Soundproofing master thread - Page 19 - AVS Forum
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post #541 of 567 Old 08-12-2014, 05:52 PM
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Quote:
Originally Posted by granroth View Post
If you do drop one, then drop the Green Glue and spend that money decoupling the walls and ceiling.

Can you dig up two STL charts to verify that assertion ? (two walls of same mass and approximately same size cavity, one decoupled but no green glue, the other with green glue but no decoupling, and possibly a third with both decoupling and green glue)
Green Glue is pretty good at reducing the resonance dip, which may be more important than other factors.
[I don't recall off hand the STL chart's values for these specific situations]

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post #542 of 567 Old 08-12-2014, 06:33 PM - Thread Starter
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It is very difficult coming up with comprehensive tests comparing Green Glue with the rest of the components. The NRC didn't test it at all, likely because their tests pre-dated Green Glue. I'm also a little loath to directly compare STL numbers when we don't know if the tests were done in compatible ways. Still...

The Green Glue company did a comparison of Green Glue vs resilient channel (along with one using Green Glue + resilient channel) here: http://www.greengluecompany.com/site..._Channel_1.pdf

DW+DW + 2x4 w/ Insl + Resilient Channel + DW + DW = STL 55
DW + GG + DW + 2x4 w/ Insl + DW + GG +DW = STL 52

Those numbers don't tell the full story because decoupled rooms, as you say, will have a dip at the low frequencies and that can make a perceptible difference. That comparison is odd, regardless, since it assumes a double layer of DW on the "outside" of the room, which is rarely done with home theaters. I would guess (with no proof) that the STL value of only one layer of GG would be notably lower.

Also, they are comparing against resilient channel, which while inexpensive, is thoroughly frowned upon in the modern soundproofing realm. Clips + Channel are touted as the way to go for low profile decoupling. Here's an example of that in play: http://www.acousticalsolutions.com/t...r-whisper-clip

DW + 2x4 w/ Insl + Clip + Channel + DW + DW = STL 61

That test doesn't show the expected notable drop in the low frequencies, though, which is a little odd.

On a less controversial note, let's look at the NRC test TL-93-271, with a double stud wall configuration: http://archive.nrc-cnrc.gc.ca/obj/ir...r693/ir693.pdf

DW + 2x4 w/ Insl + air gap + 2x4 w/ Insl + DW + DW = STL 62

A double stud wall gives the best performance, with the lowest cost... if you do the work yourself and don't mind losing the most space of all options. If I'm answering the "bang for your buck" question (independent of other factors), then I'll suggest a double stud wall setup nearly every time.

Of course, I've LOVE to see numbers for this setup:

DW + 2x4 w/ Insl + air gap + 2x4 w/ Insl + DW + GG + DW = STL ???
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post #543 of 567 Old 08-12-2014, 08:46 PM
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Granroth:
I was looking for the STC charts (TL graph 80hz to 5000hz, with unofficial data from 25hz to 10khz), not the single STC numbers.


Any comparisons would best be done from Green Glue's website's Test Data. (although if no pairs were available there, I would have been happy with NRC charts for the corresponding result)


The best pair I could find there were:
Report OL08-0324.pdf
aka "5/8" Drywall
5/8" Drywall
Wood 2" x 4" Studs // 16" o/c
Green Glue Clip + Hat Channel
R19 Fiberglass
5/8" Drywall
5/8" Drywall"
on http://www.greengluecompany.com/test...oducts_tid=159


vs


Report OL05-1049.pdf
aka "5/8" Drywall
Green Glue Compound (2 tubes/sheet)
5/8" Drywall
Wood 2" x 4" Studs // 24" o/c
R13 Fiberglass
5/8" Drywall
Green Glue Compound (2 tubes/sheet)
5/8" Drywall"
on
http://www.greengluecompany.com/test...oducts_tid=158


which should be two fairly similarly priced walls (same drywall, same wood studs),
a) one with green glue and thinner insulation and thinner wall cavity, vs
b) one without greenglue but with clips and more insulation and thicker wall cavity


and the difference is huge at 100hz (11dB difference, namely 26dB vs 37dB) in the bass in favour of the clip wall.
The coincidence dip at 2500hz on the clip wall isn't important, given the transmission loss of that wall is still over 60dB between 500hz and 5000hz.




