Green Glue [Text View] - Page 2

Brian Ravnaas

01-31-05, 01:21 PM

hey clarence, not a scary thing at all.

my CAPITOL LETTRES ALL DRAMATIC LIKE (lol) were to outline that the goal is to get it to make a nice thin film, and if you let the trowel ridges dry, that can't happen, and the wall won't perform as advertised. Don't let the trowel ridges dry.

imagine you have a very large blob of it dried in the middle of where the next sheet will go - that's a bad thing becaue it will prevent sheet #2 from getting close to sheet #1. Same would apply to a blob of drywall mud or whatever, if you can picture what i'm saying.

but to answer a bit more: Green isn't particularily sensitive to some of the area between sheets being imperfect. A typical lab drywall/gg/drywall sample has about 85% ideal contact and 15% not, for example, a typical wall is a bit better in our experience. Construction isn't a perfect thing, and a product that needed perfection would not be worth much to that industry.

the important things are:

1. work one sheet at a time, it's usually or often most convenient to put the GG on the sheet while on the floor, then raise it into place
2. don't let the ridges dry, lest you get no damping "layer", but just damping stripes
3. don't get a huge chunk/blob/whatever of something that will prevent the two sheets from being squeezed together. That applies to normal glues and normal constructions with no adhesive as well, of course.

anything that will let the two sheets come together reasonably well is fine, and have small areas of imperfections is wholly tolerable.

that clear it up a bit? :)

Brian Ravnaas

01-31-05, 01:26 PM

hey mark, that's a great method, no question.

bob md

02-01-05, 01:01 PM

Brian - 2 questions:

1. Regarding smearing the stud face - a couple of my walls have kraft-faced insulation, w/ paper stapled to the stud wall. Is it worth trying to use GG over the paper?

2. If you put on 1 layer & let it dry, is there any problem letting the first layer set up for several days? Or should you do the 2nd layer right away?

Thanks,
Bob

Toeside

02-01-05, 08:22 PM

My Green arrived today.

I'm very curious as to what the consistency is, but I don't want to open it until I'm ready (should be 2-3 weeks).

I expected it to be the consistency of ceramic tile mastic--which is very thick and rubbery--but then Mark mentioned he pours it out. Mastic can't be poured.

I'm worried that this is going to be a big mess. The hall side of the wall I'm building is already finished. Carpet is already there. Of course, it will be pulled back from the wall a bit during the work, and I'll have a couple layers of dropcloths down just-in-case.

Just how soupy is this stuff?

Thanks!

OneBadMutha

02-01-05, 09:34 PM

thanks for the info

vid53

02-01-05, 10:47 PM

I just got done using the Green Glue about a month ago and really wont know how good it will work until I get done drywalling and setting up some type of sound system.
It was very easy to apply with the supplied trowel.I just measured and cut each sheet and after making sure it would fit correctly I applied the GG by scooping it out of the bucket with the supplied trowel and put on a coat of 100% coverage and attached it to the first layer of drywall.
I wore disposable gloves every time I worked with it ,because it was so easy to get it over everything. I will also say that Brian was excellent to work with, especially when FedEx sent my order to another state and he made sure all problems were taken care of.
All I hope is that I wont hear my wife say:
TURN IT DOWN!!
after I am done.

If she does, Ill tell her to go call Brian!!

Sandwedg

02-01-05, 11:20 PM

Originally posted by Toeside
My Green arrived today.

I'm very curious as to what the consistency is, but I don't want to open it until I'm ready (should be 2-3 weeks).

I expected it to be the consistency of ceramic tile mastic--which is very thick and rubbery--but then Mark mentioned he pours it out. Mastic can't be poured.

I'm worried that this is going to be a big mess. The hall side of the wall I'm building is already finished. Carpet is already there. Of course, it will be pulled back from the wall a bit during the work, and I'll have a couple layers of dropcloths down just-in-case.

Just how soupy is this stuff?

Thanks!

definitely more like mastic. I have cracked mine open and used some on some soffit framing. Hopefully using on sheetrock in 2 days. Not sure how the other guy poured it either.

Rubber gloves is a good idea!

markfh

02-02-05, 01:30 AM

What Vid53 said about measuring (twice at least) cutting and TRIAL FITTING first is a really good point. The last thing you want to do is get cocky with a cut sheet with GG on it only to find you cut it wrong. And it can happen if you don't trial fit first. Especially if you measure and cut holes for lights or recepticals.

It's extra work but worth it.

I tried the gloves but had one piece slip out of my hands and had to recut so I just went naked... :D

It washes off (your hands) real easy so don't worry about it. Everything else you don't want it on cover.

If you get it on the outside face of the drywall wipe it off. I don't know if the mud will stick to it real well so I'm doing a test on some left over drywall. I had a couple places where my cousin got his hand sized print on the drywall (he wore the gloves). Wiping it off still leaves a residue.

Toeside, I'd take that carpet up if you can. Covering it might not be enough. All it would take is one slip of the foot to pull the cover off and have some GG fall on it. And you know how Murphy works... :(

Oh yeah, my wife says it takes several washings to get it off the jeans... :rolleyes:

Brian Ravnaas

02-02-05, 08:06 AM

Originally posted by vid53
I just got done using the Green Glue about a month ago and really wont know how good it will work until I get done drywalling and setting up some type of sound system.
It was very easy to apply with the supplied trowel.I just measured and cut each sheet and after making sure it would fit correctly I applied the GG by scooping it out of the bucket with the supplied trowel and put on a coat of 100% coverage and attached it to the first layer of drywall.
I wore disposable gloves every time I worked with it ,because it was so easy to get it over everything. I will also say that Brian was excellent to work with, especially when FedEx sent my order to another state and he made sure all problems were taken care of.
All I hope is that I wont hear my wife say:
TURN IT DOWN!!
after I am done.

If she does, Ill tell her to go call Brian!!

three things

1. i'm glad you had a straight-forward go of things with the GG
2. it's REALLY CHEAP to get a box of disposable gloves at Wal MArt (or Sams Club or Grainger or KMart or a grocery store or a pharmacy), and it saves alot of cleaning up. It's also cheap to get a long sleeved throw-away shirt, and you can shampoo the stuff off your skin easily enough, but it's no fun losing arm hair
3. if i get a call from your wife i'm going to blame Tom Cruise and immediately sue paramount pictures

but i'm sure you'll get what you wanted out of it, just make sure to bother with the details, the vents and the caulk and the caulk and the doors and the caulk

take it easy,

Brian

Brian Ravnaas

02-02-05, 08:08 AM

Originally posted by Toeside
My Green arrived today.

I'm very curious as to what the consistency is, but I don't want to open it until I'm ready (should be 2-3 weeks).

I expected it to be the consistency of ceramic tile mastic--which is very thick and rubbery--but then Mark mentioned he pours it out. Mastic can't be poured.

I'm worried that this is going to be a big mess. The hall side of the wall I'm building is already finished. Carpet is already there. Of course, it will be pulled back from the wall a bit during the work, and I'll have a couple layers of dropcloths down just-in-case.

Just how soupy is this stuff?

Thanks!

it's a light paste. you could use a 1/2" notch trowel and those huge ridges wouldn't run all over the place.

but it can sort of be poured in "glops" so to speak out of larger containers like the pail

Brian Ravnaas

02-02-05, 08:10 AM

Originally posted by markfh
What Vid53 said about measuring (twice at least) cutting and TRIAL FITTING first is a really good point. The last thing you want to do is get cocky with a cut sheet with GG on it only to find you cut it wrong. And it can happen if you don't trial fit first. Especially if you measure and cut holes for lights or recepticals.

It's extra work but worth it.

I tried the gloves but had one piece slip out of my hands and had to recut so I just went naked... :D

It washes off (your hands) real easy so don't worry about it. Everything else you don't want it on cover.

If you get it on the outside face of the drywall wipe it off. I don't know if the mud will stick to it real well so I'm doing a test on some left over drywall. I had a couple places where my cousin got his hand sized print on the drywall (he wore the gloves). Wiping it off still leaves a residue.

Toeside, I'd take that carpet up if you can. Covering it might not be enough. All it would take is one slip of the foot to pull the cover off and have some GG fall on it. And you know how Murphy works... :(

Oh yeah, my wife says it takes several washings to get it off the jeans... :rolleyes:

these are some very good tips.

WRT the gloves: get some latex gloves (if you aren't allergic, of course) that are one size too small so they fit nice & snug and it should be OK.

WRT drywall mud: it will stick to green glue at least as well as to drywall paper, so don't fret about it too much

WRT cleanup: an ounce of prevention is worth a pound of cure, Goo Gone works wonders (so i'm told, i plan to test it ASAP)

Brian Ravnaas

02-02-05, 08:12 AM

Originally posted by bob md
Brian - 2 questions:

1. Regarding smearing the stud face - a couple of my walls have kraft-faced insulation, w/ paper stapled to the stud wall. Is it worth trying to use GG over the paper?

2. If you put on 1 layer & let it dry, is there any problem letting the first layer set up for several days? Or should you do the 2nd layer right away?

Thanks,
Bob

WRT #1: i don't know, i doubt it, but i'll put it on the lab agenda for today, some ballpark idea by late this week. You mean putting GG between the drywall and the insulation paper to improve damping a bit, right?

WRT #2: do you mean over the studs? let it dry as long or as short as you wish.

For over the large expanses of drywall, i wouldn't recommend bothering to let it dry, as you just wind up using more as you have to put new wet stuff over it.

bob md

02-02-05, 08:50 AM

Originally posted by Brian Ravnaas
WRT #1: i don't know, i doubt it, but i'll put it on the lab agenda for today, some ballpark idea by late this week. You mean putting GG between the drywall and the insulation paper to improve damping a bit, right?

You were advocating using GG on the edge of a stud before installing a sheet of drywall to prevent drywall to wood contact & potential problems. Many basement HTs will have some sort of vapor barrier - kraft paper or poly. So perhaps that vb will prevent drywall to wood contact. The question is would GG help at all? Let us know what the lab thinks - drywall is going up this weekend!
Thanks,
Bob

Brian Ravnaas

02-03-05, 03:36 AM

ah, i'm with you now, Bob.

yes, GG between that layer is a fine idea, and would have the same effect. Before you proceed, try it on a small area to make sure that nothing causes installation trauma.

now if my memory works at this time of day, you are building staggered stud walls, correct?

bob md

02-03-05, 09:22 AM

3 of my walls are cinder block, 2 exterior and one cinder block wall that splits my basement. My back wall is staggered studded.

Thanks for the reply - I'll slap some GG on top of the paper, should be simple.....

Bob

Sandwedg

02-03-05, 09:54 AM

w00t!

Just ordered the sheetrock this morning, will be delivered tomorrow. Contractor is lined up for Saturday morning. GG is ready to go!!! I will take some installation pics.

BTW.... anyone get really strange looks from drywall contractors when you tell them you want the entire room in 2 layers of 5/8"?

bob md

02-03-05, 10:21 AM

My sheetrock is being deliver tomorrow as well. Unfortunately, the only contractor lined up for Saturday is me (and a rented lift). I'll probably get a strange look from my wife when she sees all that drywall....

markfh

02-03-05, 11:40 AM

But... after my wife watched me diligently try to teach the contractor to do the job right without desired results SHE told me to fire them and WE would do it ourselves.

Let me tell you she's a real trooper. 5ft, 100lb aint a lot of beef to have when slinging around 5/8" sheetrock but she was better than the contractors.

Like I said before if you have contractors do any work watch them like a hawk. Don't be afraid to correct them. If they get too snippy or won't do the work at the level you want fire them.

Save your blood pressure and your project.

bob md

02-03-05, 11:58 AM

In my case I'm the contractor, she better not fire me!

markfh

02-03-05, 12:23 PM

In our cases Bob the fringe bennis are great...;)

Ted White

02-03-05, 12:28 PM

Mark, I don't understand. Perhaps a diagram is in order?

markfh

02-03-05, 12:32 PM

Excuse me... roflmao

Brian Ravnaas

02-04-05, 11:31 AM

hey good luck with that, bob.

if the group is curious, i will take a moment and expound the nature of Green glue between studs and drywall. In the common 2x4 wall, and in other constructions like the more de-coupled designs bobmd is working on.

backdoor

02-04-05, 08:25 PM

I've taken delivery on 6 tubs of GG... project now delayed... should I be concerned about the shelf life??:confused:

Toeside

02-04-05, 08:53 PM

Originally posted by Brian Ravnaas
hey good luck with that, bob.

if the group is curious, i will take a moment and expound the nature of Green glue between studs and drywall. In the common 2x4 wall, and in other constructions like the more de-coupled designs bobmd is working on.

I'm always curious!

talo

02-04-05, 11:54 PM

With GG on the studs and in between, it seems one should apply GG along the outside edge of the drywall for corners, between panels, the floor
and the ceiling.

Not sure why one would try to decouple physical contact with 1/4 space which seems to defeat the purpose the entire work effort when using GG. Rather than have all that mass sealed tightly, you rely on caulk. Does not make alot of sense to me, especially considering the use of GG would provide some form of mechanical decoupling better than caulk would.

If you have any info on GG/Studs, it would be welcomed. I decided to rip out all of my plaster/lathe so I can start fresh. It is a TERRIBLE mess, so hopefully Im getting something out of this rather than the plaster/gg/5/8 i planned to do.

Originally posted by Brian Ravnaas
hey good luck with that, bob.

if the group is curious, i will take a moment and expound the nature of Green glue between studs and drywall. In the common 2x4 wall, and in other constructions like the more de-coupled designs bobmd is working on.

Toeside

02-05-05, 12:05 AM

Talo, I'm pretty sure plaster/lathe performs better than drywall for sound isolation. I grew up with plaster, and our first house had plaster. Man, was that a quiet house.

Unless you really need to get into the walls, I'd leave the plaster/lathe in place, then add GG and 5/8 to that. That's just my opinion, of course.

talo

02-05-05, 12:20 AM

Part of the issue was the walls were very uneven, which would have caused pockets between the drywall. No insulation in the walls and a few other things got me down that path. Trust me, I did not make the choice lightly and it some ways regret starting it, but the finished product will be better than what was planned before.

Toeside

02-05-05, 12:33 AM

Brian Ravnaas

02-05-05, 07:42 AM

Originally posted by talo
With GG on the studs and in between, it seems one should apply GG along the outside edge of the drywall for corners, between panels, the floor
and the ceiling.

Not sure why one would try to decouple physical contact with 1/4 space which seems to defeat the purpose the entire work effort when using GG. Rather than have all that mass sealed tightly, you rely on caulk. Does not make alot of sense to me, especially considering the use of GG would provide some form of mechanical decoupling better than caulk would.

If you have any info on GG/Studs, it would be welcomed. I decided to rip out all of my plaster/lathe so I can start fresh. It is a TERRIBLE mess, so hopefully Im getting something out of this rather than the plaster/gg/5/8 i planned to do.

hey talo,

taking plaster off your wall doesn't sound like any small undertaking! And i've no doubt that after something like that the best results are in order.

the info on gg/studs is forthcoming, if i don't get to it this morn, i will soon enough. You took down all that plaster, and toeside commented that a place he lived in w/plaster was quiet. plaster is pretty dense, and depending upon how thick it was, it might be fairly massive. My childhood home was one of the first things that spurned an interest in sound isolation. it had stucco - two coats- an ancient coat and a re-application. and when all that mass was removed, the house got louder from things like passing farm equipment and all.

you, though, Talo, are in good shape. you have a chance to build a new wall with insulation and gg sandwich, and i'm sure you'll be happy with the end results. GG isn't really a de-coupling material but rather a damping material. The two are not unrelated, of course, as the damping dissipates energy as it tries to transit from one side of the wall to the other. But GG isn't merely a new form of de-coupling (yawn), but something more important in that it allows the construction of walls with controlled low frequency resonance. ~95% of walls are defined by this low frequency resonance, so that's a good thing.

Truly i can imagine your TERRIBLE mess, and insulation + studs/gg/drywall/gg/studs is a very nice wall. The question of caulk -vs- gg - if you meant using GG as a sealant in lieu of caulk, well... it meets all the requirements, flexible, damped, etc. when we get gg to the market in tubes for the best convenience of you, our customers, we may bring to the market an acoustical sealant as well. The lab has an experimental model now that is ~ as dense as raw concrete and nearly critically damped. might prove useful.

if i/we can be of any service, never hesitate to write.

Brian

Brian Ravnaas

02-05-05, 07:43 AM

Originally posted by Toeside
Talo, I'm pretty sure plaster/lathe performs better than drywall for sound isolation. I grew up with plaster, and our first house had plaster. Man, was that a quiet house.

Unless you really need to get into the walls, I'd leave the plaster/lathe in place, then add GG and 5/8 to that. That's just my opinion, of course.

hey toe, you're observation is a nice one. see the five principles of isolation - mass is one of those. :)

Brian Ravnaas

02-05-05, 07:45 AM

Originally posted by talo
Part of the issue was the walls were very uneven, which would have caused pockets between the drywall. No insulation in the walls and a few other things got me down that path. Trust me, I did not make the choice lightly and it some ways regret starting it, but the finished product will be better than what was planned before.

insulation in your walls, talo, is good. DE correlates the lack of it with in-room acoustical problems, so you're on the right path.

i'm sure that the labor you're facing is immense, and i've no doubt that you didn't take the task lightly!!!!!!!!!!!!! the finished product has great potential, make sure to mind the details - ventilation, the doors (seals on the doors), and all of those.

DE often says the sound is like the water in an aquarium. seal 5 sides perfectly, but if the 6th has a hole, it doesn't matter, the water will get on the floor. So it is with sound, the devil is in the details once the walls reach a certain level of performance.

Brian

Toeside

02-05-05, 08:41 AM

Originally posted by Brian Ravnaas
hey toe, you're observation is a nice one. see the five principles of isolation - mass is one of those. :)

Sorry for going off on a tangent a little here, but a little more info about that old house--built in 1918.

There wasn't an ounce of insulation in that house wen we bought it. The outside walls were about 15" thick--multiple layers of brick with plaster directly on top of that. Talk about mass! Unfortunately as a result, there were only 2 outlets in any exterior wall. Two, total, throughout the entire house. (To put that in perspective, each bedroom had 1 outlet!).

Slightly more on topic: We had beautiful solid wood doors throughout the house, including enormous pocket doors seperating the living room and dining room. This pocket thick! It was essentiall a double wall with approx 2.5 inch air gap in between to create the pocket. So that wall was plaster&lathe/2x4/2.5 in air/2x4/plaster&lathe. Then the pocket doors had to be 7ft tall, and the opening was 6ft wide, I guess. When those 2.5+ inch thick doors were closed, you couldn't hear much through that wall. Definitely conversation was gone. We didn't have a great surround system at that house, so I have no idea how this wall performed on the low end.

Sorry for the rambling. :)

talo

02-05-05, 10:56 AM

The assumption that an old plaster wall may have the properties one would expect may not be entirely accurate. One thing to consider about old plaster is its mechanical stability. In many cases, you may find the plaster composition has devolved over time, like sandy mush on your wall. While at one point it may have had mass, those benefits are not universal over time. If anything you would likely need to dig out areas of failing plaster, wet the area, Durabond90 a base, then skim with join compound. It is a technique that an old Irish plasterer told me to use, so I have done this and will continue to in all other rooms in my 1860s home, but for a media room trying to reduce sound, I didnt think it to be the best use of resources and time.

Toeside

02-05-05, 11:29 AM

talo,

Sounds like a great way to fix the old plaster. And you are right, if your walls aren't solid anymore, the mass is gone.

There's also the problem with plaster keys breaking over time, causing the plaster to sag. I can only imagine this would vibrate pretty seriously under the right conditions.

One way to fix sagging plaster walls/ceilings is to use Plaster Washers, available here: http://www.trusite.com/store_detail.asp?store_id=9473&num=1

When I used them, I wasn't trying to build a sound proof room, and I didn't take into consideration if the plaster would vibrate or anything. My goal was to save my wall. It worked very well! I only had a few placed that needed this treatment, it saved a lot of time in the repair process.

Good luck with your old house. I wish our new, 6-month old house, was as solid as that 1918 house.

talo

02-05-05, 12:02 PM

I would like to invest int he company that makes the plaster washers I have used so many :)
There are a few hardware stores around here (Winchester MA) and Boston that sells them. Usually the guy at my local hardware stocks them for me.

It is a struggle with an old house, finding the balance in preserving the character that drove you to buy an old home while accomodating aspects of a modern lifestyle. One of my objectives for the house has been to preserve all of the old windows. Personally I cannot stand replacements in an old home when most people could restore the ones they have. The windows in the house are over 150 years old with wonderful wavy glass. With some TLC, they will last another 150. I have not found another window sold with that kind of staying power ;)

Brian Ravnaas

02-06-05, 12:04 AM

Originally posted by talo
The assumption that an old plaster wall may have the properties one would expect may not be entirely accurate. One thing to consider about old plaster is its mechanical stability. In many cases, you may find the plaster composition has devolved over time, like sandy mush on your wall. While at one point it may have had mass, those benefits are not universal over time. If anything you would likely need to dig out areas of failing plaster, wet the area, Durabond90 a base, then skim with join compound. It is a technique that an old Irish plasterer told me to use, so I have done this and will continue to in all other rooms in my 1860s home, but for a media room trying to reduce sound, I didnt think it to be the best use of resources and time.

