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Discussion Starter #1
Hello. First I would thank you all out there for getting me as far as I have gotten in my HT construction. Most of the studding is done and I should have some pics soon.


I have attached a mock picture of the theater and have a few questions for you geniuses out there.


First some background on the room.


It's in the basement. The room is odd shaped with a cutout for a bar, etc and is about 22 feet by 23 feet. Two walls are poured 10 inch thick concrete. The ceilings are 9 feet to the joists. The supply and returns run right above the seats and throughout the middle of the screen which brings the ceiling down to 7' 8" or so.


The house is an "open" design in the upper two floors and sound travels way too much. Currently, if I play a boombox on relatively low levels, the sound still makes it up to the second floor (through the vents I suppose).


Planning: I plan to spend the money on a product such as green glue and sandwich that between a 1/2" and 5/8" sheetrock on all the inside walls and ceiling. All walls and ceiling would be filled with R-13 insulation.


Questions:

1) Does it matter if you put the 1/2" rock up first or the 5/8"?



2) I don't plan on staggering studs on the concrete walls. I assume the concrete would be enough. Would this be correct?



3) I have not studded the back wall by the furnace or the dividing wall beyond the screen yet. Would I benefit from staggering the studs on these opposite walls?



4) Is staggering with a 2x6 plate versus (2) 2x4's to make a 7" plate anything but a waste of 1 1/2 inches?



5) I'm really worried about all the cutouts I need in this room. I plan on two vents in the ceiling to get some air from the supplies above the seats. I'm concerned that it won't matter how much I spend or do to soundproof the ceiling as the sound from the speakers will travel right up the vents to the upper floors making the soundproofing project futile. How do I know that this is not the case?


6) Louvers. Louvers. Louvers. Code requires that I put a 10" louver at the top and bottom of a wall going into the workshop to make up air for the furnace.


7) The Rack. I can get to the rack from the furnace area. To soundproof the front of the rack from the noises coming from the furnace area, would would be the best approach? A sealed glass door? I can fan the rack from the top and get air flow from the furnace area.


8) Does GOM sound proof or is this only used for correcting the sound?


9) Ceiling soundproofing. Would it help to use one layer of 5/8 rock, green glue and then one layer of Quiet Rock? - or just two layers of sheet with the green glue? Also fill all the joists above with R-13 insulation (planned on this).


Thanks to all who take the time to read this, I have been searching the forums and reading on soundproofing and it has gotten me this far (understanding the terms and products available...)


Gary
 

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1. Acoustically, I don't think it matters. However, I believe 5/8 is usually put up first. That is how I did it.


2. No need to stagger, just keep the stud wall from making contact with the concrete wall to reduce sound transmission.


3. no answer


4. If you use two 2x4 walls, separate them to reduce sound transmission. Yes, this is more effective than a staggered stud on 2x6. I don't have the STC values handy.


5. Try to introduce sound baffles or additional bends in your duct work, and line with linacoustic or something similar to reduce sound travelling between the rooms.


6. Can you duct the openings to pass the air from the furnace to the workshop, instead of just having wall cutouts? Alternatively, use the wall cavity as a duct baffle and make a simple maze for the air to pass through, instead of two openings directly across from each other.


7. A sealed door using weatherstripping is what I had in mind for my equipment closet.


8. GOM is acoustically transparent -- strictly for aesthetics. You can omit from the room, but it won't look as nice :)


9. Pack insulation in your empty cavities for sound insulation. You should use at least double the amount of batting as opening. For instance, if you ceiling joists are 9" TJI joists or 2x10 dimensional, use 18" of insulation. This would be 3 rolls of R-19, IIRC.


Looks like a nice layout.


Geordon
 

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Quote:
Originally Posted by Geordon
4. If you use two 2x4 walls, separate them to reduce sound transmission. Yes, this is more effective than a staggered stud on 2x6. I don't have the STC values handy.
STC is a horrible measure of sound isolation for 90% of applications at least.


the important thing is deeper air space, and yes it will pay off...



Quote:
9. Pack insulation in your empty cavities for sound insulation. You should use at least double the amount of batting as opening. For instance, if you ceiling joists are 9" TJI joists or 2x10 dimensional, use 18" of insulation. This would be 3 rolls of R-19, IIRC.
I beg a pardon for differing, but this is not true. don't use 18" of insulation. don't bother with exotic insulation. if you look at most sound tests run by manufacturers on ceilings, ... they typically use R13 or R19. if paramount gains could be had by more, more would be used. gross over-stuffing might couple the two leaves somewhat, and the only examples of any over-stuffing are from RSIC and Isomax lab tests (as far as i know) where R19 was used in walls slightly less thick than 5.5"
 

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Quote:
Originally Posted by garykagan
9) Ceiling soundproofing. Would it help to use one layer of 5/8 rock, green glue and then one layer of Quiet Rock? - or just two layers of sheet with the green glue? Also fill all the joists above with R-13 insulation (planned on this).