But as expected, the clips have a deeper resonance dip. If you scroll down to the unofficial results, 31.5hz to 63hz:
clips: @31hz 25dB, @40hz 17dB, @50hz 20dB, @63hz 29dB, @80hz 35dB
green: @31hz 27dB, @40hz 24dB, @50hz 26dB, @63hz 21dB, @80hz 23dB

If you open each report PDF, and scroll down to page 2 in each, the graphs are difficult to compare as graphs, but the right hand chart of frequency and transmission loss is easy to compare.




My conclusion is
a) if the home theater builder is elderly and watches a lot of drama (loudest 63hz to 2khz), then the clip wall is best
b) if the home theatre builder is young and watches a lot of action movies (loud 20hz to 50hz), then the green glue wall might be a better choice.

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post #544 of 567 Old 08-12-2014, 10:29 PM - Thread Starter
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Bob, I'm never going to argue with you when it comes to recommendations related to acoustics since you have forgotten more than I'll ever know... but that doesn't mean I won't raise a few points

The wall assembly that I'd like to compare to OL05-1049 would be the NRC TL-93-283. It also uses double layers of 5/8 Type X (16mm) on both sides and has the studs 24" OC (610mm), but is a double wall. It has an overall STC of 69 compared to the Green Glue wall's overall of 55. Indeed, if you look at the upper frequencies, the double wall destroys the Green Glue wall with differences @ 500Hz of 70dB to 58dB all the way up to @ 5000Hz of 91.5dB to 70dB.

But right, those are all upper frequencies and Green Glue shines in the lower frequencies. Unfortunately, the NRC doesn't show the unofficial values so I had to run them through Wolfram Alpha. That gave me a best fit linear curve of 0.253741 x+15.0635. I'm assuming linear if only because the graph certainly looks linear at that point. Yeah, that could very well be a bad assumption. Anyway, if we add these results to the set so far:

clips: @31hz 25dB, @40hz 17dB, @50hz 20dB, @63hz 29dB, @80hz 35dB
green: @31hz 27dB, @40hz 24dB, @50hz 26dB, @63hz 21dB, @80hz 23dB
double: @31hz 23dB, @40hz 25dB, @50hz 27dB, @63hz 32dB, @80hz 37dB

So the linear curve calculation @31hz is lower than even the clips, which seems highly unlikely. I can't say I'd trust that the curve is that accurate at two clicks past the last measured data point. @40hz (one click) and @50hz (measured), it's still mildly in the lead. Above that and it's solidly in the lead.

And one final thing -- I still don't think that OL05-1049 is representative of what you'd see in a typical home theater. It assumes double drywall plus Green Glue on the OUTSIDE of the theater. I'm sure there are some theaters that have done that but, honestly, in all of the many theaters I've seen here on AVS Forum, I can't remember a single one that did. Plus cost-wise, we're now looking at $1100 or so for Green Glue. If that's now my budget, then I'd look at doing double walls or clips+channel PLUS one layer of Green Glue... which is the canonical example of what most people do use and are loving.
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post #545 of 567 Old 08-12-2014, 11:00 PM
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Quote:
Originally Posted by granroth View Post
Bob, I'm never going to argue with you when it comes to recommendations related to acoustics since you have forgotten more than I'll ever know
We're all but babes in the lap of Brian R @ Green Glue, and others.
And I'm not an expert. I merely spent a few years sitting at the internet feet of giants, some during the years they figured things out themselves with preliminary research, and buying every book they recommended.


Quote:
Originally Posted by granroth View Post
but that doesn't mean I won't raise a few points
Good.


