Are there any Green Glue alternatives, 2nd layer of drywall?

Hi all, I have started to price materials for my build that will start Oct 1st. I was pricing Green Glue and wow thats expensive and I figure it will take around 5 cases to complete my control room. Thats alot of dollars that I really cannot afford. What other options do I have when it comes to attaching my second layer of drywall? Also what manufacturer of Acoustical Caulk or Sealing compound do you suggest? Thanks Eddie

There are no other adhesives that compare to Green Glue as far as I know. A lot of others share this opinion and Rod’s book states it. Regular construction adhesive or drywall adhesive is not recommended when trying to achieve sound isolation. Next best cost effective thing to Green Glue is another layer of drywall. You can use as low as 50% coverage with Green Glue which would be 1- 30oz tube for 1- 4x8 sheet of drywall, which gets 70% effectiveness according to directions. Caulk: http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2045 I just bought 24 tubes of OSI Pro-Series SC-175™ Acoustical Sound Sealant From: http://www.contractorstoolsupply.com/index.php?main_page=product_info&products_id=2591 ...for around $100 with shipping. I’ve had no problems so far, others have reported the stuff works good. PS, don't forget to go through the reference section sticky: http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2125 Would have found the same answers there. Marc :twisted:

Just to clarify: Green Glue is for use between two layers of drywall. And as Marc said, you cannot use adhesive to MOUNT your second layer. You MUST use screws. Read more about Green Glue and you'll see how it works. Green Glue is awesome stuff, but it is expensive as you discovered. That "2 cases of OSI acoustic sealant for $100 delivered" is a good price. I buy it for just over $4 per tube plus sales tax here locally. --Keith :mrgreen:

Rod's book arrived today finally! woohooo! I waited 2 weeks for this thing to arrive and finally its here. I have a session Sat and Sun but hopefully Sunday night when everyone leaves I will have a chance to get into it. Hopefully this will be the last month I have to record at home and can move into the new place. Thanks for the info on the green glue! Not sure I can afford it and not sure I can afford not too. I have some reading to do. Im not sure where I read it or if I misunderstood but I was under the impression that the 2nd layer of drywall should be glued not screwed in. Thanks Eddie

Eddie D wrote:

Im not sure where I read it or if I misunderstood but I was under the impression that the 2nd layer of drywall should be glued not screwed in. Thanks Eddie

Eddy, Perhaps Rods book covers it. For me, I glued my first layer, then used 2 1/2 inch drywall screws in a full course on the ceiling and walls, gluing the ends of the panels wherever the did not conveniently fall on a stud. Obviously I did not use Green glue, as I imagine the softness of it fills voids and slightly decouples the 2 layers with a somewhat limp mass. I would think it a scary thing to have glued only sheetrock over my head, perhaps imy fear is unfounded as long as the first layer was attached well enough to support it own weight PLUS the weight of the second layer, but sheetrock is not a structural panel like wood is when it comes to loading hanging weight. Tom

Perhaps a construction expert will disagree or clarify this, but here is my understanding. Each layer of overhead drywall should be installed on wood joists/trusses using ring shank nails or course threaded drywall screws (I like screws better), or on steel joists/channel using fine threaded drywall screws. Minimum screw penetration in wood studs is 3/4" of full diameter and minimum screw penetration in steel studs is 1/4" of full diameter. I'm not sure of the minimum penetration for ceilings screws, but Rod likes 1 3/8" as a bare minimum. It is not appropriate to attach one layer of drywall using the above method and then to attach a second layer of drywall to the first layer using adhesive. This does two things: increases the load on the screws of the first layer (not safe); and changes the resonant properties of the drywall (in a "not good way" either) by joining them into a single, thicker panel. The only way I see making it work safely is to double the number of fasteners in the first layer... But then where is the time or cost savings? :roll: I'm also pretty sure that you need at least two edges of a panel to be attached to studs or joists -- that using a construction adhesive along the edge to keep it from "flapping" is not appropriate. In other words, the subsequent layers are fastened in exactly the same fashion as the first layer, with one axis' edges always lining up over a stud/joist/truss/channel. I also recall reading somewhere that drywall does provide some level of shear protection on walls, so to say that drywall is not considered "structural" like plywood may not be completely accurate -- or at least there's more to that story than can be covered here. I know there are building codes that govern this, and although I'm reasonably sure the above accurately covers aspects of them, always consult your local building department to be sure you're in compliance (a.k.a., my standard disclaimer ;-)). For my outer leaf ceiling, I scrapped my plan to tear down the existing ceiling and hat channel and put up new, stronger joists able to support 3 or 4 layers of drywall, and instead installed one extra layer of drywall on the existing ceiling using a Green Glue sandwich. However, in doing so I decided against installing the second layer onto the existing hat channel, as that would have doubled the load on that channel, and especially the 24" o.c. screws that hold the hat channel up! :shock: So, with my building department's approval, I fastened the second layer directly into the bottom chord of the trusses. Ceiling Plan Change: Building Department sign-off: --Keith :mrgreen:

sharward wrote:

