Noise Isolation for 3rd Floor Theater Room

[csm_274]

I'm almost ready to finish my third floor space and want to make it a home theater room. It's approximately 30x20x10-12 (no limit on height but probably stick to 10-12 feet). There are bedrooms directly below the space and I'm concerned about noise problems. I'm aware there are tricks to help reduce the amount of noise seepage (e.g. double sheetrock with air space in between, sound deadening material under the carpet, building subfloor with space barrier to reduce sound transfer, etc.).

My question is this...is it realistic to think I can significantly reduce the noise seepage to the rooms below with a well designed space (without having to spend a fortune building a sound vault)? My goal is to set up a pretty solid system. For example...two JL Audio 10 inch subwoofers, 3 tower speakers upfront (left, right and center) pushed by a solid amp, and so on. Total spend of A/V equipment in the 20-30K range. Not the most amazing system, but still robust.

If it is realistic, can some of you comment on ways to accomplish my goal and perhaps provide very, very rough guestimates as to how much the suggested steps might cost? Thanks in advance.

 

[Rickster71]

Sounds like a nice big theater.


Without putting words in your mouth.
If you're asking if people can be asleep in the bedrooms below while you have a movie like The Transformers on?
All without spending much money...it's not going to happen.

IMHO you'd have to know the specific monies allocated to sound attenuation, which will need to be done at the point of the building's frame.
Lower frequencies will travel throughout the framing of the house.


I'd call a professional or two, to get the ballpark figure.

 

[csm_274]

Thanks and very fair criticism. As for money, I can't truly say but ballpark would consider 10-20K to address sound isolation. I've read good things bout the "room within a room" approach for nullifying the tranmission of low frequencies. I assume that's the most expensive approach - fair assumption?

 

[GIK Acoustics]

Thanks and very fair criticism. As for money, I can't truly say but ballpark would consider 10-20K to address sound isolation. I've read good things bout the "room within a room" approach for nullifying the tranmission of low frequencies. I assume that's the most expensive approach - fair assumption?

It can get much more expensive than building another room within your room. Thats actually one of the cheaper ways you can go considering the room is already built.
I would recommend getting a book or two on the subject if you don't plan on hiring a professional and reading for a bit. I recommend this book by Rod Gervais often: Home Recording Studio: Build It Like the Pros: Rod Gervais: 9781435457171: Amazon.com: Books

It is geared towards a music studio, but most of the book is simply about construction and a good half of it is purely about isolation. Tons of construction diagrams, HVAC baffle boxes, isolating electrical outlets, etc. It helps to lay down the basics, how to test the room and figure out the exact isolation levels you need, etc. And tons of info on smoke & mirrors products and what to avoid.

I usually recommend hiring a professional to do the design if you really need a good amount of isolation. The nice thing is you can contract an agreement for the exact amount of isolation that you need, this way you won't be left with a room that didn't perform up to what you thought it would / needed it to.

Your budget seems like its good at a glance to achieve a decent amount of isolation, but you'd really need an initial isolation survey to know how much you need to spend to get to #dB reduction at #Hz.

 

[Gordonj]

You are facing a big challenge in trying to isolate your speakers and subs from the rooms below. While you could build a floating floor to help isolate, in your case it would not gain a tremendous amount of reduction (although any could help). In most cases like you have, a good way to help mitigate the noise transfer is to build an additional ceiling system BELOW the floor/room in question. Therefore, you would need to add to the ceiling system in each room below the theater room. That may not be manageable.

A built up floor systems success depends on too many factors to cover here and could prove rather expensive for less reduction and normally is considered as part of entire approach to isolation and vibration control. While floor corks and underlayment are more designed for impact isolation (foot fall) then control of a speaker, any would help in your case. I would take a look at the AcoustiCork product at this website for more information on isolation underlayments.

AMORIM

Gordon

 

[avengineer]

After looking at some of the suggestions you've received so far, let me add my vote to the "hire a pro" idea. Some of what's been given has merit, some is completely wrong. No point it taking shots at specifics, though. How would you know the difference? It's all just unqualified opinion here, but it's a lot of your money at stake. Reading a book or three is nice, but no substitute for hiring a pro who's done it before. And knowing the basic principles is one thing, realizing how to avoid an installation disaster is another, picking the right isolation products still another.

