Help me turn a door into a sound barrier as well as a physical one.
April 8, 2010 11:48 AM   Subscribe

What is the best way to make an interior door a better sound barrier?

The door between my laundry room and the rest of the house is of the cheap hollow core variety. When the dryer is running, even with the door closed, I still have to turn the volume up on the music to be able to hear it clearly. So, I'm looking for recommendations and/or stories of experience regarding ways to help keep the noise from seeping through.

I'm not looking to completely eliminate the noise. Just get to the point where I can keep the stereo at a relatively low volume 20 feet away and have it drown out the rest of the noise.

My initial ideas are:

· replace the hollow core door with a solid one.

· putting carpet on the back of the door.

· putting foam egg crate up on the back of the door.

· putting foam insulation panels on the back of the door.

· put weather stripping on the door to seal it up.

While researching I learned about Mass Loaded Vinyl, but it's at a fairly high price point. I expect something else less expensive would get me there. Also, while getting a quieter drying is an option, it's one I'm going avoid. The one I have now works perfectly well. Just being louder than I would like is not grounds for replacing it in my world.

Any other suggestions? and more to the point, any idea which one (or combination of) the above would provide the most bang for the buck?
posted by StimulatingPixels to Home & Garden (24 answers total) 1 user marked this as a favorite
Solid door, and the heavier it is, the better it will block the sound.
The well-coupled double-diaphram of the hollow-core door is a miserable place to start
when you are looking for something soundproof.

Watch out for wide gaps under the door, as line-of-sight sound paths through the
gap under the door can defeat your attempts to soundproof it. That is to say, if your
drier is RIGHT IN FRONT OF THE DOOR, and you have a wide gap, you will have trouble
with DRIER NOISE. Moving the dryer or installing some sort of baffle on the bottom of
the existing door, or installing a closer fitting door with less gap might all be solutions.

Naturally, trying easy, cheap solutions first is always the best path :-)
posted by the Real Dan at 11:57 AM on April 8, 2010

The door should go, but sealing it with weather stripping going to be a good bang-for-the-buck, probably. Sound travels through duct work, gaps around electrical outlets, etc. Anywhere air can move freely, sound will move, and the more direct the route the worse it'll be (ie, line of site). Is this in a basement without a finished ceiling?

I'd also consider moving the dryer if you can. Acoustics will vary depending on where it is, so you might need to experiment (assuming it's electric and thus easier to move around).
posted by paanta at 12:00 PM on April 8, 2010

One thing people miss with stuff like doors is the air space around the door, specifically between the floor and the door. If your door is hung normally, and there's a bit of space down there, your biggest win is going to be closing up that space. The Pro Audio way to do this is to install these weird multistage wiper things to do this (but they have other issues and generally run double doors anyway), but the canonical cheapo way has always been installing weatherstripping, like you mentioned.

That said, I've always thought you could order one of those draft-blockers from a "BUY IT NOW FOR NINETEEN NINETY FIVE!!!1`1" commercial, trim it up, and put that in there and it would be even easier and very possibly better.

But definitely start with that gap.

So, once you have all the air gaps around the door taken care of, there's two ways to make progress:

- add damping, generally in the form of mass
- add additional refractive layers that will bounce sound back to you or diffuse it into the house

A foam egg crate or foam insulation won't do jack shit for this. I mean, in the barest sense of slightly dampening the vibration of the outer door panel, it might, but...not really.

If you replace the door with a solid door, that will be a win, but get something filled up with crap, like sawdust or processed wood substitute, not something made of actual wood or metal, because those are more likely to resonate.

Generally though, if you add mass to panels of the door, they will be harder for your dryer to vibrate (note: this is not strictly true because it is frequency-dependent but for our purposes here this spherical cow model will suffice). So like, putting carpet on the back of the door is not a bad idea. It will probably do something. You should glue it though, if possible. Remember, the idea is like if you go in the room with the dryer on and put your hand on the door and stop it from vibrating, thats what you are drying to do, like a metal drummer who grabs his cymbals at all the pauses in the song.

All the real tricksy magical shit in acoustics is for changing sound in a room: diffusing it, evening out the frequency response, changing how long things reverberate. Just blocking sound going from one place to the next there's no real tricks: you gotta just stop the vibrations from getting around.
posted by jeb at 12:01 PM on April 8, 2010

Why could you not drill a couple of 1 to 2 inch holes on the top of the door (not the face, the top) and blow some insulation in there (as you would with a wall)? I would bet that would be better sound proofing than a solid door?

Also, weather strip the bottom of the door.
posted by HuronBob at 12:05 PM on April 8, 2010

My first attempt would be to get a can or two of expanding foam. Drill a couple holes in the top edge of the door and start squirting it in slowly and a little bit at a time. If you go to fast and/or the door is a real POS then I can easily imagine the door splitting. But then you have an excuse to go buy a solid core door. Alternatively you might put the holes on the vertical edge of the door every 18 inches or so and put the foam in that way.

