backyard shed walls

I posted about this project a while back and received some assistance, but now I have a different question. I've read through a whole bunch of posts here... wow... and I have what may very well be some basic questions, but first the facts. The building: The backyard shed itself will be 10x16 (small). It's 9' tall on the inside sloping up to a bit over 10' (slope is on the 10' dimension direction if that makes sense). Traditional wood stud construction all around. There are windows that will all be double pane, and a solid wood door. Concrete slab. Pretty traditional. I will consider beefing up the door and windows if they become the weak point. Windows and doors are in the exact opposite direction of my neighbors. The purpose: I don't have the need to have live drums at 3am or anything. I have neighbors maybe as close as 30 feet though. I mostly record a lot of acoustic instruments, record a lot of direct instruments, vocals, etc. I will also rehearse with v-drums... maybe. Maybe not. If I record drums I'd do it during the day or in a nearby studio. So really, a lot of what I'm looking to do is keep noise out of my vocals, acoustic guitar/hand percussion, double bass, etc. I think that's enough info? Am I leaving anything important out? Where I am asking for help please: With the small size of the room, I'm thinking of the best way to build the interior walls. Surface mount electrical... seems like an easy one. I can't see any downside to this. Insulation... seems easy enough, if I'm reading correctly, the inside walls should be insulated and normal pink fiberglass is fine. Maybe better than 703 in the walls (and a lot cheaper). Interior walls... and RC... I like the idea of RC, but I don't like how much of my precious interior space it will eat up, so I'm trying to avoid that. I see that a 5/8" dual layer and 1/2" dual layer sheetrock wall measure the same but dual 5/8" is better at lower frequencies, and I suspect that is where my main problem will be... so I'm thinking dual 5/8 OR a 5/8 and a 1/2". Is a layer of each splitting the difference worth it? Sheetblock... is there any advantage to sandwiching something like "sheetblock" in between the two layers of sheetrock? Is that just throwing away money? Or will that improve things? Or... greenglue in between? How much will greenglue cost for a room like this? Floors... with the concrete slab, I wasn't thinking this would be my weak point, seems like the windows, doors, and walls will be more of a problem. Or, will "sheetblock" on the slab under the flooring be worthwhile? I've been all over this site (searched quite a bit) and tried heard not to ask obvious questions. Sorry if these have been answered! Thanks in advance.

OK... anyway, here's my plan. The studio shed itself will go in about 30 days from now. The company who is building the shed offsite will install the shell. So my plan is to wait until it's all built, then do some testing to try and determine how much reduction I will need... how much to do to the interior walls. My thought at this point is probably just to two layers of sheetrock, 5/8 and 1/2. I think greenglue will be cheap enough (not sure how much it will cost for this structure but I'm guessing it will be reasonable) that it would make sense to install it between the layers. I want to keep as much precious interior space as possible! The only thing I'm still not sure of is what to use between the pergo floors I'm putting in and the slab. Does it really matter?

until the 'Experts' reply .... It has been recommended to NOT use 1/2" drywall. Best to use 2 layers of 5/8" drywall. As for the GreenGlue ... go to their web site ... they have a calculator there that will closely estimate the # of tubes. For my build, I used 2 tubes per 4x8' drywall sheet on all walls and ceiling. You mentioned a concrete slab for the floor ... that is an excellent base. As for 'covering', I'd be cautious about the 'Pergoes' and similar. When I was researching, I found that these floors induced quite a resonant frequency [bad]. I ended up using a 'fiber' flooring [got it at Home Depot]. It LOOKS like a hardwood floor ... but has a soft padding built on, and is very nice on the feet ... and the chair can roll easily [AND QUIETLY] :) Hope this helps.

Thanks RJ... I decided on the 5/8 + 1/2 idea because in my research, the numbers I saw showed very little difference between the two. Might be that, in the real world, there IS a difference. Thanks for the idea on the greenglue website calculator, PERFECT! Regarding flooring, that is exactly what I was thinking about... I should have been more clear! Thanks for the response...

