Hi Everyone! I've been a lurker for about a year now. Picked up Rods book when I purchased a new home last fall with the hope of gaining knowledge regarding the conversion of a large standalone garage into a great sounding Live Room / Rehearsal Space / Art Studio . This will be phase 1 of a 2 phase project with the 2nd phase being a control room build-out sometime next year or so. The idea is to get the best acoustics in the space possible for drum recording. As unique as I can get. Potentially using a number of different types of wall materials (drywall, stone, wood, etc.) to get different colorization/vibe/s. If possible bringing a bit of natural light into the setting without causing too much bleed into the neighbors yard. I'm looking to do an "open-concept" recording space similar to Treys Barn for the initial phase.
I will still be mixing in the space so ideal location of monitor/control room setup will be welcomed.
I primarily record prog rock and electronic music with a fairly wide amount of dynamic range (ie when rehearsing it can get quite loud (think wall of sound during writing)). My Bloody Valentine, Mogwai, Nine Inch Nails....
So the biggest consideration for construction, outside of trying to get the most sonically pleasing room, would be to stop as much sound as possible from EXITING the space (primarily on one side of the structure).
Please excuse any vocab mistakes as I'm not a pro in terms of construction terminology.
The building is made out of steel with vinyl siding. I will be closing up the large overhang door initially and, upon beginning phase 2, will be building a control room out onto an existing slab.
Currently there is 3" styrofoam "insulation" with open joists. I had an architecture buddy swing through and he seemed to think the styrofoam was something I should keep. I doubt this from what I've read.
Flooring is concrete. I plan on keeping this as concrete.
The dimensions are as follows:
19’ 6” x 29’ x 10’ 10”(W x L x H)
There is a peak that runs the length of the garage that measures up to 17'
For wall construction I'm thinking:
Steel frame
insulation (styrofoam? rockwool?)
Vapor Barrier
5/8" Drywall
Green Glue Compound
5/8" Drywall
Wood 2" x 4" Studs // 16" o/c
R13 Fiberglass
Resilient Channel
5/8" Drywall
Green Glue Compound
5/8" Drywall
This gives me an STC rating of 62 and is the smallest footprint.
However, I'm not sure if this is overkill considering that I still have the steel shell and either the existing styrofoam insulation or the new rockwool, etc. insulation.
The ceiling is steel>3" fiberglass>and aluminum (I believe... it's some sort of metal).
I'm not certain if I need to frame the ceiling out as well or if it's possible to do the walls first, test SPL, and then determine whether to frame out or not.
There is a dedicated breaker box located in the other (attached) garage that is feeding electrical into the space.
I'm thinking of putting in a split HVAC system into this location. There is also a gas line run out into the garage as it is.
Here are some numbers:
Dimensions:
19’ 6” x 29’ x 10’ 10”(W x L x H)
Wall:
29’ x 10’10” (L x H) x 2
638 sqft
19’6” x 10’10” (W x H) x 2
440 sqft
TOTAL WALL COVERAGE: 1078 sq ft
Ceiling:
29’ x 29’ (L x W) x 2
841 sqft
Total Floor Coverage:
580sqft
I'm going to build some movable gobos to have some isolation when needed. Potentially a drum riser on casters as well for positioning of kit.
I measured the SPL during a heavy rain @ 60SPL. I'm NOT opposed to having some sound come in from my surrounding environment. There's a train that passes by as well. I'm OK with it as I think it will add some unique elements to my recordings. However, I know it may be a two way street. sounding coming in.... sound going out....
Attached you will find some terrible drawings of the place and some pics. I will be getting rid of the old, non-fuctioning freezer and the loft in the back. The door in the back (entranceway from the initial garage) can/may also be relocated. That architecture friend is going to draw me up legit plans sometime this week which I will up.
MY QUESTIONS:
Thoughts on the dimensions as they are? issues with standing waves, etc.?
Is it necessary to remove the existing styrofoam insulation? Any negatives of leaving it?
Am I correct in my wall design?
Thoughts on leaving the ceiling as-is and assessing after wall build?
What is the best option for electrical runs? Romex?
Is a split HVAC system a good idea?
I appreciate any and all input regarding this. Thank you VERY much for this forum and all of it's info!
Live Room / Studio Design
Moderators: Aaronw, kendale, John Sayers
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andy1908
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- Location: Northeastern Illinois
Live Room / Studio Design
Last edited by andy1908 on Fri Aug 17, 2018 11:20 pm, edited 2 times in total.
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Soundman2020
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Re: Live Room / Studio Design
HI there Andy, and Welcome! 
So there's a conflict. A room that is great for mixing is lousy for tracking. A room that is great for tracking, is lousy for mixing. The solution, once again, is variable acoustics: a set of treatment panels on the walls and ceiling that normally provide the correct acoustics for mixing, but that you can change in some way to greatly modify that, and get acoustics that are better for tracking.
Also, at nearly 600 ft2 your room is going to be close to the limit for the maximum area specifications for a control room....
“These single-number ratings correlate in a general way with subjective impressions of sound transmission for speech, radio, television and similar sources of noise in offices and buildings. This classification method is not appropriate for sound sources with spectra significantly different from those sources listed above. Such sources include machinery, industrial processes, bowling alleys, power transformers, musical instruments, many music systems and transportation noises such as motor vehicles, aircraft and trains. For these sources, accurate assessment of sound transmission requires a detailed analysis in frequency bands.”
It's a common misconception that you can use STC ratings to decide if a particular wall, window, door, or building material will be of any use in a studio. As you can see above, in the statement from the people who designed the STC rating system and the method for calculating it, STC is simply not applicable.
Here's how it works:
To determine the STC rating for a wall, door, window, or whatever, you start by measuring the actual transmission loss at 16 specific frequencies between 125 Hz and 4kHz. You do not measure anything above or below that range, and you do not measure anything in between those 16 points. Just those 16, and nothing else. Then you plot those 16 points on a graph, and do some fudging and nudging with the numbers and the curve, until it fits in below one of the standard STC curves. Then you read off the number of that specific curve, and that number is your STC rating. That's it. There is no relationship to real-world decibels: it is just the index number of the reference curve that is closest to your curve. To clarify: the STC number is NOT how much isolation you will get: it is just the number that somebody once assigned to a curve on a graph. So for the STC-70 curve, they could have called it "STC-GGFQRT" or "STC-Delta-RED" or anything else, and it would tell you just as much about isolation as "STC-70" does: ie, nothing. It's a REFERENCE number, not an actual isolation number.
When you measure the isolation of a studio wall, you want to be sure that it is isolating ALL frequencies, across the entire spectrum from 20 Hz up to 20,000 Hz, not just 16 specific points that somebody chose 50 years ago, because he thought they were a good representation of human speech. STC does not take into account the bottom two and a half octaves of the musical spectrum (nothing below 125Hz), nor does it take into account the top two and a quarter octaves (nothing above 4k). Of the ten octaves that our hearing range covers, STC ignores five of them (or nearly five). So STC tells you nothing useful about how well a wall, door or window will work in a studio. The ONLY way to determine that, is by look at the Transmission Loss curve for it, or by estimating with a sound level meter set to "C" weighting (or even "Z"), and slow response, then measuring the levels on each side. That will give you a true indication of the number of decibels that the wall/door/window is blocking, across the full audible range.