An example might be, building an isolated room on a floating floor system only to find that your room built with 60dB STC walls performs more like 30dB STC because somebody didn't pay enough attention to HVAC. Or necessary wall perforations for electrical devices. Or one of the floor isolators was inadvertently shorted out. Or under specified. Or, based on bad advice, somebody spec'ed the wrong product that did almost nothing.

The other thing a Pro has in hand is an awareness of the current products that can be used for the job. They change all the time, and are difficult to find in the first place. An example, high performance wall board. A lot of books suggest several layers of standard dry wall as a sound partition. But they never mention there are high performance wall materials that can achieve better than triple layer standard walls but use only one layer of a special composite wall product.

I know someone who spent 100K on an isolated room, but it underperforms by at least 20dB because in inner and outer wall systems are connected to each other.

OK, enough horror stories, you know what to do...

See what I mean? This is one case where DIY won't save you money, it will cost you.

 

[Gordonj]

The other thing a Pro has in hand is an awareness of the current products that can be used for the job. They change all the time, and are difficult to find in the first place. An example, high performance wall board. A lot of books suggest several layers of standard dry wall as a sound partition. But they never mention there are high performance wall materials that can achieve better than triple layer standard walls but use only one layer of a special composite wall product.

While there are some "newer" products out there they are all still dealing with the same principals and the same approaches. No new "ah ha" things out there. Knowing what to use, where and how is why anyone undertaking such a task needs a pro.

The high performance wall materials that is being referred to above actual are products by two manufactures. One is Quiet Rock and the other is Sound Break. Both are good products and while I have designed around both with good results I have had better success with the Sound Break mainly form a delivery time issue and an identification issue in the field by the contractors. Both products can be bought from a Lowes or Home Depot. The Quiet Rock is from the west cost while the Sound Break is from the East Coast.

In general you will see about a 5 point improvement in the STC score with these products vs. standard gyp board. These products in general cost on average around $3sqft vs $.90sqft for gyp board.

1 Layer of 5/8" gyp board type X (fire rated) will result on average in an STC of 28 while a single layer of Quiet Rock #530 will result in a STC of 33. These are averages and can be effected by many conditions. Quiet Rock also has a product "specifically designed for home theaters" (545) that should provide better isolation figures especially for the LF then the "standard" Quiet Rock product.

Here are some links:

http://quietrock.com/quietrock-product/quietrock-545-thx

http://quietrock.com/quietrock-products

National Gypsum Company

Both of these sites do have "do-it-yourself" sections and show some basic wall details and how those wall builds effect the STC scores.

I hope that helps some more.

Gordon

 

[Pyrrho]

Are you dead set on putting the home theater above the bedrooms? What about the space below them, or better still, on a lower floor under other rooms in the house? Normally, it is easier to hear things from above than below in a house. Usually, in an apartment, one is more likely to be bothered by noise from the floor above than the floor below.

Now, if you had not yet built the house, you could have put in concrete floors for every level, which works a lot better at noise isolation than a wood frame building is generally going to give you. But that does not seem to be an option at this point, so, again, can you locate the home theater to some other part of the house? You don't need windows in a home theater, and in fact, they tend to be a problem.

 

[avengineer]

As far as the benefits of working with a Pro, the point has been well made. Let me add that while companies may have DIY sections on their sites, there's a lot they don't tell you. Building a very high STC wall, regardless of composition, is pointless if penetrations aren't addressed. One badly done electrical box, and your high STC wall becomes less than standard.

There's a third high performance company, also in California, Suppress Products...google 'em.

A pro would also know that while STC figures are the ones everyone quotes, they are only a reference point. The STC curves don't deal with sub-woofer type bass...at all. The bottom band is 125Hz, well above crossover. Some manufacturers have the foresight to have products tested by a lab that goes below that, not the numbers are never impressive, so you don't see them, and if you do they bottom at 80Hz or possibly 50Hz.

The real issue is cost savings. It's a ratio of $:dB. Is it cheaper to hire a pro who can design for the best performance at best price, or don't hire the pro, DIY, read the data and build your own wall? Example: Quietrock 545 is great stuff, a single layer is STC60. So, which is a better $:dB ratio, a wall that uses one layer of 545 on the inside, then standard 5/8 on the outside, or a wall that uses a layer of 545 on each? That stuff is rated at STC 60, so two layers would be STC 120, right? Nope. In fact the wall with the standard layer is 4dB better than the double 545. And that wall switch just made it all an STC-30 wall. We won't even talk doors or HVAC.

