# Soundproofing an apt. ceiling



## joepro0000

I got a small gig to sound proof a ceiling, and want to keep the material cost low. I know this topic has been discussed in the past, and there many solutions. However, the QUIETROCK solution is out the question, because the owner doesn't want to spend the extra money. This is an old apt ceiling with plaster ceilings.

My plan - 7/8" hat channel installed perpendicular to the trusses over the old plaster ceiling. I have a bunch of "RADIUS" 2x2 acoustical tiles, maybe I can some how tack them up there for more sound insulating, then install 5/8" rock. I also got a bunch of green glue, that I will install in every joint and corners. Then I plan on finishing the ceiling.

I already got the 7/8" hat channel, acoustical tile, and green board. Any suggesstions you guys think I can do to achieve a better sound resistant ceiling without purchasing quietrock?


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## Whitey97

They sound proof townhomes by doubling up the 5/8ths and using insy in between


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## Bevelation

Hi, here are some things I can think of:

Ummm.... I wish you all the best.

Really...if you can convince the HO at all of at least adding a second layer of 5/8ths using green glue and screws, that would be your best value.

Is the apartment full of asbestos? Can you somehow talk him into tearing down the old plasterboard and stuffing some new bats of insulation and then do what you're gonna do?

You wouldn't want to install quietrock anyway because if the plaster ceiling stays intact, the board MUST be screwed directly to a stud/joist.

I can't offer info on acoustical tile...it just ain't my style. 

My .02 = two layers on top of the hat channel.


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## Custom Drywall Svc.

joepro0000 said:


> I got a small gig to sound proof a ceiling, and want to keep the material cost low. I know this topic has been discussed in the past, and there many solutions. However, the QUIETROCK solution is out the question, because the owner doesn't want to spend the extra money. This is an old apt ceiling with plaster ceilings.
> 
> My plan - 7/8" hat channel installed perpendicular to the trusses over the old plaster ceiling. I have a bunch of "RADIUS" 2x2 acoustical tiles, maybe I can some how tack them up there for more sound insulating, then install 5/8" rock. I also got a bunch of green glue, that I will install in every joint and corners. Then I plan on finishing the ceiling.
> 
> I already got the 7/8" hat channel, acoustical tile, and green board. Any suggesstions you guys think I can do to achieve a better sound resistant ceiling without purchasing quietrock?


If by hat channel, you are referring to something along the lines of 'resilient channel' than that i feel, is the best bet........and just as you described, installing perpendicular to the framing.

resilient channel (or RC-1) is designed for soundproofing as one of its main uses -- so i would definitely look into this if you are in fact not already using it.....i think the 'hat channel' u keep talkin about may be the same thing.

good luck nonetheless.


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## R.E. Plaster

Yeh the resilient channel is the way to go they also make an RC-2 channel which may be eaiser to screw your drywall to, just a thought


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## joepro0000

well guys heres what we did:

We installed 7/8" hat channel (hi hat or resilent channel as you call it) then screwed in r5 styrophone insulation into the existing plaster ceiling. (between the hat channel)
Then I installed the 5/8" reg. rock, and green glued all joints, and angles. 

After the contractor told me he did want the quiet rock, so I had to bust the mission and go buy 10 more sheets of 1/2" QUIET ROCK, and installed it on top of the new drywall. In the end, it was a great result.

1 thing- Quiet rock is hard to cut, you need to give it like 10 scores, and on both sides before it cuts, or use a router to cut it.


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## Ted White

I realize this is an old thread, and the OP has likely completed his job.

For those who may be searching through old posts looking for answers, I feel it's important to set the record straight.

You never want to install channel over existing plaster or drywall. Your two options with a ceiling are:

Remove the existing ceiling and THEN use the channel.

or

Simply add more drywall and some damping material to the existing ceiling.

