Author Topic: Sound Reducing Wall Options  (Read 1107 times)

Jon Bon

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Sound Reducing Wall Options
« on: January 07, 2021, 07:18:09 AM »
I have two units separated by a single 2*4 wall with regular sheetrock and insulation between them. It stops almost no sound. As this is a shared wall I want to improve it's sound reducing properties.  I added a handy picture. I'd like your opinions on my options. I have a few ideas from easiest to hardest.


1. Acoustic Panels, just attach some to both sides cheap and easy - likely wont do much.
2. Remove drywall (on one side) attached resilient channel, add noise reducing insulation and drywall.
3. Build second wall for acoustic break. Leave current wall as is, build second wall 1 inch from existing, use rockwool and resilient channel.

Anyone have any other ideas? Will any of this work? or will sound simply travel through the attic?
« Last Edit: January 07, 2021, 07:42:39 AM by Jon Bon »

zolotiyeruki

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Re: Sound Reducing Wall Options
« Reply #1 on: January 07, 2021, 08:15:59 AM »
I'd go for option 3, probably.  It's pretty easy and fast to frame up a wall like that, and with rock wool, it should do a decent job of deadening the sound.  Since it's not there for fireproofing or structure, you could build it out of 2x3's to save a little money.

As for the attic, I wouldn't bother.  The sound would have to go through one ceiling, through the insulation, bounce off the underside of the roof decking, penetrate the insulation on the other side, and then finally pass through the drywall ceiling.  I'd expect it to muffle the sound at least as well as a double wall.

lthenderson

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Re: Sound Reducing Wall Options
« Reply #2 on: January 07, 2021, 08:17:37 AM »
I once lived in an apartment with a shared wall and found that after removing the covers for the switches and outlets on the shared wall and spraying a lot of foam around the junction boxes before putting the covers back on reduced noise a lot more than I had thought.

YttriumNitrate

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Re: Sound Reducing Wall Options
« Reply #3 on: January 07, 2021, 08:26:47 AM »
All three of these options will provide some benefit, but to varying degrees based on the frequency of sound that is problematic.

Jon Bon

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Re: Sound Reducing Wall Options
« Reply #4 on: January 07, 2021, 08:36:46 AM »
Yeah I was leaning option 3, its not that many feet long, maybe 20 feet? I think it was only 6 sheets of drywall.  Also if I have to mud drywall its all the same to me. Cost will be about the same. I would if I should should build that second wall AND do the resilient channel?

So original wall
Break
New 2x3 and rockwool wall
Break (R-channel)
New Drywall.

That would be a whole bunch of barrier to make it through. 2x3s is a good idea as well.


trollwithamustache

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Re: Sound Reducing Wall Options
« Reply #5 on: January 07, 2021, 08:42:15 AM »
What about a second layer of drywall? as in the cheapest/easiest option also likely less effective that other options. I'm assuming one unit is empty?  Then later when the other unit empties, a second layer on that side.

Papa bear

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Re: Sound Reducing Wall Options
« Reply #6 on: January 07, 2021, 08:47:06 AM »
If you really want to take a deep dive, read about sound proofing for home theaters.   For higher frequency stuff, itís not too hard.  Air seal between the 2 units, physically block any intrusions, foam around boxes, caulk between the floor and your drywall, etc. 

For low frequency, from mens voices down to low bass stuff, you need mass.  So double up your drywall with 5/8.  Or change out the insulation from fluffy fiberglass to mineral wool.  Or decouple the entire wall with another wall.  But doing that, do you have enough wire to extend out your electrical? What about other finishes? Doors, windows, etc?

I would air seal to your best ability, then look at green glue between another layer of 5/8 drywall.  That should help.


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Jon Bon

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Re: Sound Reducing Wall Options
« Reply #7 on: January 07, 2021, 08:50:49 AM »
What about a second layer of drywall? as in the cheapest/easiest option also likely less effective that other options. I'm assuming one unit is empty?  Then later when the other unit empties, a second layer on that side.

yeah that's possible, but some 2x3s and screws don't cost much and easily in my wheel house. What I Want to avoid is mudding and painting more drywall, but I don't think I can do much about that.

Also There is only a single outlet box in the wall, so not much in the way of holes.




bacchi

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Re: Sound Reducing Wall Options
« Reply #8 on: January 07, 2021, 09:14:10 AM »
What's your flooring look like? Noise also travels through the slab. You can add cork underlayment to help with that and replace any tile on both sides.

https://www.primaryacoustics.com/images/Controlling%20the%20Transmission%20of%20Impact%20Sound%20Through%20Floors.pdf

Jon Bon

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Re: Sound Reducing Wall Options
« Reply #9 on: January 07, 2021, 10:57:49 AM »
Anyone heard of this green glue stuff? Do that and a 5/8 sheet of drywall?

Having hard time finding data. If 1 sheet of drywall allows X amount of sound, 2 sheets allows Y amount of sound type thing.

