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What is the amount of space needed between floating walls for proper iso?
Old 3 weeks ago
  #1
What is the amount of space needed between floating walls for proper iso?

I read some technical manuals on the subject but did not see a standard amount of air needed between decoupled walls in a studio build. We are planning a 1/4" space between our walls, ceiling and floors. Is this acceptable? Thank you in advance.
Old 3 weeks ago
  #2
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That is 6 mm?
That wil provide you a constrained layer effect, comparable with Green Glue,
The gap between walls is one of the main reasons why you get isolation, next to mass. You need more of both, always, 8 mm is nothing.
Old 3 weeks ago
  #4
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Are you building ar least one drywall? The distance is between the layers, not the frame(s). Standard construction half an inch between leafs.
Old 3 weeks ago
  #5
Check out this diagram I sketched. Staggered studs with 2 sheets (greenglue between), then stud then 3/8 air space then stud then another sheet. Is 3/8' air space enough tho? We think we're gonna step it up to 1/2" (or more?) Thanks in advance

(bathroom is not necessarily bathroom nor live room necessarily control. Control could be live and bathroom could be closet or hallway or whatever)
Attached Thumbnails
What is the amount of space needed between floating walls for proper iso?-img_8367.jpg  
Old 3 weeks ago
  #6
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Quote:
Originally Posted by jml designs View Post
Check out this diagram I sketched. Staggered studs with 2 sheets (greenglue between), then stud then 3/8 air space then stud then another sheet. Is 3/8' air space enough tho? We think we're gonna step it up to 1/2" (or more?) Thanks in advance

(bathroom is not necessarily bathroom nor live room necessarily control. Control could be live and bathroom could be closet or hallway or whatever)
Terrible idea. That's a 3 leaf system. Remove the middle sheet of drywall, and add it to the bathroom side instead. Its more than a 3/8" gap though. Airgap is from drywall to drywall. In your example it would be the 3.5" of the stud + the 3/8" = 3 7/8" airgap.

Read the pdf i linked
Old 3 weeks ago
  #7
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Quote:
Originally Posted by jml designs View Post
Check out this diagram I sketched. Staggered studs with 2 sheets (greenglue between), then stud then 3/8 air space then stud then another sheet. Is 3/8' air space enough tho? We think we're gonna step it up to 1/2" (or more?) Thanks in advance

(bathroom is not necessarily bathroom nor live room necessarily control. Control could be live and bathroom could be closet or hallway or whatever)
The diagraam is showing a triple leaf
If that is correct, stop right lnow and learn about sound isolation.
Old 3 weeks ago
  #8
Quote:
Originally Posted by avare View Post
The diagraam is showing a triple leaf
If that is correct, stop right lnow and learn about sound isolation.
Unhelpful and rude
Old 3 weeks ago
  #9
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Quote:
Originally Posted by jml designs View Post
Unhelpful and rude
So you have no idea about designing for sound isolation. Have fun listening to the toilet sounds.
Old 3 weeks ago
  #10
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**** in, **** out
Old 3 weeks ago
  #11
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Quote:
Originally Posted by Jason Foi View Post
Terrible idea. That's a 3 leaf system. Remove the middle sheet of drywall, and add it to the bathroom side instead. Its more than a 3/8" gap though. Airgap is from drywall to drywall. In your example it would be the 3.5" of the stud + the 3/8" = 3 7/8" airgap.

Read the pdf i linked
Yup! +1

And here's another image that says the exact same thing. The middle one is what the OP is proposing. Classic three-leaf, with poor isolation in the low frequencies. By doing what you say, and taking off the drywall in the middle, he would get an improvement of about 7 points. So very roughly, that wall would now block nearly ten times more sound. A pretty darn good improvement from taking something OUT of the wall!

And adding an extra layer of drywall to the two outer sides of that wall would get the OP to the final situation on the right, for another 6 point improvement. Compared to the original situation, that's a 13 point improvement in isolation! I can't be bothered to do the math right now (but I'm sure Andre could do it in his head!), but at a rough guess, that final wall blocks maybe about 25 times more sound than the original suggestion would have.

