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Sound deadening my media room - a little DIY

post #1 of 53
1/15/13 at 3:21pm
Thread Starter 
My wife and I decided to start working on getting the media room setup. Picking the equipment and getting the AV stuff is all well and good, but our primary concern is sound deadening. The media room is pre-existing, and I have access to the other side of most of the walls from the attic, so I have some options there. There is no insulation or drywall on any wall that is exposed to the attic. In fact, there is no insulation in any wall or floor, whatsoever. The attic has been insulated with sprayfoam directly onto the roof itself. Great for heating/cooling bills, but not so great for sound.

So my questions:
1. I plan to take up the carpet to lay down another layer of plywood. While I'm at it, I'll probably cut up the existing floors in order to add insulation to subfloor. Is this worth it? Will insulation and another sheet of plywood really cut down on noise?

2. Would Quietbrace be more worthwhile for the floors? Or is that even ok to use on flooring?

3. When is comes to layering things like drywall up, what is so special about Green Glue? What makes it any different than a quality silicone that won't harden?

4. Is fiberglass or wool batting better for sound deadening?


Thanks all!
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post #2 of 53
1/15/13 at 5:39pm
For the floor, you might consider a layer of Serenity Mat , then put OSB on top of that, then your padding and carpet.
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post #3 of 53
1/16/13 at 1:01pm
Green Glue is a viscoelastic material specifically formulated for sound damping. Silcone caulk (more expensive) is design to fill cracks and gaps and is worthless as for CLD (Constrained Layer Damping). Why not start with a little light reading at http://www.soundproofingcompany.com/soundproofing-products/green-glue-products/green-glue-soundproofing-for-walls-ceilings-floors/
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post #4 of 53
1/16/13 at 2:08pm
Thread Starter 
Yeah, I'd done a LOT of reading on that site, which has been very helpful and informative. However, I can't help the feeling that they might be a little impartial to their own products. That's fine, it seems like a good company with good products, but I just don't buy into the whole Green Glue thing as anything different from silicone. I think the true benefit is that after doubling the mass of the wall with a 2nd layer of drywall, you further remove vibrations by making sure the 2 panels have absolutely no ability to vibrate with each other. The wall would act as a single piece of double-thickness drywall. The thicker the wall, the more unlikely it is to resonate and vibrate from sound waves. Even screwing down the 2 layers of drywall on top of each other won't be enough to stop vibrations. Gluing them together makes them effectively one unit.

So, I understand how the glue helps, and yes, the glue itself has mass, which adds to the effect, but what is so special about green glue? That site doesn't mention it, and no one else seems to know...
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post #5 of 53
1/16/13 at 2:40pm
I have a closet full of Green Glue stained work clothes. One consideration is the viscosity of Green Glue versus silicon. It is thinner. What this means is that when you attach the second layer of drywall to the wall it flattens (puddles) out and you get a fuller coverage pattern. If you were to use silicon you get a bunch of flat worms between layers.

Here is a scientific paper on constrained dampening layers and their use in controlling vibration. It is not about adding more mass it is about the constrained dampening layer effect on reducing vibration. Yes more mass is good, adding more damped mass is better.

http://scholar.lib.vt.edu/theses/available/etd-10102008-124400/unrestricted/Thesis_CraigGallimore_Rev1.pdf
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post #6 of 53
1/16/13 at 2:50pm
You may also want to pull up the MSDS sheets for Green Glue and silicon.

I can't imagine doing a full theater with silicon considering they tend to be airtight windowless rooms.

caution about silicon

"Use with adequate ventilation due to the evolution of acetic acid vapors in moist or humid conditions. Avoid eye and
skin contact. Store at room temperature for best shelf life. Keep away from oxidizing materials. Keep container
closed and stored away from excess moisture or humidity."
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post #7 of 53
1/16/13 at 3:02pm
Quote:
Originally Posted by Adoniram View Post

but I just don't buy into the whole Green Glue thing as anything different from silicone.

Independent. Lab. Results.

http://www.soundproofingcompany.com/lab-tests/green-glue-transmission-loss-testing/

Take a look at the two tests with 2x 5/8" drywall on both sides, wood studs, R13. One study without GG and the other with GG. Roughly 10dB and a 16-point STC improvement. Now, you asked about the difference if you used silicone, but since it wasn't designed to do anything regarding damping, and costs more to apply, I think that answers your question. And yes, the stuff works.

Without: http://www.soundproofingcompany.com/media/green_glue_testing/OL05-1059_Report.pdf
With: http://www.soundproofingcompany.com/media/green_glue_testing/OL05-0414_Report.pdf
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I think the true benefit is that after doubling the mass of the wall with a 2nd layer of drywall, you further remove vibrations by making sure the 2 panels have absolutely no ability to vibrate with each other. The wall would act as a single piece of double-thickness drywall. The thicker the wall, the more unlikely it is to resonate and vibrate from sound waves. Even screwing down the 2 layers of drywall on top of each other won't be enough to stop vibrations. Gluing them together makes them effectively one unit.

