SPD

Regarding your walls, you might consider a single tube on the 3 decoupled walls. The "standard" wall, perhaps you could decouple in some fashion (convert to staggered or use clips)? THen use a single tube there as well.

Can you decouple the ceiling? That would be excellent, but I would recommend 2 tubes on the ceiling. Generally, throw everything you can at the ceiling.

SPD

Regarding your walls, you might consider a single tube on the 3 decoupled walls. The "standard" wall, perhaps you could decouple in some fashion (convert to staggered or use clips)? THen use a single tube there as well.

Can you decouple the ceiling? That would be excellent, but I would recommend 2 tubes on the ceiling. Generally, throw everything you can at the ceiling.

The ceiling is already decoupled from the floor joists down (had to drop the ceiling down to get it level all the way across- darn HVAC trunk lines), then ferring strips run perpindicular to the new floor joists and the drywall attached to the ferring strips (see here for pics (http://www.avsforum.com/avs-vb/showthread.php?p=13104649#post13104649)).

I think I'll end up adding another layer of drywall w/ green glue to just the standard interior wall (2 tubes against the wall pre-existing from the steps, then 1 tube the rest of the way) and then DD w/ 2 tubes all the way on the ceiling.

Nice ceiling! Consider three sheets on the ceiling. As far as ceilings go, there is no such thing as overkill. Even if you deploy two thinner layers of Green and three sheets of drywall.

More mass and a more thoroughly damped mass.

Thanks!

Wow! 3 sheets of drywall? I'm not sure if I want to drop the ceiling down any further given the height of my riser. I'll have to hear how it sounds w/ the DD/GG combo.

3 sheets on ceilings is pretty common.

1. They allowed GG people to assemble and bring in THEIR OWN drywall already glued and attached together.

From the report..

""The gypsum board panels were laminated together with green glue. The client reported that the green glue was applied from adhesive cartridges in 3/16" beads in a random pattern over the whole panel. The aging period was over 40 days, greater than the 14 days period stated in ASTM Standard E90 for waterbase adhesives. The assemblies were dried on 4' x 8' wood-stud frames, spaced out and with forced air ventilation according to the client""

The lab should have done this work themselves and not trusted GG people to do it. That's like the fox designing the hen house. Glaring error. ..continuing..

""The specimen arrived at the laboratory still mounted on the wood stud frames. Fastener heads on the base layer panel were accessible via pre-drilled holes through the face layer, approximately 1/2" in diameter. A new wood-stud frame was erected in the specimen opening. The glued wall panels were demounted from the drying frames, and then remounted on the frame in the opening.""

""Representatives of the client constructed and installed the specimen wall assembly. A qualified representative of Orfield Laboratories observed the installation and visually inspected the specimen.""

The testing lab should have never let the GG people anywhere near any drywall and the lab should have assembled the wall themselves with GreenGlue bought anonymously along with standard drywall bought in any local store. This is how Consumer Reports does their testing. There is just way too much possibility for hanky-panky if the manufacturer themselves is anyway involved in the testing. This is NOT an true independent test.

<And so on>

The only reason these panels are pre-built is the long curing time, which should occupy that lab for so long that no lab should be interested to block that lab for such a period. It should be extremely expensive to occupy such a facility with all its resources for the needed time to do valid measurements.
Any consumer report should be confronted with exactly the same problem.

Such lab technicians monitor construction people on a regular basis and know when things are done right or not. They understand the influencing parameters as well or better than the builders.
In a lab they're interested to know, not to play games.

In the beginning I even made a joke about this stuff with the technical director (Brian), wondering: "how do you measure that? That must cost you a fortune, ........", referring to this long curing time. And another guy fun intervened (free words, can't remember how he said it): "I thought they were sitting there for weeks in some chair just looking at these walls"
You can be sure that this is not "just allowed" by the lab but discussed with the lab beforehand in order to find the most representative procedure.
If this curing time shouldn't be an important factor to get valid results the lab most likely should "NOT allow" it.
And Green Glue should not be interested in this procedure since it only complicate things, thereby increasing measurement cost.

No serious lab in the world will block itself to do only 10 to 15 measurements a year. Brian has even investigated to build their own lab, to overcome these limitations and offer more research possibilities, but even when it should be accredited, you should hear the same comments as here, questioning the validity.

Bob here speaks about a curing time of a week. I believe, from practical real live experience, this curing time is much longer and goes more to a month (depending on circumstances).

You tell that a CR should buy drywall in the local store: there are a rather large range of differences between drywall. It should make such test less valuable.

That things could go wrong (within limits) is always possible, but that's why lab technicians are professionals which just don't take words for granted.
And that's why lab procedures are under continuous investigation world-wide.
And that labs must be accredited.

If you disagree with something it's OK, but then give a substantiated alternative. Vaguely referring to consumer reports is no alternative because they rely on the same experts, resources and facilities that companies do.
And if they try to do it with own people, well it's impossible that they have people and resources specialized in everything.
If a read NUMEROUS consumer reports in audio magazines about absorption treatment, I mainly or often read the lack of related knowledge. I rather have an official dry lab report, than stories about that piece of music sounding like heaven of which they heard details for the first time in their live, which is then assigned to a brand and type of material, rather than a basic physical principle they don't know about (and used by many others as well).

And you need the finances. These consumer reports also live and operate from income generated by an interested market.

Blaming or questioning a company, who invested more in measurements, than any other I know (in this application range), to prove their point, because they know they have a point is a bit cheap don't you think?
Green glue makes comparisons with other solutions.
A lot of these comparisons are triggered by regular questions originating from forums of which AVS is a very important one.
Well the best check is that the competitors offering these other solutions, do NOT dispute these reports which should be the easiest way to disarm Green Glue.
Just proving ONE SINGLE report to be misleading or wrong in whatever manner and all other Green Glue tests loose their credibility as well.
It should be THE cheapest manner to weaken GG's competition.
In fact GG shouldn't need to do such comparisons. This data should exist from other products.
A better question than wondering about GG's comparisons is the WHY of the lack of real measurement data from other alternative solutions.

Give them a valid alternative, and prove what's better about it. I'm sure they're interested to listen.
Or trigger consumer organizations, and see if they're interested to invest in such research. I'm sure Green Glue should be glad, but however, they have no control over that.
They invest in the best they know: official world-wide accepted standards, procedures and facilities. And when questions arise, forcing them to divert from standard procedures, this will be discussed with such labs (beforehand), in order to find a solution respecting the spirit and intent of these standards.
Most new customers for a lab will do this anyhow, because they're not familiar with these procedures.

Brian himself already referred once to the possibility of cheating (:D but he referred to hypothetical competitors). If someone buys or makes Green Glue giving it another color and name, no acoustic lab technician can recognize that. If remembering correct Brian even gave a simple recipe as example how to alter that color.

It's easier to describe limits (there aren't things without) than producing VALID or BETTER alternatives.

Eric
.

Great post, Eric!

And as krasmuzik correctly asked, what exactly would be secretly substituted for the Green Glue in the rigged tests? Some viscoeastic damping compound not known to our earth science, but developed by aliens? http://www.getsmileyface.com/sm/aliens/alieneyesa.gif

The fact is that we know of no viscoelastic material that works better than Green Glue at problem audio frequencies.

Regards,
Terry

I wonder if it adheres to transparent aluminum?

Yeah, to help hold in the whales, right? Everybody does talk about how soundproofing is like an aquarium...

This is too funny... Scottie

I just don't want to hear the darn whales mating.

Does anyone know how GG on the studs is vs the Super Soundproofing Isolation Tape on the studs?

Does anyone know how GG on the studs is vs the Super Soundproofing Isolation Tape on the studs?

Green glue isn't designed for studs. I asked the same question last year, and heard a definite No from the green glue company folks.

Green glue is designed as a damping compound between two sheets of material (think 4x8 sheets of plywood or sheet rock). It doesn't really 'isolate' the sheets (keeping vibrations from one sheet away from the other), it lets them vibrate, but acts as a shock absorber quickly damping the vibrations over time.

I'm guessing the Isolation Tape you are talking about is attempting to isolate the sheet rock from the studs. A better comparison would be RISC clips (you can do a search in the forum).

I understand how it works, but many in this series of posts have used it betwen the stud and the first layer of drywall. That is why I asked my question, to see if anyone had experience with the isolation tape and to see if there has been a comparison of it and what others had done.

I understand how it works, but many in this series of posts have used it betwen the stud and the first layer of drywall. That is why I asked my question, to see if anyone had experience with the isolation tape and to see if there has been a comparison of it and what others had done.

I would have to agree with Paul. Green Glue is for damping, and the tape I believe is intended to be a decoupler. Keep in mind that if you already have a decoupled wall like a staggered or double stud wall, you would not need to use tapes or clips.

Others have tried using GG on the studs and tests were even done to answer this question, but it was determined that there is no increase in performance from doing this. Damping is diminishing energy over time and distance, and a stud just doesn't have the surface area for GG to do its job.

In the past 90 days, I have submitted material for ASTM E330, ASTM E-90, 24CFR3280.401, ASTM D6815, ASTM E455, ASTM E72, ASTM E661, D1037, D1761, D3043, D4442, D790, D695, D638, D4442, D828, D5034, D3045, D2718, D2719, D3500, D3501, D5456, E96, C271, C272, C273, C297, C365, C393, C481, NFPA 286, ASTM D1037, TAS201, 202, 203, and ASTM E2126-07a.

Here's what I know ... there's a troll on board that doesn't have a clue about certified labs (ANSI, ISO, NVLAP or otherwise), materials testing, protocols, processes, audits and methods. Further CR reports are biased in their very nature of data acquisition, they are largely subjective, methods and metrics will not only change from year to year, test to test, but in the middle of a test. If CR was soooo good and reliable, they'd have ANSI certification as a test lab/facility and would be taken far more seriously than they are. Their format, however, certainly is somewhat profitable.

Ahem, you are forcing me to repeat myself since you decided to ignore my salient points. To have a true unbiased test, you need to have the material sourced from somewhere besides the vendor/marketer. This is quite elementary testing 101 and it is laughable that you have the temerity to lecture me on proper testing methods since you seemingly fail to understand this.

The only reason these panels are pre-built is the long curing time, which should occupy that lab for so long that no lab should be interested to block that lab for such a period. It should be extremely expensive to occupy such a facility with all its resources for the needed time to do valid measurements.
Any consumer report should be confronted with exactly the same problem.

That's no excuse to compromise the testing protocol. Besides, IIRC, some GG marketing says it cures in a week. In addition, a drywall wall laid up won't take up much space in any facility.

Such lab technicians monitor construction people on a regular basis and know when things are done right or not. They understand the influencing parameters as well or better than the builders.
In a lab they're interested to know, not to play games.

Since the source material was constructed off-site of the lab, (by the VENDOR!) your statement has no relevance.

No serious lab in the world will block itself to do only 10 to 15 measurements a year. Brian has even investigated to build their own lab, to overcome these limitations and offer more research possibilities, but even when it should be accredited, you should hear the same comments as here, questioning the validity.

I have to imagine that labs are capable of doing more than one test at a time.

You tell that a CR should buy drywall in the local store: there are a rather large range of differences between drywall. It should make such test less valuable.

But a hell of a lot more valuable than source material from a vendor making revolutionary claims!

That things could go wrong (within limits) is always possible, but that's why lab technicians are professionals which just don't take words for granted. And that's why lab procedures are under continuous investigation world-wide. And that labs must be accredited.

Oh stop. Don't be so naive. Face it, the reality of the situation is that the lab will test anything that the customer (vendor of the product) brings it. That's how the lab gets revenue. The lab has no vested interest in verifying that the product being tested is the same as the product being marketed.

If you disagree with something it's OK, but then give a substantiated alternative.

I did. I said the lab should buy the source material on the open market anonymously.

Blaming or questioning a company, who invested more in measurements, than any other I know (in this application range), to prove their point, because they know they have a point is a bit cheap don't you think? Green glue makes comparisons with other solutions.
A lot of these comparisons are triggered by regular questions originating from forums of which AVS is a very important one. Well the best check is that the competitors offering these other solutions, do NOT dispute these reports which should be the easiest way to disarm Green Glue.

How can they dispute them? Maybe because GG won't actually name the competitors in their comparison tests! Why not? Don't you find that curious?


They invest in the best they know: official world-wide accepted standards, procedures and facilities.

If world-wide accepted standards include massive vulnerability to compromised product testing, then all consumers worldwide are in trouble.

And when questions arise, forcing them to divert from standard procedures, this will be discussed with such labs (beforehand), in order to find a solution respecting the spirit and intent of these standards.

If standard procedures raise questions, it's time to get new procedures, don't you think?

Brian himself already referred once to the possibility of cheating (:D but he referred to hypothetical competitors). If someone buys or makes Green Glue giving it another color and name, no acoustic lab technician can recognize that. If remembering correct Brian even gave a simple recipe as example how to alter that color.

And Brian is incapable of cheating (we've already mentioned Elmer's glue) and I am labeled a troll for pointing out the numerous flaws in testing? Interesting logic you guys display on this thread.

I think we've been through this before. No new information.

My first ignore.

I just did the same thing Paul.

I haven't had a laugh like this for a long time. He probably buys cars based on CR vs something like Road and Track, or heaven forbid, actually driving the car himself. Do you think CR builds their own cars from independent parts rather than sourcing from the manufacturer? That's absurd.

The lab's job is to test and to do so in a prescribed manner according to established protocols and to do so exactly the same of all products of a given type. If they don't, then the relative test results are absolutely meaningless.

I'm also flabbergasted by the idea of double blind testing for this particular product. To what end? Where is the human tricked into thinking he's hearing something he's not? It's a simple measurement - How much sound gets through various barriers at what frequencies.

If they had some super-secret formula that would perform better than Green Glue, why wouldn't they sell it? The whole argument is just laughable. As for being naive and having bias, do you really think that nobody at CR ever had any personal bias toward a given product?

I for one can tell you from personal experience that CR has basically zero credibility in my book. I've looked at some of their reports and rankings of items that I was very familiar with. Their results were in no way matching up with my personal experience. They have no standardized test methods. If they're comparing speakers, do they tell you what they listened to? What they used to drive them with? What the room was like? Nope. Is it the same every time? Nope.

If they're so good and independent, why don't we let them do car crash test ratings? How about drug evaluations and clinical trials?

