Best way to sound-insulate a hollow metal door and bare hallway?
March 31, 2007 1:04 AM   Subscribe

How can I sound-insulate my rental apartment's hollow metal door and bare entrance hallway? They're amplifying the already loud noises in the common hallway outside.

In my studio apt, I'm lucky enough to have (at least for now) quiet neighbors on both sides of me. The hallway outside my apt. is another story, though: slamming doors, loud yelling, barking dogs, etc. This is an intermittent problem but it's a 24-hour problem (the groups of guys passing through the hall are loud enough to regularly wake me up at 3am).

This common hallway is all tile (i.e., all echoes) and I can't change that. My own entrance hallway is bare walls + wood floor, and my door is hollow metal, so clearly I should change both those things.

So I'm trying to figure out how to make my own hallway less echoey, and my door less able to transmit sound -- as cheaply and non-security-deposit-losingly as I can. (Although the noise level is bad enough that, honestly, sound insulation is a bigger priority than getting my deposit back next year.)

First few ideas:
- weather stripping or something else around the door (there's a slight airspace around the door now)
- rugs along the full length of my hall (what kind of rugs? thick/dense better, or deep/fluffy better?)
- blankets (or some other material?) lining the inside of my door
- blankets (or some other material?) lining my hall's walls (but how to suspend them, and how to get lots of cheap blankets that look okay together?)
- thick blankets hung to make a fabric 'door' at the point where my hall opens up into my apt.
- actual door (in a wood frame) installed at the point where my hall opens up into my apt.

I care about aesthetics and would like to avoid a cobbled-together or dormlike feeling as much as I can. But I know this may be impossible on a tight budget.

Many thanks for your recommendations...
posted by lorimer to Home & Garden (10 answers total)
Response by poster: In case I wasn't clear enough: from the common hallway, you open my apartment's main door, then walk though my apartment's narrow entry hallway, to get to the main room of my apartment. It's a small one-room studio apartment, so my hallway and front door are the only thing between my bed and the noise of the common hallway.
posted by lorimer at 1:08 AM on March 31, 2007

I wonder if it would be possible to remove the door, find a spot that is open to the hollow interior, or drill one in at the top or bottom, and fill with foam insulation?

You can buy the insulation in cans at hardware stores, but I have no idea if you could adequately and cheaply fill the hollow, or if filling it with the foam would add the level of insulation you are looking for.
posted by qwip at 1:24 AM on March 31, 2007

Response by poster: Great idea, qwip. I think my door would definitely take a specialist to remove (it's a common urban-apartment type of door where the hinges are the industrial/thick kind and they attach deep into the wall). HOWEVER, there must be a way to remove one of the door locks, or the enclosure around the peephole, so I could spray stuff inside the door.
posted by lorimer at 1:41 AM on March 31, 2007

Best answer: The most effective broad spectrum noise dampening materials you could apply to inside of the door will all add some weight to it; you'd need to evaluate the door hinges and frame to see if they likely could stand 10 to 15 pounds of additional weight. If so, you can purchase fairly effective complete door sound control kits, or if that is too expensive, somewhat less effective sound dampening mat kits at automotive parts stores. These mats can also be covered with carpeting, or plywood panels, to add additional mass, if your door can take the weight. Weatherstripping is easy to do, although unless there is wide open slot that it can fill, the amount of noise reduction you'll get is minimal.

Inside the door, the more surfaces you can cover in damping material, and the greater the thickness and density of those dampening materials, the greater the noise reduction you'll achieve. But be careful with hanging large amounts of potentially flammable textiles near your only egress from the room. Any materials you do install in that area should be selected for their flame retardant properties, as much as for their acoustic dampening. Accordingly, I'd recommend an over application of some product like Supress Sound-Engineered Drywall, if you have some basic carpentry skills and tools. Failing something as comprehensive as an absorptive drywall solution, you could affix acoustical panels to the walls in your hallway, but these won't do much about dampening conducted sound, although they will reduce reflected sound somewhat. Same for rugs in the hallway; they'll help a bit in absorbing reflected sound, but not as much as you might hope. Again respecting fire issues, some kind of parachute ceiling treatment [link for illustration only] in the hallway might be easily rigged, which could support 5 or 10 pounds of soft dacron batting.