Quote:
Originally Posted by granroth View Post
green: @31hz 27dB, @40hz 24dB, @50hz 26dB, @63hz 21dB, @80hz 23dB
clips: @31hz 25dB, @40hz 17dB, @50hz 20dB, @63hz 29dB, @80hz 35dB
double: @31hz 23dB, @40hz 25dB, @50hz 27dB, @63hz 32dB, @80hz 37dB


So the linear curve calculation @31hz is lower than even the clips, which seems highly unlikely.
Green, narrowest between two leafs, resonance dip around 63hz. (flipping through NRC should say if that's normal)
Clips, mid distance between two leafs, resonance dip around 40hz
Double, largest distance between two leafs, resonance dip around 31hz.


I'd bet there are more than a few theatres with green glue on the outside leaf of walls.
I'd bet there are few theatres with green glue on the floor above.
Ted White would have instinctive stats better than my guess.


I never really thought of soundproofing from a $ point of view, within $ reason, since integration difficulty and engineering tend to dominate my planning.
I thought of it as an engineering problem. How much TL at which frequencies do you need, and then which of the NRC walls/ceilings would accomplish that -- invariably followed by a reduction in required TL because it's impractical for some reason or another to build the first choice assembly and a revisit to the NRC charts to find a nth choice assembly that is acceptable (or flanking limitations making more 'wall' a waste).

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post #546 of 567 Old 08-13-2014, 04:24 AM
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Tanks a lot for all this info.

Since I would like to save space I would not do a double wall...I would like to, but space is more important to me.

A tought about this solution: DW + GG + DW + 2x4/insulation + DW (for interior walls) becuse I thinks it is the most efficient, simple to construct and saves the most space.

Sure GG is not cheap, but double walls too since you double all 2x4 and need clips to fix them to trusts...

I looked at the Green Glue site and the vibration absorbtion is excellent.

Opinions, comments and your experience is so valuable to me so I don't make an error while building.
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post #547 of 567 Old 08-13-2014, 05:30 AM
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Originally Posted by AlphaCentaurus View Post
Since I would like to save space I would not do a double wall...I would like to, but space is more important to me.

A tought about this solution: DW + GG + DW + 2x4/insulation + DW (for interior walls) becuse I thinks it is the most efficient, simple to construct and saves the most space.
In Ceiling Installs when people want to save space and still decouple, they used Blocking between the Joists, and you can add Clips & Channel for as little as 1/4" additional space. I haven't seen reference to this in walls, but seems like it might work. The consideration might be to the impact on the insulation and if adequate space is still available.

Another option. is a 2x6 Top & Bottom Plates, and staggering 2x4' vertical studs (one stud on 'left' of plate, the next stud on 'right' of plate, and repeated.) This takes another 2" of space and provides some decoupling benefits.
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post #548 of 567 Old 08-13-2014, 06:13 AM
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Yes staggered walls are an option but low frequency vibration is not manages well since coupled by the 2x6..I think
If Green Glue is too expensive I'll go with channels and clips...maybe this way use only one DW ?

DW + channel/clips + 2x4/w insulation + DW (interior walls)
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post #549 of 567 Old 08-14-2014, 07:22 PM - Thread Starter
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Quote:
Originally Posted by BasementBob View Post
[...]
By way of example, there was a recording studio that was made out of two very thick six sided prefab concrete rooms, one inside the other mounted on precisely engineered springs. A broom handle fell between the two, bridging the gap, and what had been a 100dB separation dropped to a 50dB separation. They removed the broom handle and isolation was restored.
This is a great example of a small defect making a huge impact on the overall effectiveness of a soundproofing strategy and why the details absolutely matter. Is this particular case detailed somewhere where I can see the specifics? After hearing that story, I find myself worried about the decision I made constructing my theater door.