Bryan

I have been trying to find all those double blind tests on some drywall screws I was thinking about buying. Can't find any results though, so I guess I can't put up drywall. Dang. Where are the double blind tests on toilet paper? Guess I can't wipe now.

not sure if this has been answered before, but here goes:

i've got a limited budget, so i want to use 2 tubes of GG per 4' x 8' plywood subfloor.
i plan on adding 2 layers of 1/2" plywood ontop of my 5/8" ply subfloor.
is it better to use 1 tube of GG per 1/2" ply sandwich, adding another tube for the top layer, or is it better to use both tubes per panel and get more glue on a single panel?

and finally is the special still available for this product?

thx alot

is it better to use 1 tube of GG per 1/2" ply sandwich, adding another tube for the top layer

Yes, this is better. More thoroughly damped mass. Same amount of Green.

I think the AVS special (10% off) is relatively permanent. It was on two months ago when I ordered my last batch and a year ago when I ordered my first.

From the green glue site, it appears that one tube/sheet does 70% of two tubes. It's not clear what that 70% number refers to (STC? Energy absorbed? Damping time?) more mass is good (2x1/2" vs 1x3/4").

It's not clear to me that there would be a gain, however, and the 2x1/2" could easily be less effective. Just doing the math (with made up numbers and lots of assumptions!):

3/4" plywood, two tubes: baseline value. Just for grins, lets say this is stopping 90% of the sound energy getting through at some frequency (just a random number so we have something to calculate with, no data).

1/2" plywood, one tube: 70% factor for 1 vs. 2 tubes, some factor (90%?) for less mass. Baseline x .7 x .9. This layer only stops 57% of the sound energy. 43% still getting through.

Add another 1/2"/single tube layer. Stops 57% of the remaining 43% energy: 27%.

Total stopped: 84%. Slightly less than the 90% of a single 3/4/two-tube application.

----------------

This calculation is sensitive to the assumptions, however. If I assume the 3/4" with 2-tubes stops 70% of the energy, all other factors being the same, then the two 1/2" layers stop ~80% and are somewhat more effective.

YMMV. Clearly these are back of the (torn, dirty) envelope calculations just to see if there is an obvious difference.

--------------

My gut feel: unless you really want to do 2 1/2" layers for some reason, or unless real test data shows value, I'd stick with the single 3/4" layer. Less work for known good results, vs. more work for results that could be better or worse and no good way to find out.

Yes, this is better. More thoroughly damped mass. Same amount of Green.

So much for my random calculations. :D

Ted, have you actually tested that? I believe you, just curious.

Paul

After years of testing all sorts of interesting variables, it has become quite obvious. Given a fixed mass and a fixed amount of damping material, the damping performance is better if the fixed amount of damping is equally divided into two layers, between 3 layers of mass.

Scenario #1: Two sheets of 5/8" and two tubes of GG
Results: Good

Scenario #2: Three sheets of 1/2" and one tube of GG per layer (x2 GG layers)
Results: Better

We'll assume same mass and same amount of GG in both scenarios. Scenario #2 is more thoroughly damped.

1/2" plywood, one tube: 43% still getting through.

Add another 1/2"/single tube layer. Stops 57% of the remaining 43% energy: 27%.

Total stopped: 84%. Slightly less than the 90% of a single 3/4/two-tube application.


I see the logical progression here. If damping functioned like layers of lead and a directed radiation, then your layered analogy would be right on. Since the entire system is flexing all at the same time, having two GG layers flex rather than one given the same mass more damping capacity.

thx guys...appreciated

i also double-checked with GG and was given the same answer: spread the total quantity of GG over 2 layers instead of 1

any guesses as to how my floor/ceiling will fare acoustically?
basement has 5/8" drywall screwed to joists
joist cavity has been densely filled completely with celullose fiber
5/8" ply subfloor
GG layer (1 tube/panel)
1/2" ply
GG layer (1 tube/panel)
1/2" ply
tar paper
3/4" solid oak flooring

i'm curious about impact sound vs airborne sound in this scenario. is an underlayment recommended to redcuce footsteps? or will GG absorb that?

If I'm reading that right, you have the GG already in your floor above? So the question about an underlayment for footfall fits in how?

If I'm reading that right, you have the GG already in your floor above? So the question about an underlayment for footfall fits in how?

i'm considering adding the underlayment as the last layer, just below the 3/4" thick oak flooring, to aid with impact footsteps, mostly for the basement below

from what the GG guys have said, the glue actually helps impact noise as well, so i'm wondering if this is overkill for the benefit imparted; i don't want to raise my floor too high

, the glue actually helps impact noise as well, so i'm wondering if this is overkill for the benefit imparted; i don't want to raise my floor too high

Vibration is vibration, whether airborne or impact. So damping works. The reason impact noise is so difficult to deal with is the concentration of the energy. Airborne sound waves are quite diffuse, whereas impact noise (vibration) is extremely concentrated under a heel of a shoe. So the vibration from impact noise easily overwhelms most systems.

An additional layer on your floor isn't a bad idea, but what about the theater noise coming up through the floor? Is that an issue for you? If so, I would recommend using the last layer of GG on the ceiling below with another sheet of drywall.

You have an entirely coupled ceiling, so you're looking to make up some ground with layers of damped mass. Is the ceiling insulated? In a perfect world, you would go on vacation while a crew removed the existing ceiling drywall and installed clips for decoupling. Install R19. Then two sheets of damped drywall.

well i'm finally getting around to installing the 3/4" hardwood flooring, but before i lay it all down, just another question: is it suitable to use GG underneath oak floors? they're 3/4" thick and have channels grooved in the back, to aid with expansion. they're also 6" wide planks, random lengths averaging 3' long. they're going to be nailed down in any case. But will using GG cause any sort of floor failure in the future, and have there been any tests/users who have experimented with this?

If the bottom of the wood flooring were flat, you would be able to consider this. The grooves are generally quite deep, however and therefore don't allow the surface area contact needed with the floor. This is not an optimal situation at all for damping.

Ted and gang,

I am looking to finish off my theater in the basement. My main concern is noise coming up to the first floor. I have 10' ceilings and was thinking about the "room within a room" concept and as was curious about just lowering my ceiling a bit. What if it installed 2x4s or 2x6s across the top of my framed wall and used these boards to install my drywall? This would completely remove attaching drywall to the 1st floor floor joists. Sounds better and easier than using clips. I would still dd/gg. Any thoughts?

That would be a floating ceiling. Better than installing clipsfor sure. Fill cavity with R-19Ted and gang,

I am looking to finish off my theater in the basement. My main concern is noise coming up to the first floor. I have 10' ceilings and was thinking about the "room within a room" concept and as was curious about just lowering my ceiling a bit. What if it installed 2x4s or 2x6s across the top of my framed wall and used these boards to install my drywall? This would completely remove attaching drywall to the 1st floor floor joists. Sounds better and easier than using clips. I would still dd/gg. Any thoughts?

Ted - so I would still get good decoupling even if the 2x4s or 2x6s (which is the new ceiling) are attached to the side walls which are in turn attached to the ceiling?

Any details on a floating ceiling?

It's a greater degree of decoupling so yes, much better.

Guys im in the UK - is there anywhere i can buy Green glue from ? Im at the drywalling stage and need to get my hands on a few crates...

Thanks!!!

Hello Youngjob. We can ship you. You have a PM

Guys im in the UK - is there anywhere i can buy Green glue from ? Im at the drywalling stage and need to get my hands on a few crates...

Thanks!!!

http://greenglue.co.uk

I'm not sure if this is the right place to ask this question but I'll give it a stab...

I am building a multi-family home right next to a freeway. I'm using 2 x 4s for the exterior wall, mineral fiber insulation and 5/8" Quiet Rock. The exterior portion is 5/8" standard plywood w/Tyvek wrap, DensGlass and stucco exterior.

My goal is to create a wall with a minimum 55 STC.

I called GG (spoke to a tech) and asked them if it would be helpful to lather the GG on the Tyvek and install the DensGlass over it.

Surprisingly, the tech said it would be MORE effective than a standard drywall sandwich installation granted temperatures on the exterior don't drop below 40 degrees (which they don't in my tropical climate).

He said it would be more effective because I would be tackling the problem (source of noise) on the exterior, rather than letting the noise vibrate the frame and then trying to stop in on the interior wall. Also, the exterior wall has no holes (except windows) unlike the interior which has many penetrations for light switches and electrical boxes.

This sounds right but I have NEVER heard of anyone installing GG between Densglass and Tyvek attached to plywood.

Should I order several cases and lather this stuff all over the Tyvek on this building? Any potential problems? Does everyone here agree this would work well? Is this just crazy?

Thanks in advance... I'm a newbie here but have been perusing/reading for a very long time. If I'm not posting in the best place, please let me know.

Some comunication problem here. You would not install Green Glue between a rigid board and Tyvek. I can't imagine that whomever you spoke with clearly understood your assembly. You want two massive panels with similar stiffness. This would mean two sheets of 7/16" OSB, for example. Also, if you are planning mineral fiber for acoustic reasons, fiberglass will work as well. R13 max thickness.

Treating a wall on the sound producing side is a best practice, and will work well as long as the surface is warm.

Your planned wall with the QR would get you in the mid to upper STC 40s, assuming no Green Glue. If the exterior walls are 2x4, then they are 16" OC. No way to get to mid 50s without incorporating more mass or introducing flex or decoupling. Even with this, your windows will be the weaker link.

Some comunication problem here. You would not install Green Glue between a rigid board and Tyvek. I can't imagine that whomever you spoke with clearly understood your assembly. You want two massive panels with similar stiffness. This would mean two sheets of 7/16" OSB, for example. Also, if you are planning mineral fiber for acoustic reasons, fiberglass will work as well. R13 max thickness.

Treating a wall on the sound producing side is a best practice, and will work well as long as the surface is warm.

Your planned wall with the QR would get you in the mid to upper STC 40s, assuming no Green Glue. If the exterior walls are 2x4, then they are 16" OC. No way to get to mid 50s without incorporating more mass or introducing flex or decoupling. Even with this, your windows will be the weaker link.

Thanks for your response, Ted. I'm sure that there was no communication error between myself and the GG tech. He clearly said that the GG product could be placed between the 1/2" DensGlass and 5/8" plywood and would perform VERY well. I then mentioned that the plywood would need to be wrapped with Tyvek and he said that the Tyvek would make no difference as it's sheathed onto the plywood, acting no differently than a layer of paint over it. He said that the Tyvek would not affect the performance of the GG. He also mentioned that the GG must be placed between two rigid pieces of material to perform well but specifically stated that the two pieces do NOT need to be identical in material or thickness... just that both sheets are rigid. This did make sense to me.

I hired a local acoustics engineer and he said my existing exterior wall (using QR) would yield an STC of about 50. He had no numbers on performance with the GG as he said he couldn't test it or create a scenario to accurately depict performance. But I figured it could only help... and would likely add at least a couple points. Your mid-high 40's STC may be a bit conservative? I hope so because I paid this guy good money!

If the walls are only going to be 45 STC, this is going to be a big problem. I am installing 50-52 STC windows in the bedrooms. They consist of TWO XX sliders in tandem. One slider will have 1/4" lam, 1/2" airspace and 1/8" plate. The second slider on top (interior) will consist of a single pane of 3/16" lam glass. Between the two windows will be a roughly 2" airspace. So the window is technically a triple pane assembly that consists of:

1/4" lam + 1/2" airspace + 1/8" plate glass + 2" airspace + 3/16" lam

The manufacturer could not guarantee an STC but my acoustics engineer came up with 50-52 STC as a "ballpark". I would hate for the exterior walls to be the weak link. These windows are NOT cheap.

And if you're wondering why I'm going with 2 x 4 construction vs 2 x 6, it's because I was very limited on interior space and my preliminary research showed that when using QR for interior drywall, the difference in STC was marginal. The loss of 2" to all walls was not worth the small increase in STC. Some of the loss would have resulted in a complete overhaul in floor plans and ingress/egress (stairs) to meet code. That's how tight this place is.

Thanks for the reply. If I may, I’ll comment on a few points and perhaps some of this may help you. I certainly mean no disrespect to any of the manufacturers you are considering, or to your consultant. There is likely many variables that I am not aware of with your installation.

I hired a local acoustics engineer and he said my existing exterior wall (using QR) would yield an STC of about 50.

Per the Quiet Solution data as well as QR data I was personally involved with testing, a single sheet of 5/8” QR in a lab environment (labs reduce flanking paths and remove many variables) will get an STC between 50 and 52 on a 2x4 wall with 24” spacing. The reduction in flex and increase in conductive surface area created by moving to a 16” spacing will bring this result down considerably. Damped panels function better when they can flex. So in a lab, moving that construction to 16” spacing would drop STC several points. Additionally, due to common sound flanking seen in the field, a Field STC (FSTC) typically comes in 5 points lower, though not always. So that reasonably moves the STC to low 40s. However you have added mass on the exterior, which will help by adding a point or two. I would estimate the FSTC of that wall would be in the mid 40s, presuming you have moderate insulation density. Packing insulation is common, and unfortunately may reduce your results.

He had no numbers on performance with the GG as he said he couldn't test it or create a scenario to accurately depict performance.

There is ample independent Green Glue test data available online to produce an armchair extrapolation. In similar assemblies, a Green Glue wall will generally be a few points higher in the STC measurement from 125Hz to 4000Hz than Quiet Rock, but the GG wall can be 10 or more points better in the lower frequencies where the Mass Air Mass resonance occurs. This resonance is generally below the 125Hz cutoff of the STC measurement, but certainly in the problem zone for you.

So the window is technically a triple pane assembly that consists of: 1/4" lam + 1/2" airspace + 1/8" plate glass + 2" airspace + 3/16" lam, but my acoustics engineer came up with 50-52 STC as a "ballpark".

Windows are very problematic because of the seals. It’s common to caulk a window sash in place and test it, removing the frame from the equation. Also common to test a model of a window that is only 2’ x 2’. However, I have no idea how your windows were tested. To give a rough idea, double ¼” laminated glass with a 2.5” airspace would get an STC of maybe 42. This is data supplied by the NRC in Canada back in 1998. Counter intuitively, this STC number will not be improved because of that intervening 1/8” plate glass. Data shows that a “triple glazed” window will produce two small air cavities, not one larger, thereby no improvement in STC. You might see a small improvement because the outer layers are dissimilar (1/4” and 3/16”), however even if the seals were 100% perfect all of the time, you would probably not see much past STC 45.

