Voiceover booth design, 2nd floor, on exterior wall

I am working on a voiceover booth design that will be placed at the exterior corner of the structure. The residence is located in Culver City, CA. The exterior walls will be framed with 2x6 wood studs. The booth will have independent interior walls (room in a room). The owner asked me if we could flat stud the interior walls of the booth to maximize the interior square footage. Since we are using 2x6's, would the air gap be technically the same as if we used 2x4 stud walls on both sides in a conventional way? Are we sacrificing anything if we go flat studs with a 2x2 stringer? Also, how do I resolve the drywall at the two points on this drawing where I have it circled? The small area is an airlock/equipment closet. http://grab.by/2jmP Thanks, George

George, Are the 2 X 6s structural? If so, I suggest (to increase room size) adding 2 X 2s to the bottom and top plates & using 2 X 4s stagger-stud in the wall. This will give you panel strength for the interior shell and the airspace needed and you will only lose 2" in the process. (I'll post a drawing if you need...) You will have flanking paths through the floor and ceiling joists anyway, so an independent wall on it's own floor plate would be over-kill. I would recommend against using the interior wall studs flat. This would be approximately the same as using 2 X 2s as far as wall flex is concerned. - More rigidity = more LF containment. What are your TL goals?? (TL=transmission loss) Have you analyzed your location and determined how much attenuation is needed from the wall construction? both ways... Cheers, John

John: The 2x6's are structural, they hold up the roof. I know what you mean by the stagger stud wall concept with the 2x2 bottom and top added on. With the ceiling mounted to the interior wall framing, aren't I solving the flanking issue? I know there will still be some flanking through the floor, but it will be somewhat mitigated because there will be 1" 1/2" concrete slab poured inside the booth area. The slab is being poured inside the booth's exterior wall stringers. The booth interior wall stringers will be fastened to the concrete slab. See attached image for more detail.

soundgun wrote:

With the ceiling mounted to the interior wall framing, aren't I solving the flanking issue? ... I know there will still be some flanking through the floor, but it will be somewhat mitigated because there will be 1" 1/2" concrete slab poured inside the booth area. The slab is being poured inside the booth's exterior wall stringers. The booth interior wall stringers will be fastened to the concrete slab.

Yes. However, if the interior framing is connected any anyway to the exterior shell, your isolation will be compromised. A staggered stud wall inherently has flanking paths. The design as drawn below will eliminate flanking paths through the wall and ceiling. A floating floor needs to have a resonant frequency of 10Hz and below to be effective and that requires quite a lot of mass. 8) Have you looked into spring isolators? Still, a structural engineer will need to check the building for that weight load... My suggestions to increase the room volume will compromise the TL of your original drawing/design. It depends on your design requirements and what compromises you and your clients are willing to agree upon. :wink: Cheers, John

Floating the floor on springs would be cost prohibitive. The only noise he'll be dealing with from below in the garage space is possible playing children. Unless they decide to beat on a bass drum, we should be in good shape there. TL requirements are difficult to predict in this situation. As the end result is a voice-over booth, we need to have a least a -60db noise floor across most of the frequency spectrum. A small amount of low frequency noise would be permissible below 70 hz because we usually do a step slope HPF on voice-over tracks since there's nothing in the human voice below that range. What makes this studio unique are the large floor to ceiling sliding doors at one end of the room, which the owner would like to be able to leave open in nice weather. This means that effectively the booth does not have the advantage of another layer of isolation from an exterior wall on that side. Therefor we are trying to maximize TL, within a reasonable budget.

You need to build another wall.

jhbrandt wrote:

George, Are the 2 X 6s structural? If so, I suggest (to increase room size) adding 2 X 2s to the bottom and top plates & using 2 X 4s stagger-stud in the wall. This will give you panel strength for the interior shell and the airspace needed and you will only lose 2" in the process. (I'll post a drawing if you need...) You will have flanking paths through the floor and ceiling joists anyway, so an independent wall on it's own floor plate would be over-kill. I would recommend against using the interior wall studs flat. This would be approximately the same as using 2 X 2s as far as wall flex is concerned. - More rigidity = more LF containment. What are your TL goals?? (TL=transmission loss) Have you analyzed your location and determined how much attenuation is needed from the wall construction? both ways... Cheers, John

It is pretty obvious this is an over head area John. Staggered studs, double frames...its all moot at this elevation on a wood framed deck.

Before I question pretty much everything you have posted...like it needs it, what the hell does this mean: "My suggestions to increase the room volume will compromise the TL of your original drawing/design" Brien

Hey Brien, thanks for joining in. Am I headed down the right path, or is there anything grossly incorrect with my design? I am reading the "John L Sayer Recording Manual" to see if I missed anything. I've already read the excellent book from Mr. Gervais.

Upon sharing my design with the owner, he tells me he wants the booth window to extend to the ceiling of the booth. I can't begin to imagine how to design that structurally! There would still need to be a header for the window, right? And the top frame would be "invisible" above the ceiling drywall. Hmmm...

soundgun wrote:

Hey Brien, thanks for joining in. Am I headed down the right path, or is there anything grossly incorrect with my design? I am reading the "John L Sayer Recording Manual" to see if I missed anything. I've already read the excellent book from Mr. Gervais.

For me, you do not provide enough information to make much of a call. Thing is, in an upper floor, double walls or staggered stud may only be useful >if< the floor and ceiling are also modified to resemble the surroundings in some respect. The floor will flank under the walls, no matter how many walls you put there. There again that will depend on the framing of the floor. And the ceiling is always an issue...always. I would agree with Lilith that your mass air mass or double wall configuration is broken. But I am not so convinced it is a requirement until more detail of the floor is examined. Still. 2X6 would be better due to the depth of the framing member in respect to the walls. But the flanking cannot be underestimated. Brien

soundgun wrote:

There would still need to be a header for the window, right? Hmmm...