Gary
it will help, as the quiet rock is heavier than normal 5/8"


it will not perform as well as 3 layers of normal drywall and 2 layers of GG, and will be far more expensive
 

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Quote:
Originally Posted by Brian Ravnaas
I beg a pardon for differing, but this is not true. don't use 18" of insulation. don't bother with exotic insulation. if you look at most sound tests run by manufacturers on ceilings, ... they typically use R13 or R19. if paramount gains could be had by more, more would be used. gross over-stuffing might couple the two leaves somewhat, and the only examples of any over-stuffing are from RSIC and Isomax lab tests (as far as i know) where R19 was used in walls slightly less thick than 5.5"
I agree with the statement "gross over-stuffing might couple". Maybe I got my numbers wrong, and I only used 12" of insulation in a 9" void, in which case I stand corrected. I was just tring to follow Dennis Erskine's directions to "pack empty joist cavities". Placing R-13 batt insulation in a 9" cavity is not packing anything in my opinion, but should help insulate the room.
 

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Discussion Starter #6
Quote:
Originally Posted by Geordon
4. If you use two 2x4 walls, separate them to reduce sound transmission. Yes, this is more effective than a staggered stud on 2x6. I don't have the STC values handy.

Geordon
Brian / Geordon - I have the space in the furnace area to stagger. Should I bother is the real question. I really don't want to build two walls if I can get away with that. I do want to ensure I don't hear the furnaces turn on and off, etc. I can afford doing 2 layer of sheetrock + green glue on the theater side. I was planning on leaving the furnace side undone, but may have to do something there.

Quote:
Originally Posted by Geordon
5. Try to introduce sound baffles or additional bends in your duct work, and line with linacoustic or something similar to reduce sound travelling between the rooms.

Geordon
The original duct work is there and "working" so I don't want to move it. I did wrap the supplies from end to end with R-13 insulation already. The new ductwork will be with that flexible stuff from home depot which is insulated on the outside. I wonder if that stuff is helpful with soundproofing.

Quote:
Originally Posted by Geordon
6. Can you duct the openings to pass the air from the furnace to the workshop, instead of just having wall cutouts? Alternatively, use the wall cavity as a duct baffle and make a simple maze for the air to pass through, instead of two openings directly across from each other.

Geordon
I didn't think of this - good idea. I can put 2 10/10 openings in the furnace area ceiling and put duct work over to the workshop to make up air for the furnace. The workshop to the rest of the rooms are already connected with air openings. This way there are no openings in the back wall except for the sealed window on the rack and the one door on the left. If I stagger the studs on the back wall, I will have extra room where the door goes in to add a false front panel with some soundproofing in front of the door. That might help.


Quote:
Originally Posted by Geordon
7. A sealed door using weatherstripping is what I had in mind for my equipment closet.

Geordon
I like this idea.
 

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Discussion Starter #7
Quote:
Originally Posted by Brian Ravnaas
it will help, as the quiet rock is heavier than normal 5/8"


it will not perform as well as 3 layers of normal drywall and 2 layers of GG, and will be far more expensive
I could not find any pricing on Quiet rock. Could you PM me if you know the cost of this product?


I'll never know how good the soundproofing will be until I get the sheetrock up and try it out - that is what makes this so hard....


When I install the air vents in the theater ceiling, I can add some additional turns. I hope that will keep some of the ambient noise from the furnaces out.
 

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If your furnace is in adjacent space, no matter what you do the sound will get into the theater by your duct and the ceiling which is the weakest link. Unless you have a floated ceiling as well but if you don't want to use double wall and floated ceiling 2x6 staggered method should help.
 

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Quote:
Originally Posted by garykagan
Brian / Geordon - I have the space in the furnace area to stagger. Should I bother is the real question. I really don't want to build two walls if I can get away with that. I do want to ensure I don't hear the furnaces turn on and off, etc. I can afford doing 2 layer of sheetrock + green glue on the theater side. I was planning on leaving the furnace side undone, but may have to do something there.
My furnace and two hot water heaters are just outside my theater room next to the equipment closet. I would personally just go with staggered studs. But, you will want to put at least one sheet of drywall on the outside (furnace side), or you aren't providing an air space between the rooms.