I decided on the 5/8 + 1/2 idea because in my research, the numbers I saw showed very little difference between the two. Might be that, in the real world, there IS a difference.

Yes there is. The difference is that the 1/2" stuff is too thin, too flexible, and too low in mass to be recommendable for isolation. What many people don't realize is that all of the layers of mass in a wall act both independently and together. Yes, a layer of 5/8 plus a layer of 1/2 is just mass, from the point of view of MSM, and the equation for that only sees a total "leaf" of mass, regardless of how it is made up. Some people think that there won't be a difference, because its only a 1/8" difference, but in reality, there is a difference. Going from 1/2 to 5/8 adds about 30% extra mass (per layer). Not an enormous amount but enough to make a difference. Take a look at IR-761, and you might be surprised. But that's not all. Apart from adding mass to the MSM, the 1/2" drywall also acts by itself, and therein lies another big issue. 1/2" is thin, flexible, and low mass, when what you really want is thick, rigid and high mass. Stiffness is important in the region below resonance, for example. And yes, it is true that there is a slight advantage in the region of the coincidence dip for the wall (by having two different materials the dip is broader and less pronounced), as well as a slight advantage for refraction, but in reality neither of these "slight advantages" even comes close to outweighing the much larger advantage of thickness, rigidity and extra mass. And as it turns out, all of the gains from 5/8 over 1/2 are in the low end of the spectrum, where you need it most. :) - Stuart -

Soundman2020 wrote:

And as it turns out, all of the gains from 5/8 over 1/2 are in the low end of the spectrum, where you need it most. :)

Thanks Stuart! I can't find where I pulled the actual number from, but it showed that 5/8 an 1/2 were almost equally effective in two layers... but it seemed to good to be true, so it probably is. No reason to risk it, so 2x 5/8" it is.

I've searched the forum and read up on quietrock... seems like the agreement is it is not cost effective.... However... I'm in California where the land costs are so expensive I can only do a small building... and thus I'd like to eat up as little of my interior space as possible with walls and r/c, etc. So my question... though expensive, will quietrock or similar give me the same results as multiple layers of 5/8" sheetrock? Put another way... will paying more money for quietrock be a reasonable cheat for getting the same reduction eating up less of in precious interior space? Their materials: http://www.quietrock.com/drywall/quietr ... rison.html So... quietrock, STC: 49... and Greenglue and dual 5/8": STC: 55 Close enough or... ? Probably not, eh?

If you want high isolation and still want thin walls, then you need greater density. Replace one layer of drywall with something far more dense, such as fiber-cement sheeting, which is probably nearly twice as dense. So you could go with 5/8" drywall plus 1/2" fiber-cement, and that would actually be even better than 2 sheets of 5/8! Add Green Glue in between, and you'd have an excellent wall in little space. Or you could add a layer of lead sheeting to the wall: that is REALLY massive. A little pricey, though. Or you can resort to adding drywall between the studs, inside the wall, for more mass (if you build inside-out). Or a combination of the above. Plenty of ways of getting good isolation in a thin wall. The only caveat: it won't be as cheap as just using drywall. - Stuart -

Thanks Stuart... You have me thinking now... :) I don't know if standard 2x4 16 on center walls are strong enough for some of those things... :) I'm going to see how much those ideas would cost. I'd imagine though they wouldn't work for ceiling... I will just go with the dual 5/8 sheetrock with green glue for the ceiling.

I don't know if standard 2x4 16 on center walls are strong enough for some of those things...

The total WEIGHT doesn't change: You are just using things with higher DENSITY but also THINNER to get there. That's the idea. So your ceiling and walls will still have the same mass (weight) as if you had used 2 x 5/8, but will take up half as much space (thickness) since the materials are twice as dense. - Stuart -

...came across this stuff today: http://www.soundisolationcompany.com/ed ... oss-tests/ I was thinking about whether it would make sense to apply greenglue to the studs (apparently not) but then found this stuff. Anyone have experience with it? Anyone think that it would make things worse?