Your comments are very wise, Talo. Very true. Also, things like sealing the wall might be unduly challenging, or perhaps you may not be able to accomplish this to a satisfactory level at all.

Cured plaster is gypsum - the same stuff drywall is made of. Plaster of Paris is actually made by decomposing gypsum - heat drives water out, and forms the reactive plaster of paris.

decomposition can also occur under non-oven conditions given lots of time, and IT DOES, as talo noted. Ancient drywall may meet a similar fate.

Brian Ravnaas

02-06-05, 12:07 AM

well, Talo, i certainly appreciate that you are in the midst of quite an undertaking here!

I would like to extend to all AVS members all support that Audio Alloy can offer, right down to things like how to not get a mess everywhere.

dial the digits, email someone, just abuse the resources Audio Alloy has to offer.

talo

02-06-05, 01:12 AM

Originally posted by Brian Ravnaas
Your comments are very wise, Talo. Very true. Also, things like sealing the wall might be unduly challenging, or perhaps you may not be able to accomplish this to a satisfactory level at all.

Cured plaster is gypsum - the same stuff drywall is made of. Plaster of Paris is actually made by decomposing gypsum - heat drives water out, and forms the reactive plaster of paris.

decomposition can also occur under non-oven conditions given lots of time, and IT DOES, as talo noted. Ancient drywall may meet a similar fate.

Brian,
Prior to 1900 or so, most plaster was lime based. Lime has qualities that are actually better than gypsum, but cure time is VERY long hence the desire to shift to something like gypsum. My understanding is lime based plaster is less fragile and have self healing properties when they get wet. Not talking a soaking, but in cases where water would screw you with drywall or plaster based gypsum, lime should hold up well enough.

Most plaster wall should be about 7/8 thick, which is great. But, in many cases I have seen some crap work and they only did 3/8 to 5/8. Even 150 years ago, contractors were shorting us :)

If anyone cares, there is some great info on how to keep up your old home @ the National Park Service site:
http://www.cr.nps.gov/hps/tps/briefs/brief21.htm

Thanks for all the feedback, this is great. Where would be be with communities like this?

Brian Ravnaas

02-07-05, 04:49 AM

hey, that's news to me about lime plaster. always something new to learn.

i agree that AVS is a unique forum. it seems nicely diverse, and there is always good quality of discussion, minimal negativity. i like it.

Jneel

02-08-05, 11:24 PM

I am sure this has already been covered...but I am sure it would take me way to long to locate it.

When using green glue between two layers of drywall...does the second layer need the typical number of fastners? Is green glue a "glue" as well as a sound control substance?

Thanks,
Jneel

Sandwedg

02-09-05, 12:03 AM

OK... for anyone interested here are some action photos!

Lying in Wait (http://www.h2aproperties.com/XmasCDs/goo1.jpg)

Up Close (http://www.h2aproperties.com/XmasCDs/goo2.jpg)

Starting to Spread (http://www.h2aproperties.com/XmasCDs/goo3.jpg)

Working It! (http://www.h2aproperties.com/XmasCDs/goo4.jpg)

The Lift is Wobbly (http://www.h2aproperties.com/XmasCDs/goo5.jpg)

Fatman513

02-09-05, 06:59 AM

Nice photos! From the pictures (Up Close especially), GG looks almost like green cake icing.

Brian Ravnaas

02-09-05, 09:49 AM

Originally posted by Jneel
I am sure this has already been covered...but I am sure it would take me way to long to locate it.

When using green glue between two layers of drywall...does the second layer need the typical number of fastners? Is green glue a "glue" as well as a sound control substance?

Thanks,
Jneel

hey jneel. I don't think that you can just use Green Glue or any other adhesive and follow building code. Basically, i think building code mandates that you use mechanical fasteners.

Green Glue is designed to work with screws, using screws in the normal fashion won't hurt your wall, and that is what we recommend.

When dry, GG is strong enough to hold drywall, but when wet i'm not sure it's thick enough - we have made no effort to accomodate that type of use due to the code thing.

take care,

Brian

Brian Ravnaas

02-09-05, 09:50 AM

Originally posted by Sandwedg
OK... for anyone interested here are some action photos!

looking good, good luck with the rest of it

Nice photos! From the pictures (Up Close especially), GG looks almost like green cake icing.

i think pistachio pudding maybe...?

Brian Ravnaas

02-11-05, 10:56 AM

ok, i had offered to expound on the behavior of GG between the studs and the first layer of drywall. i'll re-iterate DE's recommendation of putting something in there to prevent the possibility of a wall rattle.

and then onto the technical discussion:

screws are often touted as the great killers of sound isolation, because sound can pass through them. For example, the "short-circuit" problem with resilient channel - a single screw/short circuit can drive STC down to that of the wall without channel, so says common chit-chat on the topic.

and this is all true - screws do transfer energy, and screws can mangle the performance of an RC wall.

But, let's talk about RC for a moment... the screw will effectively "stabilize" the drywall over some region, prevent it from moving forward and back. RC is a spring-mass isolator, and if you constrict the motion of a spring-mass isolator, it won't function anymore. So it should perhaps be said that some vibration may transfer through the screws, but lots through the immobilized channel itself. Channel is, after all, steel. NOTHING transfers vibration from point A to point B as well as steel. except maybe berrylium or solid carbide

and on the common 2x4 wall, the screwing of drywall directly to the stud without a resilient mount (RC, sound clips, etc.) is said to cause the mediocre mid and high frequency performance typically seen in that wall type. but...

but...

but... the majority of the energy transfer isn't via the screws, it is via drywall-to-wood contact where the screws smash the drywall up against the stud.

and something like Green Glue can work towards preventing this, or minimizing it. Even putting a square of wood under each screw so that the conctact area was reduced will improve the performance of a 2x4 wall.

rubber will work better, a viscoelastic material is nicer still. Green in that area will also add a bit (nothing like doing the whole sheets) of damping, which is very good to have, as well. Wood cirlces won't damp anything, of course.

the goal is to prevent rigid contact/smashing of drywall to stud. you should find results with any of these:

1. a good non-drying acoustic caulk ( don't use silicone or latex caulk)
2. rubber strips or pads or pucks
3. even rigid materials IF THEY ARE VERY SMALL to minimize contact area
4. Green

etc.

this phenomenon will be thoroughly explored someday.

hope that helps

Brian

t

Brian Ravnaas

02-11-05, 11:09 AM

some other ideas, outside of green:

get some rubber strips (don't use the cheap gray weatherstrip, it'll probably compress to the point of nil)

if you can find it (not so likely) for a reasonable price, use butyl rubber strips, you can stick them to the studs with double-sided tape. Also, use the softest butyl rubber sealant that you can find.

GRBoomer

02-12-05, 01:18 PM

Just curious, anyone with a Green Glue room have any empirical isolation data on the effectiveness of their room yet? Running sub-woofers or even running power tools?

Although the power tools wouldn't test the low frequency characteristics.

Brian Ravnaas

02-12-05, 01:35 PM

hey boomer,

i know this thread is a monster, and i know that the talk of GG is spread around all over the place here, and many of the people from AVS who've used it aren't finished or aren't regular posters, but you can find discussion of that stuff here and there and everywhere.

i don't have a list of links or anything, but happy hunting!

Brian

jtymann

02-12-05, 11:20 PM

Brian... After reading this entire thread, I still have a few questions...

With my project, I am finishing my basement with one room being a dedicated HT. I'm thinking 2x4-GG-5/8-GG-1/2 everywhere in the HT. If I want to improve sound isolation between 1st floor and the rest of the basement, how effective is 5/8-GG-5/8 in the ceiling only with recessed lighting and then non treated walls/doors for sound to leak. Is this an application that you market your product for currently?

Are caulk tubes available yet? Thought about putting product packaging details or pictures in the website. AFAIK, the only way to get GG is in 5 Gallon buckets. Is that still the case?

Also any recommendations as far as finding a competent drywall contractor that will know how to deal with GG properly and quote the project appropriately to deal with the extra labor time involved. A couple independent contractors I've talked to had never even done double drywall much less apply GG. Specifically any questions to ask them.

jtymann

02-12-05, 11:36 PM

For those who have used GG and also have soffits...

Do you recommend drywalling the entire room with DD and GG and THEN installing the soffits, or just frame out soffits and DD/GG over them.

In the case of buiding soffits over DD/GG, would you do DD/GG or say 1" MDF or MDF-GG-5/8 drywall to minimize resonance in the soffit itself... My soffits are mostly decorational, but cover an air return along most of the right wall.

GRBoomer

02-13-05, 01:18 AM

Originally posted by jtymann

Do you recommend drywalling the entire room with DD and GG and THEN installing the soffits, or just frame out soffits and DD/GG over them.

The generally recommended practice is to build the soffits inside of the Drywall envelope. Then you can run wiring and HVAC through one common point in the drywall and route it throughout the room via the soffits.

In my case, I will have to frame out one soffit and drywall around that because it contains the trunk line for the HVAC. The other soffit will be within the room. The advent of Green Glue will make the isolation of my HVAC trunk line soffit much easier and more isolated with minimal increase in soffit size compared to traditional isolation methods.

Bulldogger

02-13-05, 11:33 AM

Would dry wall with green glue be difficult to remove? I ask because I may consider adding http://www.wiretracks.com/prod-rf.html to my wall at some point so that I can move equipment to a closet in the back of the room and it requires removing a little drywall long the base board. Would it be easier to just add the wiretracks during installation of the second layer drywall? I'd rather do it latter. My current theater has mass loaded vinyl behind the drywall which does a good job but I'd like more.

Brian Ravnaas

02-14-05, 11:53 AM

Originally posted by jtymann
Brian... After reading this entire thread, I still have a few questions...

With my project, I am finishing my basement with one room being a dedicated HT. I'm thinking 2x4-GG-5/8-GG-1/2 everywhere in the HT. If I want to improve sound isolation between 1st floor and the rest of the basement, how effective is 5/8-GG-5/8 in the ceiling only with recessed lighting and then non treated walls/doors for sound to leak. Is this an application that you market your product for currently?

you mean treat the ceiling, but leave the walls/doors of poor-fair performance? in general, GG or not, that will be asking for limited performance. Noise that gets out the door can find it's way somewhere, up the structure via the walls, etc. see what i'm saying?

Are caulk tubes available yet? Thought about putting product packaging details or pictures in the website. AFAIK, the only way to get GG is in 5 Gallon buckets. Is that still the case?

caulk tubes are in the works, but not available at this time. gallons are also available.

[/quote] Also any recommendations as far as finding a competent drywall contractor that will know how to deal with GG properly and quote the project appropriately to deal with the extra labor time involved. A couple independent contractors I've talked to had never even done double drywall much less apply GG. Specifically any questions to ask them. [/QUOTE]

boy, that's not my area, but it is a very good question. double drywall would primarily be related to fire-compliance. an industrial contractor would likely have had to make a "2 hour fire wall", which mandates double drywall.

with respect to utilizing the Green, it is a fairly/very straight-forward process, if you email audio alloy, we'll get you the .pdf file outlining the process of using the stuff.

Brian Ravnaas

02-14-05, 11:55 AM

Originally posted by Bulldogger
Would dry wall with green glue be difficult to remove? I ask because I may consider adding http://www.wiretracks.com/prod-rf.html to my wall at some point so that I can move equipment to a closet in the back of the room and it requires removing a little drywall long the base board. Would it be easier to just add the wiretracks during installation of the second layer drywall? I'd rather do it latter. My current theater has mass loaded vinyl behind the drywall which does a good job but I'd like more.

well, it is hard-to-impossible to score and break Green Glued drywall, sort of like safety glass ,the glue layer holds it together and it doesn't go well. but other than that, i do not know why it would be difficult to remove at a later time - GG'd drywall cuts with saws, etc,. easily.

Brian

strange_brew

02-14-05, 09:41 PM

Brian, I am going to need to frame underneath a Steel Beam with 2x6 framing. (pictures and description posted here: http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=509560)

From reading this thread it seems to me that this may be a very good application from an acoustic standpoint, but I am curious whether GG and tight studs are enough to hold the wall, or if I definitely need to figure out a mechanical connection? Thoughts?

strange_brew

02-14-05, 09:42 PM

BasementBob

02-15-05, 02:44 AM

Brian Ravnaas:

A slightly different question from strange_brew's.
Imagine a steel beam holding up the next floor with a steel lolly column.
Imagine a RSIC supported ceiling under it that spans under the steel beam without touching it.

Questions - from a TL point of view (ignoring if it would fall down):
a) would it make sense to green glue some MDF to the bottom of the steel stud. i.e a bit of CLD to reduce any ringing in the stud (that already has weight on it)
b) would it make sense to sister all the joists in a basement with MDF and green glue. i.e. CLD sound traveling down the wooden 2x8's.
c) if putting a new subfloor the next floor up, would it make sense to green glue the additional layer of wood?

Brian Ravnaas

02-15-05, 05:42 AM

hey fellas, i'll be back to my 'puter thursday.

Toeside

02-15-05, 04:51 PM

Just thought I'd chime in with my green glue experience.

I started my project today, and have the subfloor about 1/2 finished. I'm putting 7/16" OSB on top of my 3/4" plywood subfloor.

I have found, like others, it's easiest to pour this stuff out and spread it, then put your panel in place. I seem to get getting about 52 sq ft of coverage per gallon of Green, vs the 60ft I used to calculate how much I'd need. I guess I'll start spreading it thinner, or start doing a checkerboard pattern with it to stretch out my supply.

So far so good, except I'm about 4 hours behind schedule.

kromkamp

02-15-05, 05:01 PM

I think i'm getting a little less coverage, but part of the problem is that I'm only guessing how 'thin' to spread it.

With the included spreading tool, theres still lots of different thicknesses you can impart depending on how hard you press the tool down.

Any photographs of recommended thickness?

bob md

02-15-05, 05:09 PM

Interesting comment on the coverage. I'm done the 2nd layer of my ceiling - I'd guess I'm getting about 45-50 sq. ft. per gallon. At this rate I'll be buying more (I have 2 pails). I'd guess I'm about 4 days behind schedule! Plus this weekend we are thinking of a NYC trip to see Christo. I'm thinking of asking him to donate his fabric after he's done as diffusers.

Toeside

02-15-05, 07:10 PM

Originally posted by kromkamp
I think i'm getting a little less coverage, but part of the problem is that I'm only guessing how 'thin' to spread it.

With the included spreading tool, theres still lots of different thicknesses you can impart depending on how hard you press the tool down.

Any photographs of recommended thickness?

I've learned most of my home repair skills from my dad--he's a big DIYer.

He taught me that notched trowels should always be perpendicular to what you are applying the material to. It should also be pressed down firmly. This will give you the most uniform coverage.

Brian Ravnaas

02-18-05, 10:45 AM

Originally posted by Toeside
Just thought I'd chime in with my green glue experience.

I started my project today, and have the subfloor about 1/2 finished. I'm putting 7/16" OSB on top of my 3/4" plywood subfloor.

I have found, like others, it's easiest to pour this stuff out and spread it, then put your panel in place. I seem to get getting about 52 sq ft of coverage per gallon of Green, vs the 60ft I used to calculate how much I'd need. I guess I'll start spreading it thinner, or start doing a checkerboard pattern with it to stretch out my supply.

So far so good, except I'm about 4 hours behind schedule.

Originally posted by Kronkamp
I think i'm getting a little less coverage, but part of the problem is that I'm only guessing how 'thin' to spread it.

With the included spreading tool, theres still lots of different thicknesses you can impart depending on how hard you press the tool down.

Any photographs of recommended thickness?

Originally posted by bobmd
[B]Interesting comment on the coverage. I'm done the 2nd layer of my ceiling - I'd guess I'm getting about 45-50 sq. ft. per gallon. At this rate I'll be buying more (I have 2 pails). I'd guess I'm about 4 days behind schedule! Plus this weekend we are thinking of a NYC trip to see Christo. I'm thinking of asking him to donate his fabric after he's done as diffusers.B]

coverage... WRT kronkamps suggestion: the 60sqft/gallon spec was arrived at after a round-robin sort of test with a few operators, instructing them to keep the trowel gently pressed against the drywall so that the drywall is sort of "visible" in the cracks between ridges.

if your coverage goes long, that's a bummer for cost, but good for performance.

what would you fellas think of, presuming that caulk tubes cost could be kept reasonably low, of using a calibrated number of tubes and laying beads?

Brian Ravnaas

02-18-05, 10:50 AM

Originally posted by BasementBob
Brian Ravnaas:

A slightly different question from strange_brew's.
Imagine a steel beam holding up the next floor with a steel lolly column.
Imagine a RSIC supported ceiling under it that spans under the steel beam without touching it.

Questions - from a TL point of view (ignoring if it would fall down):
a) would it make sense to green glue some MDF to the bottom of the steel stud. i.e a bit of CLD to reduce any ringing in the stud (that already has weight on it)
b) would it make sense to sister all the joists in a basement with MDF and green glue. i.e. CLD sound traveling down the wooden 2x8's.
c) if putting a new subfloor the next floor up, would it make sense to green glue the additional layer of wood?

a) you mean GG some MDF to the hat channel of the RSIC clips and then screw drywall onto the MDF strip? no benefit of any significance to doing that rather than screwing the MDF striup to the hat channel. once the tubes are available, you could just lay a bead of GG on the channel and drywall up against that to accomplish the same purpose. don't use GG as a structural adhesive as i don't think that is code-compliant. but you are the code master, Bob, so you already know that. :)

b) yes. whether the gain is worth the cost, i have no test to verify, but it will cause decay of vibration traveling down the joists, and it will eliminate/mitigate any resonant activity involving joist "warble"

c) yes, absolutely. this is my #1 favorite use of GG, and if i was building a house and was told i could put GG in only one place, i'd pick the floors. They are typically very resonant, and you get the boosted benefit of impact noise reduction, both in the room below and in the room above - deader sounding floors. lots of folks like that touch - the dead floor above their theater.

Brian Ravnaas

02-18-05, 11:00 AM

Originally posted by strange_brew
Brian, I am going to need to frame underneath a Steel Beam with 2x6 framing. (pictures and description posted here: http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=509560)

From reading this thread it seems to me that this may be a very good application from an acoustic standpoint, but I am curious whether GG and tight studs are enough to hold the wall, or if I definitely need to figure out a mechanical connection? Thoughts?

i don't think ANY adhesive is code-compliant when used to support a house structure. GG included. My answer WRT the use of GG there would be don't use GG as a replacement for mechanical fasteners where code calls for mechanical fasteners. If code does not call for mechanical fasteners, then i give the concept two thumbs up!

from an acoustic standpoint, it's a great idea.

kromkamp

02-18-05, 02:30 PM

Originally posted by Brian Ravnaas
coverage... WRT kromkamps suggestion: the 60sqft/gallon spec was arrived at after a round-robin sort of test with a few operators, instructing them to keep the trowel gently pressed against the drywall so that the drywall is sort of "visible" in the cracks between ridges.

Thanks Brian. It might be worth throwing a couple photographs on your web site to illustrate both the thickness of the coat and the opacity/spacing of the cracks between ridges,

For example, you are suggesting 'gently pressed' whereas toeside assumed 'firmly pressed'. This does make a difference in my experience thus far.

Andy K.

BasementBob

02-18-05, 10:43 PM

Brian Ravnaas

a) would it make sense to green glue some MDF to the bottom of the steel i-beam. i.e a bit of CLD to reduce any ringing in the i-beam(that already has weight on it)
--------------------------------------------------------------------------------
a) you mean GG some MDF to the hat channel of the RSIC clips and then screw drywall onto the MDF strip? no benefit of any significance to doing that rather than screwing the MDF striup to the hat channel. once the tubes are available, you could just lay a bead of GG on the channel and drywall up against that to accomplish the same purpose. don't use GG as a structural adhesive as i don't think that is code-compliant. but you are the code master, Bob, so you already know that.

Thank's Brian.

That's not what I meant.

Please have a look at the i-beam in this picture
http://www.bobgolds.com/HomeTheatreDesign/OLD/Bob03Room3_close.jpg

One of the things I'm concerned about is sound traveling through that beam into the floor above. It's so close to the ceiling drywall under it that it might be acoustically coupled, even though it's phsically decoupled except for the springs.
So my question is
- does it make sense to try to damp the bottom horizontal, or the vertical part, of the i-beam.
from a TL to the floor above point of view.