Consider this: It is quite possible to have a door rated at STC-30 that does not provide even 20 decibels of actual isolation, and I can build you a wall rated at STC-20 that provides much better than 30 dB of isolation. There simply is no relationship between STC rating and the ability of a barrier to stop full-spectrum sound, such as music. STC was never designed for that, and cannot be used for that.
Then there's the issue of installation. You can buy a door that really does provide 40 dB of isolation, but unless you install it correctly, it will not provide that level! If you install it in a wall that provides only 20 dB, then the total isolation of that "wall+door" combination is 20 dB: isolation is only as good as the worst part. Even if you put a door rated at 90 dB in that wall, it would STILL only give you 20 dB. The total is only as good as the weakest part of the system.
So forget STC as a useful indicator, and just use the actual TL graphs to judge if a wall, door, window, floor, roof, or whatever will meet your needs.
There's also no way that you would get STC-62 from a 3-leaf system such as you describe, and even if you did, the low frequency isolation (read: Drums, bass, keyboards....) would not be good.
Same question: can you isolate a studio by only building the walls and not the ceiling?
I think the above answers your question! Your ceiling needs to be every bit as massive as the walls, and built to the same level of isolation.
Standing waves (modes) are good, and you need more of them, not less. The bigger the room is, the more it will have, so that's good. But the actual distribution of those modes in the low end of the spectrum can cause problems. And that will depend on the final inner dimensions of the inner leaf, which you didn't mention. Modes form between the final, solid, rigid, massive finished inner surfaces of the room (in all three dimensions, including the ceiling), so you will need to know where those are in order to use the room mode calculators that can tell you if your room is any good or not.
That's how much difference it would make if you just build the walls but not the ceiling. Now close the last door on your car: that's how much extra isolation you get if you also add the ceiling....
- Stuart -
It sounds to me like what you need is "variable acoustic" devices that you can swing, flip, slide, rotate, open, close or whatever to change the sound of the room, as well as having different "zones" in the room where you can get different sounds.The idea is to get the best acoustics in the space possible for drum recording. As unique as I can get. Potentially using a number of different types of wall materials (drywall, stone, wood, etc.) to get different colorization/vibe/s.
That is entirely possible. Glass is expensive, but as long as you have the budget to do that, there's no problem acoustically.If possible bringing a bit of natural light into the setting without causing too much bleed into the neighbors yard.
Mixing and tracking in the same room presents a rather large acoustic issue: it is not possible to have one single acoustic response that works well for both. So there's even more reasons why you will need variable acoustics. In order to mix well, the acoustic response of the room must be flat, both in frequency response and in time domain response. There's a set of specifications that the room must meet in order to be usable for mixing, and the the best spec for that is ITU BS.1116-3. It defines exactly how the room must be in order to be able to mix well. Basically, the room must not sound like anything it all! It must be neutral, transparent, flat, and must not "color" the sound in any way: it must add nothing to the sound, and remove nothing from the sound. On the other hand, a live room / tracking room needs to have "life" and "character" and "air" and "warmth", and all those other things that musicians and producers love about great rooms. You can't mix in such a room, because it is lying to you: it IS coloring the sound, because that's what live rooms do. It enhances certain frequencies, and lengths some decays, while also attenuating other frequencies, or killing the decays. It has reverb, maybe some echo. It has spice and sizzle and depth.... but a control room CANNOT have any of those.I will still be mixing in the space so ideal location of monitor/control room setup will be welcomed.
So there's a conflict. A room that is great for mixing is lousy for tracking. A room that is great for tracking, is lousy for mixing. The solution, once again, is variable acoustics: a set of treatment panels on the walls and ceiling that normally provide the correct acoustics for mixing, but that you can change in some way to greatly modify that, and get acoustics that are better for tracking.
Also, at nearly 600 ft2 your room is going to be close to the limit for the maximum area specifications for a control room....
So isolation is also a key issue here. Drums are the hardest of all instruments to isolate. So you'll need some pretty hefty isolation, in addition to the treatment.I primarily record prog rock and electronic music with a fairly wide amount of dynamic range (ie when rehearsing it can get quite loud
You've read Rod's book, so you already know that you can't isolate a room on just one side: Isolation is "all or nothing". Hoping to isolate on one side because that's where the neighbors are, is sort of like hoping that, because you only ever need to turn left in your car, you won't need to put wheels on the right hand side...So the biggest consideration for construction, outside of trying to get the most sonically pleasing room, would be to stop as much sound as possible from EXITING the space (primarily on one side of the structure).
Exactly! Styrofoam has no useful acoustic properties. It's great for thermal insulation, yes, but not for acoustics. It would seem that your architect doesn't know too much about acoustic s...Currently there is 3" styrofoam "insulation" with open joists. I had an architecture buddy swing through and he seemed to think the styrofoam was something I should keep. I doubt this from what I've read.
Flooring is concrete. I plan on keeping this as concrete.
Excellent size. That's over 550 ft2. You could actually fit in a very nice control room AND a decent live room, in that area. If you wanted to, of course. If not, then that can be a great live room all on it's own, with the control room outside on the slab.The dimensions are as follows:
19’ 6” x 29’ x 10’ 10”(W x L x H)
So you are going for a three-leaf system? Since you are starting with a metal shed basically, that's probably a good way to do it. However, you won't get the extreme isolation you are looking for with that plan. Yes, you likely will need 3-leaf (despite the obvious drawbacks), but I would do that as two separate frames, rather than one frame with RC. You can't get high isolation with RC, for several reasons, and especially not for a 3-leaf. You can get high isolation with separate frames, even with a 3-leaf.For wall construction I'm thinking:
Steel frame
insulation (styrofoam? rockwool?)
Vapor Barrier
5/8" Drywall
Green Glue Compound
5/8" Drywall
Wood 2" x 4" Studs // 16" o/c
R13 Fiberglass
Resilient Channel
5/8" Drywall
Green Glue Compound
5/8" Drywall
Forget STC. STC is no use at all for telling you how well your studio will be isolated. STC was never meant to measure such things. Here's an excerpt from the actual ASTM test procedure (E413) that explains the use of STC.This gives me an STC rating of 62 and is the smallest footprint.
“These single-number ratings correlate in a general way with subjective impressions of sound transmission for speech, radio, television and similar sources of noise in offices and buildings. This classification method is not appropriate for sound sources with spectra significantly different from those sources listed above. Such sources include machinery, industrial processes, bowling alleys, power transformers, musical instruments, many music systems and transportation noises such as motor vehicles, aircraft and trains. For these sources, accurate assessment of sound transmission requires a detailed analysis in frequency bands.”
It's a common misconception that you can use STC ratings to decide if a particular wall, window, door, or building material will be of any use in a studio. As you can see above, in the statement from the people who designed the STC rating system and the method for calculating it, STC is simply not applicable.