This is from Gervais' book:

Quote:
Originally Posted by Rod Gervais (Home Recording Studio - Build it Like the Pro - p93)
I’ll let you know right now that this is one place I don’t worry about maintaining the separation of wall assemblies with the frames, even when using totally separated assemblies. ... As I noted above, tests have proven that a through jamb does not effectively lessen the total isolation value of a wall assembly to any great degree. So don’t worry about any minuscule amount of isolation you may lose. Just build the frame straight through the cavity.
With that in mind, I created a door jamb that was between 3/4" and 1-1/4" thick and spanned both of my decoupled walls -- it's one piece and screwed into both walls. I felt pretty good about that.

But now let's apply the lesson of the recording studio you refer to. A broom handle bridged the gap between the two walls and resulted in a 50dB drop in separation. Wouldn't my door jamb be even more of a bridge than a loose broom handle? If a broom handle can result in a 50% drop, then maybe a solidly attached bridge would result in even more!? That wouldn't be "minuscule" by any measure.

So... to ease my worried mind, I'm trying to track down specifics on both this recording studio example as well as what tests show that through jambs are okay.
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post #550 of 567 Old 08-14-2014, 09:17 PM
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Originally Posted by granroth View Post
With that in mind, I created a door jamb that was between 3/4" and 1-1/4" thick and spanned both of my decoupled walls -- it's one piece and screwed into both walls.

If your 'decoupled walls', are mounted on the same floor below, or mounted to the same 'floor above' (aka ceiling joists) possibly even with isolation clips (sway brace) you were supposed to use, then Rod's advice is correct (as it always is) and I've heard it verified elsewhere.




If you made your room with a floated floor (engineered by a professional using pucks or springs), and free ceiling, and even the ductwork has flexable duct connectors, then I've often considered making airlock/companionway doors without the jamb crossing between the two, but having a quarter inch separation, and fabric covering the walls and ceiling of the companionway and carpet covering the 'floor' portion. If any of the walls are outside walls, then it's not immediately obvious where to put vapor barrier (obviously not at the door as that won't be an outside wall, but as you go around the room). Some have used rubber seals around gaps like this.




As for the studio
please see
http://www.galaxystudios.com/about-us/


specifically


Quote:
So, we started to look for highly-qualified industrial builders. This is how we met with Eric Desart of the Gerber Group and later on Gerrit Vermeir, professor at the Universty of Leuven, already renowned authorities in their fields of expertise. They explained our wishes were far beyond anything that had been achieved until then. Nevertheless we believed it was worth trying. They developed industrial solutions to achieve the unheard insulation value of plus 100 dB between 2 rooms, with a visual connection and a distance between the units not exceeding more than 60 cm

and


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post #551 of 567 Old 08-15-2014, 02:29 PM - Thread Starter
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Quote:
Originally Posted by BasementBob View Post
If your 'decoupled walls', are mounted on the same floor below, or mounted to the same 'floor above' (aka ceiling joists) possibly even with isolation clips (sway brace) you were supposed to use, then Rod's advice is correct (as it always is) and I've heard it verified elsewhere.
So it's really the extreme lengths that Galaxy Studios went through that required that all components work flawlessly together, thus allowing a simple connection to make a drastic impact? Maybe I can look at it from the perspective that my shared slab floor that spans the walls already conducts a massive amount of sound and so from a percentage point of view, the spanning jambs barely register?

(and, indeed, whilst the entire theater and attached house is on the same slab, my theater ceiling is on floating joists completely disconnected from the rest of the house)
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post #552 of 567 Old 08-17-2014, 01:21 PM - Thread Starter
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Applying Putty Pads

Putty pads are a very typical way to seal off outlet boxes and are part of many a theater build. Curiously, though, the instructions I found for using them were sparse at best and non-existent at worst. I got the impression that it should be "obvious" how to install them. Well... it wasn't for me, and it might not be for others. I finally got a method that worked well for me after maybe four outlet boxes and figured that I'd describe that method here.

I make no guarantee that this is the "right" way to do it. In fact, if I'm clearly doing something wrong, don't hesitate to correct me.