Brian Ravnaas

02-20-05, 04:27 PM

hey everybody, i'm very sorry if i have failed to answer anybodies question. life has been wild, and i've been traveling, and more to come. But i'd hate to have someone ask and me fail to do my best to answer, so please PM me or post something like "BRIAN YOU CRACKHEAD, LOOK IN HERE", i'll take no offense.

bob,

i'm going to put your question to one of the folks at my lab who has done the most work with mechanical structures like your beam on monday, and i'll report back then.

the short (but more costly) answer is both, and i'll talk it over and explain what i can tomorrow.

Brian

Brian Ravnaas

02-20-05, 04:28 PM

Originally posted by kromkamp
Thanks Brian. It might be worth throwing a couple photographs on your web site to illustrate both the thickness of the coat and the opacity/spacing of the cracks between ridges,

For example, you are suggesting 'gently pressed' whereas toeside assumed 'firmly pressed'. This does make a difference in my experience thus far.

Andy K.

hey andy K, how's the install coming?

if the trowel "teeth" touch the drywall, thenyou get ~60 sq ft/gallon. if you press too hard you can start digging up the paper a bit.

but pressed to the paper was my point, and the instructions given to the folks in our round-robin

a picture is needed here, n oquestion

Brian

Brian Ravnaas

02-21-05, 03:24 PM

hey again, bob

attached is a pic that outlines the thought on your query. given my choice of one place to put the gg, i'd opt for the bottom, not the side. Given my druthers, i'd damp the whole works, right down to the back of my chair. (j/k)

if the pic is inadequate, please advise

Brian Ravnaas

02-21-05, 03:33 PM

hey, a couple-few weeks to tubes being available is the word :)

should keep the PITA factor right down, and it's my understanding that the per-volume cost will only be a smidge higher.

Toeside

02-21-05, 03:36 PM

Originally posted by Brian Ravnaas
hey, a couple-few weeks to tubes being available is the word :)

should keep the PITA factor right down, and it's my understanding that the per-volume cost will only be a smidge higher.

That's great news! If you need someone to test out the caulk tubes, let me know. You can't let them hit the market untested. ;) j/k (or am I?)

Brian Ravnaas

02-21-05, 03:40 PM

hey toe, this forum was a good part of the impetus for getting disposable tubes, and i think we'll extend AVS folks pricing just above what everyone has been paying for pails gallon-to-gallon, so perhaps future AVSers will buy a case of tubes instead of a pail&trowel. I can appreciate that this would be handy. There is one guy here who does most of the building in the lab, and he loves the trowel, but after taking part in the building of some walls in a test lab recently... well, point taken.

i hope it makes the GG experience a little less "tacky", hee hee

kromkamp

02-21-05, 04:14 PM

Originally posted by Brian Ravnaas
hey andy K, how's the install coming?

if the trowel "teeth" touch the drywall, thenyou get ~60 sq ft/gallon. if you press too hard you can start digging up the paper a bit.

but pressed to the paper was my point, and the instructions given to the folks in our round-robin

a picture is needed here, n oquestion

Brian

Coming along good, Brian, thanks for asking. I just finished this weekend the layer of drywall 'inside the joists' using Green Glue at ~50% coverage. It seems I have a little less than half the pail left on approx. 200sqft coverage so I must have been using a little thicker than anticipated. Based on your description I think I was spreading it just about right. I may have done more than 50% coverage (I used a zig-zag pattern down the drywall strips, tough to estimate coverage)

Man, was that ever a chore to drywall inside the joists! Especially considering its an older house so the joists are not exactly parallel nor are they evenly spaced :) I think the results will be worth it though.

This weekend I'm insulating, next weekend I'll do the 2 1/4" layers of drywall sandwiched with the remaining green glue. (I'll probably need another gallon from you though)

Andy K.

bob md

02-21-05, 04:41 PM

Originally posted by kromkamp

Man, was that ever a chore to drywall inside the joists! Especially considering its an older house so the joists are not exactly parallel nor are they evenly spaced :) I think the results will be worth it though.
Andy K.
Andy - my hat off to you - drywalling inside the joists! I hadn't thought about it and I'm glad I didn't:D. I hope to get my last wall layer up this week.

mbkintner

02-21-05, 05:03 PM

Originally posted by kromkamp
Coming along good, Brian, thanks for asking. I just finished this weekend the layer of drywall 'inside the joists' using Green Glue at ~50% coverage. It seems I have a little less than half the pail left on approx. 200sqft coverage so I must have been using a little thicker than anticipated. Based on your description I think I was spreading it just about right. I may have done more than 50% coverage (I used a zig-zag pattern down the drywall strips, tough to estimate coverage)

Man, was that ever a chore to drywall inside the joists! Especially considering its an older house so the joists are not exactly parallel nor are they evenly spaced :) I think the results will be worth it though.

This weekend I'm insulating, next weekend I'll do the 2 1/4" layers of drywall sandwiched with the remaining green glue. (I'll probably need another gallon from you though)

Andy K.

Andy-

Can you elaborate on this? I'm trying to figure out which of the following you did.....

1. Put a layer of drywall in-between the joists at the top of the joist cavity.
2. Put a layer of drywall at the bottom of the joist cavity flush with the bottom of the joist.
3. Fill the joist cavity with drywall.

kromkamp

02-21-05, 05:21 PM

mbkinter, its #1. I mounted drywall inbetween the joists to the subfloor above. My headroom is so tight in my basement I didnt want to sacrifice even another half-inch. Maybe I'm crazy :)

My ceiling cross section is going to be (from top to bottom): subfloor above/GG/.5"drywall strips/3" Roxul insulation/1" air gap/3" Roxul/GG(on joist edges)/.25"drywall ceiling/GG/.25"drywall ceiling.

BasementBob

02-21-05, 05:28 PM

Brian Ravnaas:

attached is a pic that outlines the thought on your query. given my choice of one place to put the gg, i'd opt for the bottom, not the side. Given my druthers, i'd damp the whole works, right down to the back of my chair. (j/k)if the pic is inadequate, please advise

That's pretty much what I was thinking thanks, although I'd probably move the MDF from the bottom of the bottom, to the top of the bottom.

I take it the implication is a safe one: that GG will stick to painted metal and MDF/wood in a useful way.

mbkintner

02-21-05, 11:44 PM

Originally posted by kromkamp
mbkinter, its #1. I mounted drywall inbetween the joists to the subfloor above. My headroom is so tight in my basement I didnt want to sacrifice even another half-inch. Maybe I'm crazy :)

My ceiling cross section is going to be (from top to bottom): subfloor above/GG/.5"drywall strips/3" Roxul insulation/1" air gap/3" Roxul/GG(on joist edges)/.25"drywall ceiling/GG/.25"drywall ceiling.

1/4" drywall is pretty thin stuff. Aren't you worried about sagging? What's your joist spacing?

kromkamp

02-22-05, 01:39 AM

two layers of 1/4" drywall sandwiched with green glue (and staggered in both directions) should be at least as stiff as a single layer of 1/2" if not stronger to my thinking.

The joists spacing is all over the map, from ~11" to 16" OC. I think it'll be fine.

kromkamp

02-22-05, 01:41 AM

RLM5150

02-22-05, 12:41 PM

I am about ready to do the same thing (GG drywall to subfloor). I just got a bunch of dryall scraps for cheap. Should be ready to order the GG in a week or two.

Can you elaborate on how you did this please? How did you attach it? I have been unsure of the best practice for attaching the drywall to the subfloor. Is the Green Glue enough to keep it attached or did you use stringers to support it?

Thanks,

-Rod M.

markfh

02-22-05, 02:18 PM

You might want to give up another 1/4" and go with at least 1/2 and 1/4".

You might also want to add some joist so that you have even spacing.

I think dual 1/4" is too flexible to be used if you want your ceiling to stay straight.

kromkamp

02-22-05, 02:43 PM

I screwed it into the subfloor above using drywall screws at a minimum course.

The Green Glue will not keep the drywall in place even temporarily. It was a 2-person job, although the strips were not that heavy so it was quite manageable.

Mark, let me consider it some more. I may add some perpendicular joist structs at regular intervals. I just dont necessarily see how a 14" span (at most) of green-glued drywall is going to sag? Maybe I just havent worked with it enough.

It was suggested maybe I use 1/4" plywood for the first layer for a little extra strength, that seems like a decent idea. Not sure how much stiffer that is.

Brian Ravnaas

02-22-05, 10:38 PM

hey everybody, i won't be around for a day or 3

but FWIW: a green glue laminate of 2* 1/2" will be considerably less stiff than a slab of 1"

same for 2* 1/4" -vs- 1/2", etc

kromkamp

02-23-05, 12:46 AM

Well, there you go :)

Brian Ravnaas

02-23-05, 02:23 AM

Originally posted by kromkamp
I screwed it into the subfloor above using drywall screws at a minimum course.

The Green Glue will not keep the drywall in place even temporarily. It was a 2-person job, although the strips were not that heavy so it was quite manageable.

that's true when wet, when dry it will hold sheets easily, but DON'T DO IT, IT WON'T MEET CODE.

mbkintner

02-24-05, 09:51 AM

I've searched the forums (and archived forums) to no avail looking for a thread I remember reading. It discussed recessed lights, the bezels, and mounting depths as they relate to doubled drywall. Can anybody point me in the right direction?

Probably a little off-topic but I figured the GG thread would be my best shot.

Thanks

strange_brew

02-25-05, 07:59 AM

Brian,

Can you comment on the relative difference between doing a ceiling with double drywall (5/8 and 1/2) with GG on the joists and between the drywall sheets, and the same structure but with RSIC clips? I'm trying to conserve as much ceiling height as possible so I'm wondering if RSIC clips are worth the extra time and money? Any thoughts on how much of a difference it would make?

FYI, you can see what I'm trying to achieve in this thread:
http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=512084
outlier2's post is what got me thinking...

Brian Ravnaas

02-26-05, 10:03 AM

Originally posted by Dennis Erskine
The product is worth it even for room within room type of construction.

along those lines, here are some graphs of lab-tests for GG -vs- other tests for double-stud walls (room within a room)

http://audioalloy.com/greenglue2bstudwall.gif

there you have it. It is more satisfying to me than i can possibly express to note that the data below 100hz (the only relevant area of Green performance for this wall type) is nearly identical to measurements taken by me long ago in a very modest (i'll say modest to avoid saying half-cocked jerry-rigged) test rig. Dennis Erskine got a copy of that, and i think at least one AVS member has it as well, although i'm not sure how...

Data from the lab we tested at is compared to other labs full-band data to make a point or two, which i can elaborate on later. Basically, one lab gets lower values in some of the midrange and treble, apparently.

But FWIW, that's as-advertised, and that's the best wall ever tested (that i am aware of), more on that in a later post.

a normal 2x4 wall + green with 5/8" drywall got an STC of 52, which i think is the best ever for that wall type (?) with no decoupling. Remember, that's not moving problems out of harms way, just reducing their magnitude. the opinion of this lab is that fully dried GG walls would yield mid 50's (or a bit better) and represent on heckuva wall.

it's worth mentioning that neither wall was at full performance. The double-stud wall was at about 65%, and the 2x4 wall about 45%. What differences this would have made is not clear, as that double-stud wall was probably just measuring how much noise is coming through the concrete. The 2x4 wall will eventually test mid to high 50's for STC.

here is another pic showing low frequency results (albeit from diff labs) for the best overall LF walls that i can find:

http://audioalloy.com/lowfreqdiffwalls.gif

it's fun to note that only a double-block wall with air space & insulation (many, many times the cost, more space, many times the weight, etc.) has measured better (again, as far as i know).

Brian Ravnaas

02-26-05, 10:13 AM

it's worth mentioning that the cost of testing GG walls is unfortunate (when considering dry time), and we will never run the wealth of tests at 3rd party sites that we ran here via informal methods over the course of it's development. The cost would probably run into mid six figures if not worse. LEt's say you were testing a staggered stud wall, you can just keep lopping on more drywall and test every couple hours. With GG, to do it ideally, every change is every 2 weeks (or worse if humid)

if we are a 50 million dollar company one day, then maybe we'll just rent the NRC's facility for six months for fun. And perhaps we'll release the scads of tests we've run here.

it should be called into question whether the double-stud wall tested above was the limiting factor for transmitted noise or whether the concrete floor/walls and the various air gaps and doors in the facility were. this is called "flanking limit" in TL testing jargon.

So, as i've said before: if you want to REALLY stop alot of sound, build a double-stud wall or room within a room with GG, add a third layer of drywall and GG to one or both sides if you want. it is preferable to use 3 layers of drywall with 50% coverage of GG on each to 2 layers with 100% coverage of GG if you need to keep material costs down.

Brian Ravnaas

02-26-05, 10:13 AM

Originally posted by mbkintner
I've searched the forums (and archived forums) to no avail looking for a thread I remember reading. It discussed recessed lights, the bezels, and mounting depths as they relate to doubled drywall. Can anybody point me in the right direction?

Probably a little off-topic but I figured the GG thread would be my best shot.

Thanks

hey mbk, i don't recall that thread, but i'll keep an eye out for it

Brian Ravnaas

02-26-05, 10:15 AM

Originally posted by strange_brew
Brian,

Can you comment on the relative difference between doing a ceiling with double drywall (5/8 and 1/2) with GG on the joists and between the drywall sheets, and the same structure but with RSIC clips? I'm trying to conserve as much ceiling height as possible so I'm wondering if RSIC clips are worth the extra time and money? Any thoughts on how much of a difference it would make?

FYI, you can see what I'm trying to achieve in this thread:
http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=512084
outlier2's post is what got me thinking...

hey strange, no i can't.

RSIC + ceilings are a match made in heaven. figure you have 2x10's + the ~2" of depth that the RSIC clips add, and you wind up with a REALLY deep air space, which is just great with a de-coupled system.

bobmd has found a means of using RSIC with minimal ceiling height but MAKE SURE THE DRYWALL IS AT LEAST A BIT SPACED FROM THE JOISTS.

i guess the short answer is the obvious answer is the expensive answer is both RSIC + GG

as for which is better if you had to pick just one... probably the RSIC wall with 12" of air space, but i have never tested a GG ceiling.

Toeside

02-26-05, 10:27 AM

Brian...

3 layers on each side? Really?

Everyone I've told about my room/walls have thought I was completely nuts--except one person who now wants me to help him build his recording studio in his basement.

My parents and in-laws, coworkers--they all think I'm crazy. That's with double stud wall, 2 layers of 1/2" and Green.

As crazy as they think I am, every last one of them wants to see/hear the final results.

Brian Ravnaas

02-26-05, 10:28 AM

FWIW, the GG wall got 4 and 5 points higher STC than double stud wall with double 5/8 on both sides and insulation tested at the same lab. It got a higher OITC and every other ranking for walls that i can think of than any wall that i am aware of short of double concrete block with air cavity and insulation.

so i guess if you want to float a concrete bunker on springs inside another concrete bunker, be my guest.

Brian Ravnaas

02-26-05, 10:29 AM

for the record, that wall above was 2 layers per side

3 sides would give just sick performance. but what was tested was 2 layers per side.

Brian Ravnaas

02-26-05, 01:08 PM

one more comment and then i'll shut my pie hole:

a GG wall will be vastly more tolerant to real world installation than will other types of wall. Well, GG and walls with similarly high damping will be.

the reason is that in these lab tests you de-couple everything so perfectly as to get an ideal situation (with the exception of noise coming through the doors and things, which you can clearly see limiting the GG wall at higher frequencies above)...

but in the real world, there will always be some level of coupling (via studs being bolted to the same slab, etc.), and the destruction of energy over distance aspect of damping will then play a paramount role.

wall details were: normal 5/8" drywall. one side of that wall was stored for a couple years at this lab, apparently, one side was new. pink fiberglass insulation, which i installed (something i'm not very happy about, i had never installed insulation in ANYTHING before, i hope i did a decent job), screws 12" OC for both layers and aoustic caulk used everywhere liberally.

have a great day, folks

BasementBob

02-26-05, 05:10 PM

Toeside
3 layers on each side? Really?
Every day I read Paul Woodlock's DIY STUDIO BUILD DIARY (http://forum.studiotips.com/viewtopic.php?t=107), which is about 1200 posts now, and that fellow has seven (7) layers of drywall on the inside leaf, and brick/concrete on the outside leaf of the about 3' thick walls. His room-in-a-room is on a properly floated concrete slab.

This was how people used to deal with LF resonance in the old days. When was that. Last week?

BasementBob

02-26-05, 05:23 PM

Brian Ravnaas:

Re the top right hand HF part of this diagram from this post (http://www.avsforum.com/avs-vb/showthread.php?postid=5242358#post5242358) that reads "this high frequency roll off".
http://audioalloy.com/greenglue2bstudwall.gif

the reason is that in these lab tests you de-couple everything so perfectly as to get an ideal situation (with the exception of noise coming through the doors and things, which you can clearly see limiting the GG wall at higher frequencies above)...

I'm confused by that. Usually just about everything is good at TL of HF, including doors and things. When I saw the diagram I thought it was a test equipment roll off error. Are you saying it was something about the room that caused this HF dip? That it's not a GG induced coincidence dip of some sort ?

The enormous challenge of getting Green Glue tested is dry time... the double-stud wall above got 7 days of dry time and after disassembly, ... The green glue between studs was still basically wet, and ... exhibited damping of about 65% what would be expected for the fully dried panel.
Every once in a long while here at AVS I read about someone who's done an entire Home Theatre from an unfinished basement to completely finished including acoustical treatments in less than a month.
I guess this means you'll never
a) go on Extreme Makeover Home Edition, where they build a new house in 7 days
b) on the evening of day 6 they drywall with GG
c) on the morning of day 7 have Terry Montlick come in and do a complete room analysis and add acoustic treatment.

Brian Ravnaas

02-26-05, 05:33 PM

hey bob, its probably related to the background noise thing, i just included it to outline that things don't always measure as they are supposed to.

read up on ASTM E-90... there is no phenomenon at all other than poor seal that could cause high frequency TL to get worse like that. As far as i know the wall was reasonably well sealed.

as for the other plots, i simply intended to outline that diff labs have diff results and diff flanking limits.

don't worry about the high freq TL thing, it's an anomaly probably relating to the extremely high absorption in the "recieve" room at those frequencies (due to air). you compensate for absorption when testing things... so in this case the noise levels were a dB or so above background noise (but that's background noise earlier in the test process, so it might have changed).

they are meaningless and i just included them to humor tech junkies.

as for the 7th day, and dry time: nope. GG used to dry faster, but based on customer feedback, we slowed that guy down. now we suck, and terry would scoff at us in the above scenario :(

Brian Ravnaas

02-26-05, 05:34 PM

Originally posted by BasementBob
Toeside

Every day I read Paul Woodlock's DIY STUDIO BUILD DIARY (http://forum.studiotips.com/viewtopic.php?t=107), which is about 1200 posts now, and that fellow has seven (7) layers of drywall on the inside leaf, and brick/concrete on the outside leaf of the about 3' thick walls. His room-in-a-room is on a properly floated concrete slab.

This was how people used to deal with LF resonance in the old days. When was that. Last week?

there you go, do that. that'll outperform a GG double-stud wall with 2 layers of drywall on both sides... i admire that dude.

mikemav

02-28-05, 10:29 PM

On the DIY Net shows on home theater building, they suggested spacing the drywall at the room corners (wall to wall, wall to ceiling, etc..) slightly apart and then sealing w/ acoustic caulk, rather then butting the drywall sheets right up against each other. This was in a room w/ RSIC walls to hang the drywall on hat channel and a Kinetics RIM floating floor. I will probably not scarifice the height needed for the floating floor, nor the width for the channel on the walls, since I read such good things about GG. When using GG in a stud+ GG+ 5/8"+ GG + 5/8" or 1/2" sandwich, should the drywall be tight in the corners or gapped like in that show? If gaps are left, should they be filled in w/ GG from tube (when available) or acoustic caulk?

Finally- regarding the comments earlier on drywalling in between the joists w/ GG to the subfloor above- would this yield big improvements? Like many here I'm sure, I am torn between using GG an double drywall direct to the GG buttered joists, or RSIC clips for the ceiling. I'd like to keep the ceiling height and keep things simpler for the contractor, but this compromise of treating some of the subfloor above is intriguing. What if it was even just partial coverage? Would partial drywall+ GG inside the joists using left over scraps from the side walls be better that nothing at all? Thinking of a patchwork of left over drywall cut into 16" wide strips & GG+ screwed into the subfloor. If there was no need to be precise or demand total coverage (thinking any is better than none), it might not be a bad way to convince myself to drop the ceiling clips. What do you think? Worth theeffort even if I can't (don't) get the total exposed subfloor covered?

