Green Glue

Recently a client commented on how expensive green glue was and should he invest in it. So I checked out the green glue site and found the specs page. http://www.greengluecompany.com/greenGl ... rywall.php I found the following chart rather spurious.

If you look at the figures apparently 3 layers of Drywall cost the same as 4. and the labour to install 3 sheets is the same as four etc. in fact 6 sheets of drywall are $2.04 yet 4 sheets are $2.72 and the labour for 6 sheets is $3.60 yet 4 sheets is $4.80. All the floor space adjustments etc make for credible figures for their product but I found the way they derive it rather strange. Here is an alternative chart using their figures (which are wierd as .40c of framing will give you a piece of pine 1 foot long in my country) and comparing single wall construction with double wall (i.e. room within a room construction) cheers john

John: I guess these charts are calculating costs per square foot??? No where does it say the area... Jon Frost

Very interesting research, John. I'm inclined to think that these are just oversight in the details of their charts, and that it doesn't throw the credibility of their product into the toilet. I'm sure something good will come from your discovery, one way or another. Thanks....

jwl - I wasn't questioning the cred of the product - that speaks for itself in their other figures. It's the construction figures I'm pointing out and the expense of creating soundproof walls. I have always used the double wall system and it works fine without the added expense of green glue which as you can see is high as a proportion of the cost which - yes Jon, I agree is probably by the sqft. $3.84/sqft! The double wall system is $1.71 cheaper yet has higher STC. What I'm suggesting is that if you go double frame you will be the best off - even without green glue, but if you can't afford the space or need to beef up existing walls, then go green glue. cheers john

John, Maybe you want to PM forum member Brian Ravnaas (Technical director, Green Glue Company) and inquire about the spurious chart. Brian posted this thread panel trap experiment outline on this forum. IMO green glue is most useful and cost effective in ceiling applications where adding weight is an issue AND other areas such as beefing up in-between stud bays (adding air to MAM by using less drywall to increase TL in the lows) and when iso rooms are really small to begin with and the extra 1 or 2 inches crucial. As a result I am using 3 layers of drywall where I can and 2 layer of drywall with GG where needed (ceiling & stud bays). Most users of this forum seem to see Green Glue one of the most honest isolation product companies out there because of there extensive qualified testing. Marc

thanks for that marc - I totally missed that thread, I'm reading it now. my apologies if I appear to be attacking Green Glue - I'm not intending to. I am questioning it's application though. cheers john

John Sayers wrote:

thanks for that marc - I totally missed that thread, I'm reading it now. my apologies if I appear to be attacking Green Glue - I'm not intending to. I am questioning it's application though. cheers john

John, it seemed you were more confused over the data than attacking them - at last to me it did. For my clients the recommendation to use GG comes if they plan to use more than 2 sheets with double wall construction. At that point = a double wall assembly w/ GG with Dbl sheets out-preforms the same double wall with 3 sheets of drywall. Ands *(using your numbers just to keep this in perspective) it would cost a total of 16.03 for that construction - yet the same 2 walls with 3 layers of drywall would be 16.56. BTW - those numbers are very close to my original numbers when looking at th So it begins to make sense at that point in time and not before. Sincerely, Rod

Yeah John, I didn't read your post as an attack on Green Glue at all. More like, "hey, I noticed this, these numbers don't quite add up.... what's this about?"

Yeah, that did not seem like an attack, more like just pointing out something that does not seem to add up... Marc

Thanks for you understanding guys. Can I say - my main concern is for the many people who come to this site to get advice on how to fix up their basement studios. It's actually an American thing as we don't have basements in Australia and there's not many in Europe either. I can definitely see an application for Green Glue in basement ceilings as that is the major problem area and adding another frame is usually hindered by ceiling heights. What I'm concerned about is the overkill that's developing on this site. In most cases a double wall with one layer of 5/8" drywall is sufficient for isolation in a basement studio. If you need more, then two layers. I see no need for the triple layer, it's just overkill. Left Bank is just a double wall with a single layer of 5/8" and that studio can operate 24 hours if necessary. It's above ground and with 50 - 60 yards to the nearest neighbour. In Oasis we used a double 5/8" layer as the neighbours are closer and as expected the isolation is excellent. I'm pointing this out so that forum members don't feel obliged to build triple layer with green glue walls. It can get overtly expensive adding all those layers let alone having the added expense of GG. ;) cheers john

Some of us have very small setbacks (mine is 5 feet to the side) so our neighbors' houses are very close (my side neighbor's house is 10 feet away)... Plus, strict noise ordinances are generally in effect at the property line... :roll: I also have a wife who wants the house kept quiet when I'm jamming away at a heavy metal groove. :twisted: Many of us are in need of pretty extreme low end isolation, where mass rules. I tend to stretch my Green Glue usage to 50% to 75% of the recommended dosage too. --Keith :mrgreen:

I don't doubt that there are some errors on the GGCo website. Almost all of the material that is on there has been for a while, and we're working on a total re-vamp. We had a fair ( :cry: ) amount of problems with "lost in translation", with translation being the process of going from some word document to the web. I will offer some basic thoughts on the cost calculations present on our site. The data should be stated as being taken from Craftsman publishings "National Construction Estmator" database, and derived from the national average or some specifically stated state. You can sort of browse the data that are present in the Estimator software by going to www.get-a-quote.net, which has state-by-state average material and labor costs for most everything you may want to use in construction (even including MLV). In some instances we have adjusted the labor rates DOWN for other products (MLV only comes to mind, as the Estimator had an estmated per-square-foot labor rate of >>$1/sq ft, which is just on the high side). The basic calculations are also at least a year (or much more) old and will be updated with the current estimates with the site changes. The Estimator software is just that and no more, but to make cost-calculations that are explorable and, well, based on something, we had to choose a standard reference for basic costs and that was it. Finally, the floor space cost adjustment is rarely relevant and should be ignored. But all that said, if anybody wants me to take a look at this data and put forth the piece-by-piece info from the software, i'd sure be happy to do so, but the chart seems reasonable. its 8 total layers of drywall in a conventional wall -vs- 6 with partial-coverage Green Glue in a GG wall. The costs of finishing, sealing, framing, insulation, etc. are the same, the drywall costs are the same in all instances, and the GG cost/labor rates would be based on our prices when the chart was made and wood floor adhesive rates from the software. I really do apologize if the info caused any confusion, but all prices are per square foot and based on the above source/calculation.

sharward wrote:

Many of us are in need of pretty extreme low end isolation, where mass rules. I tend to stretch my Green Glue usage to 50% to 75% of the recommended dosage too. --Keith :mrgreen:

I really think thats a good idea. Stretch the glue to higher coverage. We have (though not published yet) plenty of tests to show that using 1/2 as much glue gives more than 1/2 the benefit, making it cost effective. Also, 1/2 glue in two layres between 3 layers of drywall is simply far better for the same $$$ of glue, as its alot heavier, and 2 50% damping layers is better than 1 100% layer. I know the drywall costs more, etc., but the times people opt to use 3 tubes (150% coverage) with 2 layers of drywall befuddles me, as they would be better off to just use more weight and 2 damping layers.

:mrgreen: I thought the easiest way to help a bit was grabbing Brian in his neck and bringing him here. ( :) something like that).

i don't mean to barge in and post 3 times on a GG thread and run. Eric said i should post here over at Studiotips earlier. for this picture you have these: $0.34 per layer of drywall $0.60 per layer of drywall in labor (which is way higher than people pay for labor near me, but we simply followed the estimator) Whatever for framework (which the software gave by the board*foot), insulation (sqaure foot), caulk (linear foot), etc. These are fixed costs for all walls as you don't add more studs when adding more drywall, etc. Unless i'm dense, the figures add up. If John meant "you don't get a discount when putting in more layers", that is how we treated the calculation as we decided to base it on the software, etc., and it didn't report any volume labor discounts. But anyway, about using GG, 25% coverage (pretty much a big X with some dots in the spaces) is even more effective in a $$$/benefit analysis than 50%.

John: I don't know if this is the source of the confusion, but photo #3 is wrong. The text shows 8 layers of drywall (4 layers per side), but the photo shows 4 layers of drywall (2 layers per side). Photo #2 is also wrong, since it shows GG, but the text doesn't use GG. ( photo = wall drawing ) The drywall materials line should work out to 0.34 cents per layer. The first column is wrong, as it shows $1.36 when it should be $1.02 (three layers). The others - Photo #2, $1.36 = 4 layers (correct) - Photo #3, $2.72 = 8 layers (correct) - Photo #4, $2.04 = 6 layers (correct) Similarly, the first column's "Drywall Labor" is also too high by one layer, or 60 cents.

z60611 wrote:

John: I don't know if this is the source of the confusion, but photo #3 is wrong. The text shows 8 layers of drywall (4 layers per side), but the photo shows 4 layers of drywall (2 layers per side). Photo #2 is also wrong, since it shows GG, but the text doesn't use GG. ( photo = wall drawing )

that's exactly my point. Actually the second picture is also wrong as it shows green glue when it's not included in the figures. My whole point is that a double wall frame build without GG is more effective and cheaper than a single frame build with GG. If you are limited to single frame then yes, use GG otherwise I recommend you go double frame. As i said before - the number of drywall layers has a workable limit. To add 4 layers per side is just overkill and would only be necessary in the most extreme circumstances and even then sandwiching with MDF or soft fiberboard could be just as effective. I've witnessed studios built like Joe Egans where a double framed triple layer (Drywall, Soft fiberboard, drywall) was used and with a full band blasting inside absolutely nothing got through. the only application where I would see the need for more iso would be in Galaxy Studios where three control rooms were sharing the one studio and we all now know how Eric achieved that kind of Iso and I'm sure he now wishes he had access to GG then. ;) cheers john