I'm also pretty sure that you need at least two edges of a panel to be attached to studs or joists -- that using a construction adhesive along the edge to keep it from "flapping" is not appropriate. In other words, the subsequent layers are fastened in exactly the same fashion as the first layer, with one axis' edges always lining up over a stud/joist/truss/channel.

Keith, Just clarify what I did (anyway) I put the first layer up running parrallel with the joists and wall studs, and the second layer up perpendicular, with a full set of fasteners. The ends fell mainly on studs / joists, but a few fell wherever they may and I glued and used laminating screws to hold the ends, but otherwise they were fully screwed into studs with a full course of 2 1/2 inch screws. Nothing "flapping around". I dont want to give the impression I did anything unsafe. Tom

I'm just curious could you substitute acoustic caulk for GreenGlue? Green Glue is so pricey, kinda like Quietrock...I may add a second layer of 5/8" to my drum room and was thinking of spreading USG Acoustic caulk on each sheet before screwing it in. Any ideas? :idea:

PaulieSkiDrum wrote:

. . . could you substitute acoustic caulk for GreenGlue? Green Glue is so pricey, kinda like Quietrock...

Absolutely, positively NOT. Study the Green Glue Web site. The principles under which it works are extremely well documented there, and you can believe their claims. QuietRock is excellent at MARKETING their product, but the product itself falls flat on price-to-performance and the fact that they push STC ratings. STC is utterly meaningless and quite possibly detrimental as a yardstick when it comes to DRUMS. There are two reasons Green Glue is expensive. 1, it works. Two, they spend big bucks on engineering and independent lab testing to make better product and to prove it works. Slather on anything you'd like, but if you want to go beyond speculation and wild ass guessing, use products and techniques that are credibly proven to perform. --Keith :mrgreen:

did they really use peanut butter to make mister Ed talk?

In all honesty I heard peanut butter may be a good alternative to GreenGlue for my drum room. But then I'd have to get rat traps huh?? :twisted:

Can't I just use some of the many others acustical sound sealant instead of green glue, since I only need like 3-4 tubes...? Maybe this? http://www.contractorstoolsupply.com/in ... ts_id=2591 I do not feel like using so much money on something I don't need :)

Apples and oranges. Green Glue is not a sealant! It is a "constrained dampening layer." You cannot use a sealant as a CDL. Again, study the Green Glue Web site. to learn the principles under which it is engineered to work. And reread everything I wrote in this thread. --Keith :mrgreen:

I'm sorry, but I don not understand every part of your posts, since I'm from Denmark... But can you then tell me when I should use the Green Glue, and when I should use and a sealant...?

I'm sorry, but I don not understand every part of your posts, since I'm from Denmark... But can you then tell me when I should use the Green Glue, and when I should use and a sealant...?

Most of this is already in the reference section and/or on other threads, hopefully an easier read for Danish friend AND for the shear joy of typing. :twisted: Applying Green Glue, acoustic caulk/sealant & drywall mud with tape (joint compound): 1st layer of drywall: 1. Mud and tape all seams of drywall pieces, that is where two pieces meet that you're putting on the same wall, same layer. Drywall (in US at least) is tapered on edges for tape and mud, have to fill in the tapered portion with something or you'll have a small AIR pocket in middle of drywall. 2. On perimeter of drywall (all corners to other walls, ceiling & floor) use backer rod and acoustic sealant. Some skip the backer rod which is not recommended. 2nd layer of drywall: 1. Apply green glue to back of drywall, put it on wall against 1st layer of drywall, make sure to get it fully fastened within 15 Min's of applying green glue (something I almost screwed up, had to run like crazy when I encountered a problem). Fastening the 2nd layer of drywall will squish , spread the green glue between the two layers evenly. 2. repeat same steps for 1st layer of drywall. Finished corners: you can rake back the caulk enough so that you can apply mud and tape in order to make it look like a regular corner of wall when painted... it'll be a pretty corner depending on your drywall skills. ALSO see reference section for more details on how to drywall, caulk etc... AND www.greengluecompany.com Marc