A traditional load bearing header is not a requirement if this is a retro fit that does not change the structure of the building or alter any of the loads that are currently being supported.

soundgun wrote:

What makes this studio unique are the large floor to ceiling sliding doors at one end of the room, which the owner would like to be able to leave open in nice weather. This means that effectively the booth does not have the advantage of another layer of isolation from an exterior wall on that side. Therefor we are trying to maximize TL, within a reasonable budget.

George, I hope he plans to have some gobos in front of those big windows inside the booth as the large expanse of glass will cause detrimental comb filtering. I have no data for the type of floor that you have designed. ~shrug~ So, I understand your concern about the TL and flanking paths there. I'm sure that Rod will agree with me that you will have flanking transmission through the floor to the outside walls and vice-versa. How much is unknown. Gotta do some testing. :wink: The door wall must still have a header for structural support over the glass, otherwise it will compress the frame and eventually open seals at the least and/or make the sliding door bind. Many times I've told my clients, "you can't do this if you want that -- how about this approach??". As designers/builders/consultants we must sometimes be teachers. I'm sure that you can get him to compromise to his best interest. :mrgreen: Cheers, John

This is the problem with a home owner bringing a studio designer too late in the game. I have no ability to change the design of the structure frame below the studio, and that much is already built. The contractor is moving forward like a freight train, like they always do once they start on a project. Here's a very short video the owner sent me yesterday showing the stage in the construction and location of studio: http://idisk.mac.com/eldorec/Public/IMG_1325.MOV At this point, would there be any advantage at all to floating the floor inside the booth on rubber?

soundgun wrote:

At this point, would there be any advantage at all to floating the floor inside the booth on rubber?

No. You have so many unknowns, that any in depth accurate response is not possible. Honestly, Andre

If you were to provide an accurate response, what information would I need to provide? Details on how the structure is constructed? Thickness of the floor joists?

soundgun wrote:

If you were to provide an accurate response, what information would I need to provide? Details on how the structure is constructed? Thickness of the floor joists?

The second one, which includes the third question. The main question remains of the desired TL. From what I can gather from the thread: - the first floor is a garage, - it will be used mostly as a play room, - low fequency (below vocal range) isolation is not significant for the recorded product, although it can impact the environment that is conducive to good performance, - limiting factor in overall NR is the large windows to the outside. Developing some numbers to the above data, recording levels may be as low as 70 dBA, noise from in the floor below may be as high as 85 dBA from children. Vehicles will not be running engines in the garage during recording. Background level target is 30 dBA. This starts to give specific design targets to work with. From the above numbers, 55+ dB TL is required in the range of children's voices. This peak's around 1 kHz. So what kind of floor construction meets that criteria and has 1.5" concrete in it, as I understnd is part of the current floor? The floor construction shown in TLF-02-045a pdf page 81 in NRC RR 169. That has TLs greater than 55 dB from 200 Hz up. What you have described is planned for the floor may already be good. Details are needed to confirm. Andre

:mrgreen: Excellent as always. Thank you, Andre. Good to see you here.

jhbrandt wrote:

:mrgreen: Excellent as always. Thank you, Andre. Good to see you here.

Thanks John. As you may have noted from my number of posts, I have been here for a while. A belated welcome to JLS RSD! :D Andre

I am highly grateful for the experienced studio designers who volunteer their time to help us out. I want you to know how appreciative we are for your contributions. Andre, those rough numbers you crunched for me really help, thank you. The owner will be quite happy to save money on building a floating floor and retaining more ceiling headroom, since he is 6' 4". Is there any point to adding a dense rubber mat under the carpet padding, such as this product: http://www.soundproofingamerica.com/flooring.asp Specifically the "Impactless" product. On the subject of the ceiling, does it make sense to drywall the ceiling joists on the top surface, or drywall the roof joists above, or is this just added third leaves? Should special material be added between the roof joists, since they'll just be using your standard plywood with tar paper roof? I know it is important to maintain as large an airspace there as possible, with room for Ultratouch between the ceiling joists.

soundgun wrote:

I am highly grateful for the experienced studio designers who volunteer their time to help us out. I want you to know how appreciative we are for your contributions.

You are welcome.

Andre, those rough numbers you crunched for me really help, thank you. The owner will be quite happy to save money on building a floating floor and retaining more ceiling headroom, since he is 6' 4".

Remember, those are rough numbers based what little we know. Confirmation is required to be certain. I can appreciate the desire for headroom, as I am 6'2". Ever walk upright in a commuter aircraft? I haven't. :D

Is there any point to adding a dense rubber mat under the carpet padding, such as this product: http://www.soundproofingamerica.com/flooring.asp Specifically the "Impactless" product.

Remember the confirmatiion required? There has been nothing in the thread indicating concern about impact noise, or for that matter any noise, emanating from the space.

On the subject of the ceiling, does it make sense to drywall the ceiling joists on the top surface, or drywall the roof joists above, or is this just added third leaves? Should special material be added between the roof joists, since they'll just be using your standard plywood with tar paper roof?

I do not understand the question. Details on the roof construction are required to give an accurate answer. Oh, and what type of sound isolation is expected from the roof? Rememebr the limiting factor for sound isolation to the outside is large operable window.

I know it is important to maintain as large an airspace there as possible, with room for Ultratouch between the ceiling joists.

It depends on how much TL is desired from the roof. More information is required. We want, information! Number 2, uh, Andre