Simple summary:
Two-leaf = good.
Three-leaf = bad.

- Stuart -
Attached Thumbnails
What is the amount of space needed between floating walls for proper iso?-classic-multi-sample-triple-double-quad-leaf-msm-walls.gif  
Old 3 weeks ago
  #12
Quote:
Originally Posted by avare View Post
So you have no idea about designing for sound isolation. Have fun listening to the toilet sounds.
Quote:
Originally Posted by avare View Post
Quote:
Originally Posted by jml designs View Post
Unhelpful and rude
So you have no idea about designing for sound isolation. Have fun listening to the toilet sounds.
Quote:
Originally Posted by avare View Post
Quote:
Originally Posted by jml designs View Post
Unhelpful and rude
So you have no idea about designing for sound isolation. Have fun listening to the toilet sounds.
Again with the condescension from this guy. Wow, you are one needy SOB aren't you. So you just facelessly bully everyone beneath you that doesn't come from a studio building background huh? So because I have conservatory masters degree ad a degree in graphic design... but not from where you studied studio building I'm an idiot? Because I have a totally reasonable question about something I missed in my research I deserve your snark little sardonic jabs? Did I ever claim to be a studio builder professional? Why is there always a "you" on these forums? I've clearly stated I am doing this for the first time, which is why I am here asking ADVICE and HELP. You know what the great poets, thinkers and philosophers throughout history say about needy little manbaby's like you? People who gain amass knowledge and use it to bully the guy next to you? It ain't pretty. And yet you keep exposing yourself when someone has a totally legitimate question.

To everyone else, any help on my research results is greatly appreciated. Clearly I'm struggling with this part of the build so any guidance is genuinely appreciated. I am trying to do it right, by myself with no help from anyone so it's tough to learn and apply so many theories and techniques I have only just learned in the last 4 months, I am sure that makes sense to any rational human. I've read some books but like any other human on earth, I did not retain 100% of it and could use a helping hand. Thanks in advance for any corrections & advice. Looks like my research is off, I'd like to get it right. That's all. Thank you
Old 3 weeks ago
  #13
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Quote:
Originally Posted by jml designs View Post
Again with the condescension from this guy. Wow, you are one needy SOB aren't you. So you just facelessly bully everyone beneath you that doesn't come from a studio building background huh? So because I have conservatory masters degree ad a degree in graphic design... but not from where you studied studio building I'm an idiot? Because I have a totally reasonable question about something I missed in my research I deserve your snark little sardonic jabs? Did I ever claim to be a studio builder professional? Why is there always a "you" on these forums? I've clearly stated I am doing this for the first time, which is why I am here asking ADVICE and HELP. You know what the great poets, thinkers and philosophers throughout history say about needy little manbaby's like you? People who gain amass knowledge and use it to bully the guy next to you? It ain't pretty. And yet you keep exposing yourself when someone has a totally legitimate question.

To everyone else, any help on my research results is greatly appreciated. Clearly I'm struggling with this part of the build so any guidance is genuinely appreciated. I am trying to do it right, by myself with no help from anyone so it's tough to learn and apply so many theories and techniques I have only just learned in the last 4 months, I am sure that makes sense to any rational human. I've read some books but like any other human on earth, I did not retain 100% of it and could use a helping hand. Thanks in advance for any corrections & advice. Looks like my research is off, I'd like to get it right. That's all. Thank you
Andre's reply's are short and to the point, but made with the intent of helping you. He is 100% correct though. You do need to learn about isolation, and theres nothing wrong with that. Perhaps your own ego should be examined if you are going to lash out at those helping you for pointing out your mistakes.
Old 2 weeks ago
  #14
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IMO 3/8 is an impractically small space between the studs. It's critical that nothing from the one set of framing touches the other and it would be risky during construction that a bowed 2x4 or one that even twists up a bit after framing could easily touch the other side, bridge the two together and make the whole double frame pointless.