What does that document have to do with green glue?

xSpace wrote:

What does that document have to do with green glue?

Well, again, I was thinking about whether green glue would work when applied to studs instead of when applied between layers of sheetrock. The answer appears to be no... but the document I linked to shows a product that claims to go between studs and the first layer of rock and attempt to decouple the studs from the first layer.

The issue with that type of approach is that as soon as you put a nail or screw through the drywall and into the stud, to hold the drywall in place, you create a flanking path that totally bypasses and short-circuits that "decoupling"... Those graphs look rather suspect too. Clearly, something major is going on at higher resolution: to me, 1/3 octave averaging with huge swings like that indicate that there are bigger things going on, hidden in the averaging. And since the tests don't seem to have been done by an independent acoustic lab, who knows how accurate they are, what standards were followed, or even how they were conducted at all! - Stuart -

mfassett wrote:

xSpace wrote:

What does that document have to do with green glue?

Well, again, I was thinking about whether green glue would work when applied to studs instead of when applied between layers of sheetrock. The answer appears to be no... but the document I linked to shows a product that claims to go between studs and the first layer of rock and attempt to decouple the studs from the first layer.

The attempt is most likely at dampen the panel, people have been using soundboard and other products for years to approach this. It is what might be considered dry friction with a dampen ability. And in respect to greenglue, if they aren't saying you can do this or you can do that....do not get caught up in another persons unsupported ideas based mainly on myth....and dry friction :)

Soundman2020 wrote:

The issue with that type of approach is that as soon as you put a nail or screw through the drywall and into the stud, to hold the drywall in place, you create a flanking path that totally bypasses and short-circuits that "decoupling"...

But isn't that the case with greenglue too? Why does it seem to work?

xSpace wrote:

The attempt is most likely at dampen the panel, people have been using soundboard and other products for years to approach this. It is what might be considered dry friction with a dampen ability. And in respect to greenglue, if they aren't saying you can do this or you can do that....do not get caught up in another persons unsupported ideas based mainly on myth....and dry friction :)

Regarding the first paragraph, do you think it is likely it's effective and/or worth doing? Regarding your second one, are you suggesting that greenglue isn't as effective as the tests show it to be? I would really like to know this one... as it would certainly impact my decision. Interesting, how complex all this stuff is... :shock:

But isn't that the case with greenglue too? Why does it seem to work?

Actuall, no, that isn't the case with Green Glue, and I don't see Green Glue Company recommending their product for decoupling drywall from studs! I'm not sure who told you that it "seems to work", but I thoroughly doubt that that is true. That's not what it is designed to do. Where did you see this suggestion that GG can be used between studs and drywall to decouple? Like Brien implied: whoever told you that GG can be used like that just doesn't understand what GG is or how it works. - Stuart -

Regarding your second one, are you suggesting that greenglue isn't as effective as the tests show it to be? I would really like to know this one... as it would certainly impact my decision.

I don't see Brien saying that at all! Green Glue works very well in the application it was designed for: constrained layer damping between sheets of drywall. I doubt that it works at all as a decoupler between studs and drywall, which is what you are wanting to do. And there isn't anything on the GG web site that even suggests this would work. GG has been tested extensively in independent laboratories, and the results of those tests are openly published on the GG web site. Conclusion: it works as advertised, when used as directed. But for CLD between layers of drywall, not for decoupling drywall from studs: that has never been tested, as far as I'm aware. If I'm wrong on that, please point me at the test results. - Stuart -

Soundman2020 wrote:

But isn't that the case with greenglue too? Why does it seem to work?

Actuall, no, that isn't the case with Green Glue, and I don't see Green Glue Company recommending their product for decoupling drywall from studs! I'm not sure who told you that it "seems to work", but I thoroughly doubt that that is true. That's not what it is designed to do. Where did you see this suggestion that GG can be used between studs and drywall to decouple? Like Brien implied: whoever told you that GG can be used like that just doesn't understand what GG is or how it works. - Stuart -

I could have been more clear. You talked about how putting a nail or screw through the drywall and into the stud would create a flanking path that bypasses any decoupling. I accept that, but I was wondering, if that is true, then why isn't the same thing the case with greenglue between two sheets of rock? I never suggested that greenglue would work between stud and sheetrock... as a matter of fact, a say a few posts above that they say it won't work. So the point I'm getting at was... if nail or screw is bad for decoupling, why then does it not matter to have a nail or screw when two layers of sheetrock are separated and breached by a nail or screw? I hope I asked it more clearly...

