Super Soundproofing Community Forum

Soundproofing Forum Topics => Other Soundproofing Questions => Topic started by: induray on October 31, 2005, 11:50:03 AM

Title: Audio Alloy Green Glue
Post by: induray on October 31, 2005, 11:50:03 AM
I am planning to install an extra layer of sheetrock 5/8" to an existing wall for noise abetement. Has anybody used the Green GLue? How do you rate it? Is it worth the extra cost? Please no endorsements fm Audio Alloy employees ;D
Title: Re: Audio Alloy Green Glue
Post by: supersoundproofing on November 01, 2005, 11:01:26 PM
While the product is too new to rate, folks like you would be a real asset if you were to report how it worked.  Issues involved would be ease of use and odor, how difficult to get the things together, etc.  Hope to hear from you!

BJ Nash
Title: Re: Audio Alloy Green Glue
Post by: induray on November 02, 2005, 10:53:20 AM
If I decide to go for it I will. Now here is a question. What would be a good homemade test to measure subjectively the reduction rate. I know that in order to do that
A. I must have a reproducible source of constant amplitude at a give frequency and output. A boombox will do and I think I can create a CD with a mid range tone at constant amplitude . Maybe using NERO software?.

B. I must have a way to measure sound energy and this is where I fall short. Any cheap Ideas????I should measure in db but  I can't figure out RTC rating based on  db ratio  before and after installation. db_before/db_after= ratio. Or I could just report db before and db after.

Please forgive me. I am an engineer by profession (acft structures). And cheap by birthright. (I am a do-it yourselfer) ;D

Title: Re: Audio Alloy Green Glue
Post by: induray on November 02, 2005, 10:57:37 AM
To the Moderator. By reading the technical info on their  website. By your experience, do you think Green Glue has potential/merit?? ???
Title: Re: Audio Alloy Green Glue
Post by: supersoundproofing on November 03, 2005, 12:30:17 AM
To answer the question about sound measurement first- a cheap but useful sound measurement meter is available from Radio Shack for about $30.  We've used it and it compares faorable with expensive (impressive) meters  used by the trade.  Keep it simple- measure with and without without the math....

Regarding the effectiveness of the glue- I would think it should be very effective.  Quiet rock has obtained very good STC rating with their use of it in sheetrock assemblies and that should easily be duplicatable by DYI'ers.

In fact we are investigating thse issues as we speak...

BJ Nash
Title: Re: Audio Alloy Green Glue
Post by: induray on November 03, 2005, 10:52:21 AM
Excellent. I am encouraged to do it and test it. I am currently painting the outside of my house, but soundproofing  is the next project to tackle. Will keep you posted on issues as ease of installation, fumes/smell and noise reduction.

Thanks for the info.

Title: Re: Audio Alloy Green Glue
Post by: MrCoolGuy on May 16, 2006, 07:51:35 PM
A local and highly respected acoustician is advising me to use SikaFlex rather than Green Glue. He claims to have used both and says "SikaFlex is just as good". So, anyone in here have any experience with both and want to weigh in?
Title: Re: Audio Alloy Gren Glue
Post by: Hickory_Stick on May 18, 2006, 04:49:53 AM
What kind?  There are many types of sealants.  Exactly which?

Title: Re: Audio Alloy Green Glue
Post by: hickory_stick on June 08, 2006, 02:24:13 AM
I see Super Soundproofing is now carrying it.

Title: Re: Audio Alloy Green Glue
Post by: noisetwentyone on June 21, 2006, 05:20:42 PM
Green glue seems to improve the STC of a wall by 9 points if you use 8 tubes per 4' x 8' area of wall. That would be 4 tubes on each side of the wall.  At least according to Audio Alloys web site for a 2x4 construction wall with thermal insulation and two layers of 5/8" rock on both sides:

comparing apples to apples:

So each 4'x8' area of wall space would cost $143.60 or about $4.48/sq. ft. if you pay $17.95 per tube.

Nine STC points is not bad, almost 50% of perceived noise.

