Soundman2020 - Studio Design Forum

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The Truth About Green Glue

This is a group of test results that I have found about Green Glue compound over the years, some of it published by the company itself, others from different sources, unrelated to the company, and that I have collected as reference material. Please note that I do not sell this product, and I do not accept advertising on the forum: this has nothing at all to do with advertising. However, there seem to be a lot of rumors and plain old wrong information on the Internet about Green Glue compound, what it is, and what it does, so I'm putting up this page with actual test data from independent testing facilities, so people can judge for themselves.

Basically, it's a good product, and it works well, but it is expensive. Very expensive. So it is not for everyone. On a tight budget, don't use it (unless you need very high isolation, and can find more money!)

On the other hand, using full coverage recommended by Green Glue (three tubes per 4'x8' / 120x240cm sheet of drywall) is about the same as adding THREE TIMES AS MANY layers of drywall to your wall (on each side).

How can I make such a ridiculous statement? Where do I get that from? Right here: That comes from the tests comparing Green Glue compound to MLV, and shows the clear superiority of Green Glue, but also note the comment in the test description: the improvement from using Green Glue is similar to the improvement you would get from "tripling the mass", which implies adding three times the number of layers of drywall to the existing wall, on each side. That alone is mighty impressive. (Also note that this testing was done down to 31 Hz, which is also impressive!)

My purpose here is not to promote the product, but rather to provide valid, correct test data about it, to correct some common misconceptions.

Drawbacks? Cost. It is expensive. It is also messy to apply, slows you down in your build as it takes a lot longer to apply it, and it only reaches peak performance after a month.

So, here's the data, in no specific order, except to start with a test done in Australia at the independent CSIRO ("Commonwealth Scientific and Industrial Research Organisation"), showing the rather impressive results that can typically be obtained: The rest of the data:

A quick follow-up, to just clarify as there is often confusion about which "Green Glue" product to use.

The Green Glue company makes several products, among them two that can easily be confused. The one I'm talking about here is this:

"Green Glue Noiseproofing Compound". (It is also sold in "sausages" and tubs or buckets, for larger jobs.) That's the stuff that you squirt on the back of your second layer of drywall just before you put it up. It creates a "Constrained Layer Damping" buffer between the two layers, that works in several ways to improve isolation.

I am NOT talking about their other product:

"Green Glue Noiseproofing Sealant". That is an entirely DIFFERENT product, for a totally different purpose: caulking. Basically, it is acosutic caulk, or acoustic sealant, for sealing joints, gaps and cracks. I DO NOT RECOMMEND THIS SEALANT PRODUCT! It shrinks as it dries, and can crack or pull away from the sub-surfaces. I have had problems with this product on a few studios. Do not use it.

Instead I recommend other products for this application of caulking and sealing. Most good-quality bathroom and kitchen caulks will do the job just fine. The one I have had most success with on many studios, is this:

It is also available in "sausages", for larger caulking guns:

This is a much better product than Green Glue sealant (cheaper, too). it is both adhesive and also flexible caulk, all in one. It never hardens and remains soft, pliable rubbery, even when fully cured. It does not shrink and crack, like the GG sealant does. So that's what I use, and recommend, for sealant.

So don't confuse the two! the "Green Glue Compound" in the green tubes (and tubs) is great stuff, for improving isolation by spreading it in a thick layer between sheets of drywall, and recommended. Use it if you need it and can afford it. Green Glue Sealant in orange tubes, is for caulking cracks, gaps, and joints, is NOT a great product. Avoid it. If you bought the wrong (orange tube) stuff by accident, then return it for a refund.

I'll try to write a follow-up article here, at a later date, about how GG actually works, acoustically. It's quite clever.

- Stuart -

Thanks Stuart. I have a box of the stuff to apply when the time comes to improve some walls.

One thing though, the instructions that came with the box recommend 2 tubes per 4'x8' / 120x240cm sheet of drywall. The Green Glue FAQ says the same, "Each case of our Green Glue Noiseproofing Compound contains 12 tubes and covers approximately 192 sq. ft. at the recommended 2 tubes per 4’ x 8’ (3 m²) sheet coverage."

Is it possible they changed the recommended amount?

The box instructions also mention that you can use 1 tube per 4'x8' sheet and get 70% of the benefit.

Cheers,
Jennifer

Is it possible they changed the recommended amount?