Here's how it works:
To determine the STC rating for a wall, door, window, or whatever, you start by measuring the actual transmission loss at 16 specific frequencies between 125 Hz and 4kHz. You do not measure anything above or below that range, and you do not measure anything in between those 16 points. Just those 16, and nothing else. Then you plot those 16 points on a graph, and do some fudging and nudging with the numbers and the curve, until it fits in below one of the standard STC curves. Then you read off the number of that specific curve, and that number is your STC rating. That's it. There is no relationship to real-world decibels: it is just the index number of the reference curve that is closest to your curve. To clarify: the STC number is NOT how much isolation you will get: it is just the number that somebody once assigned to a curve on a graph. So for the STC-70 curve, they could have called it "STC-GGFQRT" or "STC-Delta-RED" or anything else, and it would tell you just as much about isolation as "STC-70" does: ie, nothing. It's a REFERENCE number, not an actual isolation number.
When you measure the isolation of a studio wall, you want to be sure that it is isolating ALL frequencies, across the entire spectrum from 20 Hz up to 20,000 Hz, not just 16 specific points that somebody chose 50 years ago, because he thought they were a good representation of human speech. STC does not take into account the bottom two and a half octaves of the musical spectrum (nothing below 125Hz), nor does it take into account the top two and a quarter octaves (nothing above 4k). Of the ten octaves that our hearing range covers, STC ignores five of them (or nearly five). So STC tells you nothing useful about how well a wall, door or window will work in a studio. The ONLY way to determine that, is by look at the Transmission Loss curve for it, or by estimating with a sound level meter set to "C" weighting (or even "Z"), and slow response, then measuring the levels on each side. That will give you a true indication of the number of decibels that the wall/door/window is blocking, across the full audible range.
Consider this: It is quite possible to have a door rated at STC-30 that does not provide even 20 decibels of actual isolation, and I can build you a wall rated at STC-20 that provides much better than 30 dB of isolation. There simply is no relationship between STC rating and the ability of a barrier to stop full-spectrum sound, such as music. STC was never designed for that, and cannot be used for that.
Then there's the issue of installation. You can buy a door that really does provide 40 dB of isolation, but unless you install it correctly, it will not provide that level! If you install it in a wall that provides only 20 dB, then the total isolation of that "wall+door" combination is 20 dB: isolation is only as good as the worst part. Even if you put a door rated at 90 dB in that wall, it would STILL only give you 20 dB. The total is only as good as the weakest part of the system.
So forget STC as a useful indicator, and just use the actual TL graphs to judge if a wall, door, window, floor, roof, or whatever will meet your needs.
There's also no way that you would get STC-62 from a 3-leaf system such as you describe, and even if you did, the low frequency isolation (read: Drums, bass, keyboards....) would not be good.
It's UNDERKILL, not overkill! The steel shell makes your isolation WORSE, not better! It's a third leaf: it won't improve isolation in the low end. The Styrofoam won't help any, but it also won't do much harm: it's the thin metal skin that does the harm.However, I'm not sure if this is overkill considering that I still have the steel shell and either the existing styrofoam insulation or the new rockwool, etc. insulation.
Quick question: Can you build an aquarium by only putting glass on the sides of the tank, and leaving the bottom open?The ceiling is steel>3" fiberglass>and aluminum (I believe... it's some sort of metal).
I'm not certain if I need to frame the ceiling out as well or if it's possible to do the walls first, test SPL, and then determine whether to frame out or not.
Same question: can you isolate a studio by only building the walls and not the ceiling? I think the above answers your question! Your ceiling needs to be every bit as massive as the walls, and built to the same level of isolation.
Cool! But you can allow only one single small penetration for the power feed that goes into your studio. You can''t have multiple power feeds coming in at different points, not can you have any holes at all in your isolation leaves, since even a tiny hole will trash your isolation. So one single power feed comes in from that panel, then you distribute that around inside the new inner-leaf as needed. But no other holes.There is a dedicated breaker box located in the other (attached) garage that is feeding electrical into the space.
That will take care of the heating and cooling, but you still need to do the full ventilation system. And that implies large silencer boxes on every place that an HVAC duct penetrates a leaf, if you want high isolation.I'm thinking of putting in a split HVAC system into this location.
Yep. It is a two-way street. So, since isolating for sound going out is your priority, that's what you need to design for.I measured the SPL during a heavy rain @ 60SPL. I'm NOT opposed to having some sound come in from my surrounding environment. There's a train that passes by as well. I'm OK with it as I think it will add some unique elements to my recordings. However, I know it may be a two way street. sounding coming in.... sound going out....
OK, this might sound a little harsh, but why would you entrust the design of a studio to an architect who doesn't even know that Styrofoam is no use for studio isolation, and thinks it is fine? It doesn't sound like you have the right guy there at all!Attached you will find some terrible drawings of the place and some pics. I will be getting rid of the old, non-fuctioning freezer and the loft in the back. The door in the back (entranceway from the initial garage) can/may also be relocated. That architecture friend is going to draw me up legit plans sometime this week which I will up.
For what purpose?Thoughts on the dimensions as they are? issues with standing waves, etc.?
Standing waves (modes) are good, and you need more of them, not less. The bigger the room is, the more it will have, so that's good. But the actual distribution of those modes in the low end of the spectrum can cause problems. And that will depend on the final inner dimensions of the inner leaf, which you didn't mention. Modes form between the final, solid, rigid, massive finished inner surfaces of the room (in all three dimensions, including the ceiling), so you will need to know where those are in order to use the room mode calculators that can tell you if your room is any good or not.If you are going to build a 3-leaf isolation system, then it can probably stay, but you might need to remove the vapor barrier as it will be in the wrong location in your completed wall.Is it necessary to remove the existing styrofoam insulation? Any negatives of leaving it?
For high isolation, no.Am I correct in my wall design?
Bad idea. Try this: drive your car to a very noisy place, such as maybe the parking lot of an outdoor rock concert. Open all the doors of your car. Hear that loud music? Ok, now close all of the doors except for one: leave that one wide open. Is the music any quieter?Thoughts on leaving the ceiling as-is and assessing after wall build?
That's how much difference it would make if you just build the walls but not the ceiling. Now close the last door on your car: that's how much extra isolation you get if you also add the ceiling.... If you do inside-out wall construction, then yes, you cold do that, running it through the studs in the normal manner. But if you do conventional wall construction, that isn't possible. In that case, the only acceptable method is with surface-mount raceways.What is the best option for electrical runs? Romex?
Yes, for the heating and cooling, but a mini-split does nothing at all for ventilation. So you will still need ventilation ducts, silencer, registers, filters, dampers, fans, etc. One duct to bring fresh air into the room, and another duct to remove the stale air.Is a split HVAC system a good idea?
- Stuart -
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andy1908
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- Joined: Mon Sep 18, 2017 5:25 am
- Location: Northeastern Illinois
Re: Live Room / Studio Design
Thanks Soundman! I appreciate the insight and guidance with this. After some thought and discussion I do not believe that a control room build out on the external slab is going to be in the cards.
So attached is the new approach with control room in the space. I'm thinking 2 phases here. Full room build out then control room build out (which consists of one wall and a door). After Phase 1 I could play around with the "variable acoustic" devices, but a completely separate CR is the end goal.
I'm not sure what the minimum size of the control room can be, but I'd prefer to have the smallest CR possible to allow for the largest LR possible.
