Live Room - Treatments and isolation

[civvie]

Hello all.

I have a room destined to be a live recording room. It will be used for mostly drums and grand piano.
Goals: The objective is to have a warm live natural sound. Technically I guess we want the majority of the reflections and diffusion to centred around the 200-1k mark. It's not a huge room so we are not expecting (or wanting) long reverb tails, we just want what is sensibly achievable in the dimensions we have and to not have a dead sounding space.

The other goal is to sound proof as much as possible to an adjacent studio on one of the walls.
For now I guess it's best we concentrate on the soundproofing bit and get to the treatment later.

The internal room dimensions in cm are: L:578 W:360 H:326

The materials are:
Both short walls: Double stud wall, triple leaf heavy 'blue board' drywall and plastered. (one is not built yet, more on that below)
Long wall 1: Double stud wall, triple leaf heavy 'blue board' drywall and plastered.
Long wall 2: Brick and cement perimeter wall
Roof: Cement. Very thick as we are top floor and it's the building roof
Floor: Very old and hard parquet floor on cement foundation.

There is another studio on the other side of one of the short walls, this is the room we want to have a lot of isolation with (the other walls face corridors and communal spaces that are less of an issue.)

The current plan is to have a double stud wall with about 40 airgap between them. Then triple layer of staggered blue board drywall and plastered. I know you can get a good STC with this method BUT we have the issue of the parquet floor. We have to build on top of it as we can't destroy it. It is very dense 230x80 mill and 15 mill thick hardwood tiles. Very tightly packed probably 100 years ago.
How badly might this impact out STC when building walls on top of this?

There is some concern from my colleagues that sound will travel through the cement roof to the other room - As I mentioned the roof is cement warehouse ceiling - is this a legitimate concern?

Budget is around £2k for the remaining wall with the rest for internal treatments.

Thank you,

Aaron.

[Soundman2020]

The other goal is to sound proof as much as possible to an adjacent studio on one of the walls.

Trying to soundproof just one side of a room is the same as trying to "waterproof" just one side of an aquarium... You can't keep water in an aquarium by putting just one piece of glass on only one side. You have to put glass on all sides and the bottom too, or the aquarium won't hold water. If you want to isolate ("soundproof") your room, you need to isolate all four walls, and the ceiling too.

For now I guess it's best we concentrate on the soundproofing bit and get to the treatment later.

Right!

There is another studio on the other side of one of the short walls, this is the room we want to have a lot of isolation with (the other walls face corridors and communal spaces that are less of an issue.)

See above. If you only isolate one wall, then sound will simply ignore that one and will go around it, through the other walls, the ceiling, the doors, the windows, the HVAC system, and the electrical system. You will achieve nothing useful, except filling the pockets of your local hardware store with money...

I know you can get a good STC with this method

STC is irrelevant here. You can't measure studio isolation usefully with STC. It 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.

“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. There is no relationship to real-world decibels: it is just the index number of the reference curve that is closest to your curve.

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 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.

It is very dense 230x80 mill and 15 mill thick hardwood tiles.

That's rather tiny! In construction, "mil" is an abbreviation for "thousandth of an inch", so you are saying that your flooring is just 15/1000ths of an inch thick.... I think you meant to write "mm" , the normal abbreviation for "millimeters", not "mill"....

How badly might this impact out STC when building walls on top of this?

Check your local building code: You will probably find that you cannot build structural (load-bearing) walls on top of finish flooring. You will likely need to cut out a section of that parquet to get down to bare concrete, then build your walls on that.

But getting back to the question; Why do you think the parquet would affect your isolation? (Assuming you are allowed to build load-bearing walls on top of it).

There is some concern from my colleagues that sound will travel through the cement roof to the other room - As I mentioned the roof is cement warehouse ceiling - is this a legitimate concern?

Yes it is a legitimate concern. That is known as "flanking", meaning when sound takes a path through the structure of the building, bypassing your isolation system. That's why studios are built as fully-decoupled "room-in-a-room" systems, where there is no physical mechanical contact between the outer leaf and the inner leaf.

- Stuart -

[civvie]

Hi Stuart,

Thanks for the in depth reply, such a privilege to have your extensive expertise on this.

Very cool to get the overview on STC - That term is talked about a lot and it's very interesting to know how useless it is in the real world when it comes to music studios!