A quote from JD Quirt with the NRC: “For a window with good weatherstripping, the STC is usually from 3 to 5 lower than that for an equivalent sealed window. The higher the STC of a sealed window, the more it is decreased by a given sound leak.”

As I said, I am only offering another look at the data presented. Your consultant is clearly closer to the situation than I am.

Ted, have there been any test on the performance of GG (drywall/GG/drywall) over time?

Hi William,

I'm not aware of any of the damping materials from Green Glue, Quiet Rock, Supress, Temple Inland, Pinta Acoustics or Swedak having tests run many years later.

What we know is that other similar compounds are used in exterior applications with severe conditions that include +100F and -20F temperature ranges, as well as water under driving wind, and of course UV. These materials have 50+ year life expectations.

With damping materials, though they are different in many respects from exterior products, they are protected from all of this safely tucked away in your wall.

So while I'm not aware of actual damping tests over time, the physical properties of roughly analogous materials is very well understood. As a side note, I have Green Glue samples that date back 5 years and the stick and flex is the same today as it was 5 years ago.

Thanks for the reply. If I may, I’ll comment on a few points and perhaps some of this may help you. I certainly mean no disrespect to any of the manufacturers you are considering, or to your consultant. There is likely many variables that I am not aware of with your installation.

I hired a local acoustics engineer and he said my existing exterior wall (using QR) would yield an STC of about 50.

Per the Quiet Solution data as well as QR data I was personally involved with testing, a single sheet of 5/8” QR in a lab environment (labs reduce flanking paths and remove many variables) will get an STC between 50 and 52 on a 2x4 wall with 24” spacing. The reduction in flex and increase in conductive surface area created by moving to a 16” spacing will bring this result down considerably. Damped panels function better when they can flex. So in a lab, moving that construction to 16” spacing would drop STC several points. Additionally, due to common sound flanking seen in the field, a Field STC (FSTC) typically comes in 5 points lower, though not always. So that reasonably moves the STC to low 40s. However you have added mass on the exterior, which will help by adding a point or two. I would estimate the FSTC of that wall would be in the mid 40s, presuming you have moderate insulation density. Packing insulation is common, and unfortunately may reduce your results.

He had no numbers on performance with the GG as he said he couldn't test it or create a scenario to accurately depict performance.

There is ample independent Green Glue test data available online to produce an armchair extrapolation. In similar assemblies, a Green Glue wall will generally be a few points higher in the STC measurement from 125Hz to 4000Hz than Quiet Rock, but the GG wall can be 10 or more points better in the lower frequencies where the Mass Air Mass resonance occurs. This resonance is generally below the 125Hz cutoff of the STC measurement, but certainly in the problem zone for you.

So the window is technically a triple pane assembly that consists of: 1/4" lam + 1/2" airspace + 1/8" plate glass + 2" airspace + 3/16" lam, but my acoustics engineer came up with 50-52 STC as a "ballpark".

Windows are very problematic because of the seals. It’s common to caulk a window sash in place and test it, removing the frame from the equation. Also common to test a model of a window that is only 2’ x 2’. However, I have no idea how your windows were tested. To give a rough idea, double ¼” laminated glass with a 2.5” airspace would get an STC of maybe 42. This is data supplied by the NRC in Canada back in 1998. Counter intuitively, this STC number will not be improved because of that intervening 1/8” plate glass. Data shows that a “triple glazed” window will produce two small air cavities, not one larger, thereby no improvement in STC. You might see a small improvement because the outer layers are dissimilar (1/4” and 3/16”), however even if the seals were 100% perfect all of the time, you would probably not see much past STC 45.

A quote from JD Quirt with the NRC: “For a window with good weatherstripping, the STC is usually from 3 to 5 lower than that for an equivalent sealed window. The higher the STC of a sealed window, the more it is decreased by a given sound leak.”

As I said, I am only offering another look at the data presented. Your consultant is clearly closer to the situation than I am.

Thanks again for your insight, Ted. This is all very helpful.

I noticed that you didn't have anything to say about the GG on Tyvek statement GG made. Would you agree that lathering GG on Tyvek would have no effect on performance? Perhaps even increasing the STC?

I've heard crazier things... like how adding paint on both sides of a standard grout-filled CMU wall will increase its STC by 3 points.

It's clear that you have a lower STC expectancy for windows and wall assemblies than my acoustics engineer. I am curious as to what you think would be a reasonable STC reduction when living directly next to a freeway. Note that this particular freeway is on an island in Hawaii... and is not typical of those massive 80 mph 12 lane highways in the mainland. At night, there are a lot of cars and trucks... but no large semis as there is obviously no interstate here. Speed limit is 50 mph with most cars averaging 55 in the area fronting my property. It's really just the sirens and Harley's that are annoying.

You'll get a remarkable reduction in noise by digging a 10' wide by 10' deep trench across the highway.

Sorry...couldn't resist.

:D That's funny.

TCJ, the Tyvek is not intimately bonded to the exterior sheathing, so this would not be the place for Green Glue.

I would see if you could add a second sheet of OSB sheathing to the exterior with Green Glue. Then proceed with Tyvek from there. The concept of installing the damping to the exterior is a good one. One of the basic tenets is to limit the amount of vibration that enters the original framing.

I would also consider adding double 5/8" drywall instead of the QR. Greater sound isolation, especially in the lower frequencies.

You can't make the walls thicker to incorporate decoupling, so your options are limited.

:D That's funny.

TCJ, the Tyvek is not intimately bonded to the exterior sheathing, so this would not be the place for Green Glue.

I would see if you could add a second sheet of OSB sheathing to the exterior with Green Glue. Then proceed with Tyvek from there. The concept of installing the damping to the exterior is a good one. One of the basic tenets is to limit the amount of vibration that enters the original framing.

I would also consider adding double 5/8" drywall instead of the QR. Greater sound isolation, especially in the lower frequencies.

You can't make the walls thicker to incorporate decoupling, so your options are limited.

I'm sorry... but I'm still not getting it. Why would the GG have to be "intimately bonded" to the sheathing in order for it to be effective? I thought GG works by decoupling noise from one rigid material to another? I mean as long as the GG is actually there, compressed between the two rigid pieces of material, why would it care if it's "stuck" to one side or not? Wouldn't it only matter if it's compressed very tightly against both materials?

Not trying to beat the drum here... just trying to make sense of it.

Let's say the Tyvek has even the slightest negative impact on the effectiveness of the GG, wouldn't it still provide a tremendous benefit to the overall STC rating of the wall?

In other words, am I just wasting my time with GG in this particular assembly?

The other question I wanted to ask was your opinion on Quiet Glue. It's easier to access here in Hawaii than GG (there aren't any GG reps here) so I could save some money on shipping.... and I think on the product itself.

Thanks again for your input!

Also, if you are planning mineral fiber for acoustic reasons, fiberglass will work as well. R13 max thickness.


Do you still recommend R13 for a 2 x 4 assembly? I have heard the STC is improved considerably if I pack the walls with insulation as loosely as possible.

I've also heard that mineral wool fiber is superior to fiberglass when it comes to sound insulation. Not true?

The differences are negligible.

Don't view GG as a mechanical decoupling agent. That is not its purpose or function. GG is a damping material ... ie, it is there to absorb a specific form of vibration. In other words, it is worthless as a free air type absorber (such as fiberglass). Techically, it is a constrained layer damping material. The key word being "constrained". It must be bonded between two layers of mass each of which are allowed to move reasonably independently of the other. It is the shearing action between the two materials that a CLD material is acting upon.

There are generally two types of damping materials: Extensional and Constrained.

Extensional damping materials are a surface application. Painting on layers to damp steel is a very common application.

Constrained Layer Damping (CLD) materials are introduced between panels. They rely on the fact that a sound wave will cause the system to bend and oscillate. This is what Green Glue, Quiet Glue, Decibel Drop, Swedak, etc are.

A CLD system isn't a thin film of rubber separating two layers. It also is not a contiguous membrane that seals the wall. These are common intuitive conclusions.

As I mentioned, a sound wave will hit a surface and cause the surface to oscillate. If the surface is a CLD system, the two (drywall) layers will slide against each other during an oscillation. When the two sliding layers are bound by the visco-elastic damping material, this sliding shear force will stretch the damping material, creating a great deal of friction. This conversion of vibrational (kinetic) energy to thermal energy is what significantly reduces the sound vibration.

If the two surfaces were not bonded, there is no shear force, and therefore no friction. Optimal damping occurs when the two layers are of similar stiffness. In this case, the exterior sheathing is not at all the same stiffness as the Tyvek.

Do you still recommend R13 for a 2 x 4 assembly?

Yes

I have heard the STC is improved considerably if I pack the walls with insulation as loosely as possible.

Low density is what we're looking for. Using R13 in a 2x4 wall is about right.

I've also heard that mineral wool fiber is superior to fiberglass when it comes to sound insulation. Not true?

Not true in the low frequencies



Good questions

Don't view GG as a mechanical decoupling agent. That is not its purpose or function. GG is a damping material ... ie, it is there to absorb a specific form of vibration. In other words, it is worthless as a free air type absorber (such as fiberglass). Techically, it is a constrained layer damping material. The key word being "constrained". It must be bonded between two layers of mass each of which are allowed to move reasonably independently of the other. It is the shearing action between the two materials that a CLD material is acting upon.

Thanks for the explanation. I never assumed GG to be anything like fiberglass. However, I assumed "constrained" was analogous to "compressed", as the GG would be if I screwed two rigid pieces of material together, with GG in the center.

There are generally two types of damping materials: Extensional and Constrained.

Extensional damping materials are a surface application. Painting on layers to damp steel is a very common application.

Constrained Layer Damping (CLD) materials are introduced between panels. They rely on the fact that a sound wave will cause the system to bend and oscillate. This is what Green Glue, Quiet Glue, Decibel Drop, Swedak, etc are.

A CLD system isn't a thin film of rubber separating two layers. It also is not a contiguous membrane that seals the wall. These are common intuitive conclusions.

As I mentioned, a sound wave will hit a surface and cause the surface to oscillate. If the surface is a CLD system, the two (drywall) layers will slide against each other during an oscillation. When the two sliding layers are bound by the visco-elastic damping material, this sliding shear force will stretch the damping material, creating a great deal of friction. This conversion of vibrational (kinetic) energy to thermal energy is what significantly reduces the sound vibration.

If the two surfaces were not bonded, there is no shear force, and therefore no friction. Optimal damping occurs when the two layers are of similar stiffness. In this case, the exterior sheathing is not at all the same stiffness as the Tyvek.

Very good explanation, Ted. Thank you.

Of the four products you listed... which do you think is the most effective for $ spent? Is there any particular brand easier to work with?

So taking all of this into consideration, what can I do to increase the STC rating of the wall assembly if I can't increase its thickness?

The option to increase the thickness of drywall (in the interior) may be a consideration but one sheet of QR for the project was already an expensive upgrade. I don't know if I can stomach the cost of TWO sheets of QR... especially considering the sq footage I have to deal with (over 5,000 sq ft). Would it make sense to go with one layer of 1/2" QR and one layer of 1/2" STANDARD drywall? And perhaps sandwich some GG between them?

Would there be ANY benefit to applying GG between the Tyvek/plywood and DensGlass? I'm still leaning towards that despite what you said, assuming there is still a decent benefit with the GG between the two materials.

Sorry for all the questions. I really want to do all I can to insulate the interior of the units from the freeway noise. If after completion the units aren't as soundproof as I wished... I at least won't kick myself knowing that I've exhausted all my options.

Good questions

OK, so mineral wool fiber only helps with higher frequency noise, like sirens? We got lots of those in my area! But seriously, the cost of the mineral wool fiber is much higher than that of the standard fiberglass but I was only considering installing it in the walls of the bedrooms - where noise penetration is most critical.

Thermafiber (3" thick) costs $76 for 53 sqft or $1.53/sq ft.
Standard fiberglass (3 1/2" thick) costs $58 for 170 sq ft or $.34/sq ft.

That is 4.5 times the cost. But the entire area of the exterior walls in each bedroom is only about 130 sq ft (after subtracting for doors and windows). So a $155 difference to upgrade to mineral wool. This should probably be worth it, right? Even if it only helps in the higher frequencies... I'll take every little bit of improvement I can.

Fiberglass is the best material for the job. It's not worth paying to move from Fiberglass to Mineral Wool.

Of the four products you listed... which do you think is the most effective for $ spent? Is there any particular brand easier to work with?

Green Glue has 4x the damping capacity of Quiet Glue. Independantly lab tested years ago. No one has ever come back with additional data.

So taking all of this into consideration, what can I do to increase the STC rating of the wall assembly if I can't increase its thickness?

All you can do is look to increase the mass and damp. Consider thinner exterior or interior layers with multiple layers of damping.

The option to increase the thickness of drywall (in the interior) may be a consideration but one sheet of QR for the project was already an expensive upgrade. I don't know if I can stomach the cost of TWO sheets of QR... especially considering the sq footage I have to deal with (over 5,000 sq ft). Would it make sense to go with one layer of 1/2" QR and one layer of 1/2" STANDARD drywall? And perhaps sandwich some GG between them?

I would recommend multiple sheets of thinner material such as cement board. This offers the great dense mass in the thinnest profile. Then damp with Green Glue.

Would there be ANY benefit to applying GG between the Tyvek/plywood and DensGlass? I'm still leaning towards that despite what you said, assuming there is still a decent benefit with the GG between the two materials.

There is no benefit. This is a waste of funds. To the point where as a distributor I would refuse the sale.

Sorry for all the questions. I really want to do all I can to insulate the interior of the units from the freeway noise. If after completion the units aren't as soundproof as I wished... I at least won't kick myself knowing that I've exhausted all my options.


I can totally appreciate this and I would be doing the same thing if it were me. You can certainly have us formally take a look at the wall construction and space parameters and look at a specific solution.

I am planning the treatment of the theater room that is going in my house about to be built. Right now I have determined that GG is probably the way I am going to go. I will probably have some questions in that regard as part of this conversation, but right now I wanted to ask about de-coupling ideas.

I know that resilient channel with clips or rails or other paraphernalia is a possibility, but I know it will just freak out my builder and they will price it out of the game so they don't have to deal with it. (They are working on a quote to install the double drywall with GG right now). This being the case, I am looking for small additions I can make that don't involve lots of "specialty" materials or installation techniques. I had one idea that was expanding on the idea of "rubber pucks" on the studs at screw locations.