See what I mean? You do get what you pay for, just pay for the right thing.

 

[Gordonj]

The real issue is cost savings. It's a ratio of $:dB. Is it cheaper to hire a pro who can design for the best performance at best price, or don't hire the pro, DIY, read the data and build your own wall? Example: Quietrock 545 is great stuff, a single layer is STC60. So, which is a better $:dB ratio, a wall that uses one layer of 545 on the inside, then standard 5/8 on the outside, or a wall that uses a layer of 545 on each? That stuff is rated at STC 60, so two layers would be STC 120, right? Nope. In fact the wall with the standard layer is 4dB better than the double 545. And that wall switch just made it all an STC-30 wall. We won't even talk doors or HVAC..

You might need to go back and check your facts again. The 545 is not STC 60 by itself. A single layer of 545 product on a single wood stud 24" oc, With 3 1/2" batt and a single layer of 5/8" type x gyp is STC 56. One layer of 545 product on a single wood stud 24"oc with 3 1/2" batt with another layer of 545 is now STC 60. A transmission class rating is much more then just the product on the surface. It is the entire assembly, including the studs, batting, etc and yes, all penetrations. Again that product by itself is not STC 60.

Most products are not tested below the 125hz band due to lab space limitations and inaccuracies of testing models in the lower octaves. With lab tests the product it is mounted or a wall assembly is built and then tested on octave bands for frequency reductions. Most STC numbers for the lower frequencies are extrapolated if provided at all.

Further, your statement that Two layers of 545 is worse then a single layer is somewhat misleading as well. A Double layer of 545 on each side with 2x4 studs Spaced 24" oc, 3" min air gap, and 9" batt gives you a STC 80.

Gordon

 

[avengineer]

You might need to go back and check your facts again. The 545 is not STC 60 by itself. A single layer of 545 product on a single wood stud 24" oc, With 3 1/2" batt and a single layer of 5/8" type x gyp is STC 56. One layer of 545 product on a single wood stud 24"oc with 3 1/2" batt with another layer of 545 is now STC 60. A transmission class rating is much more then just the product on the surface. It is the entire assembly, including the studs, batting, etc and yes, all penetrations. Again that product by itself is not STC 60.

Really? We're arguing about what part of the datasheet to read? You have stated your facts quite accurately, my examples were NOT specific. Big deal, you've completely missed the point.

Most products are not tested below the 125hz band due to lab space limitations and inaccuracies of testing models in the lower octaves. With lab tests the product it is mounted or a wall assembly is built and then tested on octave bands for frequency reductions. Most STC numbers for the lower frequencies are extrapolated if provided at all.

Exactly, yet its below 125 that a high loss wall is really needed. It's easy to block the mid band. That's the point I was making.

Further, your statement that Two layers of 545 is worse then a single layer is somewhat misleading as well. A Double layer of 545 on each side with 2x4 studs Spaced 24" oc, 3" min air gap, and 9" batt gives you a STC 80.

Um.. again, I wasn't that specific. If you must be, here's the examples: Single 2x4 studs, 24" OC, 545 both sides, you've got your STC60. Staggered 2x4 studs, 9" OC, 545 one side, generic the other, you've go STC64.

But, that's NOT the point. Anyone can read the data sheets. But your example of the STC 80 wall does illustrate my point quite well. Yes, that's nice test data, but would you actually spend the money to build that? If you did, you've wasted it. You might build a single test wall that does STC 80, but you can't actually build an STC 80 room. There are just too many holes, the door being the big one. This is exactly the kind of thing you need a pro for. Somebody reading the test data would spec that wall, but then ruin the performance of the room some other way. You still have a floor and ceiling to deal with, and a door, and HVAC, electrical, recessed light cans sometimes...or even worse, ruin the whole thing with a few simple construction errors.