They probably did! I'm pretty sure that originally their recommendation was 3 tubes per sheet, but they also mentioned 2 tubes and 1 tube, with reduced effectiveness. I may be wrong on that: I'll look back in my archives, to check on that... Maybe it was a marketing thing? Makes it look 33% cheaper if you only need to use 2/3 of the original amount...

But 2 tubes per sheet is fine.

- Stuart -

One of the advantages of asking here.

endorka wrote:Source of the post Thanks Stuart. I have a box of the stuff to apply when the time comes to improve some walls.

One thing though, the instructions that came with the box recommend 2 tubes per 4'x8' / 120x240cm sheet of drywall. The Green Glue FAQ says the same, "Each case of our Green Glue Noiseproofing Compound contains 12 tubes and covers approximately 192 sq. ft. at the recommended 2 tubes per 4’ x 8’ (3 m²) sheet coverage."

Is it possible they changed the recommended amount?

The box instructions also mention that you can use 1 tube per 4'x8' sheet and get 70% of the benefit.

Brian Ravnaas, creator and assigner on the Grreen Glue patent, posted a lot on Studiotips.com as the product was being developed. What the development team found was that sound isolation improved with each increase in product. What they figured was that they had to stop somewhere that did not make it look like that the company was just trying to sell more product.

Enjoy!

Great compilation Stuart. Thank you.

Thanks Andre! Great info about the development. I wasn't aware of that! I must go take a look at Studiotips again. I haven't been there in a while. I hope the info is still there.

What the development team found was that sound isolation improved with each increase in product. What they figured was that they had to stop somewhere that did not make it look like that the company was just trying to sell more product.

Hmmm... so in theory you could use 5 or 6 tubes per sheet, and get even better performance.... you'd just have a REALLY expensive wall!

I wonder if they have any published test results for a large number of layers? That would be interesting...


- Stuart -

Soundman2020 wrote:I wonder if they have any published test results for a large number of layers? That would be interesting...

There was the following quote from Ted White on Geatslutz, mentioned on my riser thread;

Ted White wrote:It's worthwhile to note that all things being equal, having three mass layers + 2 thin damping layers (1 tube per sheet) will be more damped than a system with two layers of mass and one thicker damping layer (2 tubes per sheet). Again, assuming same overall system mass and quantity of damping compound.

I've not found any actual test results for this unfortunately.

Cheers,
Jennifer

That's interesting. I wonder where Ted got that from. I don't recall having seen any info on that, but it sounds possible.

- Stuart -

Look at the last diagram (table of performance) in this Green Glue PDF.

Starlight wrote:Source of the post Look at the last diagram (table of performance) in this Green Glue PDF.

That is quite remarkable, and to my mind seems like a reasonable comparison.

There is another advantage to Green Glue for people like me who are not experienced at drywall construction. By that I mean those who "have never built a drywall partition but for the sake of ultimate sound will be doing it at some point in the near future" And that advantage is simple: each layer of drywall takes considerable time. Squirting a few tubes of green glue takes mere minutes.

To state it more seriously: the cost of the Green Glue is less than the cost of the additional time/labour that would be spent applying extra drywall layers.

Cheers,
Jennifer

endorka wrote:Source of the post To state it more seriously: the cost of the Green Glue is less than the cost of the additional time/labour that would be spent applying extra drywall layers.

Very true. That's in addition to losing a couple of inches along each dimension of the room... and the extra weight! In your case, you would probably not be able to even do 3 extra layers of drywall, since you are on an upper floor: structural overload? But one extra layer with GG is probably OK.

- Stuart -

Soundman2020 wrote:Source of the post... and the extra weight! In your case, you would probably not be able to even do 3 extra layers of drywall, since you are on an upper floor: structural overload? But one extra layer with GG is probably OK.

Indeed so. Agreed, I suspect one extra layer with GG will be ok. I'll consult with a structural engineer before adding anything to be doubly sure. I find that keeping these things in order helps one sleep at night.

Cheers,
Jennifer

Simple question (I hope )
How much extra depth does green glue add to the thickness of a wall?
I'm guessing 1-2mm maybe?

at most. the layer gets flattened to cover most of the surface. note that the GG company says to use the caulk method and not to trowel it as the trowel method (while faster, easier, and more like applying tile mastic), they claim it reduces the effectiveness compared to the caulk random drizzle technique...