Please note: I have never done this and cannot guarantee the results, but it sounds like it would work so why not.
posted by nestor_makhno at 12:09 PM on April 8, 2010

If you don't care what it looks like, you could glue+screw drywall to the backside of the door - this would add some mass and stop vibration.
posted by davey_darling at 12:14 PM on April 8, 2010

  1. Seal air gaps
  2. Add mass to the door (either with new door, or by attaching/filling)
  3. Add absorption in the dryer room

posted by misterbrandt at 12:26 PM on April 8, 2010

There is a larger than normal gap at the bottom of the door. I'll knock that out first with weather stripping (as well as the edges where the door meets the frame) and see what that gets me.

Hadn't thought about putting insulation inside the door. That'll be my next step largely because I'm curious to see the effect. And like nestor_makhno says, if I explode the door (which I don't think is that likely, but I'll wear protective glasses just in case), that'll make the next step of getting the new door an easy one.

Another thought that occurred while reading over these is to attack the vibrations on the dryer itself. I don't really have any other place to move it, but it seems like attaching something to the sides to help reduce the vibration of the machine itself would help to some degree.

First though, stopping the direct air transmission.

I'll report back about what I do and the results.

For now, that's for the great responses.
posted by StimulatingPixels at 12:47 PM on April 8, 2010

doors are pretty cheap btw, but they can be kind of a pain to install...get someone handy to help you if you go that route (often a new door will not fit and either needs the hinge sockets chiseled out or the edges lathed down...not too difficult but like i said...someone handy)

have you tried making the washer and dryer quieter? i bet if you got some heavy rubber pads (cut in about 3" circles) and put them under the feet, it might dampen their vibrations.
posted by sexyrobot at 1:03 PM on April 8, 2010

Putting foam in the door will not help at all, and will make a huge mess. You need mass to stop sound, not fluff. A solid-core door is a good start.
posted by Aquaman at 1:35 PM on April 8, 2010

If you need mass to stop sound, then what is up with the foam they put on walls in a recording studio?
posted by nestor_makhno at 1:39 PM on April 8, 2010

That larger gap at the bottom of the door could be there for ventilation. I'd make sure there is another way for air to get both in and out, or block it with something not permanent at first.

A rug under the dryer might help too, and new dryer might be the best solution. I suspect some dryers are quieter than others
posted by Some1 at 1:47 PM on April 8, 2010

You probably don't want to bother with putting in insulation. I replaced a door in an apartment with a hollow core door so that I could put a transom window in it to keep my cats out but allow air flow. When I cut through the door, I found that the actual door was built like corrugated cardboard: there was a wooden frame, two excruciatingly thin veneers and a series of cardboard zig-zags. Getting insulation into a door made this way would be a real bear. If the door is truly hollow, go for it, but otherwise goodnight, no! And don't forget to figure the cost of filling the gap. A typical door is what, 36" x 80" x 1 3/8" - so the interior is roughly 2880 cubic inches, which is roughly 1 2/3 cubic feet - so keep that in mind.

In terms of time/cost, try the weatherstripping and if it doesn't help just put in a solid door.

What aspect of the dryer is creating the noise? If it's motion transmitted to the floor, then something to absorb shock ought help a lot (rubber feet, etc).
posted by plinth at 1:54 PM on April 8, 2010

Another point against trying to fill the door with foam: hollow core doors that I am familiar with are often filled with an expanded cardboard "egg-crate" inside--you would just fill a cell or two and then you would have the rest of the foam left outside ... This may have been what Aquaman had in mind.
posted by Logophiliac at 2:09 PM on April 8, 2010

If you need mass to stop sound, then what is up with the foam they put on walls in a recording studio?

Those are meant to stop sound reflection - i.e. so when you are listening to a speaker, you hear the sound coming from the speaker itslef without the sound bouncing back off of the wall behind you. (a bit of a simplification, but that's more or less what you are seeing.)
posted by davey_darling at 2:30 PM on April 8, 2010

I believe that a lot of the sound that comes from the dryer is caused by it being a big metal drum with things banging around inside it. I would do two things. First, I would buy one of those pads that are made to go on the floor in your kitchen to "relieve strain from standing all day." They are thick and rubbery. Install it under the dryer. This will cut down on how much sound vibrates the floor. Next, as a test, I would wrap the top, back and sides of the dryer in a heavy blanket or bedspread. You can hold it in place with twine or a couple of bungy cords, as long as you don't cover the dryer door. If this works, you can buy a mover's furniture pad and make a more permanent cover for the dryer, possibly cutting and sewing it to fit.
posted by Old Geezer at 2:59 PM on April 8, 2010

Logophiliac's comment about the interior of a hollow-core door interested me. A quick Google search later, and I found
While the hollow core door is certainly not heavy or solid, is it also not completely empty inside its frame. Hollow core doors need some type of inner structure to add some support to the frame and there are a few different types of hollow core structures used today. One common type of hollow core door filling is structural paper. The paper is often formed into a honeycomb construction and is glued to fit inside the hollow door frame. Other types of support filling for hollow core doors include foam blocks and pieces of board placed in sections inside the door frame.
Too bad, because I like the idea of squirting insulation into the door. Not to help with the sound or anything, but just to do it.
posted by ymendel at 3:10 PM on April 8, 2010