The reason is the small trapped air cavity will not improve things much at all, and could make things worse at some frequencies. Here's an aqrticle that describes the problem and possible solutions. Note that there is test data to show this: http://www.soundproofingcompany.com/library/articles/triple_leaf_effect/


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## drywallnflorida

Ted White said:


> You never want to install channel over existing plaster or drywall. Your two options with a ceiling are:
> 
> Remove the existing ceiling and THEN use the channel.
> 
> or
> 
> Simply add more drywall and some damping material to the existing ceiling.
> 
> The reason is the small trapped air cavity will not improve things much at all, and could make things worse at some frequencies. Here's an aqrticle that describes the problem and possible solutions. Note that there is test data to show this: http://www.soundproofingcompany.com/library/articles/triple_leaf_effect/


The tests don't show being tested with the space filled with styrophone insulation that joepro said he installed so there would be no small air cavity between the drywall and plaster



joepro0000 said:


> well guys heres what we did:
> 
> We installed 7/8" hat channel (hi hat or resilent channel as you call it) then screwed in r5 styrophone insulation into the existing plaster ceiling. (between the hat channel)
> Then I installed the 5/8" reg. rock, and green glued all joints, and angles.
> 
> .


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## joepro0000

Thank you ^^^^^^^^^^^^^

I don't think it can be done more better than I did, I added 1-1/8" more of drywall, with 1/2" being soundproof drywall.


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## Ted White

Not looking to argue. No offense to anyone is intended. Again, my hope was that others reading this thread would learn from it.

Installing channel over existing plaster (or drywall) traps a small air space. Filling some of the nooks and crannies doesn't change that. Clearly the entire air cavity can't be completely filled, and a small air cavity is still an air cavity, and performance improvement will be severely limited.

If you filled that small air cavity to the point where there truly was no air then there would be no airspace for the channel to move, right? It's a trapped air cavity. 

The two choices in my original post are the correct choices.

Side note: Green Glue and other similar damping compounds are used in between layers of drywall. Like in between two pieces of drywall (sandwich) Green Glue is not a caulk to seal cracks.

Again, no one here is bad. There are jobs done everyday where an architect will spec a similar construction. Doesn't make it right, as the test data clearly shows.


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## rockdaddy

rc2 chanel. A layer of hushboard or homosote covered by a layer of 5/8x. Two layers of 5/8x on chanel with insulation works just as well. I like the hushboard because its cheap enough with the same STC results.


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## Ted White

Not sure what is being described here.

Hushboard, Homasote, Soundboard, etc really only have limited value directly on the studs and joists. Limited.

The issue is that they don't decouple all that well, don't absorb all that well, and they have little mass. So in a decoupled scenario, these products are not at all appropriate.

Double 5/8" on a decoupled channel is great, but using RC-2 isn't decoupling. 

Side note: RC-1 and RC-2 are not specified by the Steel Stud Manufacturers Association. 7/8" Drywall Furring Channel is, however.


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## joepro0000

Ted-
Have you heard of Quiet Rock drywall?


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## silverstilts

Ted just wondering with all the talk about sound proofing I see that you are sales & design but how much sound proofing do you actually do ? Or is all your knowledge just from reading .... Just a legitimate question .... hate to think that you are just book smart and that you actually can validate the way you do it works ...


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## rckslash2010

Hat channel hanging off of whisper clips, two layers of rock with green glue in between. And gyp cryte the floor upstairs.


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## Ted White

joepro, I have tested many different Quiet Solution products, including various boards they assemble. Very familiar with their performance. Also have tested Supress, SoundBreak and Comfort Guard damped boards. All are fine products. All consist of double drywall with a damping layer.

In the field, you can build a heavier damped wall for less.

Silver, been doing this for 25 years. Any of the principles that I'm discussing are not mine. They are the results of decades of specific testing and research by the acoustic community at large. None of this is the least bit speculative. No guesses or hunches.

All backed by certified independant acoustic labs. And in case anyone thinks that the laws of physics are different in a lab than in the field... they're not.

These are simple principles that are straightforward, inexpensive and highly effective. And there's great margin when installing soundproofing.


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## joepro0000

Ted,

How would you suggest to build a heavier damped wall for less?

I figure 1 sheet of 1/2" quiet rock is $45.00 - vs 2 sheets of 5/8" = 12.00 + 8.00 extra for installation twice, with fire-tape or green glue in-between, might as well be the same. Thats $20.00, plus the cost of mud, and labor to tape it.