Baseline

My outlet boxes are standard Carlon single-gang adjustable boxes, which are somewhat ubiquitous in this application. I needed 1-1/4" clearance for the two layers of 5/8" drywall that will be installed soon.

The putty pads came from the Soundproofing Company at roughly $5 each. That's a pretty standard price for these. I don't see any brand name associated with them. Hilti makes their own brand of putty pads, which may be available locally in some areas. You may need to buy them in sets of 20, though, which can get expensive. The putty pads I used had a plastic release sheet on each side. Hilti pads appear to be individually packaged. I've seen some suggestions that using readily available "duct seal putty" (found at the big box stores) can also work for quite a bit less money, but I didn't try that.

Optional Step

I didn't see this step anywhere, but I noticed that a single square putty pad would leave one side of my outlet extension (the part that extends past the stud) completely uncovered. That may not matter, but since there is physically enough material to cover the entire thing, I made a little effort to do so.

I started by cutting of just over an inch of the putty pad, while it was still covered by the plastic on both sides:



I then removed the plastic from both sides of my cut-off hunk and wrapped it around the extension, making sure to primarily cover the "other" side that won't be covered by the main pad. The pad is quite sticky and moldable, so it easily adheres to the box:



Applying the Putty Pad

Covering a three-dimensional object with a two-dimensional pad would normally mean bunching up the pad in the corners quite a bit. I got around this by cutting some slits in the pad to allow me to go around the corners easier. The slits are roughly the depth of the outlet box in and the width of the outlet box high... but I just eyeballed it, since it's not critically important:



That was done with both sides of the plastic still on. I immediately followed this by removing the plastic from one side. I then pressed the pad against the side of the outlet box away from the stud, so that the pad was flush with the front of the box:



This is the time to remove the remaining plastic! Yes, it'll make the manipulating it a lot stickier than if you kept the plastic on, but in my experience with my first guinea pig boxes, it was extremely difficult to remove the plastic once the pad was molded in place.

The top and bottom are simply folded over and pressed in place. The back is also mostly just folded over. The tricky part is to them take the remaining flaps and to mold them into the holes in the back of the box:



The most important part of all of this is to make sure that the cable entrance into the outlet box is fully covered. I accomplished this by wrapping the putty around the cables first, and then pushing the hole mess up into the hole. It covers it up very well:



You may note the exposed area on the bottom of the outlet box. I'm pretty sure that doesn't matter. It is notable that the putty wasn't as stretchy as I thought it would be, based on a video I saw for the Hilti pads. They do stretch a little, but not a lot so don't count on that.

And that's it. I tested the outlets by shining a powerful flashlight from below, behind, and above the box and looked for any light to show through. I also shined it into the box and looked for any light leakage coming out the back. I'm glad I took this step because three of my earlier boxes did have some tiny holes that weren't visible at a glance but were clearly there with the light. Fixing those was easily done by just molding the putty over the discovered holes.

Have fun!
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post #553 of 567 Old 08-18-2014, 12:48 AM
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Granroth:


a) Shouldn't you apply the putty about half an inch (or 1-1/4" in your case) from the front edge to allow for 1/2 drywall to be flush with the box ?
b) Shouldn't you be wrapping the boxes on five sides first, and then nailing them to the wall ?






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post #554 of 567 Old 08-18-2014, 06:32 AM - Thread Starter
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Quote:
Originally Posted by BasementBob View Post
Granroth:


a) Shouldn't you apply the putty about half an inch (or 1-1/4" in your case) from the front edge to allow for 1/2 drywall to be flush with the box ?
b) Shouldn't you be wrapping the boxes on five sides first, and then nailing them to the wall ?
Yeah, this is what I'm talking about with inadequate instructions. The Soundproofing Company installation PDF does, indeed, show a photo of a box that appears to not only have the gap for the drywall but also have the nails on the outside of the putty. But their own (very sparse) instructions that follow seem to contradict the photo, mostly in step 3:

3. Starting at side of the box, align the Putty Pad to front edge of box and overlap onto the stud.

"Front edge" implies no gap and "overlap onto the stud" implies that it's already installed.