Note that sound will travel very easily through sheet metal ductwork, and putting insulation on the outside will do little or nothing to effect that.
 

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Brian, I checked my progress log, and you were right. 2x was too much. I used 9/16" ceiling tile plus 2 batts of R-19 (13" total) in my 9 1/2" cavity (staggered studs 1/2" below). As you can see from the attached picture, I didn't really have to "pack" it, as I pushed in the freshly unrolled batts, which were still somewhat compressed.
 

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Discussion Starter #11
Quote:
Originally Posted by Geordon
My furnace and two hot water heaters are just outside my theater room next to the equipment closet. I would personally just go with staggered studs. But, you will want to put at least one sheet of drywall on the outside (furnace side), or you aren't providing an air space between the rooms.
I'm flip flopping between the double wall with 1/2 space between the floor plates sheet rock both sides with insulation in the middle vs. the staggered with rock on both sides. I'll flip for it...

Quote:
Originally Posted by Geordon
Note that sound will travel very easily through sheet metal ductwork, and putting insulation on the outside will do little or nothing to effect that.
Good point, the insulation around the ductwork hopefully will at least help with the bills (air stays cooler / hotter longer)


-gary
 

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Gary,


As Chris Everett has noted many times at the Home Theater Forum, there are three keys to effective soundproofing: An airtight room, dense partitions, and physical decoupling (isolation) between the two areas. The further you move from any of these elements, the less effective you can expect soundproofing measures to be.


With that in mind let’s take a look at some of your questions.

Quote:
2) I don't plan on staggering studs on the concrete walls. I assume the concrete would be enough. Would this be correct?
Yup. Density doesn’t get much better than concrete! There is no reason to isolate the studs or wall from the concrete.

Quote:
3) I have not studded the back wall by the furnace or the dividing wall beyond the screen yet. Would I benefit from staggering the studs on these opposite walls?
The only reason would be to keep noise in that room from leaking out into the HT area. But even then I doubt it would be at a level high enough to justify staggered studding, especially since you say in #6 that louvers are required by code. That nukes the airtight factor so badly that isolation and dense partitions might not help much. Still, you might go ahead and double sheetrock on both sides. If noise from the furnace room is really a problem, you could build a couple of back-to-back U-shaped tunnels for the air vents. That would allow the needed air circulation, but would help minimize noise transference.

Quote:
4) Is staggering with a 2x6 plate versus (2) 2x4's to make a 7" plate anything but a waste of 1 1/2 inches?
Any wall you feel needs staggered studs will get better soundproofing with fully independent walls, especially of the two are completely decoupled and air tight.

Quote:
5) I'm really worried about all the cutouts I need in this room. I plan on two vents in the ceiling to get some air from the supplies above the seats. I'm concerned that it won't matter how much I spend or do to soundproof the ceiling as the sound from the speakers will travel right up the vents to the upper floors making the soundproofing project futile. How do I know that this is not the case?
I wouldn’t worry about the air vents unless perhaps they are the old-fashioned metal ducts. Most everything built in the last 25 years or so has flexible ducts with built-in insulation. Those should effectively dampen the mids and highs, especially by the time the sound twists and turns through them from point A to B.


Bottom line, sound transference through air ducts is a drop in the bucket compared to what you get directly through the walls. If you were able to “go all the way†and soundproof to recording studio specs, then you might need to look at the AC system. But since that isn’t happening here, I wouldn’t worry about it.

Quote:
9) Ceiling soundproofing. Would it help to use one layer of 5/8 rock, green glue and then one layer of Quiet Rock? - or just two layers of sheet with the green glue? Also fill all the joists above with R-13 insulation (planned on this).
The ceiling is going to be your weak link, since you say the sound goes right through to the upstairs and you really can’t build a new isolated ceiling below the rafters. Therefore your best bet there is to maximize the dense partitions and make sure it’s airtight. I’d double the 5/8 for sure, maybe even use double Quietrock. If Brian’s assessment of the stuff is correct, doubling Quietrock would be equivalent to three inches of sheetrock.


A few other things:
  • Use heavy, solid doors between any rooms you’re trying to soundproof. If you’re double-walling, you’ll need double doors as well.
  • The doors should be fully weather stripped and include a threshold, to insure an air tight seal.
  • If you shoot for an airtight room, you’ll need to modify the AC system for an outlet as well as an inlet.
  • Even with all this soundproofing, you’ll still get some low frequencies bleeding through.

Regards,

Wayne A. Pflughaupt
 

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Looking at a cost / benefit plan for a moment, you might do well to consider adding an element of de-coupling to the ceiling, especially if you have hard floors above. You'll get some added benefit of reducing the impact noise from above from entering your theater.