Also, how does all this impact code for people? I envision my inspector having a hard time with the concept of room within a room or even ceiling clips, with all the rules above firestopping an draft stopping. A more conventional looking ceiling & ceiling/ wall connection in lieu of clips seems like an easier time.

nelson4u

02-28-05, 11:41 PM

Originally posted by mikemav

Finally- regarding the comments earlier on drywalling in between the joists w/ GG to the subfloor above- would this yield big improvements? Like many here I'm sure, I am torn between using GG an double drywall direct to the GG buttered joists, or RSIC clips for the ceiling. I'd like to keep the ceiling height and keep things simpler for the contractor, but this compromise of treating some of the subfloor above is intriguing. What if it was even just partial coverage? Would partial drywall+ GG inside the joists using left over scraps from the side walls be better that nothing at all? Thinking of a patchwork of left over drywall cut into 16" wide strips & GG+ screwed into the subfloor. If there was no need to be precise or demand total coverage (thinking any is better than none), it might not be a bad way to convince myself to drop the ceiling clips. What do you think? Worth theeffort even if I can't (don't) get the total exposed subfloor covered?

I am wondering this same question.

I am trying to keep the sound from traveling up to the bedrooms above the theater, but from what I have been reading here the low frequency bass is nearly impossible to stop.

I am wondering whether it is necessary to use the RSIC clips and channel on ceiling when using two 5/8" drywall sheets and green glue.

Does anyone have any comparison of a ceiling using RSIC clips , channel and 2 sheets drywall with Green Glue versus just 2 sheets of drywall with Green Glue ?

Would the extra expense and work of using RSIC clips and channel be worth it as far as suppressing the low frequencies because it sounds like the Green Glue sandwhich will take care of all of the sound except basically below 100 hz?

bpape

03-01-05, 08:32 AM

You'll never totally stop it with any reasonable kind of construction. All you can do is tame it.

I think Brian R. has some data for GG walls with and withouth the RSIC clips

Frank D

03-01-05, 09:52 AM

"I think Brian R. has some data for GG walls with and withouth the RSIC clips"

It would be very interesting to see that.

Brian Ravnaas

03-01-05, 11:04 AM

Originally posted by bpape
You'll never totally stop it with any reasonable kind of construction. All you can do is tame it.

I think Brian R. has some data for GG walls with and withouth the RSIC clips

actually, i don't. of all the configurations we have ever tested, GG+RSIC is not among them. GG + MLV either..., another thing we have gotten alot of questions about. And, for better or for worse, since the product launch our wall testing has been slowed considerably.

We have a reverb room in which the walls are staggered studs on 2x8 plates w/multiple gg/5/8" layers, and the ceiling is RSIC clips + gg/layers. I've never tested the ceiling on that assembly, although i suppose someone could crawl up there with an intensity probe and get some numbers. but... the other side of that ceiling is 4 layers of MDF/gg, so the #'s would be sickly high and not really representative of normal use.

the GG + RSIC combination is not so thoroughly explored here in our labs. It was on the to-do list for 3rd party testing, but the reality of the cost of such tests with GG has forced us lower the degree of ambitiousness we have for those tests.

Some aspects of the GG -vs- RSIC can be divined without a test, based upon the general principles of such constructions and based on existing tests. In the data that Pac has for RSIC clips, generally the walls become very good for home theater purposes when you have 2+2 layers of drywall or higher, and are generally not so good with less mass.

that's not a knock on RSIC clips. RSIC clips rule. other forms of de-coupling like undamped RC or steel studs don't make anything special with even 4 layers... RSIC clips are always going to be slave to the spring resonance, but they seem to allow the decoupling point to drop more with additional mass than other schemes.

lemme think this over for a few minutes and reply to this thread again.

CoolCanuck

03-01-05, 12:17 PM

Forgive me if this has been asked already, has anyone done a GG sandwich on an existing wall that didn't contain insulation?

So, for example it would be: ([hollow wall / stud + 5/8" + GG + 1/2")

Just trying to figure out if I'll get an acceptable level of isolation by doing a sandwich when the walls are hollow. I'd rather not have to tear down the existing wall and fill with insulation if the GG sandwich will suffice.

Thanks,
Jason

Toeside

03-01-05, 01:43 PM

Originally posted by CoolCanuck
Forgive me if this has been asked already, has anyone done a GG sandwich on an existing wall that didn't contain insulation?

So, for example it would be: ([hollow wall / stud + 5/8" + GG + 1/2")

Just trying to figure out if I'll get an acceptable level of isolation by doing a sandwich when the walls are hollow. I'd rather not have to tear down the existing wall and fill with insulation if the GG sandwich will suffice.

Thanks,
Jason

Would you consider cutting some holes in your existing wall and pumping in cellulose insulation? I think it'd be worth the work.

CoolCanuck

03-01-05, 02:03 PM

Toeside, I hadn't thought of that approach...I'd certainly be willing to do that since the additional layer of drywall and GG would cover up any access holes. What are the cons associated with pumping in cellulose insulation?

Toeside

03-01-05, 02:11 PM

Originally posted by CoolCanuck
Toeside, I hadn't thought of that approach...I'd certainly be willing to do that since the additional layer of drywall and GG would cover up any access holes. What are the cons associated with pumping in cellulose insulation?

I think veritcal applications (in walls) requires an adhesive to deal with settling issues. I don't have any experience with that, but you can probably get info at www.cocooninsulation.com.

As long as the walls are interior, you don't need a vapor barrier. Exterior walls need one, but those should already be insulated if that was the case.

Toeside

03-01-05, 02:29 PM

Originally posted by Toeside
I think veritcal applications (in walls) requires an adhesive to deal with settling issues. I don't have any experience with that, but you can probably get info at www.cocooninsulation.com.

As long as the walls are interior, you don't need a vapor barrier. Exterior walls need one, but those should already be insulated if that was the case.

Apparently, no adhesive is required.

See retrofit instructions here:
Retrofit Cocoon installation (http://www.cocooninsulation.com/retrofittingsidewalls.asp?Type=CR)

Jedi

03-01-05, 03:08 PM

...has anyone experimented applying green glue to walls and ceilings with a compressed air spatter gun, like is used to shoot splotches of joint compound onto drywall for texturing purposes?

Jedi

03-02-05, 12:01 AM

....more on the idea of using an air texture gun to apply green glue over large wall and ceiling surface areas. An air texture gun such as this pressurized model may do the trick: http://www.macezspray.com/index.htm Some manufactures warn not to spray materials containing 1,1,1 trichlorethane or any chlorinated product or mixtures containing chlorinated solvents, as these solvents may react with the aluminum equipment resulting in explosive gases. Does green glue contain chlorinated solvents or materials??

Toeside

03-02-05, 10:26 AM

As an alternative to Green Glue in caulk tubes, what do you guys think of using something like a mortar bag (http://www.acehardwareoutlet.com/productaddonsdetails.asp?id=2108645) to apply beads of Green?

Brian Ravnaas

03-02-05, 11:18 AM

Originally posted by Toeside
As an alternative to Green Glue in caulk tubes, what do you guys think of using something like a mortar bag (http://www.acehardwareoutlet.com/productaddonsdetails.asp?id=2108645) to apply beads of Green?

cool!

da tubes aren't so far out now

we are considering taking Green Glue technology and converting it into an acoustic sealant. the prototype material has greater density than concrete when dried and is alot more flexible than other waterborne sealants we've seen. self-healing if ripped and re-compressed as well.

but... it's not formally a go-forward

also, we may offer a product specifically designed for the stud-application in the tubes, as we've taken a couple of looks at that recently.

finally, and alternately, we may release self-adhesive strips of a non-GG but viscoelastic material for stud edges. all depends on the final cost/benefit analysis...

Brian Ravnaas

03-02-05, 11:23 AM

Originally posted by Jedi
....more on the idea of using an air texture gun to apply green glue over large wall and ceiling surface areas. An air texture gun such as this pressurized model may do the trick: http://www.macezspray.com/index.htm Some manufactures warn not to spray materials containing 1,1,1 trichlorethane or any chlorinated product or mixtures containing chlorinated solvents, as these solvents may react with the aluminum equipment resulting in explosive gases. Does green glue contain chlorinated solvents or materials??

looks like a neat concept, there is a large-scale job that is trying something like that, but i haven't seen it.

no chlorinated solvents or anything, no. there is a small amount of ammonia in the material, same stuff is in all latex paints (ammonia or something similar).

aluminum reacts with water to liberate hydrogen gas. can be a real problem when making silver-colored paints in water, companies like Eckart do alot of work (and make alot of money) on that problem...

it wouldn't be an issue in this case. those tiny little aluminum flakes (that's what silver pigment is) have ALOT of surface area.

Brian Ravnaas

03-02-05, 11:25 AM

Originally posted by CoolCanuck
Forgive me if this has been asked already, has anyone done a GG sandwich on an existing wall that didn't contain insulation?

So, for example it would be: ([hollow wall / stud + 5/8" + GG + 1/2")

Just trying to figure out if I'll get an acceptable level of isolation by doing a sandwich when the walls are hollow. I'd rather not have to tear down the existing wall and fill with insulation if the GG sandwich will suffice.

Thanks,
Jason

hey jason, sounds like you gents talked this over pretty thoroughly...

a GG 2x4 wall is alot more tolerant to no insulation than, say, an RC wall

Brian Ravnaas

03-02-05, 11:31 AM

Originally posted by mikemav
On the DIY Net shows on home theater building, they suggested spacing the drywall at the room corners (wall to wall, wall to ceiling, etc..) slightly apart and then sealing w/ acoustic caulk, rather then butting the drywall sheets right up against each other. This was in a room w/ RSIC walls to hang the drywall on hat channel and a Kinetics RIM floating floor. I will probably not scarifice the height needed for the floating floor, nor the width for the channel on the walls, since I read such good things about GG. When using GG in a stud+ GG+ 5/8"+ GG + 5/8" or 1/2" sandwich, should the drywall be tight in the corners or gapped like in that show? If gaps are left, should they be filled in w/ GG from tube (when available) or acoustic caulk?

i recommend (assuming new framework) putting a bead ofa coustical sealant under/over/besdie each sheet of drywall as you work across the wall. Lay a bead, set the drywall on it/into it. Just make sure you don't get sealant to keep the two layers of drywall from smashing up against each other. With GG this is doubly important, but can cause problems even without it as well.

Finally- regarding the comments earlier on drywalling in between the joists w/ GG to the subfloor above- would this yield big improvements? Like many here I'm sure, I am torn between using GG an double drywall direct to the GG buttered joists, or RSIC clips for the ceiling. I'd like to keep the ceiling height and keep things simpler for the contractor, but this compromise of treating some of the subfloor above is intriguing. What if it was even just partial coverage? Would partial drywall+ GG inside the joists using left over scraps from the side walls be better that nothing at all? Thinking of a patchwork of left over drywall cut into 16" wide strips & GG+ screwed into the subfloor. If there was no need to be precise or demand total coverage (thinking any is better than none), it might not be a bad way to convince myself to drop the ceiling clips. What do you think? Worth theeffort even if I can't (don't) get the total exposed subfloor covered?

i know some folks like Kronkamp have done the between-joist modification. we have not tried that in our labs, but GG on floors is very, very neat. footfall noise (in room below and room above) and airborne sound gains are nifty...

Also, how does all this impact code for people? I envision my inspector having a hard time with the concept of room within a room or even ceiling clips, with all the rules above firestopping an draft stopping. A more conventional looking ceiling & ceiling/ wall connection in lieu of clips seems like an easier time.

well, i think RSIC clips have had alot of fire tests done, you could write to ask them.

GG has the relevant tests done to show that it does not reduce the fire rating of walls (it got ~3* better score than necessary to meet that guideline). we don't have any of this stuff online, but will make it avialable to your inspector if needed i'm sure.

Toeside

03-02-05, 11:39 AM

Also, how does all this impact code for people? I envision my inspector having a hard time with the concept of room within a room or even ceiling clips, with all the rules above firestopping an draft stopping. A more conventional looking ceiling & ceiling/ wall connection in lieu of clips seems like an easier time.

One easy way to deal with firestopping/draftstopping is to insulate the entire area with Mineral wool. It's more expensive than fiberglass, but it's a fireblocking material (at least here it is a code-compliant fireblock).

I'm using it to "close" my 1" gap between my double wall. I have RSIC-DC04 decoupling clips "tying" the walls together, and there was NO WAY I was going to use 2-by lumber to close up this gap and couple the wall back together. Mineral wool stuffed into this gap will pass my inspection.

Brian Ravnaas

03-02-05, 11:42 AM

Originally posted by nelson4u
I am wondering this same question.

I am trying to keep the sound from traveling up to the bedrooms above the theater, but from what I have been reading here the low frequency bass is nearly impossible to stop.

I am wondering whether it is necessary to use the RSIC clips and channel on ceiling when using two 5/8" drywall sheets and green glue.

Does anyone have any comparison of a ceiling using RSIC clips , channel and 2 sheets drywall with Green Glue versus just 2 sheets of drywall with Green Glue ?

Would the extra expense and work of using RSIC clips and channel be worth it as far as suppressing the low frequencies because it sounds like the Green Glue sandwhich will take care of all of the sound except basically below 100 hz?

ok. this RSIC -v- Green question i just don't have the answers for. Generally, in the tests pac has, RSIC walls are good once you have 2 layers of drywall on each side, notably better than tests for RC. however, at less loading, that doesn't seem to hold. why?... conjecting as to why gets into alot of jabber.

For low frequency noise of <maybe 60-80hz, performance more or less boils down to mass minus resonance. above maybe 60-80hz (REALLY depending upon the construction) decoupling can benefit you. it's safe to say that above 100hz decoupling can benefit you.

In the big study on floors in CAnada, IR-811, it looks like above 80hz RC improves performance relative to just screwing drywall onto the joists. below 60hz or so it'll make it wosre, that's just the nature of the beast. on walls, with a less-deep air space, RC generally boosted performance above 100hz.

RSIC is the same beast, but maybe better, and likely to have a lower cutoff.

i am just so loathe to answer questions when i don't know.

we have more lab time budgeted in the near future, but i don't think I would use any of it to copmare branded commercial products unless another company shot such a bullet at us, as i don't think that's very scrupulous.

FWIW, bobmd has posted about a means of using RSIC clips w/o ceiling height loss.

mbkintner

03-02-05, 12:09 PM

Originally posted by Brian Ravnaas

also, we may offer a product specifically designed for the stud-application in the tubes, as we've taken a couple of looks at that recently.

Brian -

What would be different about this product versus applying GG directly to the studs from a bucket or a tube. Obviously if you're looking into a product specifically for studs it wouldn't be just the application method that's different. What would be better about this product and why?

Mike

Brian Ravnaas

03-02-05, 12:11 PM

Originally posted by mbkintner
Brian -

What would be different about this product versus applying GG directly to the studs from a bucket or a tube. Obviously if you're looking into a product specifically for studs it wouldn't be just the application method that's different. What would be better about this product and why?

Mike

probably little, and such a product would only be released if it proves to be that we can meaningfully improve performance by offering the second item. see?

on a stagg or double stud wall, there would never be something we recommended more, just for contact-reduction on a single wood stud wall.

it's not a quantum thing, just something that's under review. but the lab is so far behind now on a few projects (like stages), that i'm just gonna snap (j/k). it wouldn't be more expesnive in any case.

Jedi

03-02-05, 01:14 PM

....I'm not sure GG applied to the studs prior to drywall would perform as well as a heavy bead laid from a $2 tube of caulk/sealant.

mikemav

03-02-05, 01:16 PM

Originally posted by Brian Ravnaas
i recommend (assuming new framework) putting a bead ofa coustical sealant under/over/besdie each sheet of drywall as you work across the wall. Lay a bead, set the drywall on it/into it. Just make sure you don't get sealant to keep the two layers of drywall from smashing up against each other. With GG this is doubly important, but can cause problems even without it as well.

Brian-
Thanks for the response. Just so I am crystal clear, you are saying to NOT have a gap between the drywall in corners? I understand the desire to caulk over the seam if they are butted together, but that DIY show made a point to keep the corners separate so each wall could move independently. They left about a 1/4" gap between the panels on the side wall where they joined the panels on the ceiling or the other wall. The acoustic caulk was supposed to cover up this gap and seal the room while still allowing the walls to move. Did not make much sense to me, and now it seems you are confirming that the corners should be tight to each other then sealed over for good measure, right?

Regarding the in-between joists to the subfloor question, if it was your house, and you had a bunch of drywall scraps left over, would you think it would be of some substantial benefit to take those scraps, slap GG on them, and put them up on the underside of the subfloor above, even if you are not precise enough or have enough drywall to totally cover the subfloor between the joists? In other words, will using what I have left over there gaining me anything worthwhile, even if it is patchwork?

Brian Ravnaas

03-02-05, 05:53 PM

Originally posted by mikemav
Brian-
Thanks for the response. Just so I am crystal clear, you are saying to NOT have a gap between the drywall in corners? I understand the desire to caulk over the seam if they are butted together, but that DIY show made a point to keep the corners separate so each wall could move independently. They left about a 1/4" gap between the panels on the side wall where they joined the panels on the ceiling or the other wall. The acoustic caulk was supposed to cover up this gap and seal the room while still allowing the walls to move. Did not make much sense to me, and now it seems you are confirming that the corners should be tight to each other then sealed over for good measure, right?

1/4" gap isn't necessary, but it's helpful to leave a small gap to ensure that a substantial and continuous bead of caulk can be put in place. RSIC walls, like all clip/channel walls, are sensitive to mechanical connections of any kind, and that may well play a role in their design choice.

Regarding the in-between joists to the subfloor question, if it was your house, and you had a bunch of drywall scraps left over, would you think it would be of some substantial benefit to take those scraps, slap GG on them, and put them up on the underside of the subfloor above, even if you are not precise enough or have enough drywall to totally cover the subfloor between the joists? In other words, will using what I have left over there gaining me anything worthwhile, even if it is patchwork?

yes, i would. I'd probably lay a new layer of sub-floor and GG the whole works. Actually, i did.

Floors are resonant, and damping them can do alot.

Dennis Erskine

03-02-05, 08:08 PM

Corners should be tight. To get enough caulk in place install the ceiling drywall first. Run a heavy bead of caulk on the drywall at the corner. Run a heavy bead of caulk on the top edge of the wall drywall. Install the wall drywall by pressing the wall sheet upward tightly so the two beads come together. Where the caulk squirts out, wipe off. Do the same on the second layer.

Brian Ravnaas

04-17-05, 01:40 PM

hey folks, was gone last week running some tests on GG walls & various other things, and i thought you might like a peek at the effect of GG on a normal 2x4 wall - the wall that many of you are utilizing

here you go

http://audioalloy.com/ggand2x4wall.gif

that's a 24" OC wall with 3.5" of mineral fiber and 5/8" drywall on each side compared to the same wall with 5/8 gg 5/8 on one side and half/gg/half on the other side.

we had intended to test a wide variety of walls, but the number of tests collected turned out to be alot lower than expected

the effect of damping on frequencies not involving the two famous resonances (that big spike at 100hz in the undamped wall and the big coincidence dip at ~2500hz) is obvious, and there is a great lesson to be learned there for anyone interested in wall mechanics

in any case, i guess that (like the double stud wall) is basically spot-on with what we guesstimated from tests in our own (far from certified) labs. http://www.freewebdesign.be/smileys/images/party/party-smiley-048.gif

Brian Ravnaas

04-17-05, 01:53 PM

ok, the GG wall had R13 fiberglass of the boring yellow variety (i think that's johns mansville?), the other wall had the mineral fiber

the STC of that wall was 56, OITC 39, music & theater reduction 37

best-ever on all marks (to the best of my knowledge) for a single stud wall of 3.5" depth, or for a direct-screwed (non-decoupled) wall of any depth

Terry Montlick

04-17-05, 02:09 PM

Originally posted by Brian Ravnaas

that's a 24" OC wall with 3.5" of mineral fiber and 5/8" drywall on each side compared to the same wall with 5/8 gg 5/8 on one side and half/gg/half on the other side.

I must be really dense today, Brian, but I'm not fully understanding this. You compared the following two walls in the graph:

5/8" drywall - 3.5" insulation - 5/8" drywall
5/8" drywall - gg - 5/8" drywall - 3.5" insulation - 1/2" drywall - gg - 1/2" drywall

Shouldn't the "control" (non-gg) wall be:

5/8" drywall - 5/8" drywall - 3.5" insulation - 1/2" drywall - 1/2" drywall
?

Not meant as a criticism. I know these tests are really hard to do and expensive to boot, and we all appreciate your efforts to get hard data.

- Terry

Brian Ravnaas

04-17-05, 02:17 PM

hey terry my good man;) , nice to see you around this morn!

i explained the limited tests that were collected above, circumstance cut the total number of tests down to a handful from a couple of dozen planned. best laid plans of mice and men

so you got the one Green Glue 2x4 wall tested -vs- the best applicable non-gg wall tested. well, i have normal drywall with GG on only one side, i'll post that later, that's a good idea

and that's all there is to show. the effect of adding a second layer of drywall to an existing 2x4 wall is well documented over history, and as i'm sure you know it's not that great.

next round of wall tests will (hopefully) allow the full set to be completed.

take it easy

Terry Montlick

04-17-05, 02:29 PM

Originally posted by Brian Ravnaas
hey terry my recent antagonist ;) , nice to see you around this morn!