I am pretty sure that you don't apply the putty pads before installation not only because I've never seen any instructions or video or photos that stated that (save the one Soundproofing company photo), but also because having used it, I don't think it'd be physically possible.

As far as the gap, though, that one did throw me for a loop for awhile and I'm still not 100% sure about it. In the end, I found some tip online that explicitly suggested even bunching the putty around the front a little bit so that when you put the drywall over it, it compresses it and creates a tight seal from behind. That could suggest putting it back a little and not completely to the edge. Not sure. I guess I'll find out when I install the drywall! I'll update my post with some observations after the drywall goes up and I see how it acts.
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post #555 of 567 Old 08-18-2014, 09:56 AM
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Yea you want to trim the DW for a close fit and the putty pads actually wrap up the DW then you use accoustical caulk from the front side. You would have to put a DW strip a little taller than your boxes (not 4x8 sheet) so you could manage this.

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post #556 of 567 Old 08-18-2014, 09:58 AM
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Doing it your way actually makes the hole in the DW bigger to accommodate the putty pad you want the smallest hole possible. I have seen folks use putty pads in the box as well.
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Quote:
Originally Posted by cw5billwade View Post
Yea you want to trim the DW for a close fit and the putty pads actually wrap up the DW then you use accoustical caulk from the front side. You would have to put a DW strip a little taller than your boxes (not 4x8 sheet) so you could manage this.
and

Quote:
Originally Posted by cw5billwade View Post
Doing it your way actually makes the hole in the DW bigger to accommodate the putty pad you want the smallest hole possible. I have seen folks use putty pads in the box as well.
Hmm... that makes sense. My plan was to cut the hole in the first layer of drywall pretty tight to the putty, so that it even shaves it down just a tad. The next hole would be very slightly bigger and the gap between the drywall hole's edges and the outlet would be filled with caulk.

But yeah, that would result in less drywall (less mass) than a solution that was tighter to the box.

So maybe I can peel the putty back to the stud; cut each layer of drywall to within 1/16 of the outlet box (if possible); and apply a bead of caulk around the box each time. I do wonder what the caulk in the second layer would be backed with -- would it have a tendency to sag, with only more caulk backing it up?
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post #558 of 567 Old 08-19-2014, 05:46 AM
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When I did mine there is enough of the gypsm (sp) from the cut edges of the drywall around the box and the hair line gaps to get the caulk in there It is going to stay. Some people get the little foam things they put on water proof outlets and back the outlet cover with them so that is another layer. If putting putty in the box wait until after the inspection (LOL)

The picture above was my billard room wall that is between my theater. Don't forget the outlet boxes in the adjoining rooms. I didn't have any holes in my theater walls.
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post #559 of 567 Old 08-19-2014, 10:40 PM
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I am about to start a basement build, need to soundproof the ceiling as much as possible. I'm already planning to use those z-clips(?), a double layer of 5/8ths drywall with green goo in between. What insulation can I put between the beams for the highest bang to buck ratio?

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post #560 of 567 Old 08-20-2014, 01:06 AM
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Quote:
Originally Posted by plissken99 View Post
What insulation can I put between the beams for the highest bang to buck ratio?
Roxul rockwool, Owens Corning fiberglass pink, even that blue jean stuff. If foam it must be open cell with lab tested sound absorption coefficients.
I'm fond of Roxul Safe n Sound, but it doesn't matter.
Any thickness. As long as the sound goes through it (no path around it), it's fine. 2" to 4" is fine.

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post #561 of 567 Old 08-20-2014, 06:50 AM - Thread Starter
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Quote:
Originally Posted by plissken99 View Post
I am about to start a basement build, need to soundproof the ceiling as much as possible. I'm already planning to use those z-clips(?), a double layer of 5/8ths drywall with green goo in between. What insulation can I put between the beams for the highest bang to buck ratio?
If looking ONLY at the best bang for your buck, then nothing can touch the cheapest 3.5" thick R-13 fiberglass batt insulation you can find. You can often get it for notably less than the big box stores by finding insulation suppliers on Craigslist. It's far far less than the other options.