Good analogy on the aquarium too. I totally get that. I have Rod Gervais' book and am learning all the time.
I have attached a rudimentary sketch to give a better idea. (sorry I don't have sketch up or know how to use it - yet...)
The existing stud walls were there already there but I know the builder and they were very well constructed with AC50 acoustic caulk.

You'll note that the end wall has a large 50cm airgap - I'm guessing that is essentially redundant as it's the only wall built like this.
Would you advise that a larger airgap than the existing walls is also redundant for the wall between the control room and live space?

I get that a 'room in room' design is the ultimate but we have nowhere near the budget to float a floor. (I also have read hear that a floating floor is in most cases unnecessary) In this case, given the roof is of similar construction than the floor, lowering and drywalling the ceiling to prevent transmission and flanking to the cement roof would be overkill?

Regarding building codes - These are non-load bearing walls if I'm not mistaken. I believe in this situation it is fine as there are other studios in the complex built in this fashion. I'll bring it up with the team, it may be possible to get permission to cut a channel out of the floor.

Also, for now the windows for now are our HVAC. They are old factory windows (openable) and will be replace soon with double or triple glazed aluminium windows. When this happens we will be bricking in the window size a bit and will install HVAC then.

We have a tight budget and want to get the studio usable - we don't expect to get perfect isolation with our money - our goal is to be as effective as is possible within the financial constraints.

In summary:

Is it moot to have a larger gap between the control room than the existing walls?
Is it moot to have a lowered ceiling if the floor is to remain untreated?

Thanks again!

[Soundman2020]

This is the concept of "room in a room":

MSM-two-leaf-WallChunk-conventional--NOT-inside-out--one-room--S06.png

You have the outer shell of the building, and you need to build another two walls around that (in this hypothetical case), to complete the outer-leaf "shell". Then you build your actual inner-leaf room within that, and take great care to ensure that there is no physical contact between the outer and inner.

If you are doing more than one room, then it would look like this:

MSM-two-leaf-WallChunk-conventional-NOT-inside-out--three-room--with-corridor--S04.png

So you still have one single outer shell surrounding the rooms, then three individual rooms inside, each built as a single frame with drywall on just one side of that frame.

In both of the above cases, the pictures do not show the ceilings for the rooms, but the individual inner-leaf ceiling for each individual room rest on top of the inner-leaf walls, without touching the outer leaf or any other room. Each room has its own ceiling. So, considering that the walls support the ceiling, they are, in fact, load-bearing walls!

If you had laminated flooring, you definitely would not want to try building a load-bearing wall on top of it! Some types of ceramic flooring would be OK. But parquet is in the grey area, and might or might not be allowed. Personally, living were I do, and understanding earthquakes so very well from personal experience ( ), I would not risk it, even if it is permitted by code.

sorry I don't have sketch up or know how to use it - yet...

You can download it for free ("SkethcUp Make"), and there are many god tutorials on You Tube about how to use it. It takes a while to learn, as it's a bit quirky, but once you get used to it, it's VERY powerful.

The existing stud walls were there already there but I know the builder and they were very well constructed with AC50 acoustic caulk.

Excellent! So they are well sealed.... but how are the BUILT? Are we talking about typical 2x4 stud framing with a couple of layers of 5/8" fire-rated drywall on only ONE side of the frame, with the other side being totally open, and completely filled with suitable fiberglass insulation (30kg/m3) or mineral wool insulation (50kg/m3)? Or were they built in some other fashion?

You'll note that the end wall has a large 50cm airgap - I'm guessing that is essentially redundant as it's the only wall built like this.

Not redundant at all, actually! That's the pattern you should be following for all the walls. See the diagrams above. 50cm is probably over-kill: something more like 20cm would be fine, and most definitely never, ever less than about 10cm. But the concept of a large air gap is fundamental to isolation.

Would you advise that a larger airgap than the existing walls is also redundant for the wall between the control room and live space?

Same as above: The air gap needs to be large enough to do the job, never less than 10cm, and it's better to calculate it, rather than guess at it... If you have very high mass in your leaves, then you can go with a smaller gap. If you have low mass, you will need a much larger gap. If you don't fill the gap with insulation, or use the wrong type of insulation, then the gap will need to be larger. If you do fill the gap (cavity) completely, with the best insulation for the job, then the gap can be smaller.

The key point is that you first need to determine two things: 1) How much isolation do you need, in decibels? [not STC!! ] 2) What is the lowest frequency that you need to isolate? With those two numbers in hand, it's relatively simple to figure out the details of the wall that you will need.