Right, which is not what this assembly is designed to do - it's allowing the two Oreo cookies to vibrate and the stuffing is damping that vibration. (I just made myself hungry, and realized that they need to make Green Glue smell like Thin Mints. biggrin.gif )
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So, I understand how the glue helps, and yes, the glue itself has mass, which adds to the effect, but what is so special about green glue? That site doesn't mention it, and no one else seems to know...

It adds a trivial amount of mass, and I don't believe that that is providing any benefit. It's a damping compound (not a glue, either!). That's what makes it work.

Jeff
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post #8 of 53
1/16/13 at 4:30pm
Thread Starter 
Ok, all good information and opinions. I understand a lot of people are big fans, but I'm trying to justify it. A few people have mentioned that it's cheaper than silicone...??

Silicone tubes on homedepot.com are about $5/ea for quality GE stuff. $2.50 each for acrylic/latex.

Green Glue on Amazon.com is sold in a case of 12 for $175, making it $14.58 each. That's a LOT more than either alternative. Where are you guys getting your prices?
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post #9 of 53
1/16/13 at 5:08pm
first off get your Green Glue from The Man Ted White, ask for Bigmouth's discount.

You do realize that the $5 tube of silicon is under 10 oz and a green glue tube is 29 oz.

If you are doing a big room it is more economical to get it in 5 gallon pails and apply with a speed loader. Two tubes or speed loader loads per 4x8 sheet.
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post #10 of 53
1/16/13 at 5:24pm
Thread Starter 
No, I did not realize the green glue was 3x the volume per tube smile.gif that certainly changes things! If the price point is so close, may as well just go with green glue!

Do you have Ted's contact info, or should I just fill out a contact form on the website?
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post #11 of 53
1/16/13 at 5:45pm
I always just call, his partner John is a straight shooter as well if Ted isn't in.
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post #12 of 53
1/17/13 at 5:52am
Quote:
it's allowing the two Oreo cookies to vibrate and the stuffing is damping that vibration.

Let's not get confused here. The analgy is to peanut butter. If we go throwing Oreos into the mix, EVRYONE will be confused.
Quote:
(I just made myself hungry, and realized that they need to make Green Glue smell like Thin Mints.)

And I KNOW it will take about a day a half for someone to start saying we could just use Thin Mints between two layers of drywall. So STOP IT RIGHT NOW! Look, once the Girl Scouts get wind of the use of Thin Mints in a Home Theater application, the price of a box will go to $37.00. So, just stop it RIGHT NOW.
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post #13 of 53
1/17/13 at 7:48am
Quote:
Originally Posted by tlogan6797 View Post

Let's not get confused here. The analgy is to peanut butter. If we go throwing Oreos into the mix, EVRYONE will be confused.

Crunchy peanut butter, according to the Wikipedia page, has only an STC rating of 23. Creamy peanut butter is 34. But Oreo stuffing is 45. You're using an outdated metaphor and sound like a broken record. tongue.gif
Quote:
And I KNOW it will take about a day a half for someone to start saying we could just use Thin Mints between two layers of drywall. So STOP IT RIGHT NOW! Look, once the Girl Scouts get wind of the use of Thin Mints in a Home Theater application, the price of a box will go to $37.00. So, just stop it RIGHT NOW.

Yeah, but they'd be much cheaper by the 5-gallon bucket!


biggrin.gifbiggrin.gifbiggrin.gif
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post #14 of 53
1/17/13 at 8:06am
I DO NOT sound sound sound sound sound sound sound sound sound sound sound sound sound sound sound like a broken record.

I see no actual test reults on that Wikipage, only the nonsensical ravings of a lunatic mind. Until Ted or Dennis or someone with some ACTUAL test results chimes in, I stand by my by my by my by my by my by my by my peanut butter analogy.
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post #15 of 53
1/17/13 at 8:39am
Quote:
Originally Posted by Adoniram View Post

Yeah, I'd done a LOT of reading on that site, which has been very helpful and informative. However, I can't help the feeling that they might be a little impartial to their own products.

One would hope they would be impartial - are you sure that's what you meant to say?
Quote:
but I just don't buy into the whole Green Glue thing as anything different from silicone.

