Soundproof room divider

[NitroPress]

I have a kind of odd, narrow construction project and would appreciate some feedback before I make a choice.

My house is like many split/tri-levels here in that it has a sort of portal between the upper floor and the lower. It usually serves to tie together upper and lower common spaces for a spacious feel. In my case, though, it's right by the front door and looks down into what has been configured as a separate room (my office, but it could be a bedroom or nursery as well.) From below, it's about four feet up the wall, about four feet by eight, and oddly shaped to clear the stairs.

The real fix would be to drywall in the space, but for a couple of reasons I don't want to do that. (I'd have to have someone finish both sides, as I'm kind of iffy at texturing, and the next owner might want to open it up again - it's a Feature of these houses.) My work on this house is about 25% for me and 75% sweat equity for a sale in a year or two, so I am thinking it through for buyer appeal. (I also hate the houses I've owned that were hard-modified for some peculiar use...)

So I am going to wall it in with sheet goods on this side, and build an ambience lighting system in on the front door/stairwell side - very cool design using colored LED lighting, etc.

YOU CAN SKIP DOWN TO HERE IF YOU WANT. My construction problem is that I want reasonably good soundproofing, but only have a wall thickness plus maybe an inch to work with - about six inches in all. I need about an inch for the lighting cover (frames with frosted plexi). So if I just use, say a sheet of 5/8 or 3/4, that would leave plenty of room for the lighting fixtures. However, a single sheet, even that small and well-cleated around the edges, isn't going to be great for sound reduction.

So... at about the size of a 4x8 sheet, what can I do to increase sound reduction through this portal? It will be sealed in place, no air gaps. Is there any single sheet good that would work better? What about two sheets of, say 3/8 held apart about an inch by foam blocks? Drywall or ply or particle?

Ideas? Thoughts? Thanks!

 

[dmdc411]

I have a kind of odd, narrow construction project and would appreciate some feedback before I make a choice.

My house is like many split/tri-levels here in that it has a sort of portal between the upper floor and the lower. It usually serves to tie together upper and lower common spaces for a spacious feel. In my case, though, it's right by the front door and looks down into what has been configured as a separate room (my office, but it could be a bedroom or nursery as well.) From below, it's about four feet up the wall, about four feet by eight, and oddly shaped to clear the stairs.

The real fix would be to drywall in the space, but for a couple of reasons I don't want to do that. (I'd have to have someone finish both sides, as I'm kind of iffy at texturing, and the next owner might want to open it up again - it's a Feature of these houses.) My work on this house is about 25% for me and 75% sweat equity for a sale in a year or two, so I am thinking it through for buyer appeal. (I also hate the houses I've owned that were hard-modified for some peculiar use...)

So I am going to wall it in with sheet goods on this side, and build an ambience lighting system in on the front door/stairwell side - very cool design using colored LED lighting, etc.

YOU CAN SKIP DOWN TO HERE IF YOU WANT. My construction problem is that I want reasonably good soundproofing, but only have a wall thickness plus maybe an inch to work with - about six inches in all. I need about an inch for the lighting cover (frames with frosted plexi). So if I just use, say a sheet of 5/8 or 3/4, that would leave plenty of room for the lighting fixtures. However, a single sheet, even that small and well-cleated around the edges, isn't going to be great for sound reduction.

So... at about the size of a 4x8 sheet, what can I do to increase sound reduction through this portal? It will be sealed in place, no air gaps. Is there any single sheet good that would work better? What about two sheets of, say 3/8 held apart about an inch by foam blocks? Drywall or ply or particle?

Ideas? Thoughts? Thanks!

The method I used for a wall between a laundry room and family room was 2x6 top &bottom plates, then alternate the studs for each side of the wall. Another words, each side of the wall had it's own studs for the sheetrock to attach. I then insulated the wall. Worked very well!

Sent from my SM-T350 using Tapatalk

 

[The Cobbler]

how about a sheet of drywall with resilient channel (or z bar or sound channel) screwed to it, then another sheet on that

 

[kbs2244]

Your 2 sheets with foam idea is good.
But go 1/2 if you can.
The more mass you have the more sound it will absorb.

 

[NitroPress]

The method I used for a wall between a laundry room and family room was 2x6 top &bottom plates, then alternate the studs for each side of the wall.

Yes, I used this "decoupled wall" technique in a couple of remodeling projects. It's a great, cheap, fairly easy way to isolate laundry noise, or quiet a bedroom. I have a very narrow width to work with, though, without the whole project getting out of scale.

Your 2 sheets with foam idea is good.
But go 1/2 if you can.
The more mass you have the more sound it will absorb.

Which is why I was thinking of this "junior" version of the technique. I think I can fit in 1/2 inch, at least for one panel.

It doesn't have to be hugely effective, but given the thinness of the barrier I don't want it to be either sound-transparent, or worse, resonant.