Keeping the CR on the North side of the structure would also help to isolate the LR from the NE neighbor.
Seeing as this space shares a wall with my main garage, we're thinking that running HVAC, along with ERV, through the garage with a few bends.
This is where we are at with wall/ceiling construction with room-within-room being the approach:
Exterior wall:
Leave Existing wall with StyroFoam: (Option to remove & install batt or spray insul.)
1"-2" Airspace
2 x 4 stud wall w/ R13 or R19 Insul (R19 is thicker for 2 x 6, but you could stuff it in)
(you could probably do 24" o.c., unless you plan on hanging heavy things from wall)
Vapor Barrier
Horiz Isolation Strips
2 layers 5/8" gyp brd (use green glue if so desired)
Interior CR Wall: Single layer
2 layers gyp
2 x 4 studs @ 16" o.c. w/ insul
horiz iso strips
2 layers gyp
Thickness: 6" +/-
Or
2 layers gyp
2 x 4 studs @ 16" o.c. w/ insul
1 1/2" air space
2 x 4 studs @ 16" o.c. w/ insul
horiz iso strips
2 layers gyp
Thickness: 11" +/-
Ceiling:
Can you just spray 3-4" of insul? This may not be enough.
If not then you'll need to install some interior rafters, probably 2 x 4s
with ties ever 4-6' or so? could give the space a cool effect?
Leave a 1"+/- space from metal structure. stuff the rafters with insul.
2 layers of gyp? They also may make sound isolation strips for ceiling?
The ceiling, unlike the walls, is closed up. It does not look to be filled with styrofoam, but traditional R19 insulation. I do not believe I'm going to pull the ceiling apart.
Attached are the diagrams with dimensions.
I can't thank you enough for your insight on this!
So attached is the new approach with control room in the space. I'm thinking 2 phases here. Full room build out then control room build out (which consists of one wall and a door). After Phase 1 I could play around with the "variable acoustic" devices, but a completely separate CR is the end goal.
I'm not sure what the minimum size of the control room can be, but I'd prefer to have the smallest CR possible to allow for the largest LR possible.
Keeping the CR on the North side of the structure would also help to isolate the LR from the NE neighbor.
Seeing as this space shares a wall with my main garage, we're thinking that running HVAC, along with ERV, through the garage with a few bends.
This is where we are at with wall/ceiling construction with room-within-room being the approach:
Exterior wall:
Leave Existing wall with StyroFoam: (Option to remove & install batt or spray insul.)
1"-2" Airspace
2 x 4 stud wall w/ R13 or R19 Insul (R19 is thicker for 2 x 6, but you could stuff it in)
(you could probably do 24" o.c., unless you plan on hanging heavy things from wall)
Vapor Barrier
Horiz Isolation Strips
2 layers 5/8" gyp brd (use green glue if so desired)
Interior CR Wall: Single layer
2 layers gyp
2 x 4 studs @ 16" o.c. w/ insul
horiz iso strips
2 layers gyp
Thickness: 6" +/-
Or
2 layers gyp
2 x 4 studs @ 16" o.c. w/ insul
1 1/2" air space
2 x 4 studs @ 16" o.c. w/ insul
horiz iso strips
2 layers gyp
Thickness: 11" +/-
Ceiling:
Can you just spray 3-4" of insul? This may not be enough.
If not then you'll need to install some interior rafters, probably 2 x 4s
with ties ever 4-6' or so? could give the space a cool effect?
Leave a 1"+/- space from metal structure. stuff the rafters with insul.
2 layers of gyp? They also may make sound isolation strips for ceiling?
The ceiling, unlike the walls, is closed up. It does not look to be filled with styrofoam, but traditional R19 insulation. I do not believe I'm going to pull the ceiling apart.
Attached are the diagrams with dimensions.
I can't thank you enough for your insight on this!
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Soundman2020
- Site Admin
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Re: Live Room / Studio Design
I think that's a smart move!After some thought and discussion I do not believe that a control room build out on the external slab is going to be in the cards. ... So attached is the new approach with control room in the space.
The smallest RECOMMENDED size according to specifications, is 220 square feet, but it is possible to go smaller than that if you really want to. 220 ft2 is the smallest size for a "critical listening room" that an meet the specs laid out in ITU BS.1116-3. If you go smaller, it will be harder to meet those specs and you will need more treatment to accomplish that. The smaller you go, the less likely you are to meet them, and the more treatment you need. You soon get to the point where you need mountains of treatment inside the room, and you STILL can't get close to the specs. So it all depends on how good you want your control room to be! If you want a great room that meets the best specs, then try to stay close to 220 ft. If you aren't that interested in quality acoustics in the control room, and don't mind spending a lot on treatment then go smaller.I'm not sure what the minimum size of the control room can be, but I'd prefer to have the smallest CR possible to allow for the largest LR possible.
That might be an option, assuming that the existing HVAC system has the capacity to handle the studio load. However, the ducting is going to be a bit more complex than "just a few bends"!Seeing as this space shares a wall with my main garage, we're thinking that running HVAC, along with ERV, through the garage with a few bends.
HVAC is a big part of studio design. As you progress with your design, you'll start to realize just how big of an issue it is. It needs careful planning, and careful attention to detail.Ummmm... that is ALREADY a 2-leaf wall.... So when you add this... :Exterior wall:
Leave Existing wall with StyroFoam: (Option to remove & install batt or spray insul.)
1"-2" Airspace
2 x 4 stud wall w/ R13 or R19 Insul (R19 is thicker for 2 x 6, but you could stuff it in)
(you could probably do 24" o.c., unless you plan on hanging heavy things from wall)
Vapor Barrier
Horiz Isolation Strips
2 layers 5/8" gyp brd (use green glue if so desired)
... along with the outer metal skin, you will have a FIVE LEAF SYSTEM! It will have very terrible isolation in low frequencies...Interior CR Wall: Single layer
2 layers gyp
2 x 4 studs @ 16" o.c. w/ insul
horiz iso strips
2 layers gyp
Thickness: 6" +/-
The reason is very non-intuitive ( a lot of acoustics is like that). Every time you have a leaf, such as a couple of layers of drywall, and there's an air gap next to that, then another leaf, you have created a resonant system. The two "leaves" together with the air between them, form what is known as an MSM resonant system (MSM stands for Mass-Spring-Mass, and the air is the "spring" here). Resonant systems have some strange properties. One of those is that they provide very good isolation for sounds with tones above their resonant frequency, not for tones AT there resonant frequency they do not isolate at all: In fact, even worse than "not isolating at all", a resonant system can actually AMPLIFY the sounds at it's resonant frequency (that's how a lot of musical instruments work: by amplifying sounds at certain resonant frequencies that you an select by "playing" the instrument). Clearly, then, you need to "tune" your resonant wall so that the resonant frequency is outside the human hearing range: problem solved! Simple! But an additional problem arises when you add ANOTHER leaf to a resonant system. Due those strange properties that I mentioned above, when you add another leaf into an MSM system, it becomes an MSMSM system, and the resonant frequency is now HIGHER than it was before, for just two leaves. If you add another leaf, making 4-leaves, the frequency goes up again. And if you add yet another leaf, to get five as in your case, the frequency rises even more. Each time you add a leaf, you fore the frequency higher. So even though are adding more mass to the wall, and making it thicker, it will potentially isolate WORSE than before.