I would say 1" at a minimum and 2" really makes more sense to me just being realistic- you are doing a 2nd set of inner leaf joists as well?

The reason I ask is twofold, one is that when setting joists in a tight space it's going to be pretty difficult not to move the walls around at least a little, and the second is that if you aren't doing an inner ceiling assembly, clips and tracks, or drywall hangers, there is likely no point to the double framing in the first place.
Old 2 weeks ago
  #15
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Slightly OT: given an existing structure that cannot be changed and the need for greater sound isolation, by adding an extra layer of insulation/plasterboard with an air-gap, does that not create a 3 leaf system which is clearly the worst idea possible?
i.e the middle diagram in Soundman2020's attachment with a value of 50.

Last edited by pinki; 2 weeks ago at 04:13 PM.. Reason: new computer
Old 2 weeks ago
  #16
Quote:
Originally Posted by Jason Foi View Post
Andre's reply's are short and to the point, but made with the intent of helping you. He is 100% correct though. You do need to learn about isolation, and theres nothing wrong with that. Perhaps your own ego should be examined if you are going to lash out at those helping you for pointing out your mistakes.
Obviously I do need to learn about this, why else would I be asking a question bro? Calling out a bully on the internet has nothing to do with my ego, it really has nothing to do with me at all, I'm just calling him out. Making fun of someone and rallying hate mongers doesn't mean I'm ego maniacal, it means I don't stand for bullying. I would never speak to anyone that way, especially someone I have the opportunity to help with any knowledge I've amassed in my short 40 years on earth. I have no interest in going back and forth with you about the basic definition of bullying though so I digress. I am also an educator and I do not tolerate bullying in my classroom nor anywhere else. It's pathetic and frankly indicative of his own stunted emotional capacities and your message just condones that crap and creates a space for it here on GS. In this political climate it's wrenching to hear victim blaming and bully protecting. The shame is he knows this subject and should be an ambassador of helpfulness in studio construction but instead he chooses to belittle the guy behind him for the exact same reason a teenager pushes another kid down in the dirt who is smaller than him... but somehow I have an ego because I don't stand for bullying? hmmmm
Old 2 weeks ago
  #17
Quote:
Originally Posted by Soundman2020 View Post
Yup! +1

And here's another image that says the exact same thing. The middle one is what the OP is proposing. Classic three-leaf, with poor isolation in the low frequencies. By doing what you say, and taking off the drywall in the middle, he would get an improvement of about 7 points. So very roughly, that wall would now block nearly ten times more sound. A pretty darn good improvement from taking something OUT of the wall!

And adding an extra layer of drywall to the two outer sides of that wall would get the OP to the final situation on the right, for another 6 point improvement. Compared to the original situation, that's a 13 point improvement in isolation! I can't be bothered to do the math right now (but I'm sure Andre could do it in his head!), but at a rough guess, that final wall blocks maybe about 25 times more sound than the original suggestion would have.

Simple summary:
Two-leaf = good.
Three-leaf = bad.

- Stuart -
Great info, thanks for taking the time. What a massive difference for such a little adjustment, just what I was looking for. I think though that your attached diagram is assuming the walls are on the same floor, therefore conducting sound through the floor. However, in my situation, we are building a room within a room so the studio floor is connected only through rubber bushings to the primary floor, does your diagram still apply then? If so, that far right image is the new plan. Whats the airspace between those walls? Lastly, Do you recommend blown in cellulose or roxul? I see both touted as the best solution so we're a bit confused there as well. Thanks!
Old 2 weeks ago
  #18
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To answer my own post and bring it on topic, I think this link makes it really clear. Triple leaf is to be avoided at all costs- and that is what your diagram was depicting jml designs

https://www.tmsoundproofing.com/triple-leaf-effect.html

But given an existing double-leaf structure, is it therefore better just to bond another layer of drywall to each side? Is that all that can be done if a triple leaf is to be avoided?
Old 2 weeks ago
  #19
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At the risk of being a self appointed armchair arbiter

Yes the reply "Stop and learn about isolation" and "Thats a terrible idea" were a bit terse and in fact were not really "to the point" That said your "unhelpful and rude " was also terse and distracted from the actual "to point' of one of the replies ., that being "do not have the drywall on either of the inside stud surfaces."