Your idea of constructing some kind of hanging curtain sound barrier isn't bad, but again, pay attention to fire considerations. And be aware that to provide much acoustic benefit, you'll need enough mass to create an effective barrier to sound conduction. Something the weight of an Oriental rug hung vertically could drop conducted sound from your hallway considerably, but I think you'd tire of pushing it out of the way all the time, and it would be a pain to hang, by yourself. Better would be to find a free standing acoustic screen, which might be useful in future situations, when you move, too.
posted by paulsc at 1:49 AM on March 31, 2007

Response by poster: Excellent points, paulsc, thank you! I especially hadn't thought about how much I'd be increasing the flammability.

It's true, that first link to the door kit is out of my price range but that looks like a really useful site for me to learn from. The second looks great especially if it's only slightly less effective. I'm not sure how to evaluate the weight-bearing ability of the door but it seems VERY solidly anchored into the wall.

If I hung something like oriental rug thickness, would it still work if it were in two overlapping halves (so I could walk through it), or is it important that it be one unbroken piece?

Also, just to make sure: by reflected vs. conducted do you mean sound bouncing off my walls vs. sound vibrating in the wall itself? If so, I think I'm dealing with the latter. I think the reason these sounds are so freaking loud in is they've been reflected around it a lot already in the common hallway.
posted by lorimer at 2:28 AM on March 31, 2007

Response by poster: DUH, too tired -- for "dealing with the latter" substitute "dealing with the former." I think I am dealing with reflected noise.

Also, in the time since I posted this question at 4am, I've also had the pleasure of two random people leaning on my buzzer and yelling at me to buzz them in. Not the first night that's happened. So I uncrewed the intercom and disconnected the buzzer wire -- no more buzzer but that's very worth it. now if only all my sound fixes were so easy... :(
posted by lorimer at 2:33 AM on March 31, 2007

Heavy mass is the best noise blocker, especially for lower frequency noises. It's possible to reduce the sound, but difficult to eliminate it.

Try sound generators. I get weekend music from outdoors that keeps me from falling asleep, so I have a white noise generator. A window air conditioner also masks the sound when it's warmer. A loud fan or radio tuned to static would work, too

I'm used to traffic noises, I completely ignore them now. But music or shouting is hard for me to ignore, even if it's not very loud at all.
posted by jjj606 at 9:23 AM on March 31, 2007

Years ago, I helped with remodeling on a two family building. The two unit's bedrooms were adjoining, and the wall between was replaced with a new wall. Each side had it's own set of 2x4 studs with a gap in between to reduce noise conduction, and the cavity was filled with insulation. Then it had two layers of drywall on each side for mass. It worked ok, but you could still hear a radio in the other room. So blocking sound is hard.
posted by jjj606 at 9:29 AM on March 31, 2007

Best answer: Maybe you could open the door a bit, drill a hole in its top, and pour in vermiculite. Its super lightweight, a good insulator and fireproof. Garden supply stores carry it as a soil conditioner, but it has been used to insulate attics.

When drilling thru steel it’s a good idea to mark your spot with a center punch, put a liitle oil in the dimple and then run progressively larger drill bits, say 1/4 - 3/8 -1/2. Proceed with caution, as thin steel is notorious for grabbing drill bits just as they’re about to plunge thru the hole, causing the bit to stop and the drill to start spinning. A cordless drill with an adjustable clutch will help with that.
posted by Huplescat at 10:42 AM on March 31, 2007

I really like the idea of filling the door :P

Slits in the entry curtain are fine. Overlap is good, but if it hangs tight together it should be OK (for some unspecified definition of OK). You are basically trying to block the line of sight between the quiet space and all possible reflected paths to the loud space. So, that isn't exactly like your line of sight, some bit of reflective ceiling could direct problem noises over the top of the curtain/rug. Just imagine every surface covered in mirrors, and make sure there is no reflective path around your sound barrier. That isn't the whole story, sound waves (especially low frequency waves) aren't like laser beams, but I think the analogy will do..

All that aside, experience is much more important than theory! Try a few things out and see how they work before committing a large bundle of cash.
posted by Chuckles at 7:46 PM on March 31, 2007

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