Here's a diagram that illustrates the result quite well: That shows three possible methods for building an isolation wall. The one on the left, labeled "quadruple leaf assembly", is what you are proposing: two stud frames, each of which has a single layer of drywall on both sides. That will get you STC-44, which isn't very good.
The middle diagram shows what happens if you take OFF one of those interior leaves: even though you REMOVED a quarter of the total mass from the wall, the isolation went UP by nearly ten points! Unexpected, logically, but when you take into account resonance, it makes perfect sense. The overall resonant frequency has now gone down quite a lot, so the wall isolates much better in the human hearing range.
The final diagram on the right shows what happens if you take out the OTHER internal leaf, then use both of the ones that you took off to "beef up" the outer two layers: the isolation jumped by ANOTHER ten points! So even though this final wall has the exact same total mass and the exact same total thickness, it isolates about one hundred times better that the one on the left. This is because, once again, the overall resonant frequency went down again, and therefore the wall isolates much better in the human hearing range.
In your situation, there would ba an ADDITIONAL leaf off to one side of this, so the issue would be a bit worse in all cases. This is why it's a good idea to avoid 3-leaf walls whenever possible, but when it is NOT possible (as in your case), then you need to design the wall to compensate for the lost isolation.
That would likely do nothing at all. Spray insulation is usually closed-cell at the microscopic level, just like Styrofoam, this making it pretty useless for acoustics. In order to be useful, it needs to be "open cell", meaning that air can penetrate all the all through it, but that there are numerous tiny fibers or foam "cells" that impede the way sound moves through it. Closed-cell insulation is sealed, air-tight, so air cannot get through, and thus there are no acoustic effects. Open-cell is not sealed, air can move through, and thus it has good acoustics effects. The TYPE of acoustics effect depends on several aspects of the material itself, so you can't just use any insulation for any purpose: each type has it's own acoustical uses. Take care that you only use the correct type for each application.Can you just spray 3-4" of insul? This may not be enough.
Your ceiling shows a 3-leaf system, but in your case that's fine: it's probably the only way you can do it. However, you'll need to modify that a bit to compensate for the lost isolation with the 3-leaf system.Attached are the diagrams with dimensions.
The first thing we need to know here, is your basic definition: how much isolation do you need, in decibels? Without knowing that, it's all just guess work, and you'll end up doing the wrong thing, and getting lousy results. If you know how much isolation you need, you can look at the charts and tables and equations and research papers to find the set of materials and techniques that will get you that number. If you DON'T define that number, the obviously you'll never achieve it! So it's important to define it.
- Stuart -
-
andy1908
- Posts: 3
- Joined: Mon Sep 18, 2017 5:25 am
- Location: Northeastern Illinois
Re: Live Room / Studio Design
Hey sound man. Thanks again for the insight. I think you might have misunderstood, or I phrased incorrectly, regarding the walls. When I was talking about interior wall i was referring to the wall between the control room and the live room.
So the exterior walls are:
Vinyl
Plywood
4” metal sandwich
Existing styro
2” air gap
2x4 studs
Insul
Vapor barrier
ISO strips
5/8 drywall
Green glue
5/8 drywall
That’s it for the main “shell”
The wall between CR and LR:
5/8 drywall
Green glue
5/8 drywall
Studs
Insul
ISO clips
5/8 drywall
Green glue
5/8 drywall
I’m not 100% on what the ideal air space between studs would be. I’m assuming there’s some sort algorithm to determine this? Is 2” gap sufficient?
My thoughts are to do the “shell” first and then get in the space to get an idea for feel. The CR may be a phase that I do next year.
I’m also assuming that getting an air gap for the ceiling is going to be a non-starter, so I’m thinking:
(Existing)
Metal roof
Insul
Metal
(New)
Studs
Insul
ISO clips
Drywall
Green glue
Drywall
Ideally I’d get any noise down to 30db or less outside the space.
Thanks again!
So the exterior walls are:
Vinyl
Plywood
4” metal sandwich
Existing styro
2” air gap
2x4 studs
Insul
Vapor barrier
ISO strips
5/8 drywall
Green glue
5/8 drywall
That’s it for the main “shell”
The wall between CR and LR:
5/8 drywall
Green glue
5/8 drywall
Studs
Insul
ISO clips
5/8 drywall
Green glue
5/8 drywall
I’m not 100% on what the ideal air space between studs would be. I’m assuming there’s some sort algorithm to determine this? Is 2” gap sufficient?
My thoughts are to do the “shell” first and then get in the space to get an idea for feel. The CR may be a phase that I do next year.
I’m also assuming that getting an air gap for the ceiling is going to be a non-starter, so I’m thinking:
(Existing)
Metal roof
Insul
Metal
(New)
Studs
Insul
ISO clips
Drywall
Green glue
Drywall
Ideally I’d get any noise down to 30db or less outside the space.
Thanks again!
-
Soundman2020
- Site Admin
- Posts: 11938
- Joined: Thu Aug 21, 2008 10:17 am
- Location: Santiago, Chile
- Contact:
Re: Live Room / Studio Design
Actually, I think the misunderstanding is on your side! You are not grasping the concepts here. You originally described a three-leaf system, which I mentioned was a good idea at the time, but now you are describing only a two-leaf system, which is not going to get you good isolation. Let's take a look.
To be more clear, your outer leaf (what you call the "main shell") consists of:
- Vinyl
- Plywood
- 4” metal sandwich
- Existing styro
That's it. End. Stop. Finish. That is your outer leaf. It is your "M" in the "MSM" equation.
Your INNER leaf is the other part you mentioned:
- 2” air gap
- 2x4 studs
- Insul
- Vapor barrier
- ISO strips
- 5/8 drywall
- Green glue
- 5/8 drywall
That is NOT part of the outer-leaf, and it IS the inner leaf. It is the second "M" in the "MSM" equation. Since you have no other construction apart from that, you only have a two leaf system, not the three leaf system you originally described. And since your outer leaf is only vinyl siding on a thin plywood backer plus the thin metal sandwich (which is highly resonant anyway...) without any acoustic insulation (only Styrofoam, which has no useful acoustic properties), you are not going to get good isolation. Yes, you do have mass there (the vinyl siding plus the plywood plus the thin metal is your mass), but it isn't very high, and it is not sealed air-tight, so it's not going to act very well as part of the MSM system.
Your inner-leaf is fine, in terms of mass, but the outer leaf is not.
Also, I'm not sure what you mean by "ISO strips". I googled that term, and only found not-very-useful stuff (such as foam strips that go along the inner edge of a wall to isolate the laminate flooring from it, and also mineral wool with a felt backing) that doesn't seem to be what you are referring to anyway. Please explain what your "ISO strips" are, and provide links to the actual product you plan on using there.