Oh yeah, I didn't think about the interior construction. I've broken down enough hollow-core doors (college, don't judge) to know better.
posted by nestor_makhno at 3:15 PM on April 8, 2010

check out the door prices at home depot...IIRC holow-core doors start around $20...they also sell stick-on weatherstripping that goes all around the door frame roommate used it on his door with good results...those strips that go on the bottom of the door work good, too...the metal kinds with rupper flanges on the bottom run about 10 bucks and you just slide them on, adjust the height (to close the gap), then screw them down...i wouldn't worry too much about blocking airflow under the door (as long as the drier vents to outside the house, which is pretty standard/required), but i wouldn't wrap the drier with blankets unless you want your house to burn down...but you may try moving it a little closer or further from the wall and see if that makes it any may be resonating sound in that gap, or vibrating against the wall...
posted by sexyrobot at 5:10 PM on April 8, 2010

I wouldn't recommend wrapping your dryer in anything flammable. But I'm pretty paranoid about house fires.

I'm a little puzzled that the sound of the dryer bothers you more than the sound of the washer. Are you using those plastic dryer balls? They give something like a 5% improvement, but if they're bothering you, then it's not worth it.

Have you tried drying more clothes at once, or fewer? Are you sure your washer's spin cycle is working well enough to get the clothes wrung out properly, so they aren't as heavy?

How about buying a cubicle panel from an office supply store, and angling that between the dryer and the door? Cubicle panels are padded, and designed to absorb and block noise.
posted by ErikaB at 5:15 PM on April 8, 2010

nestor_makhno: To add on to what davey_darling said, I think it is also to help keep sound from bouncing back and forth off the walls in a way that would make it sound bad when the mike pics it up.

Some1: I keep the door open (or at cracked) most of the time. I only close it all the way when I'm running the washer/dryer.

plinth and Logophiliac: Thanks for the info on hollow core doors not actually being hollow. It make sense why they do that, but it never would have occurred to me until I was into the door.

plinth: I think the metal exterior of the dryer is a big source of the noise. I'm going to try to dampen that, but I'll do the rubber feet as well.

Old Geezer: Great idea on the standing mat. The outside of the dryer doesn't really get hot as far as I can tell, but I'm a little wary about wrapping it. My though is to find some material to use over just part of the surface the help deaden the vibrations. (Which I'll watch closely for the first several runs to make sure it doesn't get dangerously hot.)

ymendel: I was just about to do the same search. Thanks for posting that.

ErikaB: The washer bugs me a little too, but it's quieter than the dryer so I just used it for the example.

This has all got me very curious about the way sound travels in the house/room. I've been thinking about getting a SPL meter for a while, and with this, I've got a humorously justifiable reason. Once it gets in, I'll turn this into a bit of a science experiment and actually measure the reductions objectively. I'll post a link back here when I start (probably a week or so) if you want to follow along with the results.
posted by StimulatingPixels at 7:48 AM on April 9, 2010

My though is to find some material to use over just part of the surface the help deaden the vibrations.

huh. (or possibly A-Ha!)...if it seems like the most noise is coming from the cabinet of the dryer vibrating, try this: get behind it and make sure all the screws holding the cabinet (or whatever the big sheet of metal forming the front and sides of the dryer is called ;) to the back of the dryer are nice and tight...sounds like it might have been serviced and then not closed up properly. you might even try putting rubber washers on those screws if it doesn't already have them. (pro tip: the screws are probably the self-tapping kind, i.e. they dont have a nut on them on the inside of the dryer. but they might. if you unscrew it, the nut (if there is one) is going to fall off inside the dryer. if you want to try putting rubber washers on these screws, start with one on the bottom. that way it will be easy to get at if it does have a nut. here's how: disconnect the power, then slide the dryer forward a foot or two, tilt it back until it's leaning against the wall (washers and dryers are designed to be serviced from the bottom...i.e. there is no's open.) put something under the front to keep it from falling on you. you should then be able to get at the bottom screws easily (the ones higher up will be a pain in the ass)...this is all 'worst case scenario' of course...tigtening with a screwdriver might be all it needs...
posted by sexyrobot at 1:40 PM on April 9, 2010

Not sure if you're still checking this thread, but it occurs to me that you could use something like Dynamat - it is an adhesive material that stops vibrations - it is used in automotive and home theater applications to dampen noise/vibrations - applying this material to the top, sides and front of your dryer might help cut down the noise.
posted by davey_darling at 4:58 PM on April 11, 2010

sexyrobot: I'll check them when I start getting into this. I have a feeling though, it's still going to make a fair amount of noise just because of the amount of motion in the overall device.

davey_darling: Thanks. I like the idea, but that stuff may be a little more pricey than I want to go. Hopefully, I can get it quite enough that I don't need to move to that level, but it's a good option to think about in general.
posted by StimulatingPixels at 12:43 PM on April 13, 2010

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