How to Soundproof a Dishwasher

Dishwashers are a great invention, saving time and energy. But they can be loud. Specially older units. And open concept floor plans, and vaulted ceilings tend to magnify the noise. Here are 7 ways to reduce, if not eliminate, the problem. That work, are not expensive, and you can put into practice almost immediately.

7 Dishwasher Noise Remedies

Dishwashers can produce up to 75 or 80 decibels of sound, while new quieter ones should be around 40 decibels. Anything over 6o decibels is getting loud. Having an inexpensive decibel meter, to check sound levels, will let you know what you are up against. The following chart gives you an idea of what decibel ratings sound like.

Note: The decibel scale is logarithmic (just like the earthquake scale) meaning that a 1 decibel increase=30% sound increase. An extra 3 decibels doubles the sound level.

Decibel Level Comparisons

1) Mechanical

First, make sure the noise is not caused by a part that is malfunctioning. Real good soundproofing will only disguise the fact that the dishwasher pump is about to have a heart attack. As with almost anything mechanical, make sure you have the owners manual handy, or can access online instructions and parts lists. Reading these before starting will definitely make your project easier.

Safety Note: Before shoving your hands and arms under there, unplug the dishwasher; or if it is wired in directly, turn the breaker off. Some of the stuff under there is pretty low voltage and will not hurt much. Some is usually 120 volts and can make your toes curl the wrong way. And running your finger between a belt and pulley is definitely not a walk in the park either. Disconnect the power!

Pump. Failing dishwasher pumps can make some pretty rude noises like squealing, whining, and rattling. Quite often the noise is accompanied by water leaks because the seals are also bad. If you are certain it is your pump, replace it and the seals. (Note: If you are only hearing rattling, check the screws or bolts mounting it to the machine to make sure they are tight. Just tightening them may solve your problem.)
Spray Arms. Spray arms, specially metal ones can get bent enough so they are hitting other parts of the machine–usually causing some kind of weird clicking sound. You can check arm operation just by spinning them manually, with nothing in the machine, to ensure they operate freely. Replace any bent or damaged arms.
Bearings and Seals. Failing bearings can make rattling, squealing, or whining noises. Before pulling the dishwasher out of the cabinet to check things out, run a complete washing cycle with the machine empty. (Make sure it is completely empty. You would feel inadequate pulling out the motor only to find a couple of knives mating inside the wash tub.) Quite often bearing failure is caused by leaking seals allowing water to get into the bearings and washing away the grease. You will have to replace the motor if this is the problem.
Impeller and Chopper Blade. Foreign objects such as a piece of glass, a piece of bone, even an unpopped popcorn kernel can cause a grinding noise. Clean out both housings. If you find the impeller or blade damaged, you will have to replace them. (Note: Cleaning off the dishes before putting them into the dishwasher has more benefits than just helping the machine to get them clean.)
Loading. Although not really mechanical, improper loading of the dishwasher can cause noise–cutlery rattling, plates tapping, unidentifiable noises caused by something preventing one, or more, of the spray arms from rotating. Although taking a little care loading the machine will solve most of that, using dishwasher baskets is a great help. (And you want the kids to learn to put things in the machine in such a way you don’t have to re-load it.)

2) Insulate the Door

Once you have assured yourself that the sounds coming from the mechanical parts of your dishwasher are normal–or you have replaced/repaired as required–you can move on to soundproofing. Because the dishwasher door faces into the room, you should tackle it first. Open the door, remove all of the screws holding the front panel, and remove gently. (Invariably there is some electrical stuff in there, so just yanking it off could have a serious downside.) Remove the old insulation, and cut and fit new material. Here are 3 options.

Noico 80 car sound deadening mat. This stuff keeps your vehicle quiet (road noise, engine noise, etc.) so it should work just dandy for mere dishwasher noise. It is a self-adhesive butyl based product. Requires a roller to get it flat and tight. Easy to cut. Easy to apply. Comes in a 36 square foot box. (I know that is way too much for a dishwasher door–but keep reading.)
Frost King Multi-Purpose cotton insulation. 1″ thick. Can be cut to size. I would install it with double-sided tape to make sure it stays where you put it.
RoxulProRox SL 960 Rockwool. Roxul is a sound absorbing insulation product. It is fairly rigid and the 1″ thick batt should fit comfortably between the door panels without needing tape to hold it. The biggest downside is that you will have quite a bit leftover, so if you have no use for it, try to find somewhere to get just one batt. Or I have linked you to a package of two.

Once you have installed the soundproofing material, re-assemble your door–gently.

Note: I really prefer Noico Red 315 mil sound deadener (made of closed cell polyethene foam) for the dishwasher door, but it comes in a 20 square foot box. So unless you have another project that will use up the excess, the unused portion is an expensive dust collector.

Technical Note: 1 mil=1/1000th of an inch making 80 mil a little less than 1/8″ thick (2 millimeters) and 315 mil close to 1/3″ thick (8 millimeters).

3)Replace Factory Insulation Blanket

Most dishwashers come with a soundproofing blanket draped over the top and sides of the tub portion of the machine–usually held in place with 2 or 4 self-impaling clips. If you can get them out undamaged, you can re-use them. I would use twist ties, zip ties, or baling wire (if, like me, you are an old farm type person), because hopefully your new blanket is thicker than the existing. Here are a few replacement options.