 

[mcbane]

The alternating studs idea is excellent. Also look into using Roxul soundproofing. You can order it out of home depot. See https://static.rockwool.com/globala...l/low-frequency-sound-insulation-by-roxul.pdf

 

[climbernyc]

We just renovated our home and used Roxul everywhere. You can’t eliminate all sounds but it definitely is extremely quiet and solid. Roxul makes something called safe and sound and also has applications for recording studios-one might give the additional damping you are looking for

 

[Lelandwelds]

Roxul or Homasote will help some. Twelve inches of concrete is a better sound proofing.

 

[PWC Repair]

Sound moves in waves. Those waves transmit easily through solid objects. The trick is to disipate the energy. How about acoustically cut foam inside the wall cavity, its countoured and can be ordered 1 inch thick. Then staple heavy velour like fabric inside to the studs, it can be bought cheap at Hobby Lobby. 2 layers 1/2" apart should do. Then staple strips of felt to the studs to isolate the drywall from the stud. Finally install your 5/8 drywall.

Disclaimer: I have not used this method, but its a similar idea to what they do between movie theaters and should disipate sound well.

 

[LS6 Tommy]

IDK how much sound reduction you really are looking to get, but I've overseen sound recording and digital TV studio construction. At minimum, for real soundproofing you need a double wall, with each wall well insulated and a dead air gap between the two walls. The walls also have to be mechanically decoupled from the floor and ceiling.

Acousti-blok works well if you don't want the loss of square footage associated with a double wall.

https://www.acoustiblok.com/acoustiblok-product-lines/acoustiblok-wallcover-noise-barrier/

Tommy

 

[DC73]

Forget what it's called but they make an acoustical caulk designed to isolate drywall and other wall coverings from the studs to help block sound transmission. It wouldn't add much thickness to your assembly.

Roxul would help as well and comes in various thicknesses (for example one of their sound control products is 3" thick instead of the 3.5" for traditional batt of insulation.

DC

 

[7echo]

This works great. It comes in 5/8 and 1/2. There are sample assemblies with NR information.

http://www.nationalgypsum.com/products/product.aspx?ProductID=2353

http://nationalgypsum.com/file/SoundBreak Tool/SB_selector_5-8.pdf

 

[lightn95]

This works great. It comes in 5/8 and 1/2. There are sample assemblies with NR information.

http://www.nationalgypsum.com/products/product.aspx?ProductID=2353

http://nationalgypsum.com/file/SoundBreak Tool/SB_selector_5-8.pdf

We've used this hung on metal studs that are designed for sound control. There were these rubber spacers that you had to screw into that hung on the studs. It basically kept the drywall off the stud so the sound waves didn't vibrant through. And there was a special sound proof caulk also. It was a real PITA!

 

[ntn66]

It's expensive, but Mass Loaded Vinyl works very well to deaden sound. https://www.acoustimac.com/soundproofing/underlays-vinyl

 

[DRP6833]

Yes, I used this "decoupled wall" technique in a couple of remodeling projects. It's a great, cheap, fairly easy way to isolate laundry noise, or quiet a bedroom. I have a very narrow width to work with, though, without the whole project getting out of scale...

How about using 2x3 studs on a 2x4 header? It might be a little less effective but would fit in a "normal" wall space.

 

[polizei1]

In my limited research, I would look into using something like Quietrock (drywall) sandwiched with Green Glue. Then use decoupled isolators with Roxul Safe N' Safe insulation.

I have 30 bags of Roxul waiting to be installed, so I can't comment on it, but there's over 500+ reviews on Lowes and Home Depot, the vast majority being very positive.

I'll add that you'll probably get sticker shock. The cost of sound dampening is expensive, depending on your budget, you may just want to double the drywall and insulate.

 

[8mpg]

All depends on budget. Check out a home theater forum.

Double drywall with green glue. Decouple the walls with hat channel or build a double wall. Rockwool insulation. Air seal the absolute best you can. Putty pads behind each electrical box or wall penetration.

 

[sierradmax]

armstrong soundsoak.

 

[Lelandwelds]

It's expensive, but Mass Loaded Vinyl works very well to deaden sound. https://www.acoustimac.com/soundproofing/underlays-vinyl

1000lb of sheet rock is cheaper and more effective than 1000 lb of MLV.

In my limited research, I would look into using something like Quietrock (drywall) sandwiched with Green Glue. Then use decoupled isolators with Roxul Safe N' Safe insulation.

I have 30 bags of Roxul waiting to be installed, so I can't comment on it, but there's over 500+ reviews on Lowes and Home Depot, the vast majority being very positive.

I'll add that you'll probably get sticker shock. The cost of sound dampening is expensive, depending on your budget, you may just want to double the drywall and insulate.

Green Glue is used with plain old sheetrock. It is effective.