Is there some de-coupling benefit to running a strip of dynamat or acoustimat down the stud (2" x 9') before the first layer of drywall goes up? This will still be mechanically coupled, but exhibit some of the "vibration-to-friction" properties found in the GG sandwich.

I appreciate your feedback.

If you are doing new construction the most cost effective and highest performing methodology is to do room-within-room or staggered stud construction. This is in addition to 2ble drywall. Adding GG will only improve things further. The other stuff you mention is not as good as the above.
If these concepts will "freak out" your builder, (which would be odd because it is not that complicated), I'd design the space such that you can have someone else add this construction easily later.
It is much harder and more expensive to fix things later. Do it right now and you will be happy you did.

See this website for more info: http://www.soundproofingcompany.com/index.php?/library/articles/room_within_a_room

freak out my builder and they will price it out of the game so they don't have to deal with it
I know this happens; but, on the other hand, I'd suggest you not put up with this kind of nonsense.

Would there be ANY benefit to applying GG between the Tyvek/plywood and DensGlass? I'm still leaning towards that despite what you said, assuming there is still a decent benefit with the GG between the two materials.

There is no benefit. This is a waste of funds. To the point where as a distributor I would refuse the sale.

That's very disappointing because I have no other options at this point. And Tyvek is necessary (as I understand it) as a moisture barrier.

That's very disappointing because I have no other options at this point. And Tyvek is necessary (as I understand it) as a moisture barrier.

Using Tyvek is fine, just put it OUTSIDE the CLD, not IN the CLD.

If you are doing new construction the most cost effective and highest performing methodology is to do room-within-room or staggered stud construction. This is in addition to 2ble drywall. Adding GG will only improve things further. The other stuff you mention is not as good as the above.
If these concepts will "freak out" your builder, (which would be odd because it is not that complicated), I'd design the space such that you can have someone else add this construction easily later.
It is much harder and more expensive to fix things later. Do it right now and you will be happy you did.

See this website for more info: http://www.soundproofingcompany.com/index.php?/library/articles/room_within_a_room

I appreciate the feedback, and I will ask my builder to quote the staggered stud idea. I think that is the most reasonable to maintain (close to) the room dimensions. Which resources can I use (in addition to the link you provided) to help my builder "comprehend" what I am talking about and get the proper instructions to provide to the subs?

Thanks again

If you value your time more than your money, in addition to wanting a fool proof design, there are plenty of experts that post here regularly. Terry Montlick designed the sound isolation for my room and is awesome. Ted White and Bryan Pape are very knowledgeable and great to work with. I've not had the privilege of working with Dennis Erskine, but he is also highly regarded. This list is by no means complete as there are a lot of very smart people on AVS.

If you want to DIY, then you need to start researching and reading; there is tons of info on AVS. It's typically best to find and read through a couple build threads with theaters similar to what you want. There is also a lot of good info on the Green Glue website in terms of design.

You might want to also create your own build thread, as this thread is for the discussion of Green Glue and we are officially off topic.

Good luck.

Using Tyvek is fine, just put it OUTSIDE the CLD, not IN the CLD.

I apologize, but what does "CLD" stand for?

In a standard stucco wall assembly, there is no other place to put Tyvek except for between the plywood and DensGlass. It can't go over the DensGlass because this is where the base coat of stucco must adhere to.

If you value your time more than your money, in addition to wanting a fool proof design, there are plenty of experts that post here regularly. Terry Montlick designed the sound isolation for my room and is awesome. Ted White and Bryan Pape are very knowledgeable and great to work with. I've not had the privilege of working with Dennis Erskine, but he is also highly regarded. This list is by no means complete as there are a lot of very smart people on AVS.

If you want to DIY, then you need to start researching and reading; there is tons of info on AVS. It's typically best to find and read through a couple build threads with theaters similar to what you want. There is also a lot of good info on the Green Glue website in terms of design.

You might want to also create your own build thread, as this thread is for the discussion of Green Glue and we are officially off topic.

Good luck.

Trust me, I've done a ton of research online and on this forum. But I haven't found anyone anywhere discussing GG being installed on the EXTERIOR siding/membrane of a wall assembly. In fact the tech at GG mentioned he wasn't aware of it ever being done because <40 degree temps will render the product useless, so they will generally advise to not install on any wall assembly that will be subject to these temperatures. And there is no GG distributor in Hawaii (and very few industry people here that are even aware of the material) so you can see why I'm treading in uncharted territory.

I am VERY thankful for the input I am receiving on this forum. I just wish I could get some better news.

Trust me, I've done a ton of research online and on this forum...

I was referring to Everman's last post wanting to know how to do staggered stud construction, not your posts. Sorry for the confusion.

Firstly, Green Glue can be shipped UPS ground anywhere in the world. Hawaii is a simple shipment.

Next, at some point a person needs to commit to a group that will detail a recommendation based on the critical parameters. An open web forum isn't the venue.

Lastly, it is the responsibility of this group to provide materials to adequately communicate the procedures.

Ted, I have decided to go with a single lam on ALL windows for my project. That includes those that face the freeway, those that are perpendicular, and those that face away from the freeway.

The specs of the single lam (3/4" overall) are: 1/4 tempered + .060 PVB interlayer + 1/2 tempered. The manufacturer of the lite is Arch Aluminum and Glass Co. The manufacturer of the window is Oceanside Aluminum in California. The manufacturer claims an STC of 41 for the lite but has no testing data for the actual window itself. The air infiltration number on their windows comes in at .09 so I'm assuming the frame performance of their sliders and awnings is desirable. My acoustics engineer decided the single lam is the best performer in the lower frequency area, which is most critical for my application. In order to match the low frequency performance of the single lam, I would need to go with a huge IGU - at least 2 1/2" thick including a 2"+ airspace and just as much glass with one lite being laminated. Finding a window manufacturer with that kind of IGU is difficult and likely not an option for me.

I found that the OITC numbers for single lam windows are superior to double pane IGUs (w/one lam).

I found this site along with lots of STC and OITC data on various glass configurations -

http://www.saflex.com/pdf/en/archi/Saflex_Acoustical_Guide.pdf


The data shows that a single lam (the window I have spec'd for my project) consisting of 1/4" + 0.60 PVB + 1/2" has an STC of 41 but an OITC of 36 which is extraordinarily high. To match that OITC in an IGU configuration, I would need to go with a significant 2" airspace and similar amount of glass (in weight/mass). Apparently, losing the airspace altogether is beneficial for applications where traffic is the main source of noise. A single lam performed better than all IGU configurations w/single lam and <2" of airspace and similar mass. I find this interesting to say the least as the OITC focuses on a fairly broad frequency band from 80-4000.

Here is a link to the manufacturer of the laminate and its performance -

http://www.archaluminum.net/technical/documents/stc_rating_chart.pdf

Any caveats with this decision of going with a single lam window? I asked about the thermal value/benefits of going with an insulated glass unit over a single lam but the manufacturer said it would be nil as I'm in a temperate climate and the laminate itself contains a Low-E coating (for heat reflectance). Seems like a single lam configuration is a no-brainer? Not only that but now my entire building will have hurricane proof and security windows which should reduce my homeowner and hurricane policy premiums a bit.

After this research and the recommendation from my acoustics engineer, I wonder why any window manufacturer would suggest using an IGU unit if the install location is in a temperate climate and traffic, train or airplane noise is a concern. Am I missing something?

The manufacturer claims an STC of 41 for the lite but has no testing data for the actual window itself.
An STC number from a manufacturer without any test data and $5 will get you a cup of latte at Starbucks. :)

Quiet Home Windows (www.quiethomewindows.com/) (division of Quiet Solution) is a manufacturer that does have certified lab test data. Here they are:

http://www.quiethomewindows.com/WEAL_Legacy_Relief.pdf
http://www.quiethomewindows.com/WEAL_Legacy_Serenity.pdf
http://www.quiethomewindows.com/WEAL_Signature_Relief.pdf
http://www.quiethomewindows.com/WEAL_Classic_Serenity.pdf
http://www.quiethomewindows.com/WEAL_Sliding_Glass_Door_scn.pdf

Regards,
Terry

Oh, geeze... no independent, third party certified lab test results is a no go when a product is being purchased for its acoustic properties.

Now..."lower frequencies" ... what specific lower frequencies have been measured that you need to target? You may find that STC values don't cover the troublesome frequency range(s) you're attempting to target.

Sorry, but I suspect it's back to the drawing board for you.

To add to what Dennis said, the third-party lab tests are essential not only because they validate the STC numbers, but because they typically extend down lower than the official STC frequencies. STC is calculated from no 3rd octave frequency band lower than 125 Hz!

The Quiet Windows data, measured by Western Electro-Acoustic Laboratory, go down to the 63 Hz 3rd octave band. While measurements this low will not be guaranteed for accuracy by any lab I know of, they will at least provide some level of comfort that the product is effective down through at least the upper range of subwoofer frequencies.

- Terry

I'm trying to tame the sound of my HVAC unit, which shares an eight-foot section of wall with my nascent home theater (the room is 16x24). When the unit is running, I get a fair amount of low- to mid-frequency rumbling that makes me want to turn up the volume during quiet dialogue.

My first thought was to install Acoustaboard panels inside the HT, which would also add some desirable absorption to the room. But this would involve fabric wrapping and WAF considerations. It would be much easier (and possibly more effective?) to put the Acoustaboard on the other side of the wall, right next to the HVAC unit.

My question--and the reason this is in the Green Glue thread--is should I use GG to mount the Acoustaboard to the wall? Is it overkill, or simply not effective to use GG with fiberglass panels?

Or should I use drywall and GG instead of Acoustaboard?

Any advice greatly appreciated.

Hi Bob,

Acoustaboard isn't designed for soundproofing. You can use drywall with excellent mass. That helps, as long as it is being deployed properly.

The rumbling tells me low frequencies which tells me that treating one wall of your theater might be like building the aquarium with 1 sheet of glass.

Ted, thanks for your reply to a newbie in these matters. I'm happy to use drywall instead of Acoustaboard if it would be more effective. Drywall is a lot cheaper!

So Acoustaboard should be used only for reflected sound, not transmitted?

The rumbling tells me low frequencies which tells me that treating one wall of your theater might be like building the aquarium with 1 sheet of glass.
Well, the remainder of the wall adjoining the HVAC room is a brick fireplace, so there's not much I can do to improve on that. The other three walls are adjacent to outside and a sunroom, no noise problem there.

But I do need to deal with the door to the HVAC room, around a corner and down the hall from the HT. Some HVAC noise comes that route, so in addition to weatherstripping and a threshold, I'm thinking of attaching a layer of plywood to that door with GG. Is there a better way?

Unfortunately the HVAC room door also contains a 13x7 vent near the bottom, to supply air to the furnace and gas water heater. Any suggestions there?

It might be beneficial to start a dedicated thread on this topic, since it doesn't have to do with Green Glue, per say.

be like building the aquarium with 1 sheet of glass.
Ah, Grasshopper. You have discovered the Zen aquarium. Applause from everyone please (use one hand).

My house has a sub-floor made of 1x6 fir laid at a 45 degree angle. It squeaks very nicely. When I had a new linoleum floor installed in my kitchen, the installer screwed down some 3x6 sheets of plywood made for underlaying linoleum.

For my home theater floor, if I were to use green glue between the plywood underlayment and the plank sub-floor, would it 1) help damp subwoofer transmission into the rest of the house, 2) cut down on floor squeaks, or 3) make any difference at all?

(I'd of course first screw down the sub-floor to stop any squeaks I could find.)

Quick answer: maybe. It depends on a great deal of factors. Green Glue is only a part of a bigger sound isolation plan.

I would not use Green Glue under the thin underlayment. The underlay is just not heavy / stiff / thick enough.

If you want to cut back on the sound to any appreciable level, you'll have to consider all walls, floor as well as ceiling. Then look at the ventilation, doors and outlets.

You would be looking to create an envelope to control the sound.

I am already thinking of hat channel and DD/GG walls. But I had never thought much about what to do with the floor. I don't even want to think about the ceiling and its 9 recessed lights :)

You would only need clips on the ceiling, and perhaps the ceiling of the room below. Walls are easily decoupled with framing.

The ceiling will be an issue with can lights.

You would only need clips on the ceiling, and perhaps the ceiling of the room below. Walls are easily decoupled with framing.

I imagine you refer to staggered studs or double walls. I will be retrofitting an existing living room and want to limit how much thicker the walls get. I imagine the offset stud wall could be offset the same amount as the channel. That would make less volume for the insulation. But it would probably be a stronger wall, wouldn't it?

Thanks for your input. The rebuild is probably still a year off. Gives me lots of time to refine the design...

I imagine you refer to staggered studs or double walls.

Yes

I will be retrofitting an existing living room and want to limit how much thicker the walls get. I imagine the offset stud wall could be offset the same amount as the channel. That would make less volume for the insulation. But it would probably be a stronger wall, wouldn't it?

Stronger isn't the goal. Decoupling is the goal. Staggered studs can accomplish this as well as clips + Channel. Cheaper to stagger.

Thanks for your input. The rebuild is probably still a year off. Gives me lots of time to refine the design...

Planning is good

So I'll admit up front that I have only read the first and last couple pages of this thread. So if this question has already been answered, I apologize.

I am building my Theater Room and am at the point of interior walls. Two of the walls are exterior and two walls shared with the interior of the rest of my house.

My goal is to sound proof the theater room enough so that I can watch movies with the volume decently 'cranked' and have it be quiet enough in the rest of the house so that my kids can sleep in their rooms.

I am planning to do a double wall for sure.

So I'll have:
Interior of house -> Drywall -> 2x4 stud wall with R13 bat -> 1" air space -> 2x4 stud wall (24" OC) with R13 bat -> 5/8" drywall -> 5/8" drywall -> Theater room

My question is...how much added benefit does adding GG between the two layers of Drywall provide? Is it worth the expense...especially if I'm not going for complete sound proofing?? I just need the sound quiet enough that you could still hear my movie subtly in the background...but the movie is quiet enough for sleeping kids.

Maybe GG is needed to even accomplish the above goal?? I'm relying on you experts!

Thanks for any help.