Soundproof Blanket. (Better known as moving blankets.) These heavy quilted blankets have many soundproofing applications. They are inexpensive. Biggest downside is they are usually 72″ wide x 80″ long–way too big for your dishwasher. So you will have to cut it to size and sew up the cut edges. Biggest upside is they are huge so you can custom-make it fit exactly to within an inch of the floor on each side. (Do not cover the back of the machine. Although dishwashers do not produce a lot of heat, it still needs to escape somewhere.)
Factory Insulation Blanket. These are usually thin fiberglass or foam. Every manufacturer will be able to supply a replacement insulation blanket. (I am reasonable certain that they are close to interchangeable.) But if you get one from your dishwasher maker, it will fit right onto the unit without any issues.
Ceramics Fiber Insulation Blanket. At 24″ wide x 72″ long x 1″ thick, this blanket will cover the entire top and sides of the drum area. It is a high temperature blanket designed for forges, kilns, glass blowing, etc. so it is definitely a bit of overkill for your dishwasher soundproofing. But you will buy it once and transfer it to every other dishwasher you buy.

Note: Both the Soundproof Blanket and the Ceramic Fiber Insulation Blanket blanket are thicker, heavier, and more efficient than the factory product.

4) Insulate the Cabinet

Now you get to use most of the rest of the Noico 80.

Sides, Back, and Top. Our dishwasher–and I am sure many others–only has about 1/4″ clearance between the cabinets and countertop. (See picture below.) Noico 80 is 2 mils thick (about 1/8″). Once you have the dishwasher out of the cavity, you can install Noico 80 on all of the surfaces. Make sure you wash everything with a 50/50 vinegar/water solution to remove any dirt, dust, or other residue. Apply the Noico. You will need a Noico roller and may want Noico seam tape to seal any imperfect joints–although this may be a little overkill for soundproofing a dishwasher.
Floor. I would also use the Noico on the floor because it sticks down and will not move as you are re-positioning the machine. And it is thin. Thin anti-vibration pads are available, but realistically, you would have to screw them to the floor so they do not move when you are replacing the dishwasher. (The lack of room inside the cavity does not allow for you to lift it over the floor, or ‘walk’ it in.)

Note: Keep in mind that this stuff sticks like poop to a blanket. So if you are going to put new lino over the existing, be prepared for some scraping.

Our Dishwasher

5) Free-Standing Dishwashers

Some of the foregoing suggestions are meant for dishwashers that are recessed into your kitchen cabinets. Some are not. They are free-standing, or can be rolled over to the sink for water supply. Our daughter has a small one that sits on the counter and a hose attaches to the tap. All of these may make more noise than built-in units. Soundproofing suggestions for these types of units:

Mechanical, and Door Insulation. The sections above certainly apply to any dishwasher. So make sure you take care of those potential problems first by following the listed recommendations.
Soundproof Blanket. Realistically, covering these dishwashers with a soundproof blanket (at least when in operation) is the least expensive, and most effective, option–specially for the ones that are rolled to the sink to operate. A blanket is quick, easy, and can be folded up and put away when not in use. Not particularly cute, but the washing cycle is only 2 or 3 hours at most.
Noico Black 80. Noico Black 80 mil soundproofing mat is the same product as the original shiny foil product. If you want to soundproof a free-standing or movable dishwasher, this may be the product for you. Because these types of units are encased in a complete cabinet, you can cover the whole thing except the bottom. If your joints are next to perfect, you will not need to tape them and you will have produced a quieter black dishwasher. Instead of white. Make sure you wash it with a 50/50 vinegar/water solution to get great adhesion. Make sure you use a roller to make it smooth.
Floor Mat. If you have a small carpet remnant, or can get one from a flooring outlet, place it under the dishwasher to deaden the sound bouncing off the floor. (If you have a mat in front of the sink and move the dishwasher there to hook it up, don’t bother getting another one.)

6) Way Too Much Time on Your Hands Anal Remedies

If you have time on your hands, and some carpentry talent, and your wife already considers you a bit loony; consider extending the cabinet on both sides of the dishwasher, and adding soundproof doors. (Thankfully, I cannot do this to ours because the cabinet drawers on one side, and door on the other side, are almost tight to the dishwasher.)

Basically, you are going to build a 3-sided box and attach it to the face of your cabinets and touching the countertop. (If it possible get wood and cabinet doors and handles that match your existing.) Stick Noico 80 to the backside of the doors, hang them on the box you built, and with all of your other soundproofing efforts, noise from your dishwasher should never bother you again. Make sure you caulk the seam between the countertop and the small box extension.

Note: I take no responsibility when your wife stubs her toe on the extension.

7) Buy a New Quiet Dishwasher

When all soundproofing remedies fail, and your dishwasher has some other problems like leaking or not cleaning the dishes, it is probably time for a new one. Following are 3 of the quietest dishwashers. (I am only comparing quiet, not operation, but all three of these are in the $1000.00 range, which should give you a pretty good product.) Whatever dishwasher you choose, make sure you ask about the decibel rating. 40 and under are considered silent. 41 – 53 are considered quiet.

As the chart above shows: under 40 decibels falls between a whisper and your refrigerator, 50 decibels is like moderate rain, 60 decibels is the sound of conversation.

Samsung Linear Wash. 39 decibels.
Bosch 800 Series. 40 decibels.
LG Studio 40 decibels.

End Notes

Make sure your dishwasher is screwed to the underside of the counter (if wood), or to the cabinet on either side. They usually do not rock and bang into the surrounding walls like a clothes washing machine, but if they are attached as recommended, you will eliminate the possibility completely. Get new brackets if necessary.

Remember to unplug the machine, or turn off the breaker.