# Drywall/QuietGlue or Quietrock



## MLGamer (Feb 10, 2013)

Hello everyone,

I hope you all had a great holiday season.


I am finishing my basement with a home theater. After much deliberation, I decided to soundproof and "acousticize" the entire level. My question is simple and has probably been asked before: What gives me a better net STC, double layer drywall with QuietGlue or 5/8" 525 Quietrock? I know the latter is more expensive; however, I am willing to take the plunge if it is the best solution.

Thanks,

Matthew


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## bpape (Sep 14, 2006)

The double drywall and Green Glue will give better isolation. It's all about mass.


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## MLGamer (Feb 10, 2013)

bpape said:


> The double drywall and Green Glue will give better isolation. It's all about mass.


Brian,

Thanks. I love the fact that, for once, the less expensive solution wins out. I have already priced out both solutions and the double drywall/QuietGlue option is significantly less. 

I have also decided to go with isolation clips and hat track channels on the ceiling. In the home theater area, which is directly under the master bedroom, I am going to channel/clip the walls as well to help eliminate frequency transference. All the doors going in are going to be solid core with treatments. In addition, I am adding a door at the bottom of the stairs to help stop leaks to the kitchen area above. On the acoustical side, I am going with a combination of acoustic panels, bass traps and sound deadening furniture.

This is exciting as I will be doing the building and this is my first home theater.

Thanks,

Matthew


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## RBTO (Jan 27, 2010)

Since you haven't done the drywall work yet, another technique to consider is offset studs. Use alternating studs for opposite sides of the wall so sound won't carry through the studs. Use studs placed at half normal intervals on a six inch plate and cap. Shift them (alternately) to face opposite sides as you go. You can go with a four inch plate and cap but then you need to trim your studs slightly so they are less than the cap and plate width. Takes twice as many studs but it gives quite a bit of isolation and works for lower frequencies fairly well. Apply your other treatments in addition, and you should have some good soundproofing. Don't forget ventilation since soundproofing insulates for heat (and cooling) as well.


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## Blacklightning (Nov 22, 2011)

Quietrock is just two small pieces of drywall with glue in-between. Do it your self and you will safe a ton of money and you will have a more sound proof room. If you compare Quietrock to 1 regular 5/8 drywall the Quietrock will win but you are talking about over an inch of drywall with glue.

Another note do not waste your money on sound insulation spend your money on isolating the walls and just use cheap pink insulation. Bass loves dense insulation, High frequencies will be stopped but bass will have an easier time. High frequencies will already have a hard time getting pass 2 layers of drywall.


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## MLGamer (Feb 10, 2013)

RBTO said:


> Since you haven't done the drywall work yet, another technique to consider is offset studs. Use alternating studs for opposite sides of the wall so sound won't carry through the studs. Use studs placed at half normal intervals on a six inch plate and cap. Shift them (alternately) to face opposite sides as you go. You can go with a four inch plate and cap but then you need to trim your studs slightly so they are less than the cap and plate width. Takes twice as many studs but it gives quite a bit of isolation and works for lower frequencies fairly well. Apply your other treatments in addition, and you should have some good soundproofing. Don't forget ventilation since soundproofing insulates for heat (and cooling) as well.


Thanks Bob. Is the wall building technique you referring to called "staggered"? If so, that is what I plan on doing. I do not mind the money going into extra studs. I just want to get all of this done upfront so I do not have to go back and spend more money and time on it later. On the HVAC note, I was planning on using QuickCoat. What are your thoughts on that product?

Thanks again.

Matthew


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## MLGamer (Feb 10, 2013)

Blacklightning said:


> Quietrock is just two small pieces of drywall with glue in-between. Do it your self and you will safe a ton of money and you will have a more sound proof room. If you compare Quietrock to 1 regular 5/8 drywall the Quietrock will win but you are talking about over an inch of drywall with glue.
> 
> Another note do not waste your money on sound insulation spend your money on isolating the walls and just use cheap pink insulation. Bass loves dense insulation, High frequencies will be stopped but bass will have an easier time. High frequencies will already have a hard time getting pass 2 layers of drywall.


Hello Blacklightning!

I was almost lured in by Roxul's marketing but decided to go with OC Bat 15 (walls) and Bat 30 (ceilings). BTW, thanks for confirming that QuietGlue and my own 5/8" double drywall is a better path to follow. I am spending enough money between construction materials, new speakers, new components and the like.:hissyfit:

Thank you,

Matthew


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## RBTO (Jan 27, 2010)

I'm not sure what to tell you on the "staggered" term since I'm not a builder myself, but it sound's right. I'm attaching an illustration to this post to show you what I was talking about. As Blacklightning mentioned, just use pink fiberglass or loose packed cellulose fill between the drywall sheets (fiberglass is best since it won't ever pack).