If you really do plan on using only two-leaf isolation, your isolation is limited by the low mass of the outer leaf, and the fact that it is not sealed. There's also the rather major issue of the tie rods. Right now, there are tie rods running across the tops of your outer-leaf wall, and do the same job as the chord beams of a truss system: they tie the wall tops together, to prevent the building from collapsing under the weight of the roof. You CANNOT remove those tie rods unless you first replace them with something else that does the same job, such as collar ties higher up, which you do seem to mention... but you don't explain that in detail, and your diagram seems to show that the collar ties, which are part of the OUTER leaf, are somehow also inside the inner-leaf! That's impossible. Or rather, not "impossible" in the sense that it cannot be done physically, but "impossible" in the sense that doing so totally negates your entire isolation system! You CANNOT have ANY part of the outer leaf even touching any part of the inner leaf at all. They are two entirely separate and independent structures. The outer leaf is one structure, and the inner leaf is another structure: they are not connected to each other in any manner, and do not touch each other. Each one is a single "shell" with substantial surface density, and each one is completely sealed hermetically, absolutely air tight. There is no way you can meet those necessary conditions if your outer-leaf tie rods are collar ties penetrate the inner-leaf. That cannot happen. If it does, you trash your isolation.
Also, to clarify things even more here: since you have two rooms (a live room and a control room), you actually have TWO inner-leaves. There is only one outer leaf, which is the existing building itself, but then you have two rooms within that: one is the CR, the other is the LR, and EACH ON OF THOSE is built as it's own separate, independent, self-supporting structure that consists of four walls AND a ceiling.
The term "room in a room" in your case would be better stated as "two rooms in a room".
This might seem like "splitting-hairs", but getting the mental picture right, and getting the terminology right, is important.
First, for each single-leaf barrier you need the Mass Law equation:
TL = 14.5 log (M * 0.205) + 23 dB
Where: M = Surface density in kg/m2
For a two-leaf wall, you need to calculate the above for EACH leaf separately (call the results "R1" and "R2").
Then you need to know the resonant frequency of the system, using the MSM resonance equation:
f0 = C [ (m1 + m2) / (m1 x m2 x d)]^0.5
Where:
C=constant (60 if the cavity is empty, 43 if you fill it with suitable insulation)
m1=mass of first leaf (kg/m^2)
m2 mass of second leaf (kg/m^2)
d=depth of cavity (m)
Then you use the following three equations to determine the isolation that your wall will provide for each of the three main frequency ranges:
R = 20log(f (m1 + m2)) - 47 ...[for the region where f < f0]
R = R1 + R2 + 20log(f x d) - 29 ...[for the region where f0 < f < f1]
R = R1 + R2 + 6 ...[for the region where f > f1]
Where:
f0 is the resonant frequency from the MSM resonant equation,
f1 is 55/d Hz
R1 and R2 are the transmission loss numbers you calculated first, using the mass law equation
And that's it! Nothing complex. Any high school student can do that. It's just simple addition, subtraction, multiplication, division, square roots, and logarithms.
What you propose is not as easy as ti sounds: Think it through. If this is what you plan to do, it is going to need some careful though in the design process right now to ensure that it is physically feasible to do that without causing the entire thing to collapse on your head. I have designed a couple of studios where the owner had he same basic idea, and it's not as easy as you might think. It is NOTHING like simply "building a wall between two rooms". That's what it might like seem like, but it does not take into account that at the end of the process, the two rooms must be totally disconnected from each other mechanically, with not a single stud, joist, beam, plate, or even a single nail that joins them together. They must end up as entirely separate, independent, disconnected, decoupled structures, each of which stands on its own, both structurally and acoustically.
So the ceiling is not something that you add on as an after-thought. It is designed at the same time as the walls, and is designed to produce the same amount of isolation.
Ditto the doors, windows, HVAC system and electrical system: they are not additional "things" that you sort of add on later: They two must be designed as part of the total SYSTEM that forms each room. For example, the surface density of the glass in the windows must be the same as, or maybe a bit greater than, the surface density of the drywall on the walls and ceiling, and the "air gap" across the cavity between the window in the CR leaf and the corresponding window in the LR leaf, must be the same as or larger than the air gap between the drywall of the same leaves. Ditto for the doors. The surface density of the HVAC silencer boxes must be the same as the surface density of the leaf that it penetrates. Etc.
It is VERY important to stop thinking of each room as a bunch of parts, and start thinking of it as a single system that acts as one single unit, where each part of that unit has an effect on the whole. This is CRITICAL to getting the design correct!
If you design your walls in one way, your ceiling in another way, your windows in yet another way, it is going to be a disaster, and your overall isolation will be limited by whichever part gives he WORST isolation. So even if you built everything from two-foot-thick solid reinforced concrete, and then decide to save money by putting in cheap hollow doors that you got on sale at Home Depot, then your entire isolation is defined by those doors! The concrete would be irrelevant, since the doors are the weakest link, and with acoustic isolation, the weakest like always wins. If you don't believe me, then drive your car to a very noisy location (maybe the parking lot outside a rock concert). Turn off the engine and radio, but leave the doors and windows closed, and listen. That's how much isolation you get from the entire isolation system that is your car. Now open the door. Listen again. That's how much isolation you get from the entire isolation system that is your car when it doesn't have one part in place. Notice that you now have ZERO isolation. If you replace the door with a sheet of cardboard, you still have no isolation. The rest of the car is still there, but it simply does not matter: the metal in the doors, floor, ceiling, trunk, hood, etc, and the glass in the windshield, back window, side windows, and the rubber floor mats, and everything else is still there, but irrelevant: the open door, or the cardboard sheet, is what defines your total isolation, because that is the weakest part. The same happens with your studio: if you do not think of it as a SYSTEM, where every part contributes to that system, and the weakest part wins, then you will never get good isolation for your studio.
If you really do need 80 dB of isolation, then what you propose falls way, way short of that. Do the math, and see for yourself.
However, it is probably your estimate that is wrong here: Why do you think you need 30 dBC levels outside your studio? That's probably not necessary, and is unrealistic. Most project studios are isolated to about 50 dB, maybe 60 dB for a really, really good studio. Some professional studios are isolated to 70 dB, or perhaps a bit more. But that's unusual. The very best isolated studio in the planet is arguably Galaxy Studios in Belgium: they get just a fraction over 100 dB. They hired the best acoustical engineers in the world (one of whom used to be a highly valued member of this forum, but sadly passed away over a year ago), spent millions of dollars, and took over five years of careful construction. But that's an extreme case, and the vast majority of studios don't go beyond about 70 or so.
I would suggest that you should double-check your isolation needs, and re-think that need for attaining a level of 30 dB outside your studio.
If you have 110 dBC going on inside, and a far more reasonable level of 55 dB isolation, then you have 55 dBC just outside your walls. A hundred feet away, you will get your 30 dB. Fifty feet away, you still get only 35 dB. 25 feet away, it is 40 dB, which is often the legal requirement in many noise regulations, but they measure in dBA, not dBC, so you likely still have another 5 to 10 dB advantage, and would not reach 40 dBA until about ten feet away from your walls.
I really don't see the need to have 30 dB just outside your studio. I think you should work through that better, and come up with a more reasonable number.
But even if you decide that 50 dB outside your walls is acceptable, you are NOT going to get that with the plan you have right now. It seems that you are over-estimating the capabilities of the materials and system you propose, and under-estimating the power of sound.