Your walls can be either 16" or 24" OC

You might also find this helpful: http://www.soundproofingcompany.com/library/articles/elements_of_room_construction/

http://www.soundproofingcompany.com/library/articles/room_within_a_room/

http://www.soundproofingcompany.com/library/articles/flanking/

I'll let others offer their opinion about products

I am planning to do a double wall for sure.

So I'll have:
Interior of house -> Drywall -> 2x4 stud wall with R13 bat -> 1" air space -> 2x4 stud wall (24" OC) with R13 bat -> 5/8" drywall -> 5/8" drywall -> Theater room

My question is...how much added benefit does adding GG between the two layers of Drywall provide? Is it worth the expense...especially if I'm not going for complete sound proofing?? I just need the sound quiet enough that you could still hear my movie subtly in the background...but the movie is quiet enough for sleeping kids.

Maybe GG is needed to even accomplish the above goal?? I'm relying on you experts!

Thanks for any help.
As far as I know, there is no significant added benefit in using Green Glue with double stud walls. There is a significant gain in sound isolation simply by adding a second layer of drywall to the single layer you have planned for the inner side.

Also, make sure your ceiling has a comparable amount of sound isolation as your walls. The best way to do this is to add a second set of joists touching only the top plates of your inner stud wall. The ceiling gets fastened to these joists only.

- Terry

There's still plenty of panel resonance in a decoupled assembly. Green vs no Green adds several STC points.

Is it better to go with 24" oc or 16" oc if building double wall 2 layers of 5/8" on each wall with Green Glue in between the layers?

24" OC provides more flexibility, which helps with noise isolation.

CJ

IIRC, according to Ted White if its a double wall it doesn't matter. If its a singe wall or staggered stud the 24" spacing provides more flexibility, damping and isolation.

IIRC, according to Ted White if its a double wall it doesn't matter. If its a singe wall or staggered stud the 24" spacing provides more flexibility, damping and isolation.

We have a winner

I have a 1 bedroom condo in a high rise condominium (with concrete slabs between floors). I'm getting noise complaints from my neighbor (along the common wall in my diagram). As noted, that wall seems to be constructed of metal studs with 5/8" drywall on either side. There is no insulation. It is 9'11" high and 16' wide.

I'm planning to put a new layer of 1/2" drywall with green glue sandwiched in between. Will this be effective enough? I was also considering blown-in insulation, but that may be prohibitively expensive and violate my HOA rules. Would blown in insulation make a considerable difference? Moreso than GG?

I have a 1 bedroom condo in a high rise condominium (with concrete slabs between floors). I'm getting noise complaints from my neighbor (along the common wall in my diagram). As noted, that wall seems to be constructed of metal studs with 5/8" drywall on either side. There is no insulation. It is 9'11" high and 16' wide.

I'm planning to put a new layer of 1/2" drywall with green glue sandwiched in between. Will this be effective enough? I was also considering blown-in insulation, but that may be prohibitively expensive and violate my HOA rules. Would blown in insulation make a considerable difference? Moreso than GG?

I'm not an expert, but recently added a layer of 5/8" drywall to one wall of my theater room with GG. This was to keeps noise from the HVAC unit on the other side out. It made a significant difference, it's no longer noticeable when the unit comes on during quiet scenes.

I would recommend 5/8" high-mass drywall, or even two layers of 1/2". I don't think additional insulation will do much compared to GG/drywall.

I'm not an expert, but recently added a layer of 5/8" drywall to one wall of my theater room with GG. This was to keeps noise from the HVAC unit on the other side out. It made a significant difference, it's no longer noticeable when the unit comes on during quiet scenes.

I would recommend 5/8" high-mass drywall, or even two layers of 1/2". I don't think additional insulation will do much compared to GG/drywall.
Thanks for the advice. I thought that I already had 5/8" drywall on my side, but after checking again (opened the electric socket) it looks like 2 1/2" layers on each side.

I think 1 5/8" high density probably makes the most sense (is this the same as the fire rated drywall??). I read that you want to vary the density/thickness to block various frequencies.

I think 1 5/8" high density probably makes the most sense (is this the same as the fire rated drywall??). I read that you want to vary the density/thickness to block various frequencies.

You could be right about varying the thickness, but I think sheer mass may make more of a difference, that and the Green Glue of course.

Yes, fire-rated is denser, that's what I used. There weren't many 5/8" choices in stock locally, I could have special-ordered something even heavier, but didn't bother. An outlet box extender worked nicely, by the way.

Green glue between sheetrock and plaster? Would this work?

Depends on the type of plaster. If it's wood lathe and plaster, then yes. Screw drywall into original studs (if you can find them).

There are other types of plaster / cement walls that cannot be directly damped, however.

It is wood lathe and plaster. I can get as much drywall as I want for almost nothing and I was wondering if 2 layers of drywall with 2 layers of green glue would be overkill. (I'm trying to completely isolate this room)

3 mass layers and 2 damping layers is not overkill. People on this forum do it quite often.

However for high level isoloation you need to decouple those new sheets of drywall from the original studs without introducing an additional air cavity. This means the removal of the existing plaster and lathe. Not what you want to hear, but that's the physics of it.

AT $175/case ($29/wall) Green glue is pricey stuff! That's $1225 for a 15x32 room! Resilient channel over double drywall seems like a better buy given the performance.

Resilient channel is for decoupling, but does a fairly mediocre job. Much better to decouple through the framing (staggered and double stud). The common exception would be the ceiling, where clips and channel are commonly deployed.

Green Glue doesn't decouple, by the way, it damps. BTW, no one has paid that figure in 3 years.

Look at the performance data for Green Glue vs. Resilient Channel, and you'll clearly see a dramatic difference. Ask around this forum for a show of hands of how many used resilient channel. There's a reason why you won't find so very few using the product.

Even at that it isn't a big portion of the price on a theater build. That is half the price of my projector, which gets replaced every two years. The gg lasts forever. Well, hopefully. :)
That is a giant room btw. Lucky you.
Warren

That's $1225 for a 15x32 room!

That is about the size of my theater/game area. I did my entire basement in DD+GG (given the communication issue, it was a lot easier to have the crew do it one way all the way around) and it didn't me cost that much.

That is about the size of my theater/game area. I did my entire basement in DD+GG (given the communication issue, it was a lot easier to have the crew do it one way all the way around) and it didn't me cost that much.

I was planning staggered stud for the exterior walls + DD + R19
Then DD on the ceiling with resilient clips with R19 in the joist.

Using the GG calculator on their webpage, that's what it came to. That's more than the drywall itself!

Likely 2 of your walls are up against a foundation. You can use single stud walls there, since the foundation counts as one of the two "stud" walls in a "double stud" arrangement.

Use R13 in the walls, not R19

Drywall is under $0.20 a square foot, so it's less than most everything else you'll be looking at.

The point earlier is that no one has paid that case price in years. Pails are the only way to go in any event.

How exactly would I handle door and window frames with the extra thickness to the walls?

Extension jambs. Also electrical box extenders.

How exactly would I handle door and window frames with the extra thickness to the walls?

When you order pre-hung doors, you can specify a depth. You can even specify how far off the sil plate you want the door to start. (To allow for clearances for things like hardwood or carpet.

This is all happening in a pre-war house with pre-war door jambs. I guess I'll have to get all new jambs.

Also electrical box extenders.

or the adjsutable boxes if you're at the framing stage.

This is all happening in a pre-war house with pre-war door jambs. I guess I'll have to get all new jambs.

If the existing ones are painted, you can easily ad extension jambs, and re-paint

I was going to say, you want solid core doors too so you could just order them framed, but prewar doors are probably all solid core anyway :)

About a 1/4 of my room is over an unfinished basement and I think it doesn't play nice with my subwoofer. I am not able to drywall over the joists as there are pipes and vents everywhere, but could I Green Glue a couple sheets (or three?) of drywall together and place them under the subfloor to give it more strength? If so, how do I attach them to the subfloor?

Thanks,

Mike

http://www.soundproofingcompany.com/solutions/soundproofing_ceilings/

This article duscusses ceiling creatments, including diagrams of exactly what you're describing:

http://www.soundproofingcompany.com/upload/soundproofing_ceilings_adding_clips_damping_material.jpg

You just wouldn't have the ceiling part

Great, thanks for the help. So the drywall is attached to the subfloor by Green Glue?

Mike

Yes. Have a look at the article itself for much more detail, but the drywall is glued and screwed to that subfloor

Yes. Have a look at the article itself for much more detail, but the drywall is glued and screwed to that subfloor

Oops should have read before asking!

Thanks again,

Mike

Does anyone know what GG is made of or based on? Wouldn't any silicon caulking product work in the same manner -- silicon doesn't harden, so when the top panel vibrates due to excitement by bass frequencies, the energy would be transmitted to the silicon product and similarly converted into heat?? I'm just wondering, b/c silicon is 50% ++ less expensive.

Green Glue is a latex polymer. Water is used to hold the polymers, and allow their application to a surface. Once applied and the water is wicked away, the Green Glue polymers start linking up into long chains.

"Isn’t Green Glue the same as Caulk?"

The question is understandable. Green Glue is a material categorically described as a visco-elastic damping compound. Damping materials and caulk look the same, to be sure. Toothpaste also looks similar. The molecular properties of all three are quite different.

Various caulks and latex damping materials are all polymers of some sort. Small chains of polymer suspended in a water base. Caulk is designed to stay fairly rigid (viscous) and only mildly elastic, resisting dramatic temperature fluctuations, UV, and water.

Damping materials are much less viscous, much more elastic. If you felt dried samples of each you would feel a significant difference between them. High performance damping materials will remain very flexible and appear to still be “wet.”

When the viscosity and elasticity are in the correct proportions, the thin layer will effectively convert kinetic energy (sound) to thermal energy (heat). This energy conversion is what we refer to as damping.

Damping materials can’t seal, and a sealant can’t damp (from a practical consideration).

I was in the middle of typing a reply when Ted's popped up, so I'll condense mine to: "what he said". They materials look similar, but the polymers have very different characteristics.

They certainly don't feel the same. GG is some sticky stuff. Makes for a great fly or mouse glue trap.

I was in the middle of typing a reply when Ted's popped up, so I'll condense mine to: "what he said". They materials look similar, but the polymers have very different characteristics.

Does GG have an expiration date? Also, what's the best (cheapest) place to buy it? I have a 13 x 22 x 9 high room, so I'm figuring it's 900 SF of rock, so if I'd use 2 tubes/sheet (assume it's a 4 x 10 sheet (?), I'm looking at, what, 2 cases??

Everything has an expiration date but you're good for over a year if material is kept cool (vs. in the back of a pickup un southern Texas for a week).

192 sq ft per case or 365 sq. ft per pail at the coverage you mentioned.

almost 5 cases or 2.5 pails

Hello,

I'm living in germany and english is not my native language, so my description could be a little broken.

I live in an apartment in a multi family house, the walls are brick, the ceilings are plain concrete. Until the family above us decided to use laminate on their floor, it was never noisy, but now from time to time it is a very unpleasant acoustics.

So I searched the web for solutions and found green glue. It seems it is not distributed in germany but I found a distributor in UK, so this will be not the problem.

The height of my apartment is 2.5 m (8,2 feet) and I don't want to loose too much height (maximal 5 cm = 2 inch).

So could I use 2 drywalls with GG between them and install it at the ceiling with 1 cm (~0.5 inch) air gap between drywalls and ceiling? Have I to fill the air gap? How much would I gain with this construction?

Thanks

They certainly don't feel the same. GG is some sticky stuff. Makes for a great fly or mouse glue trap.
Someone else use's GG to catch mice?!?! I go through just over a 5 gallon's worth of GG per year catching mice!

Glad to hear I'm not the only one...I was beginning to think I was up in the night for using GG to catch mice...

;)

hey my first post here in AVS and am seriously considering GG for a soundproofing project.

does the damping effect of GG help across all freq...highs to lows? also is it overkill to go GG - drywall - GG - drywall or is there a point of diminishing return? I have quite a bit of room to work with here.

thanks

hey my first post here in AVS and am seriously considering GG for a soundproofing project.

does the damping effect of GG help across all freq...highs to lows? also is it overkill to go GG - drywall - GG - drywall or is there a point of diminishing return? I have quite a bit of room to work with here.

thanks
Yes, it does work across all frequencies. And I don't think multiple layers of GG work any better, though I could be wrong. Has to do with the details of constrained layer damping.

I was always under the impression that multiple layers Ie.. DW/GG/DW/GG/DW would outperform DW/GG/DW even if the DW layers were of equal mass in both situations.. or two layers of GG @50% coverage would outperform 1 layer @ 100 % coverage.

I was always under the impression that multiple layers Ie.. DW/GG/DW/GG/DW would outperform DW/GG/DW even if the DW layers were of equal mass in both situations.. or two layers of GG @50% coverage would outperform 1 layer @ 100 % coverage.
Okay, this has forced me to actually pick up a book. :D I checked my copy of Beranek and Ver's "Noise and Vibration Control Engineering," which has a good chapter on viscoelastic constrained layer damping. Eric Ungar's Structural Damping chapter covers a number of geometries, but none with multiple CLD layers. So my question is, does the Green Glue Company have lab data which shows the extra effectiveness of multiple GG layers?

I can check on the availability of formal data, however after many, many informal (no formal report) trials it was found that KNKKNK's comments ring true. Assuming the same overall mass and quantity of damping material, the system is more efficient with three layers, rather than two. i.e three layers of 1/2" drywall with 1 tube of damping in between is better than two laters of 5/8" with two tubes in between (again presuming equal mass for a moment).

Having said that, there is also a point of diminishing returns after that. I do not know where that point is.

In general however, if there is a multi-layer system (5 sheets of something) there would reasonably be a benefit to having some smaller amount of damping between layers to ensure a maximally damped leaf.

You know me Ted. Show me the money (data)! :)

Hello,
The height of my apartment is 2.5 m (8,2 feet) and I don't want to loose too much height (maximal 5 cm = 2 inch).

So could I use 2 drywalls with GG between them and install it at the ceiling with 1 cm (~0.5 inch) air gap between drywalls and ceiling? Have I to fill the air gap? How much would I gain with this construction?

Thanks

I would be happy if someone could give a short answer.