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## Ted White

Well let's look at this. It's a good question. 

You only tape / finish the final layer in either scenario, so you really only look at the labor of the second sheet of drywall.

Drywall x 2 = $12
Labor = $8 to install the second sheet
Damping material = $18

So $38 for the field assembly. Keep in mind you're going to have waste, so you can cut, score and toss a 10% waste factor of the $45 board or the $6 board...

Lastly is performance. One fundamental factor we have to look for is the mass. The weight of the wall or ceiling. The heavier, the better in general terms. The 1/2" pre-damped board is simply double 1/4" drywall. Check it yourself and see. The result is very lightweight. All of the pre-damped panels from Quiet Rock, Supress, National Gyp or Temple start with standard drywall or cement board. Same as you buy every day. In the middle they squirt and spread a damping material. Same damping material that you can buy.

In the field assembled system, you have the luxurious option to use double 5/8" rock. The difference in the mass is enormous, and will directly affect the supression of low frequency bass. 

So building these systems yourself will not only cost less, but they will perform significantly better.


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## joepro0000

very interesting, what is the damping material called? Do you think it can be rolled on the first layer of drywall then install the second layer staggered? I do know it is very touch to cut that QuiteRock from my experience, had to score it with a blade and then use a router.


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## rebel20

joepro0000 said:


> very interesting, what is the damping material called? Do you think it can be rolled on the first layer of drywall then install the second layer staggered? I do know it is very touch to cut that QuiteRock from my experience, had to score it with a blade and then use a router.


Joe try a skill saw with metal cutting blade next time or diamond blade.

Rebel


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## Ted White

No need for a metal cutting blade. Only one type of pre-damped drywall has a steel layer.

JoePro, there are various damping materials. Some work better than others. Green Glue, Swedak, Decibel Drop, Quiet Glue. All are dispensed via a standard quart size caulk tube or a specialized applicator and 5 gallon pails.

Very fast, no trowel.


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## joepro0000

Ted,

The caulk tubes are not really good, because one would want to spread it on every part of the drywall. I do have green glue, and that is very expensive. Probably there would need to be a 5 gal pail where you can throwel or roll it on.


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## mds120

Go here for more advice: 


http://www.greengluecompany.com/

http://www.soundproofingcompany.com/

And no, I don't work for green glue. This site explains the science behind sound isolation.

In our own company we decided sound isolation is like building a deck. What are the existing conditions, expectations and how much do you want to spend. This leads to custom solutions hopefully based on STC ratings.


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## Ted White

The Green Glue is not spread into a continuous layer. You want fat 3/8" beads. Never trowel, never roll.


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## joepro0000

How far apart should you spread the 3/8" beads? I thought you only put the green glue in the joints of the 1st layer.


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## rckslash2010

joepro0000 said:


> How far apart should you spread the 3/8" beads? I thought you only put the green glue in the joints of the 1st layer.


about 8 inches between the layers.


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## Ted White

Here are a couple of images of the patterns. One shows a tube of glue, the other the bulk pail and applicator



















You can see there's no pattern. Basically just get the material on the board so it's somewhat even. The screws will squeeze the glue to a thin film. Even after squeezing, there will be gaps of board with no glue. That's what we're after.


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## joepro0000

Don't you think it would be more proficient to cover the entire board?


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## Ted White

joepro0000 said:


> Don't you think it would be more proficient to cover the entire board?


Not at all. In fact when studied, fat 3/8" beads performs better than smaller beads. 

Damping compounds don't block sound , so we never concern ourselves with complete coverage.


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## shreiber

joepro0000 said:


> very interesting, what is the damping material called? Do you think it can be rolled on the first layer of drywall then install the second layer staggered?


Each company uses their own compound. Quiet Rock uses Quiet Glue. The best tested damping compound on the market is Green Glue. Here is some lab testing comparing Green Glue to other damping compounds.
The compound usually comes in tubes (you can also get them in 5 gallon buckets) so you would be caulking it out from a gun rather than rolling it on. It can be applied to the face of the first layer or to the back of the 2nd layer although most installers prefer the back of the 2nd layer as it is easier to caulk onto a horizontal surface vs. a vertical one.