What aspect of the two products makes you think they are even trivially the same? They look different, smell different, feel different, are made up of different chemicals, do two completely different things, etc etc. Do you think Green Glue is pretty much the same as every other viscous paste-like product, or just silicone?
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post #16 of 53
1/17/13 at 10:01am
Green Glue does not add enough mass to affect mass law (with two layers of 5/8" drywall);
Green Glue is NOT a glue ... it is a specifically formulated polymer for the singular application of CLD (constrained layer damping).
Silcon caulk does NOT have the physical properties to be at all effective in CLD applications (if it did, it would not have been necessary to spend piles of money and years of research to develop Green Glue and its nearest competitor from Serious Materials.
From my perspective, I don't care if you use Green Glue, silicone caulk, peanut butter, or the mysterious white material in Twinkies. It is your room. You do what you want. I would, however, suggest you not ignore the advice you're getting about Green Glue. You asked for advice. You got good and valid advice. If you want understanding ... well, MIT, WPI, GT, CalTech would all be good places to start. Good luck on your project.


http://vibratec.se/products/damping-products/constrained-layer/
http://www.earsc.com/pdfs/engineering/understandingdamping.pdf
http://dspace.mit.edu/bitstream/handle/1721.1/3705/HPCES017.pdf?...2
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post #17 of 53
1/18/13 at 6:14pm
Not like I'm adding much to the discussion here but believe me - when Green Glue first came out, everyone was skeptical. We've now seen its use widespread, spec'd in so many designs because it works. Independent lab testing doesn't only speak for the product - but the type of company as well IMO.
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post #18 of 53
1/19/13 at 7:53pm
Thread Starter 
Please don't take my skepticism as doubtful of anyone's opinion, or ungrateful for your advice! I truly appreciate all the opinions and advice given here. I just have a habit of being skeptical until I see scientific evidence, because I think like a scientist... well at least I hope I do (senior at UNT in physics). However, even an education in physics does not answer all the questions. It's really just a good base for understanding a lot of different areas of physics, and doesn't make me an expert at any one thing. Which I why I turn to you.

Now having read some of those links, and with the overwhelming voice of everyone here, I'm compelled to go ahead and buy it. The cost of green glue is almost negligible compared to all the other materials I'll be buying, plus it's not more expensive than silicone. And furthermore, it appears to do something quite different from silicone.

So, my last question (for now) is this: Has anyone used QuietBrace in their houses? it's like a 1/2" piece of plywood, but made out of something different...
Here's a link:
http://www.homedepot.com/h_d1/N-5yc1v/R-202089176/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=quietbrace&storeId=10051#.UPtqFmdmUek

I'm halfway between using this on top of the existing floors, or putting another layer of 3/4" OSB (with green glue sandwiched in between).
Thoughts?
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post #19 of 53
1/20/13 at 6:22am
That looks like the exterior sheathing they use under brick facade. Ar 28lbs per sheet, it's a lot lighter than plywood/osb (about half the weight). For that reason, I would use plywood or OSB rather than that product.

Tim
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post #20 of 53
1/20/13 at 2:31pm
Thread Starter 
Interesting. Do you know what the STC rating is for OSB? Or for 2 layers of OSB together? This sheeting allegedly has a rating of 30 per sheet. They call it "asphalt injected fiberboard"
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post #21 of 53
1/20/13 at 2:47pm
STC rating is based on installation method. If they tested it nailed to a wall with 3-1/2" insulation and drywall on the other side, that doesn't equate to STC 30 when fastened directly to another substrate.

When you start using dampening compounds it is the mass of the layers that you're after. Auralex says 1/2" plywood has an STC of 26. They also explain why you shouldn't rely on an STC rating.

Tim
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post #22 of 53
1/20/13 at 3:36pm
building sheathing has been promoted as a sound deadening layer for over a decade. The previous contender was the Celotex SoundStop boards which were nothing more than their building sheathing without the weather resistant coating and using a different label.

51a7fc02_vbattach8015.jpeg

As far as soundproofing. If you start with a basic 2x4 stud wall with 1/2 inch drywall on both sides as your baseline, Adding a layer of sheathing under the drywall and insulating the wall is better, it will put a dent on hearing two people talking in the next room, It will not achieve a satisfactory level of sound attenuation at the critical sub woofer rumble frequencies and loudness.
Adding insulation and mounting two layers of 5/8 firecode drywall with Green Glue is better
Hanging the drywall on decoupled framing or isolating clips and channel is even better.