I get that a 'room in room' design is the ultimate but we have nowhere near the budget to float a floor.

Good, because you don't need to! Here's why: http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173

(I also have read hear that a floating floor is in most cases unnecessary)

Yes! Correct!

You already have a great floor: concrete slab with parquet is a wonderful floor for a studio (except under the walls!), so there's nothing more you need to do there.

given the roof is of similar construction than the floor, lowering and drywalling the ceiling to prevent transmission and flanking to the cement roof would be overkill?

Not overkill, and that is indeed exactly what you need to do, but not in the way you are imagining. It's very simple: you just put wood framing across the top of your inner-leaf walls, and put drywall on that framing. Done! (Of course, you need to calculate the dimensions of the wood to make sure it can support the load safely, but that's not complicated). It really is that easy. That's the fifth "side" of your room (along with the four walls), and is equivalent to the glass floor in the fish tank analogy.

These are non-load bearing walls if I'm not mistaken.

I beg to disagree! See above....

I believe in this situation it is fine as there are other studios in the complex built in this fashion

If you stand inside the area where you want to build your studio, can you hear what's happening inside those other studios? Do you hear the thumping of the drums, and the boom of the bass, and the low frequency growl of the keyboards and electric guitars? If the answer is "yes", then you have proved to yourself why their method doesn't work...

Also, for now the windows for now are our HVAC.

Lots of first-time studio builders come along with the same plan, and I have to burst their bubble every time: That won't work. To prove to yourself WHY it won't work, go sit in your car in heavy traffic or some other noisy place with the windows closed. Listen carefully. Now open the window.... Convinced? Or do it the other way around: Go find a nice quiet place to park your car, turn the radio up pretty loud, and get out while someone else stays inside. Close the doors and windows. Walk around the car a couple of meters away, then signal to the guy inside to open the windows.... Point made. 'Nuf said. Your honor, I rest my case.

As soon as you open a window, your isolation drops to zero. Nada. Zilch. Nothing. Isolation is only ever as good as the weakest part, and an open window sure is a weak part!

OK, that's from the isolation point of view. Now for the HVAC point of view: If you want your instruments, mics, gear and people to perform well, stay in tune, and not die an early death, then you need to keep the temperature inside fairly constant at around 21 °c, give or take a couple for personal comfort. And you also need to keep the humidity at roughly 40% or so. If the temperature or humidity change, then so does the tuning and timbre of your instruments, and so does the response of your condenser mics. So each time you open the windows to let out the ghastly, smelly, CO2-saturated, warm, humid air, and let in some clean, dry, cool, fresh, oxygen-rich air, what happens in the room? The temperature and humidity swing wildly from one extreme to the other, all your acoustic instruments de-tune in different ways and by different amounts, and your mics start sounding different too.... not a happy picture for a recording studio! Not only that, but you have a bunch of unhappy musicians that are constantly swinging between warm and cold, moist air and dry air, fresh air and stale air....

So the situation is this: You have unmotivated, shivering, sweating artists, gasping for air, playing halfheartedly on instruments that are constantly out of tune no matter how hard they try, with change vocals picked up my changing mics, coughing and sneezing as they catch cold, in an unhappy environment... Mmmmmm... maybe that's not part of your business plan?

In other words, you might think you can get away without HVAC, but you can't. You do need a ventilation system to bring in fresh air and remove stale air, and you do need an air conditioner to heat, cool, and dehumidify the air as needed, and keep it at a constant temperature and humidity level.

HVAC is not a luxury that would be nice to have if you were a high-end pro studio: Rather, it's a basic necessity to keep you alive and well, and keep your recording sessions running smoothly, with happy musicians and instruments that stay in tune, and mics that don't drift.

hey are old factory windows (openable) and will be replace soon with double or triple glazed aluminium windows

That would be a mistake. If you put a double-glazed window in your outer leaf, then even if you only use single glazed for the inner leaf, you'd still have a 3-leaf, or even worse, a 4-leaf, system, thus reducing your isolation considerably. The method for getting the highest isolation at the lowest cost in the least space, is with 2-leaf construction. Not 1-leaf, and not 3-leaf. Only 2-leaf.

In other words, you need to replace the existing windows with non-opening single-glazed units that have thick laminated glass in them, then you need to put a similar non-opening single-glazed unit with thick laminated glass in the inner-leaf, to complete the system.

Is it moot to have a larger