So, really and truly, there are no STC80 walls in residences. You might find them in a studio, but frankly the are rare there too. A good consultant would tell the client where to spend his budget to get the best performance. That's my point, not that some specific wall designs outperform others. I've seen it done several times. One of my clients built an "isolated" home theater, used exotic wall board, mass-loaded vinyl, etc. The design wasn't bad, but it wasn't quite fully engineered. Turns out after construction his predicted STC64 walls surrounded an STC40 room. Boy, he wasn't happy, but the money is gone and he's not tearing out walls to fix it. The problem? Nobody supervised construction. His high STC walls were essentially shorted out. His floor wasn't isolated. His door only sealed for a few months then leaked. And nobody bothered with a silencer in the HVAC. Had there been someone on the project that had experience, and could design with detail, then supervise the project, he would have possibly had STC-50, but it was never going to be the predicted 64. A consultant would have been able to get his expectations into reality and avoid disappointment.

 

[Gordonj]

I have not missed the point at all. Being an Acoustical Consulatant, as I am, myself and the firm I own deals with acoustical isolation everyday including working with some of the largest single family and townhouse builders in the nation where we design their wall assemblies for products launched all over the nation. And yes after they are installed in the field and extensive testing in the lab, we go to the field and test each wall assembly for field verification of performance. Further, we do a large number of studio and broadcast facilities as well to add to our extensive experience with all of these type products. So if the owner wants a STC 80 wall and wants to spend the money and has the space then we will get them an STC 80 wall.

Oh please stop confusing HVAC noise with STC. When considering HVAC noise isolation issues that refers to NC NOT STC"

Gordon

 

[avengineer]

I have not missed the point at all. Being an Acoustical Consulatant, as I am, myself and the firm I own deals with acoustical isolation everyday including working with some of the largest single family and townhouse builders in the nation where we design their wall assemblies for products launched all over the nation. And yes after they are installed in the field and extensive testing in the lab, we go to the field and test each wall assembly for field verification of performance. Further, we do a large number of studio and broadcast facilities as well to add to our extensive experience with all of these type products. So if the owner wants a STC 80 wall and wants to spend the money and has the space then we will get them an STC 80 wall.

So...you'd be ok with giving a client an STC 80 wall, even if he could never hit that design goal for the room? Hmm...

Oh please stop confusing HVAC noise with STC. When considering HVAC noise isolation issues that refers to NC NOT STC"

Gordon

I've never mentioned noise, the HVAC issue refers to the potential sound leak through the duct system. A silencer also helps prevent sound from transitioning through the ducts from other rooms, as would proper duct layout and design. I'm sure the acoustical consultant knows that, but apparently couldn't conceive of the possibility that someone else might know something too. Point of fact, you don't know me or what I do.

Hey look. Let's stop this. My posts are specifically designed to promote the use of professionals. What you are doing here is taking shots at me to make your advocate look like a fool.

If it's that important to you to be the big dog, I'll just go away and let you. But a word of caution: making your advocate look like a fool won't get you more work. Oh, sorry, you apparently don't need more work.

Must be nice.

 

[Gordonj]

So...you'd be ok with giving a client an STC 80 wall, even if he could never hit that design goal for the room? Hmm...

I've never mentioned noise, the HVAC issue refers to the potential sound leak through the duct system. A silencer also helps prevent sound from transitioning through the ducts from other rooms, as would proper duct layout and design. I'm sure the acoustical consultant knows that, but apparently couldn't conceive of the possibility that someone else might know something too. Point of fact, you don't know me or what I do.

Hey look. Let's stop this. My posts are specifically designed to promote the use of professionals. What you are doing here is taking shots at me to make your advocate look like a fool.

If it's that important to you to be the big dog, I'll just go away and let you. But a word of caution: making your advocate look like a fool won't get you more work. Oh, sorry, you apparently don't need more work.

Must be nice.

I was not taking shots at you at all. I was pointing out that the information, no matter how promoting it may or may not be, needed to be reconsidered and pointed in the correct direction and that there are many things to consider in designing a wall system or isolating noise through a floor, which is where this conversation started (as I have said form the start). Since I have offended you in my delivery I apologize. That was never my intent. Acoustics, and noise isolation for sure, is a field that many people get tripped up in. There is a lot of science to it but a lot of art as well.

So since we both agree taking shots lowers the conversation we can BOTH stop taking shots now...

And if you are an Acoustical Consultant we are always looking for good people....

Gordon