they do they pass on through since there is little friction between the smooth strands.* The best sound absorbing material is wool, which is elastic *and* is heavily crimped, and all those crimped sections rub together when they vibrate which converts the vibrations into heat, thus dampening the sound. Many recording studios line their walls with carpeting for this reason. But wool is impractical due to cost. The best alternative is the polyester wool bunting available for quilts at fabric stores. It is more expensive than fiberglass, but it gets the job done. Think of it as the sound equivalent of Icynene (sp) foam, more expensive but a much better performer per inch. Those who have noisy pipes might also want to consider wrapping them in this bunting. Also, don't stuff the chamber with any sound insulator. You want to decouple the device generating the sound from the surrounding walls by decoupling them with an air space.

The fiberglass that came with the dishwasher has more to do with holding in heat than with reducing sound. I'd be curious to see whether premium dishwashers use fiberglass or a polyester based sound/heat insulator.

* I have noticed that my house is alot louder since the 12" of fiberglass was put in the attic. I may add some inches of cells up there to dampen the noise once all work is done (har har har).

(post #110767, reply #12 of 14)

Line the walls of the dishwasher cavity with 12x12 cork tiles, 6 on each of the 3 sides, 4 on top and 4 on bottom. They will help absorb sound and take up a minimal amount of space.