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## d-rock

I've done quite a few rehearsal and recording studios, I have to say, we've always had more success with double or triple layers of standard 5/8 rock. We also used RC to create air space between the framing and rock. Other times we isolated the framing with neoprene. In addition, adding therma fiber in the bays also helps reduce transmission. I've worked with quiet rock and I don't prefer it, costs too much and underperforms. We're pricing it for alot of jobs now.


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## Ted White

Two sheets of field damped 5/8" rock will outperform three sheets of undamped 5/8" . See the bottom of this page: http://www.greengluecompany.com/greenGlue-vs-ExtraDrywall.php


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## Mudshark

*Res Bar*

Around Vancouver Island the norm would be resilient channel (res bar or sound bar) screwed to wooden joists with 2 layers of 5/8 board over that on the ceilings. This is what you see on almost all multifamily dwellings.


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## Ted White

Res bar, also known as resilient channel or RC-1 is a fair liability. Prone to short circuits it often fails. Also, there's no North American specification for its construction. Any manufacturer can make their own. No spec, no tests.

A few older products like soundboard, res channel and MLV all have better options now.


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## NewB

Would I be able to get away with 2 1/2' standard board mounted on the sound bar/resilient channel?


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## Ted White

You could, however:

1-The resilient channel itself is still highly suspect

2-The added mass from double 5/8" is a LOT better than double 1/2"


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## NewB

Is the glue, a must on between the boards? I'm texturizing them after as well, this is a small basement about 900sq ft...but it's my first soundproof install.


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## NewB

I guess saving money as much coz owner is cheap, but then again I'm trying to build a quality finish around their price range. so here is the set up, 2 x 1/2" without glue in between, first sheet on then second sheet will be installed perpindicular to the first. What do you think Ted?


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## Ted White

This all depends on what sort of noise the person is looking to reduce. If he has an office downstairs, then double 1/2" and some R19 in the ceiling will cut the noise OK. 

If he has a theater going in, then double 1/2" is a waste of money.

Do you know what the sound is that is concerning?


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## NewB

I think just so the basement tenant couldn't hear the people upstairs, that's about it, no theatre rooms or any loud parties..


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## Ted White

I see. That makes sense. I'd still say if double 5/8" can be used, it should be. The added mass of the double 5/8" really makes a difference. You're still installing two shets of drywall, and the cost between 1/2" and 5/8" is close.


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## NewB

would you recommend res bar between the rooms though? because the power outlets are installed for 1/2" board.


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## 2buckcanuck

NewB said:


> would you recommend res bar between the rooms though? because the power outlets are installed for 1/2" board.


geez.....how many questions you going to have when you start taping.
don't forget to ask, weather you should use mesh or paper tape on this site.:whistling2::boxing:


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## Ted White

NewB said:


> would you recommend res bar between the rooms though? because the power outlets are installed for 1/2" board.


I'm not a fan of res bars. Since there's no standard for the bar construction, you have no idea what the performance will be.


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## SlimPickins

Hey Ted, is there a product like 1/8" or 1/4" rubber on a roll for putting on floor joists under sheetrock? I'm in a basement right now where the floor is going to be raised almost 2 inches, and we're already tight for head height. We're going to insulate the joist bays, and the lid will go 5/8 (single layer only), but I'm looking to reduce sound transmission through the joists. It would be similar to that rubber sheeting, but only in 1-1/2" width.


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## Ted White

Hey Slim,

Unfortunately anything applied in that fashion will do little to nothing. The main reason is that the drywall screws will pass through the foam, so any theoretical benefit is gone. Such products are sold because they appear to bring benefit and so people buy it.

You might consider:

Installing standard R19 fiberglass
Installing wood furring every 24" perpendicular to the original joists.
Attach the drywall to the furring.
24" OC framing is more sound isolating than 16" OC. Take care to pre-drill the furring when attaching to the joists. A split here could be bad news. Use a deck or wood screw for this attachment, not a drywall screw. Lastly, consider a small amount of consruction adhesive between the furring and joist.