- Stuart -
You are not grasping the concepts here. You originally described a three-leaf system, which I mentioned was a good idea at the time, but now you are describing only a two-leaf system, which is not going to get you good isolation. Let's take a look.Nope! That is NOT the main shell! This is the source of your confusion. What you describe there IS the "main shell" (more correctly called the "outer leaf") AND ALSO the inner leaf, and it is not going to give you much isolation.So the exterior walls are:
Vinyl
Plywood
4” metal sandwich
Existing styro
2” air gap
2x4 studs
Insul
Vapor barrier
ISO strips
5/8 drywall
Green glue
5/8 drywall
That’s it for the main “shell”
To be more clear, your outer leaf (what you call the "main shell") consists of:
- Vinyl
- Plywood
- 4” metal sandwich
- Existing styro
That's it. End. Stop. Finish. That is your outer leaf. It is your "M" in the "MSM" equation.
Your INNER leaf is the other part you mentioned:
- 2” air gap
- 2x4 studs
- Insul
- Vapor barrier
- ISO strips
- 5/8 drywall
- Green glue
- 5/8 drywall
That is NOT part of the outer-leaf, and it IS the inner leaf. It is the second "M" in the "MSM" equation. Since you have no other construction apart from that, you only have a two leaf system, not the three leaf system you originally described. And since your outer leaf is only vinyl siding on a thin plywood backer plus the thin metal sandwich (which is highly resonant anyway...) without any acoustic insulation (only Styrofoam, which has no useful acoustic properties), you are not going to get good isolation. Yes, you do have mass there (the vinyl siding plus the plywood plus the thin metal is your mass), but it isn't very high, and it is not sealed air-tight, so it's not going to act very well as part of the MSM system.
Your inner-leaf is fine, in terms of mass, but the outer leaf is not.
Also, I'm not sure what you mean by "ISO strips". I googled that term, and only found not-very-useful stuff (such as foam strips that go along the inner edge of a wall to isolate the laminate flooring from it, and also mineral wool with a felt backing) that doesn't seem to be what you are referring to anyway. Please explain what your "ISO strips" are, and provide links to the actual product you plan on using there.
If you really do plan on using only two-leaf isolation, your isolation is limited by the low mass of the outer leaf, and the fact that it is not sealed. There's also the rather major issue of the tie rods. Right now, there are tie rods running across the tops of your outer-leaf wall, and do the same job as the chord beams of a truss system: they tie the wall tops together, to prevent the building from collapsing under the weight of the roof. You CANNOT remove those tie rods unless you first replace them with something else that does the same job, such as collar ties higher up, which you do seem to mention... but you don't explain that in detail, and your diagram seems to show that the collar ties, which are part of the OUTER leaf, are somehow also inside the inner-leaf! That's impossible. Or rather, not "impossible" in the sense that it cannot be done physically, but "impossible" in the sense that doing so totally negates your entire isolation system! You CANNOT have ANY part of the outer leaf even touching any part of the inner leaf at all. They are two entirely separate and independent structures. The outer leaf is one structure, and the inner leaf is another structure: they are not connected to each other in any manner, and do not touch each other. Each one is a single "shell" with substantial surface density, and each one is completely sealed hermetically, absolutely air tight. There is no way you can meet those necessary conditions if your outer-leaf tie rods are collar ties penetrate the inner-leaf. That cannot happen. If it does, you trash your isolation.
Also, to clarify things even more here: since you have two rooms (a live room and a control room), you actually have TWO inner-leaves. There is only one outer leaf, which is the existing building itself, but then you have two rooms within that: one is the CR, the other is the LR, and EACH ON OF THOSE is built as it's own separate, independent, self-supporting structure that consists of four walls AND a ceiling.
The term "room in a room" in your case would be better stated as "two rooms in a room".
No. There isn't one. Or rather there is, but you are not thinking about the system correctly. The "wall between the CR and LR" is not a single wall at all! It is two separate parts. One part is actually the inner-leaf of the LR, and the other part is actually the inner-leaf of the CR. Once again, stop thinking in terms of how houses and shops and things are built normally, where you really do have walls between rooms. Not with a studio! You need to do a mental switch here, and stop thinking in normal construction terms: You do not have a wall between your CR and LR in the normal sense. Rather, you have a control ROOM which is a single self-contained, self-supporting "box" made of four walls and a ceiling, and next to that you have another room, the live ROOM which is a single self-contained, self-supporting "box" made of four walls and a ceiling. What looks like a wall between them is not really a wall between them! It is a pair of eaves from entirely different structures that just happen to be close to each other, and parallel to each other, and will therefore act as an MSM system. From the point of view of the control room, looking towards the lie room, you have a 2-leaf system between it and the LR: there is an inner-leaf, which is the CR inner leaf, and there is an "outer leaf", which is really the LR inner leaf.The wall between CR and LR:
This might seem like "splitting-hairs", but getting the mental picture right, and getting the terminology right, is important.
The air space between the studs is irrelevant, by itself. What matters is the air space between the actual LEAVES; which is the mass in each case. In other words: "What is the distance inside the cavity, from the face of the "metal sandwich" on the outer leaf to the face of the "drywall" on the inner leaf?" That is what defines the "S" in the MSM equations. That's your spring. That's what governs the MSM frequency. Or if you are talking about the MSM system between the LR and CR, then the question would be: "What is the distance inside the cavity, from the face of the drywall on the CR -inner-leaf to the face of the "drywall" on the LR inner-leaf?". That distance is sometimes called the "air gap" or the "wall cavity", or some such, and that defines the resonant characteristics of the wall. You measure that distance independent of whatever else might be in that cavity: insulation, studs, plumbing, spiders, elephants... that's irrelevant to the distance that you need for the equations. And the equations that you need for calculating total isolation of a two-leaf wall are simple:I’m not 100% on what the ideal air space between studs would be. I’m assuming there’s some sort algorithm to determine this? Is 2” gap sufficient?
First, for each single-leaf barrier you need the Mass Law equation:
TL = 14.5 log (M * 0.205) + 23 dB
Where: M = Surface density in kg/m2
For a two-leaf wall, you need to calculate the above for EACH leaf separately (call the results "R1" and "R2").
Then you need to know the resonant frequency of the system, using the MSM resonance equation:
f0 = C [ (m1 + m2) / (m1 x m2 x d)]^0.5
Where:
C=constant (60 if the cavity is empty, 43 if you fill it with suitable insulation)
m1=mass of first leaf (kg/m^2)
m2 mass of second leaf (kg/m^2)
d=depth of cavity (m)
Then you use the following three equations to determine the isolation that your wall will provide for each of the three main frequency ranges:
R = 20log(f (m1 + m2)) - 47 ...[for the region where f < f0]
R = R1 + R2 + 20log(f x d) - 29 ...[for the region where f0 < f < f1]
R = R1 + R2 + 6 ...[for the region where f > f1]
Where:
f0 is the resonant frequency from the MSM resonant equation,
f1 is 55/d Hz
R1 and R2 are the transmission loss numbers you calculated first, using the mass law equation
And that's it! Nothing complex. Any high school student can do that. It's just simple addition, subtraction, multiplication, division, square roots, and logarithms.