There are solutions beyond that that will give you better performance, but there's going to be some level of diminishing returns for any other solution. Many do find that increasing their insulation thickness to 5.5" thick R-19 is worth the money, but unless you have "free" insulation, it's usually not worth increasing beyond that.

Actual test data (quite readable, though): http://archive.nrc-cnrc.gc.ca/obj/ir...r766/ir766.pdf
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post #562 of 567 Old 08-20-2014, 01:19 PM
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I think the Roxul stuff will be a nice middle ground. I calculated around $500 worth of it from Home Depot to do the whole job, and I know there are insulation suppliers around where I can likely get it cheaper. The main goal is to stop as much sound as I can from reaching the bedrooms. It is a 2 story house, plus the basement and all bedrooms are on the 2ns floor. So that plus 2 layers of 5/8ths drywall with green goo should do nicely.

The more things change, the more they stay the same.

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post #563 of 567 Old 08-20-2014, 10:27 PM
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Great pics with the putty pads.

Is there a similar guide with pics for decoupling 2x4 frame wall from the ceiling? An Idiots guide would be perfect in the case

We will be adding wood frame walls 1" in from the concrete walls (concrete walls all around in this room). We'll be using clips/channel for the ceiling. The walls and ceiling will have UltraTouch insulation and two layers of drywall with green glue between.

plissken99, I'm also going to try to put some green glue and a layer of drywall between the joists. I'm going to try one layer, see how it is, and then add a second. I'm doing a small "test" room before I tackle the theater so I can do some practical testing and work out kinks.

At the most, my ceiling would have: GG + DW + GG + DW + UltraTouch (R19 Denim stuff) + Clips/Channel + DW + GG + DW

I'm going a bit overboard since we have wood floors above, and my wife's office is directly above the small room (aka my office) She teaches dance, so she often has the music cranked up and is working out choreography and it generates a lot of noise. We often have music battles, but my speakers are louder :P

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post #564 of 567 Old Yesterday, 06:22 AM
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Just use the IB-3 clips to your ceiling joists every 48" for your wall. On the wall parallel to the joist you will have to put nailers in for the clips.

My wall is not against concert but the principle is sill the same. I attached IB-3 clip to the existing wall but you can see the nailer I installed for the IB-1 clips and channel I could have just as easy attached to the nailer which is what you would do.


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Regarding outlet boxes - I am planning a 3-layer wall with OSB/GG/DW/GG/DW. Would it be possible to mount the outlet box to the OSB before the other layes go up? In this way there would be less of a chance for creating flanking paths to the studs.

I was thinking something like this could be attached with the flange against the face of the OSB and a small block could be glued/nailed to the backside so the side flange could be attached for a stiffer mount. Then putty pads, of course. What do you think?



Otherwise, what do you do for an outlet whose face may be 2-3" proud of the underlying stud?

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post #566 of 567 Old Yesterday, 10:02 AM
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Those adjustable boxes are nice for DD+GG directly on studs, but if you add in another layer of drywall or add clips+channel, I found they won't reach through completely.

I plan on using something like this:

http://www.amazon.com/Arlington-Elec...ef=pd_sxp_f_pt

to extend out the boxes that don't quite lay right.

My Home Theater Build: The Vortex Theater Build
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post #567 of 567 Old Yesterday, 05:07 PM
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Yah, I looked at flanged boxes, but I was worried the flanges would cause the cover plate to not seal firmly against the drywall. Is this a problem or am I worrying about nothing?

Would these flanged outlets work with a fabric wall if you built a small wooden frame surrounding the outlet to mount the outlet to the frame so it is rigid and sits flush with the fabric?

Mike
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