Not sure about the QuickCoat Matthew, I haven't heard of that before. The main thing I was referring to is to size any cooling system to take into account heat sources in the insulated rooms since you'll have to pull that heat out with the HVAC system more so than with a non-insulated space. However, it could be an advantage for heating in the winter!


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## Andre (Feb 15, 2010)

Don't forget you're also using those Whisperclips to hang the drywall. Make sure the drywall installer just doesn't drill a drywall screen straight through the whisperclip into the stud, don't laugh I've heard of it being done.


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## Blacklightning (Nov 22, 2011)

MLGamer said:


> Hello Blacklightning!
> 
> I was almost lured in by Roxul's marketing but decided to go with OC Bat 15 (walls) and Bat 30 (ceilings). BTW, thanks for confirming that QuietGlue and my own 5/8" double drywall is a better path to follow. I am spending enough money between construction materials, new speakers, new components and the like.:hissyfit:
> 
> ...


Thanks Matthew,

I'm building a home right now and I have a bonus room that will be my Music room so I did a lot of reading. Most guys/home builders will just recommend "sound proof" material because they do not do any testing and they just go off of marketing material. Contractors will not test walls STC ratings after the install is done and people trust high priced "sound proof" products because of the marketing behind it. All “sound proof” products comes from an idea in some one’s head or it’s a quick install of a labour DIY project. I contractor will use Quietrock and see that it is better than 5/8” drywall. After that he will recommend it left right and center to anyone that wants sound proofing but if he was to think as to why it works and what it really is, he would see that it is just 2 pieces of 5/16” (guessing) with glue. If I was a contractor doing my own home I would not want to pay the money for Quietrock. Since the glue is easy to get (Green glue), I would just glue two ½” pieces of drywall together to get the same performance as Quietrock. Or go one step more and do 5/8”.

Insulation is another one contractor knows nothing about, to them if you want soundproofing use sound insulation right? Well, again the contractor is not looking hard enough. Years ago some one noticed that insulation in a wall was more soundproof then no insulation so he thought what would happen if I stuffed more into the same wall or use a material that was heavier? Guess what it worked for sound but it made heat insulation worse so they made sound insulation with no “R” ratings. The reason it works is 2 fold, the second being added weight. But one more piece of dry wall is a hell of a lot heavier than insulation and it’s still cheap so no real reason to add weight to insulation. Now the other part of it (I do not know the science behind this one) is sound insulation works for high talking voices and up so I would use is in regular homes… if I had a lot of money. But the kicker is that with subwoofer the sound insulation makes the sound proofing worse so it’s hurting what you are trying to do in the first place. If you hear music from another room or another house it’s the bass that you hear because it’s the hardest thing to stop. Now your fancy insulation is going to make it worse. STC rating only go down to 160Hz (I think) because bass is hard to stop.

Another thing to keep in mind is if you have a contractor doing the work forget about z channel or sound bars as very few will install it correctly or use the right stuff. Double walls and or staggered studs are your best friend and contractors will not screw that up as easily.

Good luck with your room and think about products long and hard before you spend your hard earned money.

P.S. Doors, heat vents, and cold air returns are the most over looked things. Do research on the doors.


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## MLGamer (Feb 10, 2013)

Blacklightning said:


> Thanks Matthew,
> 
> I'm building a home right now and I have a bonus room that will be my Music room so I did a lot of reading. Most guys/home builders will just recommend "sound proof" material because they do not do any testing and they just go off of marketing material. Contractors will not test walls STC ratings after the install is done and people trust high priced "sound proof" products because of the marketing behind it. All “sound proof” products comes from an idea in some one’s head or it’s a quick install of a labour DIY project. I contractor will use Quietrock and see that it is better than 5/8” drywall. After that he will recommend it left right and center to anyone that wants sound proofing but if he was to think as to why it works and what it really is, he would see that it is just 2 pieces of 5/16” (guessing) with glue. If I was a contractor doing my own home I would not want to pay the money for Quietrock. Since the glue is easy to get (Green glue), I would just glue two ½” pieces of drywall together to get the same performance as Quietrock. Or go one step more and do 5/8”.
> 
> ...


Thanks for your insight Blacklightening. I really appreciate it.