When you are considering expensive suggestions (you should at least consider all options), you should really look at performance relative to cost.
 

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Quote:
Originally Posted by Ted White
Looking at a cost / benefit plan for a moment, you might do well to consider adding an element of de-coupling to the ceiling
I took Ted's advice to heart when I built our HT. I ran a new set of 2x? dimensional ceiling joists between the existing TJI floor joists. Only cost me 1/2" of headroom. I didn't even consider the cost, as it was one of my primary construction requirements. See my attachment earlier in this thread. If you have a 22' free span, you may need to go with engineered joists (I-joists), but the cost increase shouldn't be that great, in the grand scheme of things. If you use a front projector mounted to the ceiling within the room, this would also reduce it from being bounced around by people walking/running overhead.
 

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Discussion Starter #15
Quote:
Originally Posted by Geordon
I took Ted's advice to heart when I built our HT. I ran a new set of 2x? dimensional ceiling joists between the existing TJI floor joists. Only cost me 1/2" of headroom. I didn't even consider the cost, as it was one of my primary construction requirements. See my attachment earlier in this thread. If you have a 22' free span, you may need to go with engineered joists (I-joists), but the cost increase shouldn't be that great, in the grand scheme of things. If you use a front projector mounted to the ceiling within the room, this would also reduce it from being bounced around by people walking/running overhead.
That's an interesting thought. Not sure how feasible it is, almost all of the joists are filled with suppiles and returns that will bring the ceiling height to 7' 6" currently. Not sure If I can fit that in. Double sheetrock with GG in the center seems like the plan so far. Not sure if that will be enought though.


Ted - I'll give you a call shortly, I appreciate your thoughts as well.


Gary
 

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Discussion Starter #16
Quote:
Originally Posted by Wayne A. Pflughaupt
Yup. Density doesnt get much better than concrete! There is no reason to isolate the studs or wall from the concrete.
So can I suggest from this that double sheet rock on a wall that is 10" concrete is unnecessary, and use that money to soundproof the ceiling?

Quote:
Originally Posted by Wayne A. Pflughaupt
The only reason would be to keep noise in that room from leaking out into the HT area. But even then I doubt it would be at a level high enough to justify staggered studding, especially since you say in #6 that louvers are required by code. That nukes the airtight factor so badly that isolation and dense partitions might not help much. Still, you might go ahead and double sheetrock on both sides. If noise from the furnace room is really a problem, you could build a couple of back-to-back U-shaped tunnels for the air vents. That would allow the needed air circulation, but would help minimize noise transference.
I can get away with not using the louvers on the back wall (calling the township now) by using one of the ideas above and bypassing the theater with a Transfer Air Duct from the Furnance room to the Workshop.

Quote:
Originally Posted by Wayne A. Pflughaupt
Any wall you feel needs staggered studs will get better soundproofing with fully independent walls, especially of the two are completely decoupled and air tight.
Based on the replies, I will build a single wall by the furnace and double sheet rock with GG. If that does not do it, I can always add another wall behind it in the furnace room with a gap, and make the two walls with air in the center.

Quote:
Originally Posted by Wayne A. Pflughaupt
I wouldnt worry about the air vents unless perhaps they are the old-fashioned metal ducts. Most everything built in the last 25 years or so has flexible ducts with built-in insulation. Those should effectively dampen the mids and highs, especially by the time the sound twists and turns through them from point A to B.
The house is only 2 years old and they used metal duct work. All the new duct work will be flexible ducts with built in insulation.

Quote:
Originally Posted by Wayne A. Pflughaupt
The ceiling is going to be your weak link, since you say the sound goes right through to the upstairs and you really cant build a new isolated ceiling below the rafters. Therefore your best bet there is to maximize the dense partitions and make sure its airtight. Id double the 5/8 for sure, maybe even use double Quietrock. If Brians assessment of the stuff is correct, doubling Quietrock would be equivalent to three inches of sheetrock.


A few other things:
  • Use heavy, solid doors between any rooms youre trying to soundproof. If youre double-walling, youll need double doors as well.
  • The doors should be fully weather stripped and include a threshold, to insure an air tight seal.
  • If you shoot for an airtight room, youll need to modify the AC system for an outlet as well as an inlet.
  • Even with all this soundproofing, youll still get some low frequencies bleeding through.

Regards,

Wayne A. Pflughaupt
I'll keep researching on the ceiling, looking into what this RISC stuff is and if it with 2 layers of sheetrock and GG will help.


Thanks - attached are the latest diagrams.


 

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Discussion Starter #17
Move layout diagrams....