Personally, I'm not following you're proposed plan. Perhaps you might find this helpful:
http://www.soundproofingcompany.com/solutions/soundproofing_ceilings/

Do you mean the part "Have a Concrete Slab for a Ceiling?" in your link? But I would loose height when I first attach a thick insulation and this is what I wanted to avoid. What happens if I leave an air gap of ~ 1cm or fill only 1cm with insulation?
Or what is the best compromise/alternative when I only want a maximal loose of 5 cm?

Personally, I'm not following you're proposed plan. Perhaps you might find this helpful:
http://www.soundproofingcompany.com/solutions/soundproofing_ceilings/

Wow great link with ilustrations... nice post. Thanks

Do you mean the part "Have a Concrete Slab for a Ceiling?" in your link? But I would loose height when I first attach a thick insulation and this is what I wanted to avoid. What happens if I leave an air gap of ~ 1cm or fill only 1cm with insulation?
Or what is the best compromise/alternative when I only want a maximal loose of 5 cm?

For concrete slabs the introduction of any air cavity (compressible layer) will improve upper frequencies, while hurting the lower frequencies. See commentary here: http://www.soundproofingcompany.com/library/articles/triple_leaf_effect/

If your isolation issues are low frequency now, you would not want to add a layer of anything. In any event, you will lose headroom, as a thin air cavity is trouble

Ok, thanks.
What if I do something like acoustiblok into the thin air cavity? Is this still a problem with low frequencies?

Acoustiblok is yet another example of Mass Loaded Vinyl. You don't need mass. You need a deeper, mildly insulated air cavity

In the link you posted there is a point which I want to ask. The conclusion at the bottom is:

"As long as the system is coupled, performance will be seriously compromised in the low frequencies."

So when I find a construction to decouble the drywalls without losing too much height, with still a thin air cavity, would I have nevertheless problems although it is decoupled?

Just to be sure: I don't hear much music or talks from above, only the footsteps on the laminate. Are footsteps on laminate low frequency?

Mily,

Footfall Noise certainly has a low frequency component. This is what makes IIC such a poor metric for impact noise, just as STC is for airborne noise. Neither measure the most problematic and difficult aspect of sound control.

Going from a solid (single leaf) ceiling slab to a double leaf (slab + drywall) will obviously introduce an air cavity, and therefore a corresponding Mass-Air-Mass resonance frequency. This resonance point (frequency) can be quite high, which hurts our chances to attenuate low frequencies. We improve our isolation by lowering that resonance point.


Introducing a resilient decoupled element for the slab ceiling will help drop that low frequency resonance point (frequency) created with the new air cavity.
This is best accomplished with resilient clips and channel

Absorption (medium-density insulation) will drop that resonance point further.
So we add a bit of un-compressed fiberglass, mineral fiber or cellulose in this new air space

Mass on the resilient system will drop that resonance point even further.
This is best accomplished with more drywall

The depth of the air cavity will lower that resonance point as well.
This is why we need to drop the new ceiling down as far as is practical. It's part of the cost to obtain satisfactory isolation.


Damping compounds will not lower the actual frequency of this resonance point, but it will reduce the severity of the resonance of the established LF resonance point, as well as improve the TL at other frequencies.

@Ted White,

thank you for taking the time to explain me all this. Allow me one last question: assume I take a gypsum board, its surface will overlayed with GG in a way that there is no area without GG, so when I press it to my ceiling there is no air cavity. What will be the effect?

Can Green Glue only be used between two sheets of drywall?

just wanted to confirm if I can just GG a drywall layer onto a pre-existing painted wall or if the results are better between 2 sheets of unpainted DW-DW.

Green Glue is not an adhesive! It's not a traditional glue.

just wanted to confirm if I can just GG a drywall layer onto a pre-existing painted wall or if the results are better between 2 sheets of unpainted DW-DW.The results should be the same regard of paint, but you'll need to use screws to hold the drywall. The GG is just a viscoelastic damping material between them.

@Ted White,

thank you for taking the time to explain me all this. Allow me one last question: assume I take a gypsum board, its surface will overlayed with GG in a way that there is no area without GG, so when I press it to my ceiling there is no air cavity. What will be the effect?

Effect will be nearly zero. Visco-elastic damping materials function best when the two mass layers are of similar stiffness. In your example there is an enormous difference in stiffness between the concrete slab and the proposed drywall. Therefore no effective damping. Also the added mass is small relative to the original slab so no real benefit from mass addition either.

Effect will be nearly zero. Visco-elastic damping materials function best when the two mass layers are of similar stiffness. In your example there is an enormous difference in stiffness between the concrete slab and the proposed drywall. Therefore no effective damping. Also the added mass is small relative to the original slab so no real benefit from mass addition either.

Ok, now I press a gypsum board with GG to the ceiling, then a second gypsum board with GG to the first board. I would think this is a kind of decoupling avoiding air cavity with two boards having GG between them. Still no chance?

No chance for all of the same reasons

No chance for all of the same reasons

Ok, thanks. Maybe I will try phonewell then.

Interesting product. Sand-filled corrugated cardboard. This is essentially a limp mass concept like MLV deploys. The physics of the situation don't change, however.

This is a thin layer of mass as was the double drywall. Mass is mass. The damping capacity would not nearly approach that of a bonded damping compound.

For ceilings their suggestion is to install one of two potential very small air cavities. Again we have the reduction in low frequency isolation inherent with the introduction of an air cavity. This high frequency air cavity resonance is what is causing problems. You cannot directly damp that slab, so you have to decouple from it.

In doing so we create an air cavity. Our only hope is to drop that resonance point (frequency) as low as possible or suffer the reduction in low frequency performance as we've discussed previously. Your ultimate solution takes up space.

You could have a very competent solution if you were to sacrifice 8" of ceiling height. This would allow for spring isolators to be installed, then drywall.

You must keep in mind, however, the concrete ceiling and floor decks will conduct through concrete walls and support columns very efficiently. This is common Flanking Noise: http://www.soundproofingcompany.com/library/articles/flanking/

Interesting product. Sand-filled corrugated cardboard. This is essentially a limp mass concept like MLV deploys. The physics of the situation don't change, however.

This is a thin layer of mass as was the double drywall. Mass is mass. The damping capacity would not nearly approach that of a bonded damping compound.

For ceilings their suggestion is to install one of two potential very small air cavities. Again we have the reduction in low frequency isolation inherent with the introduction of an air cavity. This high frequency air cavity resonance is what is causing problems. You cannot directly damp that slab, so you have to decouple from it.

In doing so we create an air cavity. Our only hope is to drop that resonance point (frequency) as low as possible or suffer the reduction in low frequency performance as we've discussed previously. Your ultimate solution takes up space.

You could have a very competent solution if you were to sacrifice 8" of ceiling height. This would allow for spring isolators to be installed, then drywall.

You must keep in mind, however, the concrete ceiling and floor decks will conduct through concrete walls and support columns very efficiently. This is common Flanking Noise: http://www.soundproofingcompany.com/library/articles/flanking/

8" of ceiling height is too much for me.

After thinking about the physics over night, I've still problems to understand it right. Not the part with air cavity, I understand that it is the better way, but the part with attaching products directly to the ceiling. Assume we have two different boards, products A and B, with same thickness and same mass. Assume, data sheets says for concrete it can absorb 10% low frequency, also product A can absorb 10% low frequency, but product B can 30%. What is the physical reason that the 30% absorbtion quality of B mostly dissappears when I attach it directly to a wall? Are the absorbing qualities of the different materials get mixed so the quality with the most mass has the most influence? Is it really only a function of mass and the properties and composition of the components (different density, viscosity...) has no influence? Or is the 30% absorbtion there, but the flanking noise is erasing it?

I was rocking out in the workshop the other night (amplified electronic drums) and right around 1:30 AM the back cover to the combination deadbolt falls to the concrete, so I stop playing, walk over to the door, and clip the plastic cover back onto the deadbolt.

Continue playing, then again, the cover falls to the ground, except now I can hear someone pounding on the metal door. It's my neighbor, and he's a little hot under the collar. Turns out they CAN hear me!

Green Glue has been ordered (3 pails + gun). Just not sure how to build the "room within a room". Yes, I've read all 39 pages of this thread, and if I missed the part where steel buildings were discussed, I apologize.

So this is a 40'x50' steel framed building and is currently wide open on the inside. No interior wall partitions yet. The exterior is corrugated steel, then styrofoam, then 1x6 wood lathe as a nailer, then styrofoam, then another layer of corrugated steel lining the inside. Two layers of steel and insulation and noise is still an issue. Probably no surprise to anyone who's read all 39 pages of this thread.

I want to build my music room in the back corner of the workshop. It will be about 20'x24'x10' with 2 sides adjacent to the corrugated steel walls. I can do either staggered stud or double studs, but I'm concerned about the triple and quadruple leaf effect.

I saw this case study -

http://www.soundproofingcompany.com/products/green_glue_tubes/green_glue_club_sanctuary_case_study

...but clearly, that nightclub has only exterior corrugated steel siding. I have exterior and interior, thus the triple or quadruple leaf.

Any insight into how to design the four walls of the room will be greatly appreciated!

teeinep:

Build a free-standing room (its own ceiling joists attached to tops of its wall studs), but don't put any sheetrock on the outside walls or ceiling. On the inside, put a double layer of sheetrock with Green Glue sandwiched between. It's that easy!

http://www.soundproofingcompany.com/library/articles/room_within_a_room/

As Terry Said...

And it sounds like you have a very large space to work with. So keeping inner room walls and ceiling well away (several feet if you can manage it) from any outer walls or ceiling will considerably improve sound isolation.

Ah! If only it was that simplle! The other side of the 2 interior facing walls will eventually be part of the home gym and a tool bench, so bare studs isn't an option

This would be good to start a separate thread, perhaps. It makes a thread cumbersome to read through in coming months.

If you have FEET of separation between inner room and outer, you can finish the exterior walls of the inner room with drywall without fear of creating a triple leaf effect.

I'm going to position the room more towards the center of the building, away from the corner and exterior walls. I might lose about 160 square feet since this will create a hallway around the room, but better to lose a few square feet than to lose the entire square footage because the room doesn't serve it's purpose.

Thanks for the input.

I wanted to post a couple of photos and video that shows us applying Green Glue by using a paint roller instead of the using Soundproofing Co's Speedload Dispenser. We purchase the Green Glue in the 5-gallon buckets and initially starting using the Speedload Dispenser. However, we found that it ended up taking way more time to fill the dispenser, squeeze it out, and then clean up the tool with WD-40 afterward. PLUS, when you apply Green Glue using a dispenser, there are chances to have small gaps or pockets in between the pieces of drywall.

By using the paint roller, we're still able to apply it very thick. It has 100% coverage with no "spider web" gaps. It saves time during the application process and there is no time wasting during clean-up because you throw out the paint roller afterward. It also costs a lot less than purchasing the quick dispenser.

Application photos:
http://www.joelmueller.com/images/greenglue1.png
http://www.joelmueller.com/images/greenglue2.png

Video applying it directly to the ceiling (apply it to the other piece of drywall as well to get it super thick).

http://www.joelmueller.com/images/greenglue.mov



Hands down, this is the cheapest, fastest and most complete way that we've found for applying Green Glue to sheet rock.

Interesting, but while not full coverage, I'd think the random bead method would give a thicker layer than the rolled layer. I don't think it's so much about having 100% coverage as it is to produce a visco-damping layer. Ted, anyone from Green glue have an opinion?

As wonderful as that looks, we've tested various application patterns. The application of 3/8" beads is the best way to go by far. For many reasons. Exactly as GetGray says

You want small voids, also. They help. A continuous film is less desirable.

Also, as far as "super thick," how do you know how much you're applying? If "2 tubes per sheet" is the goal ...

Folks ... the manufacturer provides application instructions for a reason. That reason is usually not provided as a way to slow down your work but to provide assurance the end result is what it is supposed to be.

OMG.....well at least GG is cheap in the US, another couple of pails and some dry wall wont hurt too bad

We actually get it thicker using the roller method and applying it first to the piece of drywall mounted, and secondly on the piece we're about to mount (ie - like putting peanut butter on both pieces of bread).

You may have tested figure eight positions and found that it works best, but it's hard to believe why, if you are able to get enough of a "thick" coverage using this method. I would like to see someone publish how thick they were able to get the GG when spreading it using a roller. My guess is they applied it much thinner than we were able to do here.

As for measuring how much you're using, we used a 5-gallon bucket for a single small bedroom. So the application of it was pretty liberal - likely more than three bottles (vs the normal 2) which has shown to have a greater dampening effect. It's pretty easy to compare the amount being applied in general when you've done an entire house (plus you can count the square footage and compare with how far a 5-gallon bucket went with the normal recommended amount).

-j

Will using GreenGlue over paint and another layer of sheet rock be ok??

Given that this is a Green Glue thread, and people have been reading it for years (and presumably will continue to do so) I feel it necessary to set the record straight. Rolling on the product is a bad idea. I can't emphasis that enough. I applaud the creativity, but no one should ever apply Green Glue in this fashion.

Damping Layer Thickness: Thicker is not better, and piling on damping compound is not the goal. "Three tubes per sheet" is technically better, but only by a rather small amount. This is why we never recommend that much. You risk building too thick a damping layer (as you have), where damping capacity plummets. Too much is bad. Optimal is the goal.

You mention a small bedroom. Perhaps 10 x 12? So 120 square feet as an example. A pail should cover 365 square feet. Even at "3 tubes per sheet", you would use a pail to cover 243 square feet. So you used twice the max amount. Without question, your damping is poor relative to what is should have / could have been.

Contact Between Layers: We studied this by assembling walls and taking them apart to look for optimal compression of the damping layer. Boards are not flat, walls are not flat, and you would be surprised how poor the contact can be. The tall 3/8" beads proved far more effective for successful compression, and indeed tested better in the lab.

The Value of Gaps: There is additional low frequency benefit by leaving gaps in the panel coverage. A contiguous coverage isn't as high performance.

Xzener, that's a perfrctly fine application you describe.