IDK how much sound reduction you really are looking to get, but I've overseen sound recording and digital TV studio construction. At minimum, for real soundproofing you need a double wall, with each wall well insulated and a dead air gap between the two walls. The walls also have to be mechanically decoupled from the floor and ceiling.

Acousti-blok works well if you don't want the loss of square footage associated with a double wall.

https://www.acoustiblok.com/acoustiblok-product-lines/acoustiblok-wallcover-noise-barrier/

Tommy

Cavities sometimes work like a drum. Be cautious.

Sound moves in waves. Those waves transmit easily through solid objects. The trick is to disipate the energy. How about acoustically cut foam inside the wall cavity, its countoured and can be ordered 1 inch thick. Then staple heavy velour like fabric inside to the studs, it can be bought cheap at Hobby Lobby. 2 layers 1/2" apart should do. Then staple strips of felt to the studs to isolate the drywall from the stud. Finally install your 5/8 drywall.

Disclaimer: I have not used this method, but its a similar idea to what they do between movie theaters and should disipate sound well.

Not true. Mass is the best soundproofer. Decoupled mass is even better. Surface treatments like you describe are for reflected sound. There is a difference. Only the upper frequencies are affected. The bass rocks on through.

OP is looking for thin and non permanent. Homosote or Roxul wrapped in something decorative is the ticket. I would velcro or dual lock it in place with some small wood strips or wire insulation hanger spikes.

 

[strutaeng]

I agree about more mass. It is well understood in the laws of physics that mass dampens sound. The best way I can think of is using a 6" CMU solid grouted, but you need a way to support it and it is not temporary.

5/8" gypsum board is next best solution, doubled is better. I have wondered about hardibacker for soundproofing. 1/2" hardi weighs about 2.6 psf, just bit more than 5/8 rock at 2.3 psf, but much more expensive and harder to work with, so probably not worth it.

 

[LS6 Tommy]

Cavities sometimes work like a drum. Be cautious.

I'm just listing what the Pros did in th studios...

Tommy

 

[BukitCase]

Cavities will ALWAYS work like a drum, unless they're damped by absorbent material - and Leland's right about cost of MLV - unless a difference of 5/16" is crucial, you'd be paying the equivalent of $70 for a sheet of 5/8 sheet rock. So that's about 7 TIMES the cost for the exact same amount of mass, just half as thick...

There are more "snake oil salesmen" selling "acoustic" products than HONEST ones, generally if something SOUNDS too good to be true it IS.

The first clue is if they call it SOUNDPROOFING FOAM - there is no such thing, and SOME will even sell you NON-fire rated CLOSED CELL foam, which is only good for helping you DIE if you inhale the fumes...

The SECOND clue is if they use the antiquated STC rating in their ads - this ONLY works very well for CONVERSATION, that's what it was originally designed for. SERIOUS studio builders KNOW this, and will design for best Transmission Loss (TL) - the simple version of this is, if you build a wall for best BASS TL (least bass getting thru) you pretty much don't have to WORRY about the REST of the frequency spectrum, because you'll never hear it.

Generally, the more complicated you try to make wall building, the more it costs per dB of Transmission Loss - the "staples" that have worked well for years are Gypsum wallboard, aka Sheet rock, wallboard, etc - Normal 2.5 PCF fiberglass house insulation, un-backed or paper backed, placed between studs in a light compression fill (roxul also works, if it's cheaper go for it) - the goal is to dampen both sides (leaves) of a wall WITHOUT too much compression of the dampening fill - too tight, and you will COUPLE the two sides. NOT good. Also going higher density (for wall fill) is NOT good, it tends to act more like a third leaf if it's too dense - see next...

Adding a THIRD leaf (having mass in THREE places instead of just two) will ALWAYS bite you in the *** - costs more, and divides the mass-air-mass calculations so TL is WORSE - better to put that additional wallboard tight against either side of the wall - more LAYERS are fine as long as they are only in TWO planes.

In the OP's situation, best he can do is go with either the staggered stud arrangement and the heaviest material (per square foot) he can afford, or NON-staggered studs with either resilient channel or "hat" channel (regular hat channel will NOT do anything for you without resilient mounting clips to de-couple that side of the wall from the OTHER side.

As I mentioned, this is a mass-air-mass construct - the "air" needs the fiberglass/rockwool to DAMP the wall's normal resonant frequencies. Things that make TL (especially LOW frequencies) better - more mass, only ONE "air" gap, WIDER air gap, true ACOUSTIC caulk (never fully hardens, so it doesn't crack) putty packs around "leaks", such as outlets, switches, etc -

The idea is you want not even the tiniest crack in a sound wall, or BASS TL will especially suffer - so don't expect a BIG improvement if this "soundproof" wall is free-standing like a room divider - ain't gonna happen.