Title: Re: Audio Alloy Green Glue
Post by: noisetwentyone on June 21, 2006, 05:29:02 PM
Actually it's a 10 point STC improvement. I'm still learning to count.
Title: Re: Audio Alloy Green Glue
Post by: bjnash on June 21, 2006, 06:35:36 PM
The Green Glue people claim a 58 STC by the use of their product- a normal residential wall is about a 20 so thats a awesome increse in sound control.

BJ Nash
Title: Re: Audio Alloy Green Glue
Post by: noisetwentyone on June 21, 2006, 07:51:54 PM
The ad in your link doesn't say how many layers and the thickness of the drywall they used in their test to get the stated STC 56. However, according to their site, they used double layers of drywall on either side of the wall and thermal insulation between the studs:

The STC of a normal wall is well above 20:

According to the above site, the STC rating of single layer 5/8" drywall, one on each side of 2' x 4' studs with thermal insulation will provide an STC of 34 to 39. Increasing the mass by two, or doubling the drywall layers will further improve this by 4 to 6 for a total of STC38 to STC45.

The difference is 11 points.
I would love to see ASTM come up with a better test than the E90. STC applies to interior walls only and was designed in the old days when I was at college. This was in the days before subwoofers and 500 Watt stereo systems. The test was designed to provide an idea of how well an interior wall would block radio and televion noise along with conversation. It also applied to office noise.
Title: Re: Audio Alloy Green Glue
Post by: johnbergstromslc on June 21, 2006, 09:45:46 PM
Actually, the tests indicate a 10 point STC rise (44 to 54).  But this was tested on a regular stud wall with no resilient mounting, kind of the worst way to go.  One thing that caught my eye was the increase in transmission loss at 100 Hz - 18 dB for the untreated wall, 25 dB for the Green Glue wall.  7 dB at that frequency will make a huge difference.  

I think 4 tubes per side is excessive.  Their own website says that more than 3 tubes and the performance gains level out.  2 tubes per side is the recommended quantity, and even 1 tube per side (at $0.60/ sq. ft.) will do some good.  

Green Glue is a cool product and I will continue to use it, where budget allows, but to get the really high STC numbers, you can't beat resilient channels, staggered studs, double studs, additional drywall mass and good sealing.  

For example, a double stud wall, insulated, with 3 layers of 5/8" drywall per side and 2 tubes of Green Glue between each sheet of drywall (a total of 232 oz., the same amount as in the lab test) will get you an STC of 75+, massively outperforming a little, wussy STC 54 wall.
Title: Re: Audio Alloy Green Glue
Post by: induray on June 22, 2006, 09:39:43 AM
I am still unable to commence with this project due to other pressing issues. If anyone tries it first, please give us your results.
Title: Re: Audio Alloy Green Glue
Post by: johnbergstromslc on July 03, 2006, 04:23:16 PM

I have used it and it works.  It's by no means a 'miracle' product - it's not gonna magically kill all the sound - but it definitely helps at the lower frequencies.

If you're concerned about performance, check out their website (  They now have independent, third-party acoustical tests available online, both with and without Green Glue.  You can compare that way.  

If cost is the issue, it's much better to go with an additional sheet of drywall per side ($8 per sheet, per side) versus going with a lesser amount of drywall and a layer of Green Glue.  Green Glue adds $30 per 4X8 sheet, per side to the construction, at the recommended 'dosage'.  In most ways, you'll get much better performance with more mass.  The downside is it adds thickness to your wall.  Sometimes you can't afford to lose the space.

Just make sure you have excellent sealing, regardless of what you decide.  

You mentioned in one of your posts you wanted to do some tests and try to find some sort of dB ratio (dB before/dB after) to evaluate performance.  Admirable, but in my opinion, this is the wrong way to approach the problem.  

Inside a quiet house the 'background' noise level is about 30 dB.  If your neighbor comes home and plays his stereo/TV at 90 dB (hopefully the worst case scenario) and you have a standard, wood stud wall (STC 33) separating the two rooms, then his noise will impact you to the tune of 57 dB, approximately.   If you're trying to soundproof and reduce his noise to the 'background level' of 30 dB, you need to upgrade the structure to an overall STC of 60.  This is not so easy (or cheap) to do.