No really, I'm just trying to make sure I understand all the data you are posting. I sincerely do appreciate the testing you are doing. Any questions or misunderstandings are due to my own ignorance. Absolutely no antagonism is meant on my part. I think that you and your company are doing a great job!

Best regards,
Terry

Brian Ravnaas

04-17-05, 02:32 PM

i was 1000% joking, terry, i always dig your posts

drat my occasional forgetting that posts don't have inflection

B

Brian Ravnaas

04-26-05, 02:54 PM

hey, some recent work here has demonstrated that the use of simple furring strips can tack a few more dB onto the kind of sound isolation score that i talked about here:

http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=452667

recently.

use them as this:

apply them perpendicular to the existing joists/studs

use them at a spacing not the same as the studs/joists. for 16" OC, use 24" OC, for 24" OC, use 16" OC

make sure that your use is in compliance with normal good building practice and local code, however it applies.

provided that your local code does not banish this, it's advantageous to screw the furring strips to the joists/studs, and then screw the drywall into the furring in between the joists/studs.

this simple and basically free step makes things like very close joist spacing a non-factor, and i recommend it.

using damped furring strips (wood/gg/wood) is a peach.

hope that's useful. did i make sense or do i need a picture?

Bako-Dan

05-31-05, 08:36 PM

bob md

05-31-05, 10:58 PM

We'll I'm no expert, but I'd guess that your approach would be very helpful. I think Brian has stated that he was of the opinion that GG on a floor was one of its best applications. I would have loved to be able to do what you are doing - rip up the floor over my HT. In my case that was out of the question so I use GG between layers of drywall in the ceiling. I just started using the HT this past week - GG (plus all the other things I did) worked very well. I had the neighborhood boys over last night for my first HD TV sports experience (Spurs vs. Suns) - we weren't cranking the volume but it was plenty loud. My wife came home & spent a half an hour on the main floor (HT is in the basement) & didn't know we were down there - she was quite surprised when she stuck her head in. This was great news, my main concern was keeping sound out of the rest of the house.

Now I haven't finished all the doors so there's still some significant sound leakage, but overall I'm quite happy. I think that what you'll find (if you use GG between layers) is a significant reduction in sound leakage into the room (assuming there aren't other major pathways, such as untreated vents, etc.). With carpet, I think the worse you'll hear is the slight sound of footfalls. But with carpet, pad, subfloor, GG, plywood & insulation, you may not hear much of anything.

Bako-Dan

06-01-05, 10:39 AM

Thanks for the response Bob! I really need to make sure that the $500 or so that I spend on GG is going to make a significant difference. From everything I've read, I think it will, but it's sure nice to hear from experts and real world users like yourself to make sure I'm not blowing my father-in-law's money.

Dan

Brian Ravnaas

06-01-05, 11:46 AM

I've read all I can stand of this thread and the related threads - I just need to get a quick clarification.

I'm helping my father-in-law remodel a house he recently purchased. I'm installing a simple HT installation in the living room on the first floor. I'm using in-ceiling speakers for the surround speakers (7.1 channel installation.) Directly over the living room is the master bedroom. The floor of the master bedroom is constructed of 3/4" T&G plywood over 2X12 joists spaced 16" OC. We've cut sections of the master bedroom subfloor out in order to route new electrical and A/V cabling. As such, my plan for sound isolation is to fill the joist cavities with blown fiberglass insulation, close up the subfloor, spread a 100% layer of Green Glue, and add a layer of 3/8" plywood. The room will also receive a thick pad and carpet.

Will this approach be effective for isolating the sound from the HT installation below? I know it would be better if I could Green Glue the living room ceiling and add a second layer of 1/2" drywall, but that is not an option.

Thanks for your help/comments/opinions.

Dan

i do not blame you for growing weary of all the talk on the forum. although an immense wealth of info can be found here, it's voluminous to say the least. indeed, i often wish i could condense many of my posts into one... more to the point and direct offering. each discussion is indeed enjoyable, productive, and fun, but in the end for people passing by the scattering of all the thoughts is probably less helpful.

your plan sounds good. of course no sound barrier is perfect, and modifying the ceiling would help (with GG or RSIC clips, many options), but all situations wind up being a compromise of some type, save 1% of 1%, and the plan you outline should be worth the time/trouble.

if there is no reason for 3/8" plywood, utilizing 1/2" would not hurt.

Bako-Dan

06-01-05, 12:07 PM

your plan sounds good. of course no sound barrier is perfect, and modifying the ceiling would help (with GG or RSIC clips, many options), but all situations wind up being a compromise of some type, save 1% of 1%, and the plan you outline should be worth the time/trouble.

if there is no reason for 3/8" plywood, utilizing 1/2" would not hurt.Thanks for responding Brian! I figured the added mass of the 1/2" plywood would help a little bit (I also read your analogy of tin foil sandwiching GG against a concrete wall, and the lack of shear ability there, in one of your informational threads.) My Father-in-law wants to use 1/4" ply, but I think I can get him to accept the added floor height.

Time to order up some Green Glue!

Dan

usualsuspects

06-01-05, 06:33 PM

I am planning my HT (unfinished basement) and have decided to use GG on the walls and ceiling. My current plan calls for room within a room style construction and I am considering building a ceiling that rests on the new walls and is not tied to the floor above. In this thread nobody has mentioned this particular method – others have talked about using RSIC or just GG to floor joists above, but not a ceiling that rests on the studs, and I am wondering if I am on the wrong track on that? I have a fairly major issue to resolve – namely a steel I-Beam in the middle of the space – still haven’t figured out how to deal with that – but Dennis and others had some good advice, but it will not be fun to deal with.

The basement is a walkout on a sloped lot and one side the room is not all concrete – the wall starts off floor to ceiling concrete – but as you move toward the rear of the room – the wall has “stair steps” – concrete below and sheeting above. My plan is to build a stud wall 1” out from the concrete/sheeting wall – should I do something about the sheeting? GG some drywall or other material onto the sheeting?

jerrodshook

06-02-05, 08:29 AM

I considered building a new ceiling, but my room is over 14' wide and that required 2x8's (I think) for joists to support themselves and 2 layers of drywall. It's a lot of lost ceiling height in my opinion.

The RSIC clips are only 1 5/8" so you don't lose much height, and according to everyone they work very well. I just only wish I was to that point already...

Brian Ravnaas

06-02-05, 10:32 AM

hi fellas,

the best room you could build would be seperate ceiling joists.

however, i do not think that the use of RSIC clips (or other non resilient-channel decoupling products) would represent a gross loss of performance. i'm not sure it would represent ANY loss of performance in a non-Green Glue ceiling. that's a long techno-rambling story. if the lost ceiling height is of concern, just use 'em.

usualsuspects: adding GG/mass to the sheeting is an excellent idea.

Brian

dc_pilgrim

06-02-05, 10:41 AM

maddogmc

06-02-05, 12:04 PM

Brian,

What is the shelf life of unopened GG containers? I would like to take advantage of the power buy but don't won't to start ripping apart the existing room until fall/winter.

Brian Ravnaas

06-02-05, 09:30 PM

Brian, what is the pricing going to be after the powerbuy ends (soon, right?). I am a year away from starting my project, and don't think its quite worth storing this stuff that long (birth of my child comes first). Just wondering what the price bump will be so I can recalibrate the budget.

A pm is fine if you prefer not to post this.

I guess the bright side of the coin is the tubes or other variants might be available in 06.

at that point pails will probably be specail-order only, as so much work has been done on tubes ... and they're easier, cleaner & in the end (with a tweak or two) marginally more effective (long story, nothing to fret about either way), and i think they'll be about 13-14 bucks/tube, 2 tubes/sheet (or one tube/sheet to be "50% coverage" or 3 tubes/sheet for applications where the last couple of dB are more important than the last 100 bucks), so the price hike isn't so much.

call audio alloy's office and get the formal low-down. we lab rats usually only get requests for R&D and gag jokes in the mail... j/k

Brian Ravnaas

06-02-05, 09:32 PM

Brian,

What is the shelf life of unopened GG containers? I would like to take advantage of the power buy but don't won't to start ripping apart the existing room until fall/winter.

in theory, it should be less or more indefinite, with perhaps a little water puddling on the top (dark green splotches). the components won't hydrolyze or break down or anything like that.

we would guarantee 6 months, not indefinite :)

nelson4u

06-03-05, 04:25 AM

Brian,

When does the powerbuy end ?

Brian Ravnaas

06-03-05, 06:32 AM

mornin folks

nelson, alan gouger made a note of it in the thread at the top of this forum

:)

aud19

08-26-05, 06:34 PM

I just found out about this thread/product and had a couple questions/thoughts.

First thing, I saw no reference to a staggered stud 6" wall in combination with GG/double drywall (at least not on the first 6 or 7 pages I read through...lol).

I'd like to know what the optimal installation would entail assuming a cost no object scenario. Maybe listed in order of performance/dollar.

So say the most important/benefficial step is sandwiched GG between two (or more) sheets of drywall (the thicker the better).

The next benneficial maybe RSC?

Then maybe staggerred stud in a 6" wall?

What's the general concensus on the best insulation for sound damping regardless of those other steps?

Has anybody investigated the use of something like QuietRock Soundproof Drywall (http://www.quietsolution.com/Products/Construction___Building/QuietRock/quietrock.html) as the inner (theatre side) layer of drywall in conjunction with GG then "normal" drywall as the sandwich?

I'm asking to see which of these steps/products will combine to give the best performance for the dollar for us less well-heeled folks and also which steps are worthwhile in case I win the lotto! :p

My lotto setup would likely go with the staggered stud, insulated, "normal" drywall, GG and QuietRock. Would RSC add much to that design? I suppose if I won a big enough lotto I could do dual layers of QuietRock too but that just seems excessive! :eek: ...lol

Dennis Erskine

08-26-05, 08:37 PM

No, actually, you'd have a double wall, RSIC-1, 5/8 drywall, GG, 5/8 drywall on the inside and 5/8, gg, 5/8 on the outside.

Now, if you were really serious, you'd have a sand filled barrier wall, 8" of insulation, framing, RSIC-1, 1", GG, 5/8"

You're wasting money with Quiet Rock AND Green.

aud19

08-27-05, 01:55 PM

Sounds like you're not a big fan of QuietRock there Dennis, can I ask why? Or is it just that you wouldn't use both QuietRock and GG?

As for the sand filled wall... Is that using cement blocks with the empty cavity portion filled with sand? Then a 5.5" space away from the "sand wall" before starting a 2x4 framed wall leaving 8" of space to be filled with insulation?

krasmuzik

08-27-05, 02:35 PM

avare

08-27-05, 04:11 PM

aud19

08-27-05, 04:28 PM

Avare,

I don't have any "opinions" of it. I honestly wanted to know how he felt about the product. I'm just curious as to which products and methods offer the best value/dollar. I will not be offended if you don't like the product, I'm just looking for information ;)

So the reasons you don't like QR is the weight and cost then? Is that right?

aud19

08-27-05, 04:30 PM

QuietRock is sheet rock sandwhich with viscoelastic glue

GreenGlue is viscoelastic glue that you sandwhich between sheetrock.

The only difference is who makes the sandwhich, the price you pay, and the effectiveness of the glue.

See, now I didn't know this, that was quiet helpful :) I can guess buy your remarks that you feel the "effectiveness" is better with GG and that obviously doing the sandwiching yourself lowers the costs.

krasmuzik

08-27-05, 04:32 PM

They also sell QuietGlue if you want to DIY - but I think Brian is professional enough not to do a public head to head and let his product speak for itself.

1st Cav

08-28-05, 06:15 PM

1st Cav

08-28-05, 06:20 PM

Oh and my preferences are 80% movies 20% music. Ive read that the garage door may be an issue to consider, if it were you and you had a chance to buy a particular garage door system which would you buy? In case it wasnt clear, im looking a for a quiet system that wouldnt cause too much noise above in the bonus room.

Thanks again

1st Cav

1st Cav

08-28-05, 08:36 PM

As promised here is a layout of the room showing both the 3rd bedroom/playroom and my daughters bedroom, well some of it anyway. I guess its more to the left than I previously stated but still at least 4 1/2 feet from door to door.

1st Cav

08-28-05, 08:37 PM

Sorry im trying to get to 5 posts so i can post a link

1st Cav

08-28-05, 08:38 PM

Finally!! The illusive "link" :rolleyes:

http://pg.photos.yahoo.com/ph/firstcavtanker/detail?.dir=/5e16&.dnm=c3cf.jpg&.src=ph

Brian Ravnaas

08-29-05, 12:12 AM

as folks commented on above, Quiet Rock and Green Glue operate on the same basic principle - viscoelastic damping.

as such it is not inherently true that Quiet Rock + Green + 5/8" would be superioer to 5/8" + Green + 5/8", other than being heavier (quiet rock Serenity is like 93lbs, and normal 5/8" drywall is like 70lbs or so)

but for the cost of the quiet rock you could get 3 or 4 layer drywall/damping sandwiches...

anyway, kraz and DE covered it all above.

Brian Ravnaas

08-29-05, 12:14 AM

They also sell QuietGlue if you want to DIY - but I think Brian is professional enough not to do a public head to head and let his product speak for itself.

well thanks, Kraz.

we do have some same-lab 3rd party comparisons of this, but we've never published them.

FWIW, in our tests the Quiet Rock performed almost completely exactly, perfectly the same as it did in tests they've run, a nice tribute to the consistency of theirproduct, perhaps. Also to the possibility of repeatable wall testing, and perhaps also to Audio Alloy's gang for running the tests as straight-up as possible.

so a good job to everybody,, lol

:)

Brian Ravnaas

08-29-05, 12:32 AM

Well this is my 2nd post i believe and now that im in the beginning stages of having my home built i figured that its time to start asking questions. Alot and I do mean ALOT of my potential questions and concerns have been adressed in this forum by doing an enormous amount of searching and reading (about 1 years worth). Getting to the point, Ive read about all of the soundproofing techniques being used by many to seperate their HT from the rest of the home. My concern is similar but a little less intense (for now), my "theater" will be in a 20x16 step down bonus room above my garage. I want to keep all escaping sounds to a minimum due to my 3 year old daughters room being across the hallway (maybe 4.5 feet from door to door) along with the master bedroom and 3rd bedroom/playroom. Of course I wont be watching extremely loud movies after she goes to bed but the concern is still there. Will adding another sheet of drywall with GG between, along the hallway wall and possibly the rear wall help enough to calm some of the excess sound thats bound to escape? I also plan on buying a solid core Safe-N-Sound door as ive read that it does help some, but im interested in other low cost (i know thats a subjective issue) techniques to consider. Ive read about RSIC and things of that nature but i have a strange feeling that once i start considering some of those things my initial HT budget is going to explode. If anyone in the world knows about the continuing pursuit in HT excellence you guys do. If it means anything the gear i plan on purchasing to complete everything is : Pioneer 1015 , Oppo dvd player, 7.1 Ascend setup 340's across the front HTM 200's side and rear, Sanyo Z3 projector, DIY screen (MMud?), SVS PB12isd (2much for the room?). Well if ive left out any important info that would make answering my question easier please let me know. I'll try to post a layout of the room tonight when i get off of work.

Thanks in advance,

1st Cav

ok, so your theater will be across a hall from other people, that's good.

you still have door-air-door noise paths, and structural paths, those can both cause some problems.

sometimes, the biggest problem with noise in houses is this:

1) all the rooms in the house are the same - i mean have the same construction (like 2x4 wall with one layer of 1/2" drywall on each side)
1a) as a result, all the rooms in the house have the same resonance problems at low frequencies

so

2) the weakest point of the theater wall lets alot of sound in, this sound moves through the structure easily (as common structures aren't very well damped)

then

3) this sound - mostly around the low-frequency resonance of the theater wall, which is the same as the resonance of other walls - easily stimulates the resonances in the rest of the house causing disturbance maybe 3 or 4 rooms away without problem...

so one advantage of almost ANYTHING you do to your theater is at least it's different. even a resilient channel wall (generally not so good for theater applications) will have this advantage: the frequencies where it's weakest won't coincide with the frequencies where the rest of the house is weakest...

i'd recommend changing the construction of your room to not fall into this matched-ersonance trap that can really cause some almost humorous situations where, literally, 3 rooms over and 2 rooms up the kids get woken up by subwoofers. :confused:

adding GG to the hall and/or floor of your theater -to- be will massively reduce structural sound transmission. it will also change the nature of those walls.

adding clips to the walls will change the nature, and reduce structural transmission of wall-to-structure above the point where they are an effective decoupler (determined by depth of cavity and mass on the clips).

really, your situation is one where you could have success in many ways, and i feel that either of the two you mention are among them.

the doors will matter, of course, and check out zero international for some high-performance seals.

beatboy77

08-31-05, 11:19 PM

Brian Ravnaas

09-01-05, 07:39 PM

Due to budget constraints, I will only be able to have one layer of 5/8" drywall. I will also be going with Atlantic Technology System 20 THX In-Wall Speakers. If I were to apply Green Glue to the studs before putting up the drywall, would I experience a sound improvement? Also, would the GG help secure some of the bass from the in-wall speakers? Thoughts?

~Josh

Josh,

Green will help when applied to the stud edges, but this won't be remotely the effect of Green between layers.

The best answer that i can give for this is yes, it's worth it. it's not much area to cover, so cost is low, and it will give you something.

but neither GG on studs nor anything else just appleid to studs now or ever (where the drywall is still screwed to the studs) will truly make a paramount change in wall performance. you'll get improvement, but you won't get a "Green Glue wall", so to speak.

but, then, you won't break the bank, either.

Brian

kromkamp

09-02-05, 11:01 AM

beatboy77, if drywall prices are similar down there to up here, 5/8" drywall commands a 50% premium in price over standard 1/2". So, for only a little bit more money you could get two layers of 1/2".

Of course, this would require more GG but even at 50% coverage its works quite well.

chiltown

09-02-05, 03:35 PM

gregavi

09-17-05, 02:48 PM

2 Questions: Are two layers of sheetrock with Green Glue between more or less effective than one layer of 1/2" soundboard under 5/8" layer of sheetrock? When using GG, is it more effective using different thicknesses of Sheetrock (one 1/2" one 5/8")? Thanks.

Dennis Erskine

09-17-05, 03:30 PM

1. Sound board is worthless in this application. Green Glue with two layers of drywall by far exceed what soundboard/drywall will do (due to mass and damping).
2. I don't know what Brian has found out in the labs; but, I find the damping more effective as 1/2 over 5/8 (you do loose a bit of mass that way, however).

gregavi

09-17-05, 05:22 PM

No...
"two sheets of _______ " fill in the blank.

According to the Audio Allow website, when asked about using soundboard, their answer is: No. The “sound board” is not rigid and dense enough to work well. You should substitute the soundboard for drywall.

My point is: Dennis’ “fill in the blank” is not necessarily true according to them.

Here’s my plan, and please improve or correct if not a good plan:

Staggered stud wall / 1/2” soundboard glued & screwed to studs / ½” sheetrock / GG / 5/8” sheetrock taped and textured.

Dennis Erskine

09-17-05, 05:26 PM

I don't understand the 'fill in the blank' thing; but, I wouldn't waste a dime on the sound board.

I see you are 'texturing' the wall ... I hope you plan on acoustic treatments in the room as well.

gregavi

09-17-05, 09:47 PM

Brian Ravnaas

09-19-05, 02:12 PM

Any thoughts on the effective of applying acoustical caulk to the studs then drywall / GG / drywall?

Curious if anyone has tested the effect of acoustical caulk sandwiched between two layers of drywall?

the best performing caulks in this regard will be solvent based oozie-goozie sealants such as Tremco acoustic sealant or Quiet Seal

I've tested a sealant or two. it is overwhelmingly unlikely that a sealant will make an ideal damping material, for reasons that i'd prefer to not discuss, as they involve the nature of what is best for CLD in walls and what is best for sealants. One glaring contrasting factor at work.

Brian Ravnaas

09-19-05, 02:35 PM

I was just pointing out that the manufacturer recommends, I believe, only sheet rock and plywood. To me "two sheets of _______ " fill in the blank, means: 2 sheets of anything.

I find it hard to believe that soundboard is worthless in this application.

Yes I will be using some sort of acoustic treatments in the room. I just don’t know what yet.