Which implies that you will have to break down part of your inner-leaf isolation system at that time, so that you can separate it into two independent inner-leaf systems, one of which will be the LR and the other will be the CR. So take that into account now! Design the framing such that you can easily chop out a section to create the necessary division. Of course, you will need to do that for the walls AND the ceiling, since together they form a system. In concept, you will basically need to slice up one wall, across the ceiling, and down the other wall, to divide the one single room into the two separate and independent rooms, and you will then have to remove all of the ceiling joists and noggins that tied them together, as well as the wall studs, plates, and noggins that tied them together. And of course, you will need to provide temporary structural bracing while you do that.My thoughts are to do the “shell” first and then get in the space to get an idea for feel. The CR may be a phase that I do next year
What you propose is not as easy as ti sounds: Think it through. If this is what you plan to do, it is going to need some careful though in the design process right now to ensure that it is physically feasible to do that without causing the entire thing to collapse on your head. I have designed a couple of studios where the owner had he same basic idea, and it's not as easy as you might think. It is NOTHING like simply "building a wall between two rooms". That's what it might like seem like, but it does not take into account that at the end of the process, the two rooms must be totally disconnected from each other mechanically, with not a single stud, joist, beam, plate, or even a single nail that joins them together. They must end up as entirely separate, independent, disconnected, decoupled structures, each of which stands on its own, both structurally and acoustically.
Once again, you need to stop thinking of the ceiling as somthing that is different from the rest of the room. Each room is a SYSTEM: it consists of four walls and a ceiling. Each room is built exactly like that: a complete framework that has studs going up, plates on the top and bottom of those, joists that connect the top plates, and noggins in between. It is a self-supporting structure that is not attached to anything else: if you took down the outer-leaf shell, then that would have no structural effect on the inner.leaf room: it would still stand there, all on it's own, with no help from anything. That framing has drywall on only ONE side. It might have several layers of drywall, and that might be combined with layers of MDF, OSB, plywood, Green Glue, fiber-cerement board, and maybe even MLV if you have a lot of money to throw away, but that entire "sandwich" is still all together on only ONE side of the framing.I’m also assuming that getting an air gap for the ceiling is going to be a non-starter, so I’m thinking:
So the ceiling is not something that you add on as an after-thought. It is designed at the same time as the walls, and is designed to produce the same amount of isolation.
Ditto the doors, windows, HVAC system and electrical system: they are not additional "things" that you sort of add on later: They two must be designed as part of the total SYSTEM that forms each room. For example, the surface density of the glass in the windows must be the same as, or maybe a bit greater than, the surface density of the drywall on the walls and ceiling, and the "air gap" across the cavity between the window in the CR leaf and the corresponding window in the LR leaf, must be the same as or larger than the air gap between the drywall of the same leaves. Ditto for the doors. The surface density of the HVAC silencer boxes must be the same as the surface density of the leaf that it penetrates. Etc.
It is VERY important to stop thinking of each room as a bunch of parts, and start thinking of it as a single system that acts as one single unit, where each part of that unit has an effect on the whole. This is CRITICAL to getting the design correct!
If you design your walls in one way, your ceiling in another way, your windows in yet another way, it is going to be a disaster, and your overall isolation will be limited by whichever part gives he WORST isolation. So even if you built everything from two-foot-thick solid reinforced concrete, and then decide to save money by putting in cheap hollow doors that you got on sale at Home Depot, then your entire isolation is defined by those doors! The concrete would be irrelevant, since the doors are the weakest link, and with acoustic isolation, the weakest like always wins. If you don't believe me, then drive your car to a very noisy location (maybe the parking lot outside a rock concert). Turn off the engine and radio, but leave the doors and windows closed, and listen. That's how much isolation you get from the entire isolation system that is your car. Now open the door. Listen again. That's how much isolation you get from the entire isolation system that is your car when it doesn't have one part in place. Notice that you now have ZERO isolation. If you replace the door with a sheet of cardboard, you still have no isolation. The rest of the car is still there, but it simply does not matter: the metal in the doors, floor, ceiling, trunk, hood, etc, and the glass in the windshield, back window, side windows, and the rubber floor mats, and everything else is still there, but irrelevant: the open door, or the cardboard sheet, is what defines your total isolation, because that is the weakest part. The same happens with your studio: if you do not think of it as a SYSTEM, where every part contributes to that system, and the weakest part wins, then you will never get good isolation for your studio.
Not like that you wont'! You plan to have a typical band inside, with acoustic drums, bass, electric guitar, keyboards, percussion, vocalists, acoustic guitar, etc.... That's going to be producing around 115 dBC inside, perhaps a little more, but let's say that your band can play quietly, at only 110 dbC. You want 30 dBC outside. That implies that you want 80 dB of isolation. That is a HUGE amount of isolation. The plan you describe for the ceiling will get you about 0.001% of what you want (yes: zero point zero zero one percent): In other words, about 40 dB of isolation. You will need to block about ten thousand times more acoustic energy to get from 40 dB to 80 dB. the decibel scale is logarithmic, not linear: each ten point increase on the scale implies ten TIMES more energy. So increasing isolation from 40 dB to 50 dB implies ten times more energy. 40 to 60 is 10 x 10 = 100 times more energy. 40 to 70 = 10 x 10 x 10 = 1,000 times more energy. 40 to 80 = 10 x 10 x 10 x 10 = 10,000 more energy. Thus, if you are needing 80 dB of isolation, and your system only provides 40 dB of isolation, it is only giving you one-one-hundredth of what you want.Metal roof
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Ideally I’d get any noise down to 30db or less outside the space.
If you really do need 80 dB of isolation, then what you propose falls way, way short of that. Do the math, and see for yourself.
However, it is probably your estimate that is wrong here: Why do you think you need 30 dBC levels outside your studio? That's probably not necessary, and is unrealistic. Most project studios are isolated to about 50 dB, maybe 60 dB for a really, really good studio. Some professional studios are isolated to 70 dB, or perhaps a bit more. But that's unusual. The very best isolated studio in the planet is arguably Galaxy Studios in Belgium: they get just a fraction over 100 dB. They hired the best acoustical engineers in the world (one of whom used to be a highly valued member of this forum, but sadly passed away over a year ago), spent millions of dollars, and took over five years of careful construction. But that's an extreme case, and the vast majority of studios don't go beyond about 70 or so.
I would suggest that you should double-check your isolation needs, and re-think that need for attaining a level of 30 dB outside your studio.
If you have 110 dBC going on inside, and a far more reasonable level of 55 dB isolation, then you have 55 dBC just outside your walls. A hundred feet away, you will get your 30 dB. Fifty feet away, you still get only 35 dB. 25 feet away, it is 40 dB, which is often the legal requirement in many noise regulations, but they measure in dBA, not dBC, so you likely still have another 5 to 10 dB advantage, and would not reach 40 dBA until about ten feet away from your walls.
I really don't see the need to have 30 dB just outside your studio. I think you should work through that better, and come up with a more reasonable number.
But even if you decide that 50 dB outside your walls is acceptable, you are NOT going to get that with the plan you have right now. It seems that you are over-estimating the capabilities of the materials and system you propose, and under-estimating the power of sound.
- Stuart -