You can find out more about this here

http://www.johnlsayers.com/phpBB2/index.php

My screen name there is Knightfly - I haven't moderated the Construction forum for about 10 years, but I've been studying acoustics and sound control since 1980, and wrote quite a bit of the FAQ section there.

HTH... Steve

 

[8mpg]

Look here http://www.soundproofingcompany.com/labtests/

This company is third party with testing. You can see the numbers for yourself. Double drywall with green glue will be pretty darn good without spending crazy money.

 

[BukitCase]

Yeah, they're one of the companies that do NOT employ "snake oil salesmen" - dunno what their GG prices are these days, but used to be if you weren't TOO tight for room, it was cheaper and as good to just add another layer of drywall to one side... Steve

 

[couch67]

if you google NRC IR 761 you will come up with a PDF of a wealth of information on wall design and sound transmission. I stumbled on it a few years back and found it to be a great source.

couch

 

[egdede]

We had a den (w/a big TV) abutting our master bedroom. We built a second wall in the den, two inches off the existing wall. We put fiberglass between the walls, being careful that there were no air breaks.

It worked incredibly well.

 

[Lelandwelds]

.. Steve

Wow. Rare that anyone knows this subject so well. Nice read.

 

[BukitCase]

Thanks - there's nothing like a BIG-*** MISTAKE to give you incentive to learn more
1 - build a "studio" into your pole barn on one side for band practice/recording, using "normal" construction methods (but "tight")
2 - get told by wife that she can tell what song you're playing on acoustic piano that she "likes that song" (from 100 feet away inside the house - followed by 2 neighbors away, calling and asking you NOT to quit practice, they LIKE it )
3 - spend the next 20 YEARS spending a couple thousand $$$ on books and studying to figure out "what went wrong", 'cause having a REAL designer wuz about $200,000 over budget
4 - help a few people with their acoustics/soundproofing questions on a few websites -
5 - Get asked by an Australian studio designer if you wanna moderate the Construction forum on his new website -
6 - Get noticed/mentored by REAL acousticians, one being the lead designer of Galaxy Studios in the Netherlands (100 dB isolation everywhere, they land choppers on the roof during recording and NOBODY HEARS IT) - another was told by Steven Spielberg that the sound stage he'd built for a client (next to a downgrade on interstate highway, know what a "jake brake" is??) was the quietest he'd ever worked in...
7 - Get told by a client in L.A. that the set of "unobtrusive" wall treatments I designed for him to build, FINALLY got his "dialog replacement" studio THX certified...

Finally got tired of never getting my OWN projects done, so gave up the moderator thang - STILL haven't built my OWN studio yet, but I'm "only" 72, so there's still hope - but I HAVE helped 100's of people worldwide build THEIRS, and from their success I KNOW that when I finally get that "round tuit" that NOBODY will hear what I don't WANT 'em to hear... Steve

 

[BukitCase]

If your lighting display will have a plexiglas COVER, that will act as a "leaf" in your wall system - if you use that in FRONT of a 2 leaf wall (so-called normal construction) that will act as a 3-leaf wall, which is ALWAYS WORSE than a comparable 2-leaf (normal) framed wall...

Disclaimer - I've never DONE this EXACT thing, but I'm pretty sure after reading responses, that I'm more aware of the physics than most of the responses (I already MADE several of the common mistakes about 30 years ago) -

In your case (with or WITHOUT a plexi cover) I think I'd just build a normal 2x4 frame, 24" OC - on the office side, 2 layers of 3/4" MDF, seams staggered, this would have the same density as 3 layers of 1/2" sheet rock - but a little easier to work with, and since you don't wanna texture I'd find a nice wall covering for that side -

Then, between the studs I would get Roxul or other mineral wool batts of 3 PCF density (this is important, this is the density we use for "acoustic treatments" - it will ABSORB incoming sounds (if there is NOT a plexi cover) and will be the correct density for DAMPING if there IS a plexi cover.

Absorption will help DEADEN reverb of transient sounds, therefore make it SEEM like it's "more soundproof" than other ways of doing this...

Next, if there IS a plexi cover, do NOT put more wallboard in FRONT of the Roxul or you will WORSEN the Transmission Loss (3-leaf effect) - instead, your choice of an open weave cloth cover that will complement your lighting effects?? - WITH a plexi cover, the cloth WON'T degrade TL like a "middle" leaf will.

The above will act mainly as a single leaf, high mass barrier, with a slight assist from the plexi cover - but the plexi will "brighten" the NON-office side's sound a bit, might NOT be what you want SOUND-wise??

Homosote can be a fair "acoustic treatment" (reverb control, etc) but should NOT be a SUBSTITUTE for HIGH MASS materials such as gypsum wallboard/sheet rock or MDF - remember, MASS is KING here...

Your "no-gaps" thought is a good one; but foam won't do ANYTHING you will like... Steve