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## SlimPickins

Hi Ted,

Thanks for the input...we're planning on putting in the R-19, I was just hoping that I could put some foam/rubber on the joists and at least reduce the transmission from direct contact with the rock. The homeowner has just received word that he's going to be laid off soon (why are we proceeding with the remodel??), and we're trying to keep costs down, in addition to maintaining the maximum ceiling height.

So even if I put something like rim joist closed cell foam on the joists the effect will be negligible? As in, not worth the labor and material costs? Right now we're at 90" from the floor, and we're installing a 2"+ build-up on the floor to insulate from below....final ceiling height ~ 87 3/8" (with a soffit at 77 3/8" )


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## Ted White

I can't recommend foam. Try the furring strips. That has lab tested value. Wood strips are 5/8" at Lowes.


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## SlimPickins

Alright, thanks for the information. Ultimately, the choice is up to the homeowner. I'll give him as informed a decision as I am able.


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## Axecutioner-B

Ted White said:


> I can't recommend foam. Try the furring strips. That has lab tested value. Wood strips are 5/8" at Lowes.


Are you saying that styrofoam has no sound deadening value? Or spray foam? I would think they would help considerably.

So 1" foam sandwiched in between 2 pieces of drywall is no good ?

I think this is a pretty interesting topic really :thumbup:
________
Avandia lawsuit


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## 2buckcanuck

sound travels better through a solid ,rather than air.
check out the sound batt insulation.sorry but I don't know the specs on it,not sure how good it is,but it cost more.
Google:yes:


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## Ted White

Dense foam is *much worse* that light fluffy insulation in a sealed cavity. 

There's no advantage to using an insulation product labeled for sound control or acoustics. This is simply an awareness building / profit opportunity by the mnanufacturers.

This is one instance in life where the cheapest product is also the best performing.


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## Bevelation

2buckcanuck said:


> sound travels better through a solid ,rather than air.
> check out the sound batt insulation.sorry but I don't know the specs on it,not sure how good it is,but it cost more.
> Google:yes:


You mean to say that sound is dampened less through denser materials, as opposed to less dense materials like fiberglass that contain tiny air pockets.

Are you talking about ROXUL Safe n' Sound? I hear that stuff is pretty good.


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## DSJOHN

Ive followed Teds advice for a couple yrs now and he definitely knows his stuff-- He,ll help you with any soundproofing you need to tackle--just ask!!


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## NewB

Ted White said:


> I'm not a fan of res bars. Since there's no standard for the bar construction, you have no idea what the performance will be.


Oh man, after installing the res bars, I see why you don't like em, geez, those things don't seem like it would get the job done (soundproof). I just installed them perpindicular to the joist and boarded em..the waiting game begins, hope it works though.


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## Ted White

Exactly.


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## SlimPickins

Ted White said:


> Hey Slim,
> 
> Unfortunately anything applied in that fashion will do little to nothing. The main reason is that the drywall screws will pass through the foam, so any theoretical benefit is gone. Such products are sold because they appear to bring benefit and so people buy it.
> 
> You might consider:
> 
> Installing standard R19 fiberglass
> Installing wood furring every 24" perpendicular to the original joists.
> Attach the drywall to the furring.
> 24" OC framing is more sound isolating than 16" OC. Take care to pre-drill the furring when attaching to the joists. A split here could be bad news. Use a deck or wood screw for this attachment, not a drywall screw. Lastly, consider a small amount of consruction adhesive between the furring and joist.


I did all of these things, because of the homeowner's wishes...in my book you're right, it was a waste of time and energy.

Separate question for you Ted....how many tubes of Green Glue per 12' sheet? I thought the guy who asked me to use it today had said 2 tubes per 12'-er, but after I'm done he said that it was actually 2-1/2 tubes for an 8 ft. sheet. That works out to almost 4 tubes for a 12'-er....and that seems like an awful lot of a very expensive material.