YttriumNitrate

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Re: Sound Reducing Wall Options
« Reply #10 on: January 07, 2021, 12:03:42 PM »
Anyone heard of this green glue stuff? Do that and a 5/8 sheet of drywall?
Having hard time finding data. If 1 sheet of drywall allows X amount of sound, 2 sheets allows Y amount of sound type thing.

Back when I was trying to sound proof my basement, I looked at green glue. It is probably better than standard flexible caulk (e.g., butyl caulk), but it's expensive and I decided my soundproofing dollars would be spent more effectively on other things.

BudgetSlasher

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Re: Sound Reducing Wall Options
« Reply #11 on: January 07, 2021, 07:48:43 PM »
If you have time to experiment ... I would start with air sealing. Specifically around outlets and switches or gaps under doors etc. (sound will move more easily in open air).

But if time is money, well a lot the things you have mentioned are seemingly well reviewed, but I have no personal experience.

Leroy_tabane

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Re: Sound Reducing Wall Options
« Reply #12 on: January 07, 2021, 08:18:56 PM »
I agree with @BudgetSlasher. They sell a lot of soundproofing materials, but none of them work if other conditions are not met. I'm no expert and I haven't tested this but apparently, you need an air-tight seal between the two rooms. Also, I think that it is likely that the sound will travel through the attic if there is even a small air gap somewhere. I read that if air can get through, sound will too. So I would suggest you get some acoustic sealant and some poly plastic as well as putting soundproofing material in your wall.

Good luck with your project!

Jon Bon

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Re: Sound Reducing Wall Options
« Reply #13 on: January 08, 2021, 06:28:27 AM »
I agree with @BudgetSlasher. They sell a lot of soundproofing materials, but none of them work if other conditions are not met. I'm no expert and I haven't tested this but apparently, you need an air-tight seal between the two rooms. Also, I think that it is likely that the sound will travel through the attic if there is even a small air gap somewhere. I read that if air can get through, sound will too. So I would suggest you get some acoustic sealant and some poly plastic as well as putting soundproofing material in your wall.

Good luck with your project!

I only have 1 outlet on the wall, and it is the only one in the stud bay. IE there is not an outlet on the other side in the stud bay. So I should not get "flanking" that I have been reading about. I can definitely use acoustic caulk on it.

This feels like a very inexact science!

Id anything it sounds like 5/8 will in fact help (mass) but the greenglue would give me dampening. I could add a second wall to decouple in part (But not all) of the room. This is a rental so some sound is acceptable. I guess what I am looking for is someone to tell me. What products/strategies they used, and how effective or ineffective it was.


jac941

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Re: Sound Reducing Wall Options
« Reply #14 on: January 09, 2021, 10:47:31 AM »
If itís not a huge wall, QuietRock works well but is very expensive per sheet. Even if you donít want to use their product, their rated assemblies guide is still a good way to see how well different assemblies will dampen sound. It also provides the fire rating.

https://www.quietrock.com/sites/default/files/The_Sound_Design_Guide.pdf

Dicey

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Re: Sound Reducing Wall Options
« Reply #15 on: January 09, 2021, 11:11:00 AM »
Shouldn't that common wall be a fire wall by code? If it isn't now and you make it one, your insurance might go down, which would help mitigate costs.

A scrap of anecdata: our last flip was a tad close to a freeway, and we had the interior stripped to the studs anyway, so we insulated the interior walls. Just the same R-19 rockwool we used elsewhere. It made a huge difference, far beyond our expectations.

jac941

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Re: Sound Reducing Wall Options
« Reply #16 on: January 10, 2021, 03:09:12 AM »
A scrap of anecdata: our last flip was a tad close to a freeway, and we had the interior stripped to the studs anyway, so we insulated the interior walls. Just the same R-19 rockwool we used elsewhere. It made a huge difference, far beyond our expectations.

We have also found this to be true. We have insulated every interior wall that weíve opened. It definitely makes a noticeable difference but isnít practical if youíre not opening the walls anyway.

Paper Chaser

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Re: Sound Reducing Wall Options
« Reply #17 on: January 10, 2021, 07:59:08 AM »
Mass loaded vinyl under some drywall might be a good idea too. It would be interesting to me to compare the effectiveness and the economics of regular, cheap fiberglass insulation plus a layer of MLV vs just rockwool insulation.

albireo13

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Re: Sound Reducing Wall Options
« Reply #18 on: January 13, 2021, 08:17:42 AM »
One thing I did in the past was to soundproof the interior wall between the laundry room (with washer/dryer) and the family room.
They had a shared interior wall.

   I had the interior wall built with 2x6 spacing.  2x6s were used for ceiling and floor wall framing.
Then I used 2x4s for wall joists but, they were staggered between the rooms.  Thus, each stud only attached to one wall.  This removed a lot of the vibrational coupling between the rooms.   I also added pink fiberglass insulation between the walls for noise baffling.
It worked like a champ!