I am in the process of turning our basement family room into our home theater...a remodeling project so to speak. I want to make clear that I am not as "involved" in building my home theater as many on this forum have the ability to be...I have 3 kids in college at the moment...but I am not complaining... I have removed the sheet rock from the ceiling leaving exposed beams and I have put in framing along a the side walls (staggered the 2 x 4's) My question is this. I am in the process of putting up a layer of sheet rock, green glue and another layer of sheet rock in between the ceiling joists. I wanted to sandwich this with insulation followed by a layer of 5/8 sheet rock, green glue, another layer of 5/8 sheet rock to finish up the ceiling. We just priced out the insulation and my wife went crazy... ($1500). She wants me to forgo the insulation in the ceiling. My question is how much of a difference will this make as far as keeping sound out (the kitchen is directly above us). Will there really be a noticeable difference? I plan on doing the same on the walls as far as 5/8 sheet rock, green glue and another layer of 5/8 sheet rock all the way around...(except for the back wall which is completely cement...and it is already sheet rocked from the completed room before... does that make sense??? We didn't tear this wall down...) I am open to suggestions or any comments. Thanks... just need to keep the wife happy...

Some insulation is helpful, certainly. Not quite as beneficial in a coupled framing system you described, however. The insulation would provide greater benefit if the ceiling drywall were installed in a decoupled fashion.

Also, not much to be gained installing more than R19 fiberglass.

Was hoping to hear from you Ted. I always like to read your comments. I appreciate your help! We are soon to be empty nesters so we don't want to spend a lot as I don't think the soundproofing will be as much of an issue... if you know what I mean. Keep up the great work and information Ted. You're a gem!

Randy ...

Not to rain on Ted's parade ... I can understand the "empty nester" and the budgetary constraints of children in college. On the other hand, sound isolation is also part and parcel of good in room acoustics by lowering the noise floor inside the room. While you may not care to go to the expense of a decoupled ceiling construction, you might want to consider installing 1x3, 24" on center perpendicular to your existing joists. Putting your drywall on 24" centers will be a fairly good help.

Here is my take on Green Glue for anyone who doesnt have time to read the last thousand or so posts..

Cost me $1500.... slapped that stuff all over the sheet rock...made it way heavy to handle overhead...

Got the stuff everywhere..... gets on your shoe, transfers to your bedroom, gets on work shoes...ends up in your hotel 1000 miles away...

After double drywall I could still hear sound outside...drove me nuts... I did have one vent opening to the outside ... I covered it up and it helped but I could still hear the kids outside....

A couple of weeks ago I was in the HT area wondering where my kids were.... after searching I found them outside...couldnt hear them....

Now that the glue has cured a bit....HOMERUN.


I'm a fan of the snot colored green stuff. The END>

The difference between wet and dry is really remarkable.

While you may not care to go to the expense of a decoupled ceiling construction, you might want to consider installing 1x3, 24" on center perpendicular to your existing joists. Putting your drywall on 24" centers will be a fairly good help.If you don't mind me asking, what is this accomplishing? Is it similar to opting for a staggered stud wall instead of a clip/channel wall?

Dennis may have additional thoughts on this, but the 24" OC spacing allows more panel flex and has less contact area than 16" OC attachments.

Fuzzy,

Did you stagger the studs or just dd&gg over existing frame. I, too, am more concerne with ambient outside sound than spilling from the inside.

I also would like to hear Dennis' respnse. I am building a theater above my garage and current framing has 16 oc. I am contemplating staggered studs 24 oc on walls but what about the ceiling being 16 oc? I am hoping not to have to reframe the whole room.

The key is to get framing that incorporates decoupling. This is the first objective. Some options:


Take the existing single stud frame, and convert to staggered.

Take the existing single stud frame and build a second stud wall frame 1" away from the original. This is a double stud wall.

Take the original single stud frame and apply clips&channel.

All three of these options will decouple the framing, starting you down the road of better low frequency isolation. You would only choose one of these options.

After that, insulate with a bit of R13 fiberglass, add as much mass (drywall or drywall / plywood) as practical, and consider damping the panels.

Thanks Ted! I am likely going to do one of your described methods. In fact I spoke with you about 3 months ago and you suggested staggered studs for my situation. Having a finished wall on the side attached to the house would result in a large effort to control 3 walls and neglecting one. Kind of makes me wonder if its worth it.

I am concerned about room modes in a small room (14x22). I could create a new front and back wall with 24 oc framing but that would further reduce my length (but will still ave a hollow fiberglass door to the house). I also have knee walls on each side that angle from 5 foot height to 9 feet. I am concerned that low freqs could be a big problem. I am struggling with the thought of going through the expense and trouble of decoupling if the room issues will still be prevelent regardless. I am thinking dd&gg to existing structure would be enough for outside cars passing by and room treatments and eq to handle room modes.

I wonder if I pull out some wall framing to make it 32" oc and 16" oc for ceiling would make a difference? The confuson just makes me want to pop up the walls and be done with it!

Generally if you want isolation, you'll do all 4 walls, ceiling, and if above grade, you'll do the floor as well. Then deal with ventilation, doors, lighting and outlets. Leaving one or more of these off the to-do list can spell trouble.

There's nothing wrong with just building the room with single drywall and enjoying it.

Also, room modes are the result of the room dimensions, not the sound isolation materials behind the drywall.

Hmmm? Doesn't gg help with low freq room modes or is it just for sound isolation. Do you think dd&gg over my existing structure will be sufficient to keep normal outside sound out of the theater? I am not concerned about the occasional motorcycle. I coud easily stagger for the walls at 24" oc up to 5 feet and just go 16" oc for the ceiling dd&gg and go from there. Thanks for the advice!

If the sound wave has sufficient energy to "enter" the wall it's gone, largely. Room modes would result from reflected sound waves that have insufficient energy to "enter" the walls.

I have quotes around the word "enter" because that's not really how sound propagates, but it's a simple visual for people.

Double drywall and GG is fine, but if you had the ability to introduce decoupling, now's the time, and it's so very valuable...

Thanks Dennis. I appreciate your comments as well and duly noted. I put in an order for some 1x3 strips to add to the ceiling 24" oc. I hope to be able to start working on this over the weekend. You guys are awesome and I again can't thank you enough for all your help. I am always open to suggestions.

Thanks again Ted! I would need to stagger the studs and reframe the side walls and the wall facing the street 24"oc . I would need a new wall adjacent to the house and use resilient channel on the ceiling. Looks like its this or just popup the walls. I will likely opt for decoupling as I would not want to regret the cheaper alternative. My ceiling at the top is 7-71/2 feet wide at nine feet and angles down to about 5-51/2 feet high so it should be ok at about 13 1/2 wide by 18-21 length. I'll put one row of 4 seats and maybe a bar behind with stools. Much to think about but its time to start doing! Thanks for the help!!!

If these are wood furring strips then:


Pre-drill the holes before mounting the furring to the joists. THis helps prevent splits in the furring.

Apply a bit of construction adhesive between the furring and joist.

Use a good quality deck screw to secure the furring to the joists. Do not use drywall screws to attach furring to joists.


You will not need to pre-drill the holes for the actual drywall screws that attach the drywall to the furring (that's a common question)

... and use resilient channel on the ceiling.

:eek: I'd suggest clips&channel, rather than resilient channel (RC-1)

Gotcha Ted. Thanks again!

One last question? Since the unfinished bonus room has knee walls should I sheetrock both sides? I was going to dd&gg the theater side and leave the other side open where the roof angles down to the eave. If I do this wouldn't it defeat the purpose of staggering the studs since sound would enter the eave and hit the theater wall?

I would decouple from the knee wall and double drywall the theater side only.

It would appear to me sound would be more flanking than direct from above.

Generally, yes, if the roof is far above potential noise sources.

Sorry Ted I removed my last post thinking the dd&gg on the ceiling joists would be a bad idea and not worthy of mention but I don't understand your respnse. Are you saying the flanking noise from above warrants clips and channel or may not be necessary.

Sorry for being confusing. Clips&channel isn't a bad idea, but I agree the ceiling is not going to have sound coming in unless you have a lot of air traffic.

Having said that, sound from the theater will enter the roof framing and that could conduct to the house. You'd have to determine if that's likely.

Great news! My bonus room is attached to the house via a mud room and the roof is above the mudroom roof. It may travel down and flank but not directly. This may be the way to go. Thanks Ted!

Ted,
I was concerned about the width of my room decreasing since every inch counts when you get below 14'. The contractor who constructed the room said the kneewall is not structual and I can easily move it. I have about 8' on either side and am likey going to move the kneewall in to gain another foot or so. I can change the wall to 24"oc and build from there or leave it 16"oc and stagger the studs as previously planned. Any thoughts? Thanks!

I'd move it and have 24" OC. Staggering is only valuable if you have drywall attached to the other side.

Thanks Ted that was what I was thinking! It was confusing when I looked at the stagger approach and still saw the stud partially attached to the structure with the other studs. Thanks for that clarification. Now, My roof has 2x12 framing angled at about 45 degrees to 9 feet where a new frame goes straight across for 7-71/2 feet. When I move the kneewall framing to a height of about 4 1/2 feet most of my room will be the angled wall/ceiling structure to the flat ceiling. Is this 2x12 structure beneficial w/ dd&gg to sufficiently to stop outside street noise?

As with any other structure, a decoupled frame will attenuate low frequencies better. I would say that many clip&channel all of the inside surfaces of rooms over the garage.

The question we've been pondering is in your particular case, is there a need? Your room is somewhat disconnected from the rest of the house, and elevated above the traffic, but you can't go back later and fix. So it's a coin toss for you.

Thanks Ted I'll start flipping! Best out of 7!!!

Hi Ted

I am currently building my dedicated theater room and going to be using DD/GG. I'm building room in a room in the basement, 14x20,. Subfloor consists of 1" pink board under 3/4 OSB tapcon'd down into the concrete, walls drilled into the OSB and secured to the new ceiling joists via hurricane brackets. The walls are currently going up at 16 OC.

I only have 1 question left. Is there a considerable low frequency difference between 16oc and 24oc when utilizing room in a room design?

If the walls are decoupled, then stud spacing really doesn't matter.

Great! I do indeed have all the walls decoupled with double stud walls. I was hoping I wouldn't have to rebuild the 3 walls I have up already.

Thanks a bunch Ted and keep on rocking the soundproofing community. Your knowledge has been a tremendous resource to a lot of us.

Sounds good. Keep in mind that you would only build a single stud wall in front of the foundation, as the foundation itself counts as one of the double "walls"

In my HT, all the bedrooms are directly above me. I've managed to place my HT, directly above 3 rooms (DOH!). That is my only concern when it comes to sound proofing. I'm going to stagger stud the main wall, but that's it. I want to insulate, isolation clips, and DD GG the ceiling. Is it possible to just GG the ceiling? I'm learning all these new things, and I want to make sure just using it on the ceiling isn't going to be for nothing.

Hi Hoosier,

Doing only the ceiling may or may not be a waste. Each room is different, so without details on your particular build, it's hard to say.

Clips are good to consider, since if you want to beef up the system later, you can't go back and add clips (insulation, etc)

Hi Hoosier,

Doing only the ceiling may or may not be a waste. Each room is different, so without details on your particular build, it's hard to say.

Clips are good to consider, since if you want to beef up the system later, you can't go back and add clips (insulation, etc)

Thanks. Well, if it's not a given that it will drastically help, I'm going to hold off. It's way out of my price range. I also just noticed how freaking expensive any type of iso clip is. They're like 7 bucks a piece???? Then I Have to buy the furrying strips?? Never thought this would be so expensive.

It's not that expensive (your numbers are way high)

You will never have calculable guaranteed isolation if you treat only one surface in a room. Sound will leave through all 4 walls, ceiling and floor.

It's not that expensive (your numbers are way high)

You will never have calculable guaranteed isolation if you treat only one surface in a room. Sound will leave through all 4 walls, ceiling and floor.

That's good to know my number is too high. I only saw 1 website. Most make you call for a quote it seems.

It's in a basement, and it's finished already, except 1 wall (the one I will stagger stud). I'm not gonna start knockin down walls (which I'm going to my ceiling) so I don't really have much of a choice.

I'm finishing up my home theater/game room and have a few questions. The room is roughly 20x24 and will not be a dedicated HT room. I'm willing to spend $1000 if it will help with sound dampening. I'm not looking at a completely sound proof room, but would be worth it to me to block a percentage of the sound. The room is in the basement right below our living room/master bedroom. With the room unfinished we can hear conversations through the floor.

1. Is it worth just doing the ceiling and not the walls with DD and GG?
2. I plan on using can lights, but would it be worth doing a quiet box for those even if I dont do DD and GG?
3. How do you deal with HVAC vents? I can see wrapping it, but I don't see how to deal with the actual hole for the output.
4. Would I get any added benefit adding fiber glass insulation and/or solid core door if I dont use GG and DD?

Thanks

Hi, I saw a comment above about double stud walls and double drywall with and without green glue, that its only a few STC points - just how much is a few? I am considering doing double stud & floating joists construction, with double drywall all around, but maybe just GG on the ceiling.

The existing walls to the space are all cinder block, and with double stud there shouldnt be flanking issues to above. I just think its probably overkill to do GG on the walls, but now is the time to set me straight :)

Cheers,

Andy K.

I'm finishing up my home theater/game room and have a few questions. The room is roughly 20x24 and will not be a dedicated HT room. I'm willing to spend $1000 if it will help with sound dampening. I'm not looking at a completely sound proof room, but would be worth it to me to block a percentage of the sound. The room is in the basement right below our living room/master bedroom. With the room unfinished we can hear conversations through the floor.

1. Is it worth just doing the ceiling and not the walls with DD and GG?
2. I plan on using can lights, but would it be worth doing a quiet box for those even if I dont do DD and GG?
3. How do you deal with HVAC vents? I can see wrapping it, but I don't see how to deal with the actual hole for the output.
4. Would I get any added benefit adding fiber glass insulation and/or solid core door if I dont use GG and DD?

Thanks

Hi Coder. Welcome to the forum. If you're going to soundproof your room, you would do well hooking up with an advisor to discuss all of the elements involved. Ventilation is a tricky thing, as you have to provide enough air volume movement, while reducing the sound travelling through the duct. This is unfortunately most often an afterthought.

If you don't have a solid plan before you begin, you'll likely waste a great deal of effort and cash, and risk having a very compromized result.

Do you have a room layout?

Hi, I saw a comment above about double stud walls and double drywall with and without green glue, that its only a few STC points - just how much is a few? I am considering doing double stud & floating joists construction, with double drywall all around, but maybe just GG on the ceiling.

The existing walls to the space are all cinder block, and with double stud there shouldnt be flanking issues to above. I just think its probably overkill to do GG on the walls, but now is the time to set me straight :)

Cheers,

Andy K.