If you could live with 40 dB of noise (and increase the ambient noise in your space to compensate), you'd need a wall with an STC of 50.  This is much more viable.  

So, if as you've said, you'd like to do it as cheaply as possible, consult books/websites on soundproofing and find the configuration that achieves STC 50 as cheaply as possible.  I can tell you right now, it won't be with Green Glue, Quietrock, MLV, or any of the other 'advanced' products out there.  It'll have resilient mounting or structural decoupling and lots of mass.  

Personally, what I have found works best is to convert a regular stud wall into a staggered stud, sealed and insulated, with 2 layers of 5/8" drywall per side (or maybe 3 layers on one side, since you don't have access to the other).  This achieves an STC of about 57-58, and all the materials I can get at Home Depot/Lowes.  And, unlike building a double wall, you keep your fire blocking intact and don't get into trouble with the building inspector.

It really sounds like you're overthinking the problem.  I say just go for it - buy a case of Green Glue and do one wall.  Stick your ear up to it and if you like what you hear (or don't hear -  yuk, yuk..) then do the rest of them.  If not, switch to the less expensive way.  

Just keep in mind that some of the noise is going to 'flank' around the wall, and you might find you have to do the floor and/or ceiling too.

Title: Re: Audio Alloy Green Glue
Post by: johnbergstromslc on July 18, 2006, 10:50:05 PM
Give it up, Andy.  Quietrock is too goddamn expensive and you know it.  If you were so confident about your product, you would state the prices in your posts...

How about it?

Besides, this forum is run by supersoundproofing.  They might not appreciate you trying to muscle in on their turf...
Title: Re: Audio Alloy Green Glue
Post by: joel on August 04, 2006, 03:32:31 PM
Hello induray,

Green Glue was recently used by Boston University in a new student performing arts room.  The application was done by students with no formal construction experience.  Results were excellent - noise was contained within the room and surrounding areas were quiet.  Green Glue sandwiched between drywall is a simple and highly effective soundproofing solution for walls.

By the way, Audio Alloy is now known as The Green Glue Co.

Title: Re: Audio Alloy Green Glue
Post by: jamesboyd on August 29, 2006, 02:08:57 AM
Looking at some of the posts, one thing strikes me. There's a lot of talk about STC and the problems with low frequencies, but STC doesn't measure low frequencies.

For the record, the data is pretty clear that Resilient channel stinks in the low frequencies. Also, the data you see? It's OLD, and that type of RC hasn't been made in years. YEARS. The stuff available now is too stiff. Either way, it doesn't do you any favors in he low frequencies.
Title: Re: Audio Alloy Green Glue
Post by: agtrojan on August 30, 2006, 09:27:53 PM
You're right about not having a standard method of testing transmission loss below 125Hz.  However, the Green Glue Co. has invested in obtaining independent lab reports to measure the transmission loss at frequencies between 31Hz and 80 Hz.

Take a look at the following :

Using Acoustic Cotton Fiber insulation instead of fiberglass will improve the soundproofing quality of the system.  Take a look at the specs for the Cotton Fiber insulation:
Title: Re: Audio Alloy Green Glue
Post by: induray on August 31, 2006, 09:48:00 AM
Great Thread! Thanks for the info and please keep it coming!

Title: Re: Audio Alloy Green Glue
Post by: johnbergstromslc on August 31, 2006, 01:15:29 PM
Again, with the cotton...

Give us a frickin' break, it doesn't work that much better!!!
Title: Re: Audio Alloy Green Glue
Post by: joel on August 31, 2006, 09:29:39 PM
Hi induray,

I am not an audio alloy (now called the Green Glue Company) employee.  We have used it.  In fact, a contractor we know used it in his daughter's music practice room ceiling (there was not enough ceiling height to install other systems) to stop her "noise" from going up into the parent's bedroom.  It worked so well for him that he orderd another 10 cases to do the entire music practice room and one of his clients rooms as well.

The outside (independent) test data that supports Green Glue effectiveness in many construction applications is extensive and impressive.  More importantly, it can be duplicated and verified by anyone.