Thanks Dennis for all of your expert advice. It has been so valuable to me and to others I’m sure.

i'd recommend MDF over plywood. For reasons of mass, cost, and flatness.

i discussed this in another thread a moment ago, and i pitter-pattered around the soundboard commentary a bit.

the thing that you have to remember about soundboard is first, it ahs the greatest marketing name in the history of products. Second, from the inception of its use as a sound isolation product, it was backed from up on high by a huge, huge industry (the fiberboard industry)

i quote David A Harris from his very nice book "Noise Control Manual for residential buildings)

"In the 1960's the Insulation Board Institute (IBI) begal searching for new product uses for wood fiber insulation board. Someone must have said "hey, that looks like it has acoustic properties." Since the base board had been used for making wood fiber ceiling tile, this was a logical conclusion. Realizing that partitions have better sound transmission loss characteristics when a sound-absorbing material is included in the core, the industry scrambled to prove the theory. Hundreds of tests by manufacturers and IBI ensued. "

"researchers quickly found that sound-deadening board provided significant STC improvement only when the partition had staggered studs or a resilient mounting. It worked well on steel studs since they are inherently resilient. However, merely nailing sound-deadening board as an underlayment to gypsum wallboard was not acoustically worth the effort"

"additional research indicated that a resilient effect could be created by adhering the outer layer of gypsum wallboard to the sound deadening board by laminating with strips of joint compound. Tests demonstrated that the location, size, and character of the lamination strips were critical to the improvement of STC. For example, the best STC values were obtained when the adhesive was still wet - obviously not acceptable in practice, and when the adhesive was located midway between the studs. The effect was to make the board act as a "leaf spring" and thereby provide the resilient mounting needed."

and then offers "unfortunately, marketing efforts were so effective with this magical new product called "sound deadening board" that the contractors thought it would solve all their acoustical problems. Advertising failed to emphasize the "small print" about specialized construction details. Since contractors did not want to hear all of the conditions, many buildings were constructed with sound-deadening board nailed in place just like sheathing. STC values were totally lost. Manufacturers did not attempt to correct the wrongs in spite of warnings by their research engineers because it could mean lost business opportunities. This shortshighted and misleading marketing practice was promulgated through efforts by the IBI which inundated the industry with "technical literature" and articles in construction trade journals."

there, that is the entire section between and after my original quotes. The comment about resilient mounts relates, i believe, to the boards sound-absorption properties. -vs- an empty cavity this is an advantage. it does not state comparisons to an additional layer of drywall were favorable.

1/4" drywall was marketed as a sound isolation product at one time as well. used in manners similar or the same to soundboard - glue heavier drywall only to the area between the studs, and let it float on the flexible 1/4" board. None of these systems would ultimately have proved effective if the STC system extended to 30 or 50hz, but since STC goes only to 125hz, sometimes you can move a problem just under 125hz and achieve large STC gains....

i'll cease my blabbing, but simply summarize that i don't think soundboard in any configuration could ever be demonstrated to have a demonstrative full-bandwidth value, previous comment about the screw-to-the-soundboard-but-not-the-studs notwithstanding. i question the legality of that assembly in fargo, but i've never asked. and i offer that in the end i doubt full-band tests on such an assembly exist, and i wouldn't hold my breath for it to have a transformative effect on the overall performance, although perhaps a subtle one.

Dennis Erskine

09-19-05, 03:09 PM

I find it hard to believe that soundboard is worthless in this application.

Some felt the same about the earth being round. :) You can do alot better for yourself; but, you asked the question, you got the answer, and debating it with me won't change my answer unless some certified tests come along (they won't) that would prove otherwise to me. But, hey, it's your room and not mine. Have fun!

Brian Ravnaas

09-19-05, 03:24 PM

ok, based on the NRC's test TL-93-190, which has

5/8"
soundboard
2x4 wood studs with fiberglass
soundboard
5/8"

compared to the same lab, same time-period test of single 5/8" on each side of a nominally identical set of studs and insulation and so forth. The soundboard test is found on page 250 of the document IR-761, the regular drywall is found on page 82 of the document IR-693... look 'em up yourself if you please, at www.nrc.ca

Adding the two layers of soundboard under the drywall yields a net gain of ~4.2 dB on a demanding theater curve that i like to use. This is for calculated A-weighted sound reduction in dB.

For a European standard, a noise curve outlined by one Tennekes, the predicted gain is about 4.9dB.

STC went up by 8 points for adding the soundboard to both sides.

For reference, adding a second layer of drywall to each side (nominally this almost doubles mass), would be expected to yield 4.5-5dB of net gainsn on either of the two curves above based on historical measurements.

you would anticipate about 6 STC points of gain for doubling the layers of drywall.

This is the only non-audioalloy full band soundboard test ihave ever seen, it does not imply that it outperforms just adding drywall. You could argue that is has pound-for-pound merit, as the relatively small mass that it adds would be expected to yield only ~3dB for mass alone.

The tests we commissioned were on a lighter soundboard (the NRC's board was about 35 lbs/sheet for 17mm board, ours was ~20lbs/sheet for 1/2"), and the gains were inferior to adding drywall.

Think about it in terms of the five basic principles.

1. mass. it's far ligher than drywall
2. decoupling. just screwing it to studs under drywall doesn't yield decoupling
3. absorption. relative to an empty cavity it might have some benefits, but it's absorbing capacity is dwarfed by insulation in the cavity
4 &5. resonance/conduction - the two principels defined by damping - it is superior in damping to any other common building material, but the overall level is still modest.

BasementBob

09-19-05, 03:35 PM

Brian:
The soundboard test is found on page 250 of the document IR-761, the regular drywall is found on page 82 of the document IR-693I found the IR-761 pg 250 a couple of days ago, but I couldn't find a corresponding no soundboard wall so I didn't post it.

Good show on the IR-693 pg 82.

EDIT: Are you sure that's the right doc and page?

Brian Ravnaas

09-19-05, 05:37 PM

hi bob

page 82, figure 9, two are wood stud sets in the same configuration as used for the soundboard, but with single 5/8" drywall

tl values discerned with ruler, values used given below. "vertical" was the chosen comparison set as that is what is stated in the soundboard test.

frequency horizontal vertical
50 22 22
63 19 16
80 14 13
100 11 13
125 19 23
160 30 31
200 30 35
250 33 40
315 35 38
400 37 39
500 40 41
630 43 42
800 46 46
1000 49 49
1250 49 50
1600 46 48
2000 38 40
2500 38 37
3150 43 40
4000 48 45
5000 52 50

gregavi

09-19-05, 09:45 PM

Some felt the same about the earth being round. :) You can do alot better for yourself; but, you asked the question, you got the answer, and debating it with me won't change my answer unless some certified tests come along (they won't) that would prove otherwise to me. But, hey, it's your room and not mine. Have fun!

I didn't write that I didn't believe it, Dennis. I wrote that it is hard to believe. Big difference. I wasn't debating it either. It is hard to believe because anything is better than nothing, it would seem.

krasmuzik

09-19-05, 10:29 PM

BasementBob

09-19-05, 11:06 PM

gregavi:
It is hard to believe because anything is better than nothing, it would seemThat's not always true either. Sometimes adding things is bad.
For example it's fairly easy to add a floating floor which amplifies the noise into the room below, at least at resonance frequencies.

It's not just Brian and Dennis and David A Harris that dislike soundboard. There's also Rod Gervais (a VERY practical professional) and Eric Desart.

Rod Gervais's objection is centered around that there's not any proof that it's better than what the soundproofing world is doing now, so using it isn't engineering, it's prayer. If you want advice, trust the labs.

There was a time I wondered how it performed in moisture or fire -- but these days I just ignore it completely as a useless product.

Someone once explained the physics of soundboard. As I recall it behaved
a) a bit of decoupling - but very very very little
b) a bit of damping - but not very good at that
c) a bit of mass - but not much of that
d) a fair bit of absorbtion, the amount being dependant upon the kind of soundboard (the ones with the holes absorb more) -- but less than fiberglass of the same volume
e) all at a relatively high cost compared to the installation costs of drywall

(Hmm, just noticed Brian said almost the same thing above)

So the bigest (ha) effect of soundboard is from the extra absorbtion, and by its increasing the cavity depth between the drywall.

Frequency 1G16+Soundboard(IR761pg250) NoSoundboard(ir683pg82) 1G13bothsides(ir761pg22) 2G13bothsides(IR761pg26) - the right four columns in dB TL (transmission loss)

50 Hz 22.7 22 22.3 26.8
63 Hz 16.5 16 18.5 23.1
80 Hz 18.4 13 23.2 26.2
100 Hz 18.7 13 18.1 20.9
125 Hz 31.1 23 13 15.4
160 Hz 34.3 31 12.7 17.
200 Hz 38.2 35 25 30.1
250 Hz 43.9 40 37.9 41.0
315 Hz 41.2 38 35.8 41.4
400 Hz 44.9 39 36.1 47.6
500 Hz 45.1 41 39.4 48.1
630 Hz 49.6 42 39.4 50
800 Hz 52.2 46 44.2 53.9
1000 Hz 53.4 49 46.7 56
1250 Hz 55.1 50 47.4 58.1
1600 Hz 54.5 48 46.8 60.1
2000 Hz 48.9 40 40.2 57.9
2500 Hz 46.6 37 37.4 48.6
3150 Hz 52.0 40 42.5 48.6
4000 Hz 58.3 45 47.8 53.5
5000 Hz 62.4 50 52.9 59.6
6300 Hz 67.7 xx 57.2 64.3

All of these walls are simple single 2x4 studs without decoupling, so they all have MSM resonance dips at frequencies higher than 63hz.
TL above 315hz we usually aren't interested in, since whatever we build will have good TL there. There's a slight coincidence dip in the 2G16 wall (2 layers of 16mm or 5/8" gypsum) at 2800hz but otherwise over 315hz the two layers of gypsum outperform the soundboard above 315hz.
So the more interesting is the 50hz performance where the extra mass of the gypsum is giving us 15% more dB TL, for less money. Provided we don't have a resonance dip, this extra dB TL due to mass should translate from wall system to wall system.
One way to reduce the amplitide (?) of both the resonance dip and the coincience dip is to use Green Glue.
Anything that would lower the resonance frequency is a good thing in walls (double stud increased cavity depth, RSIC, more mass).

darkman2003

09-19-05, 11:21 PM

Why Why Why !!!

Brian Ravnaas

09-19-05, 11:27 PM

It might be hard to believe that a large manufacturer wants to make more of the same stuff - so they come up with dubious uses for stuff - knowing that they can get the high school drop out contractors to install the stuff - being that they already know how to install their other stuff. Hard to believe indeed!

hi Kras,

your logic isn't flawed. i so dislike this topic (more on that at the end)

I offer comments from David Harris who seems to know alot more about the history of the product than i do (and i expand quotes to include a whole 4 paragraphs from the section above)

i offer what test data that i am aware of on this planet - that being the IR-761 and IR-693 comparison i listed above. And i offer that we paid a considerable chunk of change to commission a similar test with even lesser results, and i hypothesize as to why this might be.

i offer that (and i might be one of the bigger data-junkies around) there is no full band, or even non-full-band data of which i am aware falling in line with Fargo biulding code implying that soundboard outperforms drywall for full-band performance, or even STC. you can't glue with 6" stripes between studs in Fargo, ND, YMMV.

i offer that there is a big beautiful marketing brochure chuck-full of STC ratings from one particular lab. and i offer that data from that same lab for same designs, but replacing the soundboard with drywall routinely have higher STC's than the figures in said marketing report.

i offer that perhaps you could say that the NRC tests demonstrate that it's better pound-for-pound than drywall. i offer that drywall is heavier, making a layer-for-layer claim not as relevant. i offer that if no insulation was to be used, perhaps the sound absorbing qualities would have merit. i offer that the method discussed by the homasote corporation may have merit, and i offer that i'd check with local code before trying it.

and i dislike this topic, which is frequenctly asked. it makes me feel like i'm knocking the stuff, which i'm not. i don't insult it, i observe that not data exists to the best of my knowledge to support that it is an improvement over just another layer of drywall when screwed to the studs. it makes me wonder if people would read my posts and think that i was just being a commercialish guy and "knocking" another product due to my involvement with audio alloy. none of the above are true, i simply report that bit of information that i have.

i report what information i have, i gave directions to where to find it to verify it yourselves, should you desire to do so.

so perhaps i could offer that the marketing program was so effective that not even test data can undermine it's success. ??

Brian

Dennis Erskine

09-19-05, 11:40 PM

It is hard to believe because anything is better than nothing, it would seem
Anytime you put two materials together, you no longer have two materials, you have a composite...a third entirely different material with an entirely different and unique set of properties. Even the order of the layering will make a difference. In many cases putting two layers of something together produces a third item of lesser properties than each individual layer on its own. Not uncommon.

I suspect, had they continued to call it fiberboard (as they did 40+ years ago), they'd never sell it today. Now, by calling it soundboard, they extended the life of the product.

Brian Ravnaas

09-19-05, 11:45 PM

It's not just Brian ... that dislike soundboard.

Very thorough post, but if i could argue nothing more than a semantic point: i don't dislike any product, i just observe that i am not aware of any data from any maker demonstrating full-band gains relative to just adding another layer of drywall.

The california office of noise control offers several sets of test data for soundboard assemblies. over single-wood-stud walls, the STC's range from 36 to 50.

100% of the tests with an STC over 40 in the copy of that test collection

1. have data only down to 125hz
2. have the top layer of drywall only glued in a 6" stripe between the studs to the soundboard below, no screws are used to adhere the drywall to the frame at all

2. can't be built here, not legal
1. raises the question of whether the overall STC was improved at the expense of lower frequencies - because this flexible assembly with no screws lowered the resonance to, say, 100hz from, say, 125 or 160hz.

that's all

:)

Brian

Brian Ravnaas

09-20-05, 12:00 AM

Why Why Why !!!

i guess that's why this topic is a sheepish one for me, the potential for contentiousness puts a guy at risk of getting "why why whyd"

if anybody still has further interest i leafed through the CONC's massive mound of test data and found some circa 1966 from the NRC for same-assembly comparisons.

and that, i guess, is about all i can offer. may i someday have better sense than to quote that book in the big GG thread. :p

That's why i like getting asked about RSIC clips or spring hangers from various makers. They are great products. I promise you that i could walk into any lab in america and demonstrates good performance, superior performance to RC, and good performance/$$$ on many levels. :)

gregavi

09-20-05, 10:38 PM

i'd recommend MDF over plywood. For reasons of mass, cost, and flatness.

I can understand mass and flatness, but where are you getting MDF cheaper than plywood?

So, what would be the most effective 2 layer treatment w/GG between. MDF-GG-5/8" SR; 1/2" SR-GG-5/8" SR or... something else? I'm guessing the MDF method is more effective.

gregavi

09-20-05, 10:48 PM

hey maddog,

i agree, it is very nice to put it on when the sheet is on the ground.

I seems this product would be more effective speading it with a notched trowel like mastic. It would have to come in a bucket then. Any thoughts on that Brian?

Brian Ravnaas

09-20-05, 11:44 PM

I can understand mass and flatness, but where are you getting MDF cheaper than plywood?

So, what would be the most effective 2 layer treatment w/GG between. MDF-GG-5/8" SR; 1/2" SR-GG-5/8" SR or... something else? I'm guessing the MDF method is more effective.

Home Depot, here in Fargo, in the last 24 months has had MDF cheaper than even OSB at times, routinely cheaper than plywood.

The MDF will perform better because 3/4" MDF is heaver than 1/2" drywall for the other layer. To some extent, mass is it's own reward.

BUT PLEASE UNDERSTAND: there is nothing magical about any common building material. not about MDF. not about plywood. not about cement board. not about anything

You folks can answer this type of question for yourselves in the future by following these basic rules:

-heaver is better
-two damping layers is better than one
-two damping layers at 50% coverage/layer is better than one layer at 100% coverage

Therefore for a given amount of resources, you can always make a list of what's best. I don't think MDF ever makes sense as a choice, because you can always get 2 drywall layers for ~ the same price or less.

drywall/gg/drywall/gg/drywall would outperform mdf/gg/drywall, as it would be heavier, AND itw ould have two damping layers.

make sense?

Brian Ravnaas

09-20-05, 11:47 PM

I seems this product would be more effective speading it with a notched trowel like mastic. It would have to come in a bucket then. Any thoughts on that Brian?

this is a good thread to discuss this.

In theory, troweled application has advantages over tube application, as coverage could reach 100% coverage with a near-perfectly uniform film.

In practice, the walls, frame, boards... are all somewhat bent, warped, and so forth, and the tube application consistently performs fractionally better in tests in our lab.

The nitty gritty of the how's and why's can get chatty, but all tests on GG walls since may have used tube material, and i consider the move to tubes a step in a positive direction for real-world performance with GG. :)

BasementBob

09-21-05, 02:24 AM

gregavi:

MDF is routinely cheaper than plywood here too, for the same volume.

I wouldn't put MDF as the room side layer -- due to fire.
I wouldn't put MDF as the against the studs layer -- due to fire and moisture.

But if one is putting up 3 layers on one side of the studs, MDF in the middle between gypsum on both sides should be fire safe, and allows things to be screwed to the wall anywhere and hold reasonably strongly. That's the sole reason to do it.

Some isolation (TL) thoughts: MDF is a different density than the drywall, so the coincidence dip should be flatter is a free bonus. Certainly 1/2" to 3/4" MDF is fine, although I might be concerned with 2" (two inch) MDF having a very low coincidence frequency. While green gluing two 3/4" MDF's against each other is good to ok, construction adhesiving two 3/4" MDFs is not.

tlogan6797

09-21-05, 11:17 AM

Anytime you put two materials together, you no longer have two materials, you have a composite...a third entirely different material with an entirely different and unique set of properties. Even the order of the layering will make a difference. In many cases putting two layers of something together produces a third item of lesser properties than each individual layer on its own. Not uncommon.

So...maybe I missed it, but what would the recommended order be? Since three of my walls are surrounded by poured concrete....

decoupled stud - 5/8 - gg - 1/2

or

decoupled stud - 1/2 - gg - 5/8

OR

does it not matter as long they are all the same? Would changing the layering on the ceiling from that of the walls provide any benefit, if indeed, the layering matters?

So many questions.....

Tom

Dennis Erskine

09-21-05, 01:20 PM

Your choices are:

Decoupled stud, 5/8, GG, 1/2
or
Decoupled stud, 5/8, GG, 5/8

You get slightly higher mass with the dual 5/8". Although, my own experience suggested the GG will perform better with the 1/2 outer layer. No data on THIS product to back that up, however.

tlogan6797

09-22-05, 08:59 AM

Dennis -

EXCELLENT! Thanks for the reply. I was leaning in that direction.

Tom

Brian Ravnaas

09-22-05, 12:46 PM

i mentioned the other day that i always feel sheepish when i get asked about soundboard, because it might seem like the answer is just me (a guy involved with a product) knocking another product. I guess i don't feel that i've ever given less than the straightest answer i can give to anything. Here's the straightest answer i can give, sheepishness or not.

With respect to soundboard as a product, i'd offer these:

1. it has some sound-absorption properties, like fiberglass. So, if no insulation was to be used, that would be a tangible benefit. As David Harris observed in my quote of him above, that would benefit resilient walls. if no insulation was used. but you'd be out of your skull to build a decoupled wall without using insulation, so the point is moot.

2. it has better internal damping than any other building material. perhaps 10x that of drywall. BUT, the damping of a common wall assembly is many times higher than that of the materials which comprise it due to various odd-ball factors like tiny air leaks behaving cause viscous losses, screws and friction causes losses, etc. So i massively doubt that adding soundboard will have a notable impact on the damping of an actual wall assembly.

3. it has different properties than drywall, and as DE observed above this can have an impact. This will manifest itself basically only at the "coincidence" dip, so you could anticipate that soundboard would improve performance at this problem-region a bit.

Those are the plus's relative to more drywall, here are the negatives

1. it's far less heavy. mass is one of the key components to success in any wall.

So weight -vs- an irrelevant amount of absorption and damping + this different-properties concept.

point worth noting: not all soundboard is the same. the board in the tests run at the NRC 12 years ago that i'll discuss below was 2x as heavy as the board sold around FArgo in 2005. That board - sold around fargo now - is flatly blutly less effective than more drywall on ANY wall.

Let's take a look at the one set of full-band test data that exists in all of the thousands and thousands and thousands of test sets that i have, including dozens and dozens on soundboard assemblies...

the picture "soundboard-vs-drywall" shows these things:

1. the performance of a 2x4 wall with drywall
2. the performance of the same wall with soundboard added to both sides
3. the predicted performance of the same 2x4 wall with drywall added to both sides. This prediction is generated via historical dataq for doubling layers, and there is no test from the NRC for this wall with double layers, hence the need to predict it. it's more than reasonable.

We get about these:

wall STC OITC full-band**
1 layer 41 28 22
soundboard 49 33 27
2 layers 47 32-33 27

** = full band calculation based on Robinson-Dadson equal loudness

And that's the most favorable soundboard test i've seen. The lighter-weight board that Audio Alloy tested recently did no more than just putting some foam tape on the studs, which wasn't much of anything at all - just some mid/high frequency gains. Adding a 2nd layer of drywall to one side would certainly have raised performance by ~ 2-3dB.

so at best, screwing soundboard to the studs will give the same gains as more drywall. at worst, it will yield little improvement at all, and less than just adding drywall.