 

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Quote:
Originally Posted by Wayne A. Pflughaupt
Gary,


As Chris Everett has noted many times at the Home Theater Forum, there are three keys to effective soundproofing: An airtight room, dense partitions, and physical decoupling (isolation) between the two areas. The further you move from any of these elements, the less effective you can expect soundproofing measures to be.
i beg the pardon of the group for my in-and-out presence in this discussion, it seems i haven't had so much time to spare this week.


that is a relatively short-sighted list of criteria. although not inaccurate, neither is it a recipe for success.


for example, people obsess over decoupling but do not understand the mass-spring principles that lie behind it. it is NOT good to simply decouple, it IS GOOD TO DECOUPLE AND ATTAIN A LOW FREQUENCY OF MASS-SPRING RESONANCE.


if you decouple but do not attain this - a low frequency of spring resonance - you will have harmed not helped your cause. i was in the process of entering a thread explaining this in some detail elsewhere, i'll re-post here or post a link here when it's finished.


what was said above is correct, but only partially correct.

Quote:
With that in mind let’s take a look at some of your questions.


Yup. Density doesn’t get much better than concrete! There is no reason to isolate the studs or wall from the concrete.
this is not true. concrete will benefit/suffer as much from decoupling as anything else

Quote:
The only reason would be to keep noise in that room from leaking out into the HT area. But even then I doubt it would be at a level high enough to justify staggered studding, especially since you say in #6 that louvers are required by code. That nukes the airtight factor so badly that isolation and dense partitions might not help much. Still, you might go ahead and double sheetrock on both sides. If noise from the furnace room is really a problem, you could build a couple of back-to-back U-shaped tunnels for the air vents. That would allow the needed air circulation, but would help minimize noise transference.
the nature of the compromise on isolation due to seals isn't such a simple topic. this, also, is frequency dependent, like everything else, but it's the one area where low frequencies are harmed less.


Quote:
Any wall you feel needs staggered studs will get better soundproofing with fully independent walls, especially of the two are completely decoupled and air tight.


I wouldn’t worry about the air vents unless perhaps they are the old-fashioned metal ducts. Most everything built in the last 25 years or so has flexible ducts with built-in insulation. Those should effectively dampen the mids and highs, especially by the time the sound twists and turns through them from point A to B.


Bottom line, sound transference through air ducts is a drop in the bucket compared to what you get directly through the walls. If you were able to “go all the way” and soundproof to recording studio specs, then you might need to look at the AC system. But since that isn’t happening here, I wouldn’t worry about it.
politely, that is simply not necessarily true. first, it's frequency dependent, second its situationally dependent, third i'm allergic to blanket statements.

Quote:
The ceiling is going to be your weak link, since you say the sound goes right through to the upstairs and you really can’t build a new isolated ceiling below the rafters. Therefore your best bet there is to maximize the dense partitions and make sure it’s airtight. I’d double the 5/8 for sure, maybe even use double Quietrock. If Brian’s assessment of the stuff is correct, doubling Quietrock would be equivalent to three inches of sheetrock.
i said 3 layers of drywall/gg would perform better than one layer of drywall +gg+quietrock


the reasons are these:


1. the gg is far more efficient than the other damping material, and two layers of it will outperform one layer of it + 2 layers of, well, anything else. also, with constrained layer damping the behavior of the systems when combining damping materials is not un-complex, but that's a long story


2. the 3 layers of 5/8" would be heavier than 5/8+quiet rock, and with mass comes a lowering of the frequency of mass-spring resonance when used in combination with RSIC clips






take it easy, all, and i hope to be able to stop by to contribute some more.


looks like the insulation thing got sorted out, that's great, and the link in my signature leads to a thread that might be a ltitle bit disorganized, but it stands as as complete and correct a list of sound isolation principles as you will find anywhere.
 

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to lower the frequency of mass-spring resonance and maximize the use of decoupling:


1. use as much mass as possible on both sides of the partition.


imagine a wall with 6 total layers of drywall. 3 layers on each side is superior to 1 layer on one side and 5 on the other. There are posts out and about in cyberspace to the counter of this, those posts are incorrect


2. use as deep of an air cavity as possible.


3. use insulation in the air cavity. nothing magic about insulation choice, fluffy fiberglass is AS GOOD AS ANYTHING


4. if utilizing any type of decoupling hanger, clip, or channel, know this:


-the softer the spring force of the product, the better.

-the more give in any given sound clip, the better, the stiffer the worse

-resilient channel is too stiff, even good channel is too stiff



Brian
 

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garykagan, for whatever reason, your photo's wont load here at the lab.
 
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