And from a layman's perspective simply referencing the PDF is not all that helpful as there is a bunch of general info that isn't necessary to your specific question. Only in the section about double wall is there some specific info.

And in all honesty I am not an acoustic engineer ( an may know just enough to be dangerous ) I am however a retired custom home builder and have done a number of home theater installations. So have learned some practical application.

So in layman's terms

There are two areas to address, one is airborne sound transmission and the other is direct vibration sound transmission . And while double (or wall within a wall) helps with both , it really helps limit the amount of direct sound vibration transmission by creating an air gap that is harder for the vibration aspect cross. And why location of sheetrock on the wall is important.

So for example in your sketch having the sheetrock on the inside ( between wall side of the stud ) actually facilitates some direct vibration transmission for the thickness of the sheetrock, more so than not having the sheetrock on the inside , which will increases the amount of less vibration transmission air space, by the thickness of the sheetrock. Make sense ? And is why in the graph below shows that having the sheet rock only on the outside of the stud surfaces has better rating




Just so you know while not cheap there is a material you could put on one inside stud surface called Mass Loaded Vinyl

Last edited by KevWind; 2 weeks ago at 05:39 PM..
Old 2 weeks ago
  #20
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Quote:
Originally Posted by jml designs View Post
Great info, thanks for taking the time. What a massive difference for such a little adjustment, just what I was looking for. I think though that your attached diagram is assuming the walls are on the same floor, therefore conducting sound through the floor. However, in my situation, we are building a room within a room so the studio floor is connected only through rubber bushings to the primary floor, does your diagram still apply then? If so, that far right image is the new plan. Whats the airspace between those walls? Lastly, Do you recommend blown in cellulose or roxul? I see both touted as the best solution so we're a bit confused there as well. Thanks!
Yep. That's just one of the many things about acoustics that isn't intuitive at all: Who would think that taking OUT mass from a wall would make it BETTER? But it does. The reasons are sort of complex, but it's totally correct.

I would go with either suitable mineral wool (such as some of the Roxul products, or similar from other brands), or with suitable fiberglass insulation (such as OC-703). I'm not a big fan of blown-in insulation, since you never can be sure that it was blown in properly: no unfilled voids, no bridging, even coverage, completely filled bays, etc. A good outcome depends on having a good operator to do the job. With insulation batts, its easier to get the job done right.

But whatever insulation type you choose, do make sure that it is suited to the job. And do fill the cavity completely with insulation.

- Stuart -
Old 2 weeks ago
  #21
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Sorry, wrong thread.
Old 2 weeks ago
  #22
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Quote:
Originally Posted by pinki View Post
To answer my own post and bring it on topic, I think this link makes it really clear. Triple leaf is to be avoided at all costs- and that is what your diagram was depicting jml designs