I've little doubt that on any insulated and decoupled assembly, it will perform worse than drywall. This is because mass affects the frequency at which decoupling becomes effective, and the huge loss in mass will outweigh whatever cavity-size increase effects the semi-porous board has.

so someone said they found it hard to believe that this product is made by so many and sold under the name of sound without merit... i guess i can't offer any argument but: believe.

or put the burden on somebody to prove otherwise. 100% of the high-STC soundboard walls that i've ever seen test data for are

1. reported only down to 125hz
2. use drywall over soundboard glued to the soundboard only in strips between the studs

the effect of that will be to lower the resonance frequency... lower that darn resonance to 100hz from 125 and STC might go up 10 points... doesn't mean the wall is any better. see picture #2

so again, i say that you couldn't demonstrate full-band gains -vs- just adding another layer of drywall. someone said they didn't belive, i say: believe

:)

Brian Ravnaas

09-22-05, 01:06 PM

Limp mass is another example of marketing success in the utter absence of publicized test reports, or even sensible theoretical basis.

STC=27 is awesome for a lil 1/8" sheet of limp-mass material, isn't it?

well, a sheet of 1/2" drywall would typically test to a 27
a sheet of 5/8" drywall might test to a 29
a sheet of 1/4" drywall should test to a 25 or so

you see, folks, the thing about a single sheet of anything is mass. no insulation, no decoupling, resonant behavior VERY MUCH DIFFERENT than a normal wall... mass becomes the most important factor. the advantage of the limp material in this is that the conicidence dip moves to a very high frequency where it doesn't matter at all.

The theory that limp materials are beneficial because they can "move with the soudn and absorb it" is utter nonesense. THE VERY NATURE OF SOUND ISOLATION IS TO PREVENT SOUND FROM MOVING THINGS! THIS IS WHY MASS HELPS, IT'S HARDER FOR SOUND TO MOVE HEAVY THINGS THAN LIGHT THINGS! it is the mass of the limp material providing resistance to motion caused by sound that gives it an STC=27. NOT the limpness allowing motion via sound.

Take that theory to an extreme, and imagine a material so limp that it moved PERFECTLY with the sound. would absorb all of it, right? No, it would transfer all of it, as it would represent no resistance to sound at all.

BUT, no such material can be made. For it is mass that offers resistance to sound, not stiffness. only at incredibly low frequenies or on incredibly small structures does stiffness come into play. not in the audible range or on things the size of walls. Mass is this resistance, not limpness, not stiffness, mass.

These materials originate in the auto industry. where applying them to sheet metal DRAMATICALLY raises the mass of the metal. also, just weighing down the metal can help with resonance problems in the steel - steel is amazingly low in damping.

but that 1lb/square foot... it doesn't add up to much inside a wall that already has a few sheets of 2.2 lb/sq foot and some 1lb/square foot framework. to add 1lb/sq foot of material to a normal 2x4 wall with 5/8" drywall on both sides would give a predicted 1.5 dB due to mass.

you have to make BIG changes in mass to matter, like double the mass of the wall. that would, in theory, give 6dB of gains. in historical lab tests it typically gives 4-5dB.

now, IF (and that's a big if) a limp-mass material was an effective constrained-layer damping material, you could use it in between sheets of drywall. damping can do ALOT for a wall if you add ALOT of damping. if you add a little damping, it's just like adding a little mass, who cares?

but hung limply???? oof creating at iny air cavity somewhere? double oof

the only answer that i can give to someone who would say they don't believe it's so widely recomended is, again, this clever and eloquent response: believe

if anyones test data proves me wrong, i'll paint msyelf pink and sit in the mall for 8 hours. but it won't so i'm safe...

Brian Ravnaas

09-22-05, 01:35 PM

With respect to the use of Green Glue, and materials to use it in conjunction with:

on floors i recommend OSB. If you like plywood, that's fine, but OSB is cheaper and heavier.

On walls i recommend drywall. Things like OSB and MDF and plywood and soundboard...

They are all less weight-per-dollar than drywall.

5/8" drywall current market price: $9.25
1/2" drywall current market price: $8.05
1/2" soundboard current market price: $8.00
3/4" MDF current market price: $23
3/4" OSB current market price: $23
3/4" AB plywood current market price: $38

5/8" drywall weight per 4x8 sheet: 70lbs
1/2" drywall weight per 4x8 sheet: 56 lbs
1/2" soundboard weight per 4x8 sheet: 20lbs
3/4" MDF weight per 4x8 sheet: 92 lbs
3/4" OSB weight per 4x8 sheet: 77lbs
3/4" AB plywood weight per 4x8 sheet: 71lbs

$$$/pound, 5/8" drywall: $0.13/lb
$$$/pound, 1/2" drywall: $0.14/lb
$$$/pound, 1/2" soundboard: $0.45/lb
$$$/pound, 3/4" MDF: $0.25/lb
$$$/pound, 3/4" OSB: $0.30/lb
$$$/pound, 3/4" plywood: $0.53/lb

Other things to note:

-2 damping layers outperforms 1 damping layer
-2 damping layers at 50% coverage outperforms 1 damping layer at 100% coverage

So, let's assume that we use 50% coverage if we opt for a 3-layer wall, to keep the Green Glue costs the same, we get MORE for our GG that way than with 100% on one layer (albeit not much more)

then we have these options:

3/4" MDF + 5/8" drywall = 162 lbs and $32.25 for board costs
5/8" drywall + 5/8" drywall = 140lbs and $18.50 for board costs
5/8" drywall + 5/8" drywall + 5/8" drywall = 210 lbs and $27.75 for board costs

so we save 5 bucks in total board costs, same price of GG, we gain 50 pounds, and we have 2 damping layers -vs- 1. it's an obvious choice.

use 5/8" + 1/2" + 5/8" and you'll get 196lbs and $26.55 total board cost, still a far better combination

there is never any reason to use anything but drywall in a GG wall. the fire properties of drywall are another plus, as basementbob noted above. installation costs are probably another.

now, a 3rd layer of wall adds alot of installation costs (labor isn't cheap), but sawing wood is probably more expensive labor-wise than score/snapping drywall...

another note: it is preferable to use 2 damping layers with one on each side of the wall than to use 2 damping layers on the same side of the wall.

Brian

Brian Ravnaas

09-22-05, 01:39 PM

i honestly admire the creativity of everybody with the plans they come up with. Heck, i admire the completely insane sound isolation schemes that sometimes get brought up

a layer of drywall, a layer of soundboard, then 2" of foam, then 3/4" MDF, then resilient channel and R13, then 2 layers of drywall, put heavy felt in the joist cavity, then soundboard under 3/4" plywood....

but, unfortunately for our imaginations, but fortunately for our pocketbooks, the reality of walls and their performance is really pretty simple, and weight per dollar is always a good starting point.

Green Glue will modify the resonant properties (i.e., improve them) more than any possible lamination/combination of different materials under the sun, period.

i support the concept of 5/8" + 1/2" for a GG wall, i flatly don't recommend giving up more mass than that, and i flatly don't recommend deviating from plain old drywall as the material of choice.

hope that helps

Brian

Brian Ravnaas

09-22-05, 01:41 PM

the only possible case that i can envision for using something other than drywall would be using 3/4" MDF to force some massively non-straight studs to go straight.

Brian Ravnaas

09-22-05, 01:58 PM

as long as i'm on a lunch-hour posting spree, this might be really interesting for tech-oriented folks out there:

There are 5 basic principles of sound isolation

1. mass (self explanatory)
2. decoupling (resilient channel, RSIC clips, double stud walls)
3. absorption (insulation in a cavity)
4. resonance (see below)
5. conduction (the ability of a structure to transport vibration over distance)

To improve a wall, therefore, you must

1. improve mass
2. add decoupling
3. add absorption
4. reduce or move resonance
5. reduce conduction

4 and 5 are damping controlled. moving resonance is not damping controlled but is a longer story (See later)

This post will cover the bheavior of a single panel, just a wall with no air cavity, no insulation, no studs, just a single boring old panel.

imagine a wall that was just a single panel. ok? like just a 4" concrete slab, or a sheet of 5/8" drywall supported only at it's edges with no studs.

when sound hits this single panel, it tries to vibrate it. Mass offers resistance to vibration, the heavier the panel, the less effectively sound can vibrate it. that is the first principle - mass - coming into play.

the 4th principle - resonance - also comes into play. AT resonant points of the panel, it becomes extremely easy for sound to vibrate it regardless of mass.

So for a single panel, you have a fairly simple situation of mass minus resonance. Mass defines the potential, resonance takes away from that potential at various frequencies.

in the attached pic you can see the potential offered by the mass of 3 different partitions compared to the actual results.

resonance causes the concrete to fall well below it's potential, this is the coincidence dip.

resonance causes the drywall to fall below it's potential as well, but only at very high frequencies, this is also the coincidence dip.

the plywood suffers much more severe resonance problems than the drywall because it is firmly screwed to floor joists, rather than floating on resilient channel. the stiffness of the installation causes additional resonances outside of the coincidence problem.

to improve these partitions without adding an air cavity, you have only two options:

1. add mass
2. add damping, to mitigate the resonance problems

so that's single panels in a nutshell

next post: talk about how a decoupled wall works!

Brian Ravnaas

09-22-05, 02:29 PM

now imagine a decoupled wall, let's just take a double wood stud wall for one example

the same thing that happens to a single panel happens here - sound hits the drywall on one side of the wall, and vibrates it. the resistance to vibration is JUST LIKE ABOVE, mass -minus- resonance

however, because the two sides of the wall aren't physicall connected, the vibration can't immediately transfer to the other side. pretty straightforward, that.

The thing about decoupling that many people don't grasp, is that the air in the cavity (and the force of the resilient channel in an RC wall or the force of an RSIC clip in an RSIC wall) behaves like a spring.

And with this spring force, and the mass on either side of the wall, you get a new resonance, called a mass-spring resonance. 3 frequency ranges are thusly created:

1. At this resonance point, the performance of the wall won't be so good, it will be WORSE than if you hadn't decoupled the wall

2. well below this resonance point, the performance of the wall will be the same as if no decoupling were present. At very low frequencies, performance will be THE SAME as if you hadn't decoupled the wall

3. well above this resonance point, performance will improve DRAMATICALLY. well above this resonance point, no other method is as effective at improving the performance of a wall as decoupling.

so, this mass-spring interaction results in this situation:

1. sound shakes the inner mass
2. around the resonance, the spring behavior amplifies this vibration, and MORE vibration occurs on the other side
3. well above the resonance, the vibration cannot transfer and performance soars

The attached pic shows this:

1. at very low frequencies the air + resilient channel behaves as a "stiff" mass

2. at the resonance point performance suffers considerable

3. well above the resonance point performance soars

so it is obvious from this assessment that the most important thing we can possibly do for a decoupled wall is lower the resonance frequency. This lowers the weak-spot to a frequency that's less offensive (it's harder to hear 30hz than 60hz), and it moves the frequency where the wall starts to get really, really good down.

These rules

1. use as much mass as possible on both sides of the wall
2. use as deep an air cavity as possible
3. use insulation
4. don't use resilient channel

will always help you steer the resonance point down in frequency. resilient channel has too strong a spring force, and keeps the resonance much higher in frequency than other methods, making it a worse performer below the STC frequency range (STC only goes to 125hz)

The graph below outlines this perfectly. The enormous gains at mid/high frequencies caused by the combination of decoupling + absorption are so immense, that you would have to utilize literally 40-60+ layers of drywall to match them.

But, at low frequencies, the resonance makes it WORSE than no decoupling.

I spliced some NRC data into this graph as they have a higher-limit-facility and to use the AUdio Alloy data would short-change the actual gains wrough by decoupling. I used Audio Alloy/Orfield low freq data as all that data is same lab/same time, and makes for a better comparison.

The overall gains due to decoupling sort of flatten out at mid/high frequencies for a couple of reasons

1. sound transferring through the channel, or through other slight structural connections
2. sound making it through the air / limitations of absorption in the cavity

So that's the awesomely potent, but sometimes risky, second principle of sound isolation - decoupling. awesome in potency well above it's resonance, risky because if you plop that resonance at a problematic frequency, you'll find yourself scratching your head and wondering why your uber-high STC wall still lets hoards of bass through.

And that's as good of a summary of how decouling works as you'll find anywhere, provided i explained it clear enough to make sense.

GetGray

09-22-05, 03:13 PM

Said A lot :) So don't use RC? I'm confused. What about RC mounted on RISC clips?

The more I read on this topic, the less I know. If I buy some green glue can I get some personal help/advise on from you on my wall systems? That is, what is best for my isolation goals? :)

I'm re-doing my basement and have about 3 different wall assemblies to deal with.

Mainly:

1) belowground wall:
earth->10" reinforced poured concrete -> [unfinished my choice of studwall or other assembly]

2) existing exterior wall
Brick->air->1/2" foamboard- 2x6 stud with high density fiberglass insul->existing 1/2" drywall[->second wall system acceptable since I have about 12" of wall system #1 at the bottom.]

3) A smaller amount of exisitn standard 2x4 stud assemblies with 1/2" drywall on each side.
I can add an assembly in front of the existig one. I cannot easily add more drywall layers to the other side. It's my understanding from other threads in this particualr case, it would be better to remove at least the drywall from the inner sice before building a new (decoupled) wall assembly. Yes?

4) The worst assembly, I've yet to decide what to do with:
upstairs living space -> [upstairs flooring: thick carpet+pad | 1/2 ply+vinyl | 3/4 hardwood] -> 20" 2x4 type web trusses -> future HT ceiling.

In this last case, I'm concerned about that truss space. It contains a lot of air to resonate, plus the upstairs HVAC vents. Filling it with insulation would be incredibly expensive (20" depth, 540ft^2) but mostly it's very difficult to do since the fiberglass woudl need to be cut to fit each truss web component., then the space between teh trussed could be filled.

Other options are to blow it full of cellulose (I have no idea what that woudl do to the properties) or to do a combination of blown and spreay on icenye (sp?) foam agains the floor.

Then, once the cavity is filled (or not?), what materials to use as the final wall layer.

Suggestions?

Thanks, Scott

BasementBob

09-22-05, 04:01 PM

BasementBob

09-22-05, 04:49 PM

GetGrey:

So don't use RC? I'm confused. What about RC mounted on RISC clips?
Skip the RC.
If you have double stud walls or other decoupling, then you don't need RSIC.
RSIC with hat channel is normal, RSIC with RC is never done.

Brian Ravnaas

09-22-05, 04:50 PM

Brian:

Nice effectofdecoupling.gif

The bottom line of that is similar to
http://www.earsc.com/img/engineering/whitepaper/vibration/Ifigtwo.gif
from: http://www.earsc.com/HOME/engineering/TechnicalWhitePapers/Vibration/index.asp?SID=61

But yours is about walls, so the curve is a little different.

yep, EXACTLY the same thing, exact same principle at work. they just show transmissisiblity, with the resonance up and the good stuff down, and mine was reversed, flipped upside down.

thanks, BTW

Brian

GetGray

09-22-05, 05:00 PM

GetGrey:

Skip the RC.
If you have double stud walls or other decoupling, then you don't need RSIC.
RSIC with hat channel is normal, RSIC with RC is never done.
Thanks BasementBOb: I had a fundamental misunderstanding. I thought the hatchannel that attached to the RISC clips was RC.

That cleared up, then what about my problem assembly, the truss floor (ceiling) system? Use RISC (and hat channel) on it?

So for the other walls, if I do not have them decoupled via a double wall or staggered stud, *then* use RISC, but if they are decoupled, don't?

I thought Brian was just saying to not decouple the things for LF (where I'm most worried)?

Brian Ravnaas

09-22-05, 05:08 PM

So don't use RC? I'm confused. What about RC mounted on RISC clips?

The more I read on this topic, the less I know. If I buy some green glue can I get some personal help/advise on from you on my wall systems? That is, what is best for my isolation goals? :)

I'm re-doing my basement and have about 3 different wall assemblies to deal with.

Mainly:

1) belowground wall:
earth->10" reinforced poured concrete -> [unfinished my choice of studwall or other assembly]

2) existing exterior wall
Brick->air->1/2" foamboard- 2x6 stud with high density fiberglass insul->existing 1/2" drywall[->second wall system acceptable since I have about 12" of wall system #1 at the bottom.]

3) A smaller amount of exisitn standard 2x4 stud assemblies with 1/2" drywall on each side.
I can add an assembly in front of the existig one. I cannot easily add more drywall layers to the other side. It's my understanding from other threads in this particualr case, it would be better to remove at least the drywall from the inner sice before building a new (decoupled) wall assembly. Yes?

yes, remove the drywall from the inside before building a new stud row, makes for a much larger air cavity = lower effective frequency of decoupling. A generally better resonant behavior as well.

4) The worst assembly, I've yet to decide what to do with:
upstairs living space -> [upstairs flooring: thick carpet+pad | 1/2 ply+vinyl | 3/4 hardwood] -> 20" 2x4 type web trusses -> future HT ceiling.

In this last case, I'm concerned about that truss space. It contains a lot of air to resonate, plus the upstairs HVAC vents. Filling it with insulation would be incredibly expensive (20" depth, 540ft^2) but mostly it's very difficult to do since the fiberglass woudl need to be cut to fit each truss web component., then the space between teh trussed could be filled.

don't fret about filling the whole space, it won't hurt, but using R19 fiberglass isn't so expensive, and will offer alot of performance. I can dig up some NRC data on changing insulation thickness if you like.

Other options are to blow it full of cellulose (I have no idea what that woudl do to the properties) or to do a combination of blown and spreay on icenye (sp?) foam agains the floor.

Then, once the cavity is filled (or not?), what materials to use as the final wall layer.

Suggestions?

Thanks, Scott

skip the isocyanate/urethane/expanding foam unless it's specifically stated to be open cell and acoustic. a 20" joist cavity is a good thing, not a liability. I recommend using decoupling and 2 layers of drywall. Don't use resilient channel or untested sound clips.

The weakest link in your exterior wall assembly is the foamboard on the back of the studs. I suppose that's there for some purpose that makes it not good to remove it... use double drywall on the front of those studs - is that in your plans?

a double-stud wall where the 2x4 wall is now (remove one layer of drywall, add double drywall on a new set of studs) is a great idea.

Brian Ravnaas

09-22-05, 05:11 PM

Thanks BasementBOb: I had a fundamental misunderstanding. I thought the hatchannel that attached to the RISC clips was RC.

That cleared up, then what about my problem assembly, the truss floor (ceiling) system? Use RISC (and hat channel) on it?

So for the other walls, if I do not have them decoupled via a double wall or staggered stud, *then* use RISC, but if they are decoupled, don't?

I thought Brian was just saying to not decouple the things for LF (where I'm most worried)?

all decoupled assemblies will have this problem area at low frequencies somewhere if they are not heavily damped. Damping can help with the low-frequency resonance and help the mid/high frequencies too (at other resonant points in the assembly). The effect of damping varies from system to system.

when building a decoupled assembly, you can do this AND get good low-freq isolation, you just have to take care to follow the guidelines that i offered above and make sure that the resonance point of the system is as low as possible. see?

BasementBob

09-22-05, 05:12 PM

GetGray:

I thought Brian was just saying to not decouple the things for LF (where I'm most worried)?
Decoupling increases the amplitude of the wall system mass-spring-mass resonance (often between 20hz and 100hz), becuase there's a little less structural damping.
Green Glue reduces the amplitude of both the wall system mass-spring-mass resonance, and the coincidence dip.
More mass, and larger cavity, may lower the resonance frequency below what your subwoofer generates. Getting it about an octave lower would be perfect.
Double Stud Wall style decoupling maximizes the mid to high frequency isolation, and when combined with green glue should give a pretty darn good wall for Home Theatre.

So for the other walls, if I do not have them decoupled via a double wall or staggered stud, *then* use RISC, but if they are decoupled, don't?Yep. (Please try to use positive logic, rather than multiple negatives)

That cleared up, then what about my problem assembly, the truss floor (ceiling) system? Use RISC (and hat channel) on it?There are three solutions for ceilings
a) ignore soundproofing, and use the space between the joists for acoustic treatment
b) if your ceiling can take the weight (professional advice required -- don't read joist span tables yourself for this IMO), use RSIC and a couple of layers of drywall with green glue
c) put more joists in a room-in-a-room style. These would be decoupled, so no RSIC, and dead-load calculations are DIY readable from joist span tables. Ted White has an example on his website.

Brian Ravnaas

09-22-05, 05:54 PM

the third principle of sound isolation is absorption.

Sound absorbing materials, like fiberglass or mineral fiber, can so some nice things for a wall or floor/ceiling. The basic positive effects of insulation, in order of importance, are

1. lowers the mass-spring resonance frequency in decoupled walls. In essence, this means that the decoupling is effective to a lower frequency

2. absorbs airborne sound passing through the cavity

3. eliminates resonances in the air cavity. This isn't the big low-frequency resonance, these are middle and high frequency resonances that occur like room modes inside the wall

4. damps the low-frequency mass-spring resonance. historical data suggests this is perhaps a dB or two at most.

