John Sayers' Recording Studio Design Forum

Hello all,
To preface my question - I've been doing a lot of reading about Green Glue - on their site and on this site (using the search function). My impression of the product is even more in depth thanks to explanations from Rod and Eric from other threads.
I'm very impressed and would love to use the product at my earliest financial convenience.

So here's my question: If I simply cannot afford to sandwich all my drywall together with Green Glue - what is the most acoustically sound method of doing so? (assuming I can also only afford 2 sheets of 1/2 inch drywall on every wall).

- Buying as much Green Glue as I can afford - and spreading it out amongst the walls? Would a little even help - or does it have to be used in it's entirety to be effective?
- Powernails (or similar drywall adhesive). Does this have any acoustic benefit at all?
- Drywall screws
- Some combination of the ideas above

...or something else entirely?

Thanks in advance,
Todd

_________________
“Give me six hours to chop down a tree and I will spend the first four sharpening the axe.” Abraham Lincoln

Green Glue is an excellent product, but it is indeed expensive, and to be honest, there are other ways to achieve the desired isolation.

More drywall, for example... Two layers of drywall with Green Glue in between can perform as well as four layers of drywall without Green Glue, but you can do the four layers of drywall at a lower cost (assuming you're doing the work yourself and don't mind the job taking a lot longer and/or saving money at the rate of minimum wage ).

You can also use less Green Glue (as little as 50% of the recommended amount) and still get a substantial benefit. The recommended amount is two tubes per 4' x 8' sheet of drywall, so you can technically stretch it to one tube per sheet, provided you understand that you will be reducing its effectiveness:

70% Coverage of Green Glue
Damping Factor: ~.35
If money is tight, you can obtain as much as 70% of Green’s great performance with just 50% of the surface area covered. (Source)

Green Glue is a livesaver if headroom is at a premium and you're unable to add the multiple layers to an existing ceiling structure due to the risk of overloading the framing. Each layer of drywall is about 2.3 pounds per square foot, and sometimes the joists/trusses aren't rated to handle more than one extra layer of drywall (if that).

The name "Green Glue" is a misnomer because it is not a glue. Therefore, you cannot compare it to any other kind of adhesive. One must use the same number of screws on a layer of drywall that has Green Glue behind it, as though it had no Green Glue.

For this reason, I wish they called it "Green Goo."

--Keith

_________________
"Converting a garage into living space requires a city permit . . . homeowners insurance won't cover a structure that's been changed without a building permit . . ." --Sacramento Bee, May 27, 2006

Thanks for the reply sharward!!

Thats really cool about 70% effectiveness with 50% the product.

I also didn't know about the fact that you still have to bond the 2 layers together after you apply the Green Glue.


So (and I don't want to put words in your mouth) - would you say that there is no real cheaper alternative? From my reading - it seem Green Glue is the best. It's just so dang expensive, and I can;t really afford the loss of space and the addition of weight that 2 more layers of drywall would add.

Is that mass vinyl stuff any cheaper? It seems I read that it's less effective, but maybe that's OK for the right price.
Has anyone tried acoustical sound sealant/caulk stuff between drywall? Would that even do anything?

I know I'm probably reaching for straws here - I just want to do the best with what I can afford.

Thanks again!
Todd

_________________
“Give me six hours to chop down a tree and I will spend the first four sharpening the axe.” Abraham Lincoln

Search for the term "MLV" (stands for "mass loaded vinyl") and you'll find countless references to that stuff being a waste of money.

_________________
"Converting a garage into living space requires a city permit . . . homeowners insurance won't cover a structure that's been changed without a building permit . . ." --Sacramento Bee, May 27, 2006