https://www.tmsoundproofing.com/triple-leaf-effect.html

But given an existing double-leaf structure, is it therefore better just to bond another layer of drywall to each side? Is that all that can be done if a triple leaf is to be avoided?
Its best to remove the inner leaf, and build a new single leaf decoupled wall.
Old 2 weeks ago
  #23
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Quote:
Originally Posted by jml designs View Post
Obviously I do need to learn about this, why else would I be asking a question bro? Calling out a bully on the internet has nothing to do with my ego, it really has nothing to do with me at all, I'm just calling him out. Making fun of someone and rallying hate mongers doesn't mean I'm ego maniacal, it means I don't stand for bullying. I would never speak to anyone that way, especially someone I have the opportunity to help with any knowledge I've amassed in my short 40 years on earth. I have no interest in going back and forth with you about the basic definition of bullying though so I digress. I am also an educator and I do not tolerate bullying in my classroom nor anywhere else. It's pathetic and frankly indicative of his own stunted emotional capacities and your message just condones that crap and creates a space for it here on GS. In this political climate it's wrenching to hear victim blaming and bully protecting. The shame is he knows this subject and should be an ambassador of helpfulness in studio construction but instead he chooses to belittle the guy behind him for the exact same reason a teenager pushes another kid down in the dirt who is smaller than him... but somehow I have an ego because I don't stand for bullying? hmmmm
Idk dude, you called him unhelpful and rude for no reason imo. Then he made the toilet sound comment. But whatever, its a pointless aside...
Attached Thumbnails
What is the amount of space needed between floating walls for proper iso?-screenshot_20190924-163416_firefox.jpg  
Old 2 weeks ago
  #24
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There have been too many instances of people posting questions that imply they are in the design process. It then turns out that they are in the middle of construction as que stions are answered. People have had to tear down work and return wrong materials.

I used clear words directly to the point. To keep the message clear I wrote that you should keep doing the learning about isolation. I was doing the internet version of pushing you out of the path of a truck.
Old 2 weeks ago
  #25
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Quote:
Originally Posted by Jason Foi View Post
Then he made the toilet sound comment. But whatever, its a pointless aside...
It was an aside that seems to have been misconstrued. I meant the sounds from the room which was described at one point as being a. bathroom would be heard. Nothing else was intended.
Old 2 weeks ago
  #26
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Quote:
Originally Posted by JayPee View Post
Sorry, wrong thread.
Why? You might have missed it but buried in one of the posts the op wrote that the studio floor is floating on "rubber bushings" exactly what the thread you linked is about, floating floors wrong.

Last edited by avare; 2 weeks ago at 04:13 AM.. Reason: Clarified sentences
Old 2 weeks ago
  #27
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Quote:
Originally Posted by avare View Post
It was an aside that seems to have been misconstrued. I meant the sounds from the room which was described at one point as being a. bathroom would be heard. Nothing else was intended.
I know that, and it's a true statement if he continued down the tripple leaf path. I have known you for years my friend and never seen you say any unkind words, no matter how rudely you were treated. And i read A LOT of posts. I just pisses me off that he pawns his frustrations off on you.
Old 2 weeks ago
  #28
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Quote:
Originally Posted by avare View Post
Why? You might have missed it but buried in one of the posts the op wrote that the studio floor is floating on "rubber bushings" exactly what the thread you linked is about, floating floors wrong.
So here is again : a poor mans "floating floor"




Quote:
Originally Posted by KevWind View Post
Just so you know while not cheap there is a material you could put on one inside stud surface called Mass Loaded Vinyl
What you want is mass. Mass is mass.

10 pounds of MLV = 10 pounds of Gypsumboard.

If we talk about the price....you'll see quickly MLV is very expansive mass compared to gypsumboard

Keep it simple, keep it cheap!
Old 2 weeks ago
  #29
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Quote:
Originally Posted by avare View Post
It was an aside that seems to have been misconstrued. I meant the sounds from the room which was described at one point as being a. bathroom would be heard. Nothing else was intended.
Now this reallly disappoints me.
https://www.youtube.com/watch?v=84zY33QZO5o
Old 2 weeks ago
  #30
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Quote:
Originally Posted by JayPee View Post
10 pounds of MLV = 10 pounds of Gypsumboard.
Keep it simple, keep it cheap!
Actually that is not correct. They are not equal in this context. We already determined that the sheetrock should not be located on either of the inside stud surfaces of the double wall, WHY ? because it is stiff and transfers vibration.
Whereas Mass loaded vinyl applied to one or more of the inside stud walls remains flexible and dampens vibration
Relatively more expensive? yes.... equal to NO
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