Hello Andy. How have you been? Categorically, damping improved decoupled assemblies. There's plenty of lab data. STC points are not really relevent as our concerns are for trouble that may occur well below the 125Hz cutoff of the STC calculation.

The side walls placed an inch or so from a foundation are decoupled, however sound within the air cavity has no place to go but straight up to the floor joists. We damp the wall drywall panels to minimize this flanking path.

Very well thanks! I moved on from Silicon Optix a couple of years ago (although I'm glad to see HQV Vida finally coming out, which I had a significant hand in developing). Now I just bought a new house this year and I'm looking forward to Theater 2.0 :D

If the walls are decoupled from the structural floor joists above (ie. floating joists resting on the new studs a la room-within-a-room construction) is there still that flanking concern?

You bring up something else I was wondering about - is there a minimum spacing for the walls (or anything) before they can be considered decoupled? For example, if I build the stud walls a 1/4" away from the foundation wall, is that not still decoupled?

Cheers,

Andy K.

Glad things are moving right along for you Andy. Another 2.0 theater. Very nice.

Decoupling is defined as the two leaves being able to move independent of one another. If the two leaves share the same stud, this independent movement isn't possible. So it's not the cavity depth that defines decoupling. It's the method of attachment.

The floating ceiling is an excellent means to decouple the ceiling frame.

With respect to the walls, we're not concerned about sound passing through the foundation. Our concern is the sound entering the space between the foundation and framed wall, then heading straight up. Between the wall and foundation, there are exposed joists.

Thanks Ted. I see what you mean about the sound flanking up behind the wall.

All I meant with decoupling distance is this - If I build my stud walls 1/4" away from the foundation walls, they are just as decoupled from that foundation wall as if they were 1-2" away right?

You are right. However from a practical perspective, we have to acknowledge that wood studs move, twist, warp etc, and that 1/4" could become 0" in short order. Therefore we generally recommend 1" to be safe.

Agreed 100% - you don't want those walls to short circuit against each other.

The use of triple drywall is new from when I built last time - do you have measurement curves that compare double vs triple drywall? (particularly triple w/50% GG coverage vs double w/100% GG coverage?)

Thanks

No. The TL is huge and labs are few and far between that could adequately measure such a wall. The added mass is to specifically conbat low frequencies.

You recommend it though? :)

Maybe what I'll do is sheet the room with double+gg and see where I'm at first. can always add another layer of drywall...

Cheers!

We recommend it yes. Mass is mass and adding such mass to a decoupled system we know drops the LF resonance point (frequency) down substantially. This directly translates into improved low frequency performance.

Is it worthwhile to decouple only the ceiling in a basement build? I plan to double drywall everything. Also, has anyone ever tested the drywall adhesive the sell at Lowes etc? It is supposed to stay flexible, it may have been a Loctite product, 200 maybe? Costs in the 1.50 a tube range.

1- All 4 walls and ceiling should be decoupled. Why? A decoupled frame stops low frequencies best. If the walls are not decoupled low frequencies will travel through the walls and upstairs.

2- Green Glue doesn't work simply because it stays flexible. This has been discussed over the years, including earlier in this very thread. If flexibility was the only goal, we'd all be using peanut butter in the walls. You could do a AVS Forum search under "peanut buter" and you will see what I mean. ;)

I'm converting what was once a door into a wall. I'm thinking of packing (filling) it with 1/2" Drywall GG 1/2" Drywall. Should I leave an airspace? Any tips on optimizing this, e.g. fastening? At what point does packing in more Drywall + GG no longer yield soundproofing improvement?

Muff, IMHO there is no reason to fill in the hole in the wall with materials and treatment which exceeds the construction of the surrounding wall. Tell us about the wall.

Agreed. Keep the air cavity, fill with R13 fiberglass and then your double drywall.

The wall is 1957 vintage single stud no insulation with what looks like 3/8 drywall with a thick cement finish -all told total thickness a touch over 5/8".

Just filling it in is the least hastle construction wise. ANy acoustical disadvantage to that?

That's a lot of drywall and Green Glue that provides no acoustic benefit since the rest of the wall is hollow and lightweight. The rest of the wall will define the end result.

However if you find it easier, I'd just do the drywall and forget the Green Glue.

However if you find it easier, I'd just do the drywall and forget the Green Glue.

That's what I'll do and just GG between the two outermost panels like I'm doing the rest of the wall. .

The walls adjoining the doors are all getting 1/2" drywall over 2-3 tubes of GG per panel. The project involves soundproofing one half of the house ( hallway, living-room, bedroom) from the other half (2 bedrooms, walk in closet).

One of the walls (pictured) is mirror clad. To avoid mirror removal/disposal and perhaps gain a bit of mass from the glass AND a tad of decoupling (unfortunately downgraded by a shared attic) I built a separate single stud wall that will see 5/8 GG 5/8.

Is it OK to stack, as pictured, the R13 up to the ceiling next to and touching the mirror or must it be attached between the studs (inconvenient - studs are 24" OC and R 13 is 15" wide) ?

The insulation looks compressed there. Maybe ut's jjst the way I'm looking at it. There should be no compression. Otherwise stick it in there any way you see fit.

If the final layer of drywall is 5/8" (across the whole wall) it will improve things in the low frequencies.

Also, I'd suggest just "two tubes per sheet" not three.

+1 have to have three posts

+2 sorry

Hi Coder. Welcome to the forum. If you're going to soundproof your room, you would do well hooking up with an advisor to discuss all of the elements involved. Ventilation is a tricky thing, as you have to provide enough air volume movement, while reducing the sound travelling through the duct. This is unfortunately most often an afterthought.

If you don't have a solid plan before you begin, you'll likely waste a great deal of effort and cash, and risk having a very compromized result.

Do you have a room layout?

Here's the room layout. Its one large room, but I'm really only worried about the mid-high frequencies going upstairs.

http://i28.photobucket.com/albums/c229/coderabit/codybasement5.jpg

Its one large room, but I'm really only worried about the mid-high frequencies going upstairs.


Curious why you're not as concerned about low frequencies. They are generally harder to deal with.

Curious why you're not as concerned about low frequencies. They are generally harder to deal with.

Since they are harder to deal with (and I don't want to put too much effort into sound proofing) I figured I'd be happy with getting rid of just the other frequencies. If I can get rid of them great, but I'm not going to be disappointed if I don't. I don't plan on turning the sub up when I need to be quiet, yet I don't want people upstairs to be able to hear conversations through the floor.

My current idea is to use drywall with GG between all of the floor boards and r13 to r19 insulation. Would that make much of a difference?

I've started my own thread with pictures
http://www.avsforum.com/avs-vb/showthread.php?p=19361082&posted=1#post19361082

Thanks for starting a thread. I'll reply there.

is there a general soundproofing questions thread somewhere? If so forgive me for asking here.

If I build new joists resting on the stud walls (ie decoupled from ceiling) but the stud walls themselves are not decoupled from the foundation wall (instead I use clips and channel to mount the drywall on the walls) is there a serious flanking problem there?

I want to use spray foam to primarily insulate (with some additional fiberglass for absorption) and it's doubtful I can build the stud walls far enough away that they aren't touching the foam.

There's no thread, per say, but you can start one for your build. That's always fun.

The ceiling / wall assembly you describe isn't as big a deal if the mass hanging on it is thoroughly damped. Having said that, if you could get the framing on the foundation walls 1" or so away from the foundation, the wall will be considered acoustically decoupled. That would be better / cheaper than using clips.

I guess your third point s that due to the foam, the studs will be fixed solid, and therefore not possibly decoupled? The foam is great for thermal, terrible for acoustics. So if you could manage R13 in the side walls, that would be great.

I will indeed be starting a thread, but this is more of a general question that I thought might apply to others too.

The studs will be .5" - 1" from the foundation wall but the spray foam will be 2" nominal, so the studs will be somewhat embedded in the foam and therefore coupled to the foundation wall. It's doubtful I can space the studs away from the sprayfoam. I want sprayfoam for thermal and moisture reasons which trump acoustic reasons :)

Walls would then be foam/2x4 with R13/clips/channel/drywall/gg/drywall
Ceiling would be:decoupled joists on studs with R13/drywall/gg/drywall

Well I just realized that I have some perpendicular framing in the ceiling to support the fireplace above - so that is going to prevent me from doing fully decoupled joists in-between.

At this point my options are:

1)Staggered joists (attached to the rim joist or the perpendicular framing)
2)1x3 furring strips at 24" OC
3)RSIC-V clip plus channel (the lowest profile clips I can find)
4)an extra layer of drywall and green glue

The easiest would be #2, how much more performance would I get from the other options?

Thanks,

Andy K.

FWIW, I'm building mine now and had similar issues. I have decoupled walls, but impossible to have decoupled joists (trusses and all my HVAC is running perpindicular in chases), so I'm going with clips and hat channel on the bottom of the trusses, 2 layers 5/8 +GG.

I just dont want to give up 2" for the clips and hat channel. My room is 6'9" unfinished, I'm hoping to stay around 6'6" finished.

Despite the bad rap Resilient Channel gets around here, I'm looking at the lab tests for RC/drywall/GG/drywall and it performs remarkably well, is quite tolerant to some short circuiting, and only takes an extra 1/2" for the channel. This seems like the ideal solution for me? At a minimum it must perform better than 1x3 furring strips right?

The tests you are looking at are likely not for the channel you have. Most channel data is from the 80s when USG did testing. Most resilient channel benders refer to those tests but that's not at all accurate.

If you had access to data you'd find that the low frequency performance isn't good.

Have you considered recessing the clips and channel into the joist cavities:

http://www.soundproofingcompany.com/upload/rasied-blocking-detail.jpg

QUOTE:
At this point my options are:

1)Staggered joists (attached to the rim joist or the perpendicular framing). This is true decoupling but you can't do this (you said)
2)1x3 furring strips at 24" OC This isn't decoupling. Low frequency isoolation won't be there for you.
3)RSIC-V clip plus channel (the lowest profile clips I can find) This is decoupling, but the WhisperClips perform better, especially in the low frequencies.
4)an extra layer of drywall and green glue. Obviously no decoupling

The decoupling is directly correlated to the ability to isolate low frequencies. Decoupling one of the two leaves moves the low frequency resonance point down further which allows us better LF TL. At or below the resonance point the picture is ugly. Above the resonance point things are great.

Since we're all involved with rooms generating a great deal of sound, I though some here might find this interesting. Generally the most difficult aspect of high level isolation is controlling the low frequencies (bass). Keep in mind that STC doesn't measure bass, as it does not consider frequencies below 125Hz, and we're obviously dealing with rooms that put out a great deal of sound below that. Generally construction efforts to reduce low frequencies will naturally take care of the lower energy high frequencies.

In short, every compressible cavity (such as air cavities in walls and ceilings) will define a specific resonance point (frequency) in a decoupled system. If we have a double stud wall, or ceiling with clips and channel, then we have a decoupled system. Think of this decoupled system as a spring that oscillates. This system will have a calculable low frequency resonance point, defined by the Mass-Air (spring)-Mass parameters. Let's say this resonance point is 70Hz.

At 70Hz, we don't stop a lot of sound, since resonance allows that frequency to pass fairly easily. At 100Hz, we're doing much better, but as we start looking at frequencies lower than 100Hz, Transmission Loss gets worse and worse until we hit 70Hz rock bottom. So at resonance (70Hz), and just above resonance (70-100Hz) things are not great for our sound isolation. Generally the math is from the resonance point up to around 1.5X the resonance point we don't do as well in sound isolation.

If we could move that resonance point from 70Hz. to 40Hz. we would be much better off:

Scenario #1 has 70Hz resonance point, and weakness from 70Hz through 105Hz. (70 x 1.5= 105).

Scenario #2 has a 40Hz. resonance point, and a weakness from 40Hz through 60Hz. (40 x 1.5= 60).

This is why we spend time looking to incorporate methods to lower that LF resonance point as much as possible. How do we accomplish this? Keeping in mind that a decoupled system is a spring system:

We can add absorption in the form of simple (standard thermal) insulation. This will lower the resonance point (frequency) of the system a bit.

We can add mass to the system. This essentially weighs down our spring system, slowing the oscillation = lowering the resonance. The added mass is more effective than the insulation.

We can add cavity depth to the system. For the same reason that insulation helps, so does more air in the cavity. This also isn't as effective as adding the mass.

So again, if we can progressively march that low frequency point down, we minimize the frequencies that will display weakness.

Hope this helps.

I spent the evening pouring through lab tests on green glue website and soundproofing company website, and have not been able to find this:

Are there a set of apples to apples comparisons for dd+gg and dd+gg+clips? (and ideally dd+gg+RC1)

By apples to apples I mean same wall construction (24" or 16"), same drywall thickness, same number of layers (on both sides), etc

Thanks!

There are no tests for drywall + GG + clips. Part of the reason is for accurate data you'd have to go to the NRC lab in Canada. Not simple or inexpensive. These walls are not only approaching or above STC 70, but you'd want LF data down to 50Hz. US labs weren't built to measure partitions that isolating.

Kromkamp,

I have a low ceiling too at 7' and am doing everything to keep that height. I will be using clips and channel from Ted. You can recess the clips and channels so that the drywall is attached only 1/2" below the joists! (check out Ted's diagram more closely). The cheaper Whisperclips that they carry cost me hardly anything -- (several times less than the GG).

Thanks Ted! You're right, I didn't think of that solution.

When I said staggered joists, I could still do this - they would be attached to the perpendicular framing so not fully decoupled, but decoupled the same way a staggered stud wall is decoupled right?

Do you have any feeling for how low the resonance point is driven for this type of construction(dd/gg/clips), both in a 2x4 stud wall and a 2x8 or 2x10 ceiling?

Re: the floating joists, they would be attached to the inner stud walls. Are you doing double walls all around? The inner stud walls are decoupled, and therefore the floating joists would still be decoupled.

Assuming the system is decoupled, the Low Frequency resonance point (the frequency at which the partition resonates) is determined primarily by air cavity depth and the mass of the leaves. Mass causes a greater delta than cavity depth, which is OK since cavity depth is generally not a variable (it's fixed as people won't build 3' deep walls). This is why many opt for a third sheet of drywall.

As far as what exact frequency, there are calculators, however they are for ideal (imaginary) settings that have no variables such as ductwork, etc that deviate from ideal settings. The difference in LF resonance point establishment is large relative to the cost of drywall. I think that's safe to say.