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## Ted White

Generally 2 Tubes per 4x8 sheet. Three per 4x 12. One tube per 4x8 will give you 70% of the performance of two tubes. Better low frequency (bass) performance with two. Application amount depends on what you're trying to accomplish.


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## SlimPickins

Ted White said:


> Generally 2 Tubes per 4x8 sheet. Three per 4x 12. One tube per 4x8 will give you 70% of the performance of two tubes. Better low frequency (bass) performance with two. Application amount depends on what you're trying to accomplish.


This was a wall between a conference room and an office. The builder had insulation blown in, and then I laminated with green glue and 5/8 board. Without sitting down and really doing the math, it looks like my mistake cost them 20% of the sound reduction then, mostly in the low frequency range. Maybe I'll offer to reduce my bill by 20% to make up for it. (they did save an entire case of glue though)


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## 2buckcanuck

SlimPickins said:


> This was a wall between a conference room and an office. The builder had insulation blown in, and then I laminated with green glue and 5/8 board. Without sitting down and really doing the math, it looks like my mistake cost them 20% of the sound reduction then, mostly in the low frequency range. Maybe I'll offer to reduce my bill by 20% to make up for it. (they did save an entire case of glue though)


honesty is a good virtue ,and I believe in being honest,,,,,,when asked,,!!!!
Just saying if the home owner is happy with the results ,then why stick your neck out .If their not happy ,then you can step forward .You thought you were providing the best results at the time ,so don't let guilt cloud your mind.
your family comes 1st,Or you can be honest with your family,and explain why their getting 20% less food this week.
plus I can't tell if your being sarcastic in your post,guessing you are,but in case your not..........:yes::thumbsup:


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## SlimPickins

2buckcanuck said:


> honesty is a good virtue ,and I believe in being honest,,,,,,when asked,,!!!!
> Just saying if the home owner is happy with the results ,then why stick your neck out .If their not happy ,then you can step forward .You thought you were providing the best results at the time ,so don't let guilt cloud your mind.
> your family comes 1st,Or you can be honest with your family,and explain why their getting 20% less food this week.
> plus I can't tell if your being sarcastic in your post,guessing you are,but in case your not..........:yes::thumbsup:


I wasn't being sarcastic, and unfortunately, the builder was the one who did the research on the green glue...so he knows how much material was intended to go the sheets. Honestly, I thought I was doing what I was told to do, but either I, or my partner (who's job it was), had a breakdown in communication. According to Green Glue's website, there's a wide range of effectiveness, and skimping on material doesn't cause _that_ drastic of an effect. I haven't actually offered to reduce my price just yet, but I appreciate your input. I tend to err on the side of treating everyone overly fair....sometimes to my own disadvantage. I'll tell you this though...I could hear the wall getting more quiet as I worked on it. Either way, the $300 saved on the case of material should look pretty darn good!


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## Ted White

SlimPickins said:


> This was a wall between a conference room and an office. The builder had insulation blown in, and then I laminated with green glue and 5/8 board. Without sitting down and really doing the math, it looks like my mistake cost them 20% of the sound reduction then, mostly in the low frequency range. Maybe I'll offer to reduce my bill by 20% to make up for it. (they did save an entire case of glue though)


That's plenty of GG and I would not worry about that part. What worries me is the insulation. Compressed insulation will conduct a vibration = very bad. It's ridiculously common with blown-in fiberglass or cellulose


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## SlimPickins

Ted White said:


> That's plenty of GG and I would not worry about that part. What worries me is the insulation. Compressed insulation will conduct a vibration = very bad. It's ridiculously common with blown-in fiberglass or cellulose


That's really good to know, Thanks Ted. I wasn't around for the insulation part of the decision making process...but I will bear it in mind for the future. The wall is definitely much quieter now, and the owner of the building is very happy. :thumbsup:


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## SlimPickins

Side note: that Green Glue is some weird stuff. I applied it on Friday, and there were some blobs on the box where I set the tubes while hanging the sheets. The stuff never really sets up, it's super elastic and sticky. I can definitely see how it works to reduce sound transmission. I wonder if it gets less effective over time:confused1:


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## Ted White

The material stays soft forever. Takes maybe 30 days to dry in between drywall


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