Insulation is most effective in decoupled walls. This is because there isn't a direct mechanical path, and sound has to go through the air cavity to reach the other side. In a coupled wall, like a common single-stud 2x4 wall with the drywall screwed directly to the studs, sound can easily transfer without going through the air cavity, effectively bypassing the insulation.

The first two attached pics outline this drastic change in effectiveness from a coupled to a decoupled wall.

WHAT TYPE OF INSULATION IS BEST?

Plain-jane boring old fiberglass is best. I know you've been hit with 1000 degrees of "denser-insulation-is-better", but like soundboard above, this is the result of decades of greusomely effective marketing by massive companies. Actual existing data does not support the assertion.

Taking the 350+ walls tested in IR-761 and IR-693 by the NRC in Canada, we find that plain old fiberglass yields the highest STC in the overwhelming majority of wall categories if not all. How can this be???

-denser insulation, like mineral fiber or cellulose, is a superior absorber. They generally yielded improved middle and high frequency performance.

-normal fiberglass is superior at lowering the mass-spring resonance of the walls, so they generally yielded preferable low frequency performance and higher STC's.

None of these materials can "absorb" 50hz. Try it at home - put a 3" thick piece of insulation in front of your mid/treble speakers. it'll destroy the sound. put it in front of your sub. it won't do anything much at all. They improve low frequency performance by lowering the frequency of mass-spring resonance, and this is by far the most important contribution they make to a wall.

That doesn't mean that mineral fiber is worse, it simply means that it shouldn't be considered better.

You should avoid wasting money on specialty high-density glass or mineral fiber in wall cavities. Just use regular fiberglass. If anybody vehemently protests, please send them to this thread to debate it. :)

Then the question comes up, do i need to fill the entire cavity? Historical test data suggests that the answer is no. It doesn't hurt to fill the entire cavity, but there is not reason to believe that leaving any empty space will cause problems.

In one big study - IR811 by the NRC - they found that using R9 insulation made a large improvement over no insulation. And slight incremental improvements moving from R9 to R13 to R19 to R25. But going from nothing to somethign, from nothing to R9 was by far the biggest improvement, by far.

They over-stuffed the joist cavities in that same test set slightly, but putting 270mm fiberglass into a 2x10 joist cavity, performance did not suffer.

important note: this canadien study used resilient channel on the ceiling. the impact on low-frequency behavior via location of mass-spring resonance is masked by that. The channel is stiffer than the air in a 2x10 joist cavity, and so reducing the stiffness of the air cavity has a relatively very faint effect. make sense?

In 1983, using denser Thermafiber, USG found that over-stuffing slightly a resilient channel wall's cavity had a detrimental effect at high frequencies.

So to sum, the most important thing is that you use some insulation. Things like density and do i fully stuff or half-stuff a ceiling cavity aren't going to be the make-or-break points.

Brian Ravnaas

09-22-05, 06:03 PM

stuffing cavities is ok, overstuffing cavities is ok, some benefit will come from more absorbing material.

but i would never, if in a financial pinch, appropriate resources to more insulation before more mass. Or to more insulation before other means or techniques.

For example, a resilient channel ceiling with 10" of insulation won't outperform an RSIC ceiling with R13.

With 20" joist cavities, using R13 or R19 and double drywall will do more than using 20" of insulation and single drywall.

If building a double stud wall, you'd be far better off to use 50% GG between the double drywlal on one side with single R13 than to use double R13 and standard drywall...

etc. Insulation is critically important, no serious sound partition should ever be without it.

But don't break the bank on fluffy stuff and mineral fiber. Use how much you can, and don't bother with expensive types at all unless test data exists to show they are more effective at lowering the mass-spring resonance frequency.

GetGray

09-22-05, 06:18 PM

Brain and Basement Bob:

Thanks:> " skip the isocyanate/urethane/expanding foam unless it's specifically stated to be open cell and acoustic. "Well, *they* say it is, but I see no data to justify it. I't open cell, but has a closed "skin" after installation if that matters any. In normal stud walls they cut the excess flush which exposes the cell structure. Here's a pdf (http://www.icynene.com/assets/documents/PDFs/Spray_and_Pour_Formulas.pdf) with details and some STC data. Maybe you could take a look? One nice thing about it, it *does* fill every tiny hole, gap and crevice.> "a 20" joist cavity is a good thing, not a liability. I recommend using decoupling and 2 layers of drywall. Don't use resilient channel or untested sound clips. "A good thing even without filling it with insulation? That extra airspace wont turn into a "drum"?Are RISC "tested", that was my planned clip since it was apparantly popular here.?> "The weakest link in your exterior wall assembly is the foamboard on the back of the studs. I suppose that's there for some purpose that makes it not good to remove it... use double drywall on the front of those studs - is that in your plans?"Yes, that was my plan, remove the existing drywall, build decoupled inner wall and fill extra cavity with insul. I have vapor barrier issues to deal with on that wall however and those are not to be treated lightly lest one end up with mold growth. 10" of insulation might be a bit much to dry to outside. I may leave the existing vapor barrier in place and build to allow air circulation through the "extra" wall. The foam board on the exterior wall as described is standard residential construction around here (TN). No way to change that layer.
> when building a decoupled assembly, you can do this AND get good low-freq isolation, you just have to take care to follow the guidelines that i offered above and make sure that the resonance point of the system is as low as possible. see? "Well, not exactly. I mean I get the rules you posted, but I'm not sure how to know if my resonant point is low enough. Will "5/8" + 1/2" for a GG wall" do it? Remembering I can't really treat the other (outer) side of any of my assemblies. I can add studs with insulation, and wall covering (drywall layers). They can all be decoupled. Bob:>Yep. (Please try to use positive logic, rather than multiple negatives)Sorry, I saw I had done that after posting. Let me restate to be sure I understand:

- Wall not decoupled, use RISC to mount drywall
- Wall decoupled, RISC adds no benefit and should not be used

Right?

And as a followup, Are RISC good to use FoR decoupling a stud wall assembly from the adjoining wall?>There are three solutions for ceilings
> a) ignore soundproofing, and use the space between the joists for acoustic treatmentI'd rather have the soundproofing I think. But I have not ruled out giving up since I have other places to deal with stopping the sound. No sense doing heroic wall assemblied with leaking HVAC and doors.> b) if your ceiling can take the weight (professional advice required -- don't read joist span tables yourself for this IMO), use RSIC and a couple of layers of drywall with green glueI'll check but I'm pretty sure it can handle it. I had the tursses built to over commercial standards (50lbs LL, L/480 deflection IIRC, I'll have to lookup my engineering drawings on the floor truss specs.) Always good to be sure.> c) put more joists in a room-in-a-room style. These would be decoupled, so no RSIC, and dead-load calculations are DIY readable from joist span tables. I've looked into this. Due to the mechanicals interleaved into the trusses and the long spans, I'd have to drop the joist enough to whack off at least 9" overall room height vs clips. It's at 9' now, hate to go lower.

Thanks as always for the input guys.
Scott

BasementBob

09-22-05, 06:46 PM

GetGrey

A good thing even without filling it with insulation? That extra airspace wont turn into a "drum"?A little airspace in the wall isn't a problem for wall TL.
Although in risers (raised seats) the rule seems to still be to fill the space with insulation, and with stages (under subwoofers) the rule is to fill them with sand to damp the vibration on the top because of the extreme amount of vibration energy due to the coupled subwoofer.
Another advantage to filling the space may be as a fire stop -- depending on building code in your area.

Are RISC "tested", Yep.
Click on any of the "Full Report" links here http://www.pac-intl.com/tests_wl_wood.html
(e.g. http://www.pac-intl.com/pdf_test/test_RAL_TL01-212.pdf )
and you'll see OFFICIAL test data down to 100hz, and UNOFFICIAL/DISCLAIMED test data down to 31hz.

- Wall not decoupled, use RISC to mount drywall
- Wall decoupled, RISC adds no benefit and should not be used
Right?Yep.

Brian Ravnaas

09-22-05, 11:09 PM

Brain and Basement Bob:

That extra airspace wont turn into a "drum"?

sure, but a smaller airspace is a worse one. As i commented above, the air behaves like a spring, a deeper cavity is a weaker spring, creating a lower resonance. 20" of air is vastly preferable to 3.5" of air. that's the low frequency resonance.

inside of an air cavity, the same type of room modes that happen in rooms will happen. standing waves, they are called. the lowest frequency standing wave in a 20" air cavity will be 339hz (per Jeff of Auralex's big ol spreadsheet). From Bob's absorption coefficients page: http://www.bobgolds.com/AbsorptionCoefficients.htm , we see that 3.5" fluffy pink fiberglass has an absorption coefficient of 1 at that frequency. Ample to tame that cavity resonance.

Are RISC "tested", that was my planned clip since it was apparantly popular here.?

thoroughly

I mean I get the rules you posted, but I'm not sure how to know if my resonant point is low enough. Will "5/8" + 1/2" for a GG wall" do it?

the location of the resonance with 5/8"+1/2" and GG will depend on the wall type. Different for a double stud -vs- a stagg stud -vs- a 2x4 wall, etc. GG contributes resonance control to those wall types, making the resonance alot less severe, so location becomes less important.

Remembering I can't really treat the other (outer) side of any of my assemblies. I can add studs with insulation, and wall covering (drywall layers). They can all be decoupled.

your plan of double studs should be peachy. If put double drywall on the 2x6's i'd be shellshocked if it caused problems, foam board or not.

nelson4u

09-23-05, 04:27 AM

chiltown

09-23-05, 06:25 AM

I understand that more mass is better, so can you explain why when doing two layers of drywall on the wall with GG, you recommend 1/2' and 5/8" combined instead of two layers of 5/8" ?

Getting drywall of two different thicknesses is better as they will resonate at different frequencies effectively dissapating more energy than if they were the same thiickness.

tlogan6797

09-23-05, 09:59 AM

Brian, et al....

Thanks for your recent most EXCELLENT posts. I have been lurking for a while and these posts have been of great value in pulling together the info scattered around a million other posts.

I am about to begin building (dricore delivered and should begin installing this weekend and maybe framming next) a not-dedicated room (L-shaped multi-purpose room, wet bar), but want things to be as good as I can get them through building, thinking I should do the things inside/behind the wall now, and can worry about other treatments later. In general, I'm not looking for sound "proofing" as much as minimizing sound tranmission and doing as much for the sound quality as possible (certainly NOT looking for THX reference or anything like that) with the floorplan I have.

So now for the sanity check.....

WALLS -
RSIC DC04 studs, Insulation R?, 5/8 + GG + 1/2 DW(screwed to studs) and probably linacoustic/GOM on the lower half of the "theater" area

Ceiling -
Insulation R?, RSIC EXT04 + Hat Channel, 5/8 + GG + 1/2 DW

Right track, Yes, No? Additional thoughts?

Thanks again!
Tom

Brian Ravnaas

09-23-05, 11:44 PM

Brian-

I understand that more mass is better, so can you explain why when doing two layers of drywall on the wall with GG, you recommend 1/2' and 5/8" combined instead of two layers of 5/8" ?

On my ceiling I am going to use RSIC-1 and hat channel and I am considering doing 3 layers with GG. What combination of drywall thickness would you recommend ?

I don't recommend it on all walls, but i support it because first DE has reason to believe this is a favorable configuration for GG based on his experience. Second, the overall sacrifice of mass isn't so great, and the overall effect that i describe below won't be enormous.

On these wall types, if it was my wall, i would opt for all 5/8":

stagg studs, double studs, resilient channel, thin gauge steel studs, RSIC

The reason that i would opt for this is more mass would drive the decoupling point down. On decoupled walls, mass has a sort of two-faced value. First, the simple value of mass. Second, the value in driving this resonance down.

If it was my wall, i would not utilize thin gauge steel studs as a form of decouplng unless they were 6" deep or deeper, and i wouldn't use RC at all.

On a 2x4 wall, all 1/2" will outperform all 5/8" at mid/high frequencies in combination with Green Glue or not in combination with Green Glue. At very low frequencies, all 5/8" will perform best, and around the primary low frequency resonance point, our data is mixed as to what's best. Any combination makes one heck of a good wall.

So, i've stated my $.02, but i also offer that DE is a sharp fellow, and one way or another, neither is a recipe for disaster, and neither will yield a paramount improvement over the other.

Brian Ravnaas

09-24-05, 12:43 AM

Getting drywall of two different thicknesses is better as they will resonate at different frequencies effectively dissapating more energy than if they were the same thiickness.

that is the basic theory, exactly.

However, to make a note about this and a comment in general.

the resonance that layering different materials is aimed at is coincidence. Coincidence is a dramatic resonance, but also usually a high frequency one. The only times this will occur at frequencies lower than perhaps 1000hz is in thick plywood, or masonary structures. In brick and concrete, this can be a reasonably serious problem, but in stud walls, essentially always the low frequency resonance is the problem to worry about.

The concept of using different thicknesses of drywall is a pretty old one, dating back to the 60's. It is extremely common to see tests from this era experimenting with this technique.

I have a large number of tests on 2x4 walls dating to 1968 and sourced from the NRC. The data is 125-4000hz only, and shows the effect of this technique, and also of rigidly laminating drywall (like using a rigid glue). Those are rare among modern tests, starting in the 80's with the huge studies done by USG and through the 1000's of data sets taken by the NRC, neither technique is ever used, save two examples from IR-761.

ironically, the use of insulation was reasonably rare back in those days. Owens Corning hadn't yet hammered into the heads of all that this was an imperative part of wall design.

so what is the effect? the next few posts will explore this, and i'll throw in the effect of rigidly bonding drywall just for fun.

Brian Ravnaas

09-24-05, 01:04 AM

just for fun - the effect of rigidly bonding drywall layers

Long ago when first i happened across this fine forum, a thread broke out that caused a multi-forum panic over the detrimental effects of rigidly bonding drywall. :eek:

One designer here had recommended bonding drywall, and the basic option was construction adhesive, and based on a software simulation, it had been concluded taht this would ruin all things. (i'm playing around, Z ;) )

I found some ancient (37 years old) NRC data that covers this for a 2x4 wall. Hope it helps

The first picture shows the effect of rigid bonding, which in essence stiffens the panels. The resonances move closer together. Low freq resonance moves up, high freq resonance moves down.

the data, like most all old data, only goes to 125hz. Back in the day everybody was convinced that measuring below 100hz would cause world war 3, followed by the return-to-popularity of bell bottom jeans. In 1993, the NRC released hundreds of data sets down to 50hz, and what do you know? bell bottoms did indeed make a comback. guess they were right. however, the data is good. :p

the second pic shows the probable effects below 125hz. Remember, you're adding mass as you go, so you expect things to improve.

The third pic shows the probable effect of adding non-ridigly bonded drywall.

remember, pic #2 and pic #3 are my estimations and no official data. They are important to the overall discussion, but they are just estimations.

the point is that the rigidly bonded or non-bonded fall within a dB or so of overall isolation.

The point is that rigid adhesives without damping properties don't help isolation, but they don't cause it to suffer immensely either. Thus the use of them is supported as non-detrimental to the overall goings-on.

Brian Ravnaas

09-24-05, 01:20 AM

ok, the effect of laminating layers with different properties

pic number one shows the effect of cementing 3/16" plywood onto 1/2" drywall over 2x4 studs. The coincidence dip does indeed flatten out.

However, you've added two expensive layers that have almost no mass, and as you can see the low frequency behavior doesn't improve. the slight added mass would help at lower frequencies somewhere - the whole story simply isn't shown when reporting data only to 125hz.

pic number two shows the effect of using 1/2"+5/8" drywall on one side of steel studs with just single 5/8" on the other side -vs- using all 5/8". This is 1993 modern-NRC data from their massive report IR-761, you can read this at www.nrc.ca

pic number 3 is the same thing, different test. The difference in either case is small. Indeed, a little improvement at coincidnce, indeed a little worse at low freq's for sacrificing mass. It's worth mentioning that these systems don't use Green, and I really need to quantify the effect of this with GG at once. it'll be done by october 17th, on a 2x4 single stud wall.

Brian Ravnaas

09-24-05, 01:28 AM

to contrast that, based on data on Quiet Solution's web site, and tests at the NRC, using Quiet Rock Serenity on both sides of a 2x4 wall -vs- 5/8" drywall improves performance at the coincidence dip by 33dB. in part, that is due to the fact that the dip of QRS is much higher than 5/8" drywall. Also, the low-frequency dip is 3dB better (note that the plywood above was no better), QRS is a little heavier than normal 5/8" board.

adding GG and drywall to each side, per Audio Alloy tests, improves performance at the coincidence dip by 26dB. And that's straight-damping, as the dip falls at about the same frequency. so 20dB of that is from the GG. Also the low frequency dip is fully 13 dB better, about 4.5dB of that being due to mass. I think that test short-changes GG, re-test is due in about 2 weeks.

So if you want to worry about coincidence, use a damping material. 100,000x more effective that different thicknesses.

Brian Ravnaas

09-24-05, 01:32 AM

here's an old NRC soundboard cmoparison.

one wall is 5/8" on each side of 16" OC 2x4 studs

the other is same but add one layer soundboard. no insulation in any wall.

Note that despite adding one total layer, no gain is seen in the lowest bands...

Brian Ravnaas

09-24-05, 01:34 AM

nelson4u

09-24-05, 01:41 AM

Dennis Erskine

09-24-05, 09:52 AM

I don't know how deep I want to get into this; but, the principle is likely of some interest. At the same time, 5/8"+GG+1/2" vs 5/8"+GG+5/8" is getting close to hair splitting in a residential home theater. (I would suggest that 1/2"+GG+5/8" would not be as near as helpful as it's inverse.

If we look at the principle behind a CLD material, the vibratory energy causes the laminate to flex through compression. The flexing revectors the kinetic energy due to shear forces and large parts of that kinetic energy is then converted to heat. (The kinetic energy is being used to move molecules that really prefer not to be moved ... the energy is being put to work and, hence, dissipated.

Thus, a CLD relies on the creating of shear forces in a laminate material. If both the inner and outer laminate surfaces move, we still have shearing forces between the materials, all is good, and we've dissipated the energy. If we have two laminates where the material furthest from the sound source is very rigid but the material closest to the sound source is flexible, we still will have shear forces and dissipation.

In the first example (two flexible laminates), we have a residual amount of kinetic energy that has passed through the laminate creating an MSM effect (in a sealed wall) or, alternatively, the back side of the laminate has become a speaker. In the second example, we have allowed more motion in the material closest to the sound and less in the material furthest from the sound. In this case, we're expecting a lot of the CLD. One side effect of this approach is the material closest to the sound is now the 'speaker' (but as I said, in the environments we're talking about here, of no real consequence.)

The whole process is not that simple and requires careful examination of the behaviors of all the laminate materials, the properties and thickness of the CLD material. On the other hand if one had a huge research budget and lots of time to play, it is very fascinating as a subject.

Homer1973

09-24-05, 05:30 PM

Is Green Glue availble in Canada or in a Retail store in WA state?

Ted White

09-24-05, 06:45 PM

We ship to Canada several times a week. :)

gregavi

09-24-05, 10:21 PM

Brian, any tests done on plaster walls? I have 2X4 walls with plaster (button board) on both sides. My ever-changing plan is to remove the plaster from the theater side of the wall and add a 2" top and bottom plate to the theater side of the room and then 2X4 studs to the theater side of the room, creating a staggered stud wall. Insulate with R19 fiberglass insulation+5/8" sheetrock+GG+1/2" SR. Staggered joints on the layers of SR w/ both layers taped. This to all the walls and possibly the ceiling. This is a converted garage so there is only one common wall to the rest of the house. The rest being outside walls w/ stucco on the outside.

Would you treat the other side of the common wall? GG+5/8" SR? Would you do anything different other than maybe using 2 layers of 5/8" SR? Any thoughts on the door. Steel, solid wood, or something else?

Thanks!

chiltown

09-25-05, 08:11 AM

GreenGlue is viscoelastic glue that you sandwhich between sheetrock.

The only difference is the price you pay, and the effectiveness of the glue.

Other than QuietGlue and GreenGlue, are there other makers of viscoelastic glue that are cheaper?

Brian Ravnaas

09-27-05, 10:37 AM

Thanks for the great response Brian.

So if I read this correct, for staggered stud construction walls you recomend 2 layers of 5/8" instead of 1/2" and 5/8" correct ?

What about my second question from above ?

On my ceiling I am going to use RSIC-1 and hat channel and I am considering doing 3 layers with GG. What combination of drywall thickness would you recommend ?

I do recommend 2x5/8", yes. DE recommends 5/8" then 1/2".

I do not feel that either choice is bad, or that they'd ultimately prove to be drastically different.

I recommend the same for the RSIC assembly, all 5/8". with 3 layers, performance will be peachy, and noise through the assembly will be likely flanking noise. You're a winner regardless of drywall choice.

Brian Ravnaas

09-27-05, 10:38 AM