So the point I'm getting at was... if nail or screw is bad for decoupling, why then does it not matter to have a nail or screw when two layers of sheetrock are separated and breached by a nail or screw?

Because Green Glue does not decouple! :shock: That's not what it is designed to do, and not what it does. It is CLD (Constrained Layer Damping) which DAMPS the panels, and does not attempt to decouple them. Since it isn't decoupling, then that non-existent decoupling cannot possibly be shorted out by putting a nail through it! :) Damping is not affected at all (or only negligibly) by nails. (If I recall correctly, there are some test results on the GG web site showing that nails have very little effect on how GG works.) - Stuart -

Soundman2020 wrote:

Because Green Glue does not decouple! :shock: That's not what it is designed to do, and not what it does. It is CLD (Constrained Layer Damping) which DAMPS the panels, and does not attempt to decouple them. Since it isn't decoupling, then that non-existent decoupling cannot possibly be shorted out by putting a nail through it! :)

Ahh, thank you... ...so then you might expect my further question if you don't mind... is it possible the product in question also dampens between the studs and drywall? Is that an area that, in your opinion, might benefit from that damping as well? I guess my real questions are... do you think these gaskets between the studs and drywall will make enough of a difference, given the rest of the wall is 5/8" x 2 with greenglue between? AND... in your best guess, do you think it might make things worse? Thanks again for all the answers.. :)

Damping between studs and drywall doesn't accomplish much, since the stud isn't where the problems are. The entire wall is a tuned system, that resonates at a frequency set by the mass on each side and the size of the air gap. The insulation that you put in the air gap is the damping, and it works on the multiple resonant issues in the cavity itself, just like the shock absorbers in your car work on the multiple resonances set up by the wheels on the road. Putting something between the stud and the drywall would be kind of like putting a piece of rubber between your car wheel nuts and the bolts they go on, then tightening the bolts fully: It won't accomplish very much! The shock absorbers are already doing all of the damping that is needed. The little bit of rubber under the wheel nut might make you feel better, but doesn't actually accomplish much at all, in terms of improving the ride. If you really want to stretch the car wheel analogy to the limit, then I guess you could say that Green Glue works something like the air in the tyres, but nothing like like the suspension springs, and nothing like the shock absorbers (and certainly nothing like a bit of rubber behind the wheel nut!). Sort of.... Each part accomplishes a specific purpose, and they all work together to smooth the ride overall, so you don't feel the bumps. It is the same basic principle with your wall: each part has a job to do, and they all work together, but adding a bit of rubber in the wrong place will not help much. So, damping between the studs and the drywall isn't notably useful, since the entire wall is vibrating at different resonant frequencies anyway, including the studs, and that is damped by the insulation in the cavity, not by bits of rubber on the studs. Since the entire wall vibrates, including the studs, that rubber would not actually have anything to damp! I'm not saying it won't do anything at all: just that it won't do anything worthwhile, since it won't be acting on what needs to be acted on: air-borne resonance in the cavity. - Stuart -

In simplier terms...the constrained layer damping that green glue provides inhibits the panels (sheetrock) from interacting with each other. This is an important thing to note. As it pertains to studs and installing this product there, this is a waste of your time and money. Dry friction..keep it on your mind my friend. there are materials that you can install at the stud level that many well known authors of books that have actually used this method support. Now if it is or is NOT effective, I nor can we tell you. But we can tell you that a CLD product will not perform at a stud level... Constrained Layer Damping OR Dry Friction are two different things, and these two different things are what we are talking about.

For me.. simpler terms is good... :) Thanks to you both....