Matthew


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## MLGamer (Feb 10, 2013)

Attached is another example of staggered wall construction that I thought was very helpful in visualizing the independent elements working together. As you see, 2 x 2 corner studs are added to ensure proper fastening of drywall panels. In addition, the pink stuff envelopes the inner portion of the 2 x 4s to provide maximum frequency absorption. Finally, the 2 x 4 are offset six inches on the inside from the outside studs. GOOD STUFF! 

Matthew


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## MLGamer (Feb 10, 2013)

All,

Yet another good graphic though I am not sure how accurate the STC scores are for the four constructs illustrated. 

Matthew


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## NBPk402 (Feb 21, 2012)

MLGamer said:


> All,
> 
> Yet another good graphic though I am not sure how accurate the STC scores are for the four constructs illustrated.
> 
> Matthew


Good info... I wonder what would happen if you did the double wall with 1 layer of 1/2" OSB, and 3 layers of 5/8" drywall, and green glue. I have been looking at a DIY that uses fir strips instead of clips for hanging the OSB and drywall... I think it will cut the costs down quite a bit too.


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## MLGamer (Feb 10, 2013)

ellisr63 said:


> Good info... I wonder what would happen if you did the double wall with 1 layer of 1/2" OSB, and 3 layers of 5/8" drywall, and green glue. I have been looking at a DIY that uses fir strips instead of clips for hanging the OSB and drywall... I think it will cut the costs down quite a bit too.


Hello,

The key to the clip system is that there is minimal contact with the floor joists. That means a decrease int the amount of sound that transfers from the the drywall, to the clip, to the channel and finally to the joist. I have not seen the system you are referring to so I cannot provide you any feedback. Do you have a link?

Matthew


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## NBPk402 (Feb 21, 2012)

MLGamer said:


> Hello,
> 
> The key to the clip system is that there is minimal contact with the floor joists. That means a decrease int the amount of sound that transfers from the the drywall, to the clip, to the channel and finally to the joist. I have not seen the system you are referring to so I cannot provide you any feedback. Do you have a link?
> 
> Matthew


Here ya go... http://www.hometheatershack.com/for...s/71887-has-anyone-ever-tried.html#post663848

I think the only dif is that he is using fir strips instead of metal. You would still only screw through where there is no stud.


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## MrAngles (May 1, 2012)

ellisr63 said:


> Here ya go... http://www.hometheatershack.com/for...s/71887-has-anyone-ever-tried.html#post663848
> 
> I think the only dif is that he is using fir strips instead of metal. You would still only screw through where there is no stud.


Using the fir strips looks like a reasonable alternative to using resiliant channel, maybe a little less effective just due to the higher flexibility of metal channel. A true clip and hat channel method is much more effective at decoupling, however, because the channel isn't actually screwed into the studs at all, but clipped into place.


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## NBPk402 (Feb 21, 2012)

MrAngles said:


> Using the fir strips looks like a reasonable alternative to using resiliant channel, maybe a little less effective just due to the higher flexibility of metal channel. A true clip and hat channel method is much more effective at decoupling, however, because the channel isn't actually screwed into the studs at all, but clipped into place.


Yes, but the way he did it the fir strip is hanging onto another fir strip so there is only friction holding the two together... No screws connecting the two. Wouldn't it be just as effective as the clip and channel?


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## MrAngles (May 1, 2012)

ellisr63 said:


> Yes, but the way he did it the fir strip is hanging onto another fir strip so there is only friction holding the two together... No screws connecting the two. Wouldn't it be just as effective as the clip and channel?


Well, it's gravity that connects the two angled strips together, which I don't imagine allows any flexibility once two layers of drywall have been attached. The real decoupling factors in his method are the fact that there are only two strips for the entire height of his wall, and that he's using foam tape to isolate the strips from each other, which is not generally known to be that effective anyway. The main reason why the connection points between clips and hat channel are so springy is that the channel is only snapped in for about an inch and a quarter at every third stud. His connection is along the entire length of the wood strips, so there's a lot more contact, regardless of the fact that he has foam in between the strips. Not to mention that even though the drywall is technically only screwed into the top strip, it's still making tight contact with and transferring sound right through the foam, especially low frequencies, into the bottom strip, which is screwed directly into the studs. I'm sure it provides better sound isolation than screwing drywall directly into the studs, but it's not in the same league as true decoupling such as clips and channel, staggered studs or double stud walls. Personally I'd go with staggered studs or double studs if you want to save money.


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## bpape (Sep 14, 2006)

It's all about surface contact area and flexibility/rigidity. Firring is a good cheap way to go that'll get you a lot of what clips/channel will do. Clips and channel though you have such a very very small contact area that it's pretty tough to transmit much of any motion to the studs.


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