What's my best choice?

sharward wrote:

You'll definitely want to post a detailed drawing of the anatomy of the wall as it exists today and as you propose to make it. More photos of your exsiting situation would help a lot too. I suspect that you may not need that much Green Glue. 9 cases = 84 (EDIT: no -- 108!!) tubes = enough for 42 (EDIT: no -- 54!) 4x8 drywall panels at 100% coverage. I don't think you need to use all those different thicknesses of drywall. I would think two 5/8" would be fine and would be a lot less labor. I don't see why not extending the thickness of the wall into the room would be such a big deal. It seems you have the space to spare. Are you really only trying to avoid "trimming your trim"? --Keith :mrgreen:

Ok guys, I guess they wanted to sell more Green Glue!!! It really is a hassel to extend the wall more, just is. The baseboard is quite intricate because of the flooring. I'm not the one performing the coordination of this or picking up more than the cost of the glue and labor to install it. I think we are going to try and use the (2)5/8 layer demo mass on the sheathing with a spread of GG as well. And even if it appears I have a bit too much glue... I could actually just save for future projects or what I don't use I could sell it to you Keith, for a profit. :lol: So why, from a sound transmision veiwpoint, is 5/8 GG 5/8 as good as 3/8 GG 1/2 GG 3/8 ? Seems if GG is creating more damping I would get better results with my space limitation. Forget labor and time. I will get some pics up as we prgress through it, if it is going to be helpful. We have an area where we use Hardy panels that where the outside door really thumps through there. How to deaden that area will be interesting. I also have the hallway getting into the cove area that will need extra TLC. Ok it's gonna start in a few days. I have jury duty of all things on Monday so my input is on the sidelines while the work is going on. It's not ideal working this way. They want to plow through it and I would rather take the extra step of being careful and meticulous with all the applications. I still can work when I get home and make adjustments that way but for the most part, they are carrying the load of responsibility for it. So Keith, please tell me the science behind your supposition regarding less glue and drywall layers even though the thickness remains the same. Thanks

knightfly wrote:

http://search.earthlink.net/search?area=earthlink-ws&q=site%3Awww.rondexter.com+Barifoil One of the shortest googles I've ever seen, short of nothing at all :? Don't think this is a good idea, considering that unless you put the lead side toward an existing mass you'd create another leaf in the wall - and if you DID put the lead toward the wall, you'd have a foam surface :roll: ... Steve

Right.... I checked a piece of it out. I know it's not gonna make it easy to integrate. Green Glue gonna have rule here.

I just think the main problem you have is a lack of mass plus coupled leaves. I would think Green Glue would help in this case, but a more appropriate solution would be to increase the mass and the depth of the air cavity -- especially if low end TL is your gremlin (and I suspect that it is). Let's be honest -- you got to this point beause the design and construction of that wall was rushed. To fix it, you want to do the opposite of that -- take your time to make sure it's done right the second time. Otherwise, you run the risk of there being a third time. And to be honest, if you continue at this pace, I'll sadly be betting on the latter. Rod has already weighed in on this. I'm not sure if you realize this or not, but he's one of the country's leading authorities on the subject of studio building. He recently published this book -- which you really should buy if you haven't already. Steve and I have both asked for cross-section drawings. Truthfully, Steve can do much more with them than I can -- I'm just trying to help facilitate the expectoration of details-details-details because I have a little more time than he does these days. Can you afford to do this retrofit and have it not perform according to your requirements? I'm not trying to be negative -- I really do want to see you succeed with this. We celebrate success stories around here and I want yours to be one of them. --Keith :mrgreen:

Truth is I can't rip much more apart than this. It will be a fix that obviously falls short of true mass, air spaces, decoupling, ect. I'm not in a traffic zone. It's basically very quiet here. It's not a commericial studio, it's private and easily managed from a sound encroachment perspective. You don't take into account diminishing returns based on personal needs. I didn't really understand your first sentence. Are you referring to what I am going to do or what I can't do but should? Are the three thin layers of DW with two layers of glue the same as two slighty thicker layers of DW with the one layer of glue? The answer is either yes it is better, or ...no it is equal. Then that would help me. I KNOW what I should have done but we are not there, we are here and I have presented to the best of my abilities and time available to describe my problem. The solutions are limited even morso from your answers which I cannot implement. Thanks Jeff Cooper was the designer BTW, wrote a pretty good book too. Doesn't mean you can't F up

woodlakesound wrote:

You don't take into account diminishing returns based on personal needs.

Perhaps he doesn't - but I do. I have a saying which sometimes gets lost in the mix of things - and that is this - "when you have to live with something - live with it the best that you can". Sometimes we have to live with triple leaf construction - sometimes we have to live with flanking connections - sometimes we have to live without large air spaces - Well - when these things happen - live with it - and move on getting the best that you can under the conditions.

Are the three thin layers of DW with two layers of glue the same as two slighty thicker layers of DW with the one layer of glue?

The answer is yes. All things being equal: 1 - the mass in both scenerios are exactly the same, thus the mass law side of the equation doesn't change. 2 - You will get a slight (very slight) benefit in the high to mid range due to the different thicknesses of materials (BTW - I do not usually recommend this - I generally tell people to just stick with 5/8 - the added mass makes up for the difference in the long run - and mid to high frequencies are not generally our biggest problems) 3 - I would expect you to get a big advantage through the use of 2 layers of green glue versus a single layer.

Jeff Cooper was the designer BTW, wrote a pretty good book too.

From everything I have seen Jeff is a good designer - I think he did a great job on your room. Anyone can miss something - hell we did on the last project I was on. We were adjacent to a number of busy 4 lane turnpikes - and no one ever thought to go up in a crane 200 feet in the air to take readings of the traffic 400 feet away from the building. So while at ground level we were ok ( 25' below the roadways) with readings of 45 dB - once we cleared the pikes we had levels (all the way to the 22nd floor) of 85 to 89 dB (of course I was not involved early enough in the process to pick this up - and by time I got there and questioned it - the budget was already established - so i refuse to take the blame - but get credit for the fix). Anyway - even with world class architects - acoustic engineers (the owner's even had their own acoustic consultant working the project) it ended up costing the owners an additional 250,000 to add what was needed to fix the problem. So yes - any one - Me - Jeff - or anyone else in the world can muff it once in a while - after all - we're only human. Sincerely, Rod

knightfly wrote:

... if you DID put the lead toward the wall, you'd have a foam surface...

Steve... I'm not totally understanding what you mean by 'foam surface'... Am I missing something? How can lead create a foam surface? I'm probably just overlooking something.... NEVERMIND... I just read the link to the 'Barfoil' stuff... But why not just use regular sheet lead 1psf sheet?... Unless there are weight/support issues... thanx, K

rod gervais wrote:

So yes - any one - Me - Jeff - or anyone else in the world can muff it once in a while - after all - we're only human.

Thanks Rod....yes, Jeff here the other day was just like you on that crane going "hmmmm.... didn't know dat was gonna happen". Difference was that he was here initially and we had waded through a couple of larger concept designs before my budget forced me to dowsize the Tracking Room square footage. So what ended up happening was the double outside wall got cut and I believe inadvertantly downsized to single wall two layers DW on studs. Just plain stupid oversight really. Even I should have caught it and said 'Hey! this is not going to do it.' But now... I believe I will take a page from Keith as well as your answer and push for additional drywall and worry about the resizing of moldings and trims another day. Three (maybe four!!!) 5/8 layers probably is the best I could do in addition to using the existing demo of two layers for lining and caulking the sheathing using some GG there as well. Thanks again, I can add to the thread by posting some pics of the process and if I need some additional guidance hopefully y'all can help me out :D

Cool. I think the extra mass will help you out a lot. 8)

Help!!!! Mr. Cooper just called and put forth the proposal of filling the cavities of the outside wall with sand. I was dubious as to the effectiveness with regards to stopping direct transfer from the studs to drywall we have now. So then at my request we thought of taking one of the two 5/8in layers of drywall off and Green Gluing it back on. Would that be as effective as my previous proposal of taking the two layers of 5/8in DW that is presenty on the studs, cutting it to size, GG against the sheathing, caulking ....then 4 layers of 5/8in drywall with GG in between. Is the extra demo and reinstallation of all the DW with GG gonna substantially beat out the sand idea. Thanks, I gotta get back to him ASAP.

HA HA..... there's insulation in those stud bays already so there's no way sand can be poured in until the insulation is out. So it looks as though we are demoing the DW. Now, should we put sand in the bays as we DW the first layer? (Instead of DW and GG against sheathing) Then just three layers of 5/8in DW with max coverage of GG. Sand's gotta be a mass builder.

woodlakesound wrote:

Mr. Cooper just called and put forth the proposal of filling the cavities of the outside wall with sand. I was dubious as to the effectiveness with regards to stopping direct transfer from the studs to drywall we have now.

I always adamantly oppose the thought of a sand filled drywall cavity - first off - sands weighs a lot - and the drywall isn't designed to carry that weight - remember that the load not only wants to spread out - but also wants to settle to the bottom - therefore you have the entire load trying to spread the drywall open at the bottom of each bay. Next - I always get nervous about the fact that sand soaks up moisture like a sponge - and damp sand will make drywall "dampwall" - and damp drywall likes loads lilke sand even less than it doesn when it's dry. SO nix the sand idea...... Besides - it still will not solve the problem with flanking through the studs - it would only damp the drywall and add some mass......... so effectively you would only have a one leaf system - not great for sound isolation.

So then at my request we thought of taking one of the two 5/8in layers of drywall off and Green Gluing it back on. Would that be as effective as my previous proposal of taking the two layers of 5/8in DW that is presenty on the studs, cutting it to size, GG against the sheathing, caulking ....then 4 layers of 5/8in drywall with GG in between.

Think about what you're asking here (for even a moment) and you'll realize all by yourself that it could not possibly be as effective........ Would it be enough? I doubt it - would the 2 layers relocated to the outside - with 2 layers inside be enough - I have no way of knowing for sure - although I think perhaps it might - you could always test it after the installation - and then add a 3rd (and possibly 4th) layer if you really need it.

Is the extra demo and reinstallation of all the DW with GG gonna substantially beat out the sand idea.

Absolutely............. Remember - this (thread) began with you describing to us a direction you were considering - and us letting you know that there were more cost effective methods of acheiving the same goal - but without being there - it's impossible for us to tell you exactly what you need to reach your goal....... Sincerely, Rod

You sound much smarter than my highly paid designer. OK...this is what I want to do Rod. Get this DW off and have a look see. There is some time here while the GG arrives. I'll post some closeup pics of the innards and especially the most troublesome areas. Then, we here will take a breath and sort through the various schemes they, and hopefully you and company ,can foresee as to the best (being both cost effective and effective). Maybe it'll come down to the 4 layer idea again with GG plus layering the cavity with the demoed DW against the sheathing and GG. Thanks for the help, I am immensely grateful.

Excellent. 8) Yes, "taking a breath" is a great idea. :) We'll look forward to seeing those pictures. BTW, you mentioned "Green Gluing [a drywall layer] it back on," so I should mention, just for the record, that Green Glue is a constrained layer damping compound, not "glue" in the fastening sense. You must use screws. (You probably already knew that...) --Keith :mrgreen:

sharward wrote:

Excellent. 8) Yes, "taking a breath" is a great idea. :) We'll look forward to seeing those pictures. BTW, you mentioned "Green Gluing [a drywall layer] it back on," so I should mention, just for the record, that Green Glue is a constrained layer damping compound, not "glue" in the fastening sense. You must use screws. (You probably already knew that...) --Keith :mrgreen:

Sure I knew that, whaddaya think... I'm an idiot? (don't answer that please) :lol: Yes, I've read the application notes a few times already and even printed them out for the guys. I'm off to jury duty, of all things, and will ask for a postponement to get through this and another matter which needs me here this week especially. I'll takes some pics tonight when I return, all the demo should be done and we can look at this from a fresh perpective. However the work order from the company is to do the plan I had decided on with the help of you all. GG is arriving on Friday so there will be some time to further access additional steps, if possible, to further enhance the job. Thanks

Naw, I don't think you're an idiot. :) But I did want to include that bit about screwing vs. gluing, since it is a common misconception about the product, and I wanted to be sure others who read it didn't get the wrong idea. 8) --Keith :mrgreen:

So, what ever came of this?

I've often wondered why it is called a 'glue'? Anyone else wonder, or have a line on the reason for the name? Is it even sticky? K

sharward wrote:

... I should mention, just for the record, that Green Glue is a constrained layer damping compound, not "glue" in the fastening sense. --Keith :mrgreen:

Maybe it shoulda been called "Green Glop" - they could also sell it for shoe repair - one ad slogan might be "Rigged for silent running"... Steve