Using Green Glue between layers of building fiberboard sheathing and drywall is a waste of money,
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post #23 of 53
1/21/13 at 5:51am
I don't think you want help and advice ... you're really looking for someone to agree with your premise. You are demanding reams of "scientific evidence" from those providing advice, rejecting the evidence, and continuing to suggest methods which rely on something as simple as Mass Law are not believable. On the other hand, you find a product on Home Depot's website where claims as to the product's performance are made but without independent third party NVLAP testing to support the claims. You clearly have not done any meaningful research with respect to Green Glue (or you'd not suggest a laminate of fiberboard and drywall ... clearly the principles of CLD are missing.) As well, for this application STC is NOT a valid metric, STC of a single material will not represent the "as built" STC of that material, nor can STC values of individual materials, or constructs, be added together. Upon review of the posts by those attempting to provide you with proper guidance, you are continuing to equate "fact" as "opinion".
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post #24 of 53
1/21/13 at 8:27am
Thread Starter 
Calm down there, Dennis. I wouldn't keep asking questions if I wasn't seeking advice. I had a lot of questions and a lot to learn, so I want to look at it from many angles. Everyone is giving good advice and I'm learning a lot. Don't take it personally if I have yet another idea/question, ok? Just because I didn't take your first post as gospel truth doesn't mean I didn't appreciate your advice. wink.gif


Anyway...

I can appreciate how 2 layers of 5/8" drywall de-coupled would be best, but I'm looking to do this on a limited budget, and really just don't care to deconstruct an already existing room. I don't need it to be perfect, just better than it is right now (which is bad). I guess to an experienced person, tearing down drywall and starting over might not be as daunting as it seems to me... but I'm not at that point yet. It also sounds like that quietbrace would be useless to stop subwoofer noise, which is really the thing that carries the most throughout the house. So... I've got to decide if I want to start over, spend a lot more than I originally intended, or try to just insulate the existing walls, finish the other sides with drywall, and see how that goes.

I'm definitely going to blow some insulation into the subfloor. Does anyone recommend cellulose over fiberglass, or vice versa? Or does it matter?
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post #25 of 53
1/21/13 at 1:04pm
Without deconstructing the room, you can add another layer of drywall (with Green Glue in between). If you can access the walls from behind to add insulation do that. Add two more layers of drywall if you can afford it!

My current room uses decoupling clips/decoupled walls, but my previous room was not decoupled - only double drywall, green glue, and insulation. The soundproofing was still significant, and IMO well worth it.

Forget about using exotic products - they simply do not perform as well for the money as drywall does.

Even doing double drywall without green glue is significant, but as you are seeing the cost of green glue is really not that high.
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post #26 of 53
4/22/13 at 8:32am
Sounds like a lot of people with a vested interest in Green Glue. Still don't see any evidence for it other than studies that don't even mention the product or claims made by the manufacturer or distributes, In other words, it sounds like another "Arctic Silver" to me.
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post #27 of 53
4/22/13 at 9:08am
If you discount all the personal accounts of it working, all the contractor accounts of it working, all of the industry professional accounts of it working, and all of the reports generated by a thrid-party independent testing lab (and distributed by the manufacturer, as it the case with any lab report), then yeah I guess you could claim it doesn't work.

Seriously, this has been brought up before and gone down in a giant ball of flames-- let's not go there again. You can search for it.

Tim
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post #28 of 53
4/22/13 at 9:40am
Frankly all this talk of soundproofing is just a waste of money. Any good sound system can overcome the ambient noise of a typically constructed room. If you really like your neighbors you should share your movie soundtracks. It will help them sleep.
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post #29 of 53
4/22/13 at 11:13am
funny i watched and episode of income property this weekend

long story short a couple wanted to turn basement into a apartment but didn't the person renting to hear the noise from above

so they did the genie clips and two layers of drywall and green glue and roxel insulation between the floor joist

first they tested with a speaker upstairs a 90db you could clearly hear it in the basement

after the work was done you could no longer hear the speaker in the basement

they where not pushing green clue all they wanted to do was accomplish a sound proofed place for renters and i was impressed with the results made me feel good about spending the money on spent on green glue for space.
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post #30 of 53
4/22/13 at 11:36am
Quote:
Originally Posted by snickers1 View Post

funny i watched and episode of income property....

I saw that same episode of Income Property, "Mary and Bridge" and was impressed with the improvements and the testing they did before and after with that big speaker upstairs to prove the improvements' effectiveness. It was the first episode where they did some serious soundproofing for an 'executive rental'. For most other builds, they'd do 2 layers of Roxul S&S and resilient channel in ceilings at most. This one went 'all out' with the Genie clips, hat channel, double drywall and Green glue. Considering these products are hard to find locally here, I did some digging and I found the contractor they used was Acoustiguard based in Ontario if anyone is looking for a local supplier out there and finds this post.

What was really impressive was the Green Glue demo. They basically had a gong set up of 2 sheets of drywall laminated together, and another of 2 sheets with Green Glue in between. When striking the DD with a mallet, it would produce quite a bit of 'gong'. When striking the DD&GG, it would only produce a bit of a 'thud'. The GG clearly damped the mass of the drywall. The difference was night and day! Here's a video I uploaded to youtube and sorry it's just an iphone cam rip:

Edited by Swervepf - 4/25/13 at 9:21pm
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