Brian, How about testing some 'real-world' triple leaf scenarios? This could be your next project... I know your website references: "TLF-95-107a (double leaf) and TLF-95-153a (triple leaf), taken from IR-811", but wasn't that test designed for impact reduction TL and not wall TL? I understand the concept is the same, but this area still seems relatively unexplored. How about some real-world situations, such as building a room within a garage or townhouse where demolition of existing walls is not an option? In other words, using two walls, demonstrate how GG can reduce the "triple leaf effect". Case in point: I have a finished garage. I want to build a 'room within a room'. Or, I live in a townhouse. Same thing. Basically, take an existing single stud wall and bring another wall (and GG)into the equation: Here's a scenario: Take a single stud wall- 5/8 drywall both sides(typical residential home wall partition). Then construct another wall which represents the 'room within a room' wall construction. This could be a single leaf wall consisting of two drywall layers with GG or three layers with GG, or a double leaf wall, etc, etc. I understand that a true Mass-air-Mass situation is king, but it's not always an option. In my personal situation, I know it's best if I remove the inner layers of my garage and beef up the outside, but how much of an improvement can be had by just adding a layer of drywall with GG (taking into account my 'room within a room' ? But I'm not just asking for myself- there's plenty other garages out there :)

I see at http://www.greengluecompany.com/greenGl ... rywall.php (same link as John posted in the first post of this thread) that they've fixed the pictures but not the pricing. I'll send Ted White another email...

hey z, john, you I was dense, you guys were right. thanks to everybody for bringing it up. I think the pictures were all that was messed up and the #'s are ok now. first column = 4 layers of drywall 2 layers of green 2nd column = 4 layers of drywall no green 3rd column = 8 layers drywall no green 4th column = 6 layers of drywall, 3 layers of green (75% x 4 layers = 3 layers) all the drywall columns add up to $0.34 per sheet, $0.60/sheet labor (too high). So i think its ok now, and thanks again for the feedback. If i'm dense again i'm sure you guys will let me know. I think it was always correct in the .pdf file, and it just got confused in translating to the web page. The one thing that could be adjusted on that page, and all of the pages, is to adjust caulk usage for different assemblies. If one puts a bead of sealant under every layer of drywall, this would have the effect of increasing costs. And i think the software over-estimates the cost/time of blobbing out some sealant. Additionally, walls where it may be important to "float" the drywall and fill a more sizeable gap with caulk would have a somewhat higher amount of sealant. But that's not that big of a deal in the grand scheme.

cjbdrm wrote:

Brian, How about testing some 'real-world' triple leaf scenarios? This could be your next project... I know your website references: "TLF-95-107a (double leaf) and TLF-95-153a (triple leaf), taken from IR-811", but wasn't that test designed for impact reduction TL and not wall TL? I understand the concept is the same, but this area still seems relatively unexplored. How about some real-world situations, such as building a room within a garage or townhouse where demolition of existing walls is not an option? In other words, using two walls, demonstrate how GG can reduce the "triple leaf effect". Case in point: I have a finished garage. I want to build a 'room within a room'. Or, I live in a townhouse. Same thing. Basically, take an existing single stud wall and bring another wall (and GG)into the equation: Here's a scenario: Take a single stud wall- 5/8 drywall both sides(typical residential home wall partition). Then construct another wall which represents the 'room within a room' wall construction. This could be a single leaf wall consisting of two drywall layers with GG or three layers with GG, or a double leaf wall, etc, etc. I understand that a true Mass-air-Mass situation is king, but it's not always an option. In my personal situation, I know it's best if I remove the inner layers of my garage and beef up the outside, but how much of an improvement can be had by just adding a layer of drywall with GG (taking into account my 'room within a room' ? But I'm not just asking for myself- there's plenty other garages out there :)

The question that you raise is without a doubt a very good one. I've only a brief amount of time to post this morning, but i would like to try to address that both from the standpoint of GG and not. The simplest and most relevant downside of a triple leaf system is that for a given amount of weight and space, you wind up with a higher frequency of MSM. And that means that whatever decuopling efforts you have will start to work for you at a HIGHER frequency, which is bad. The next downside is the potential for chaotic low-freq behavior (resonance behavior) as you introduce multiple systems. In some instances - such as the famous double stud system shown in quadruple, triple, and double leaves - this can be catastrophic. But moving past the basics and into your specific question, I do really feel that there is enough data and information available in the world and on my 'puter to address what you describe. What you need to do is build a wall in front of the existing wall with enough mass on both sides, and enough air space to force a predictable set of behavior from the now-triple leaf. I'll have to address this later, and if this is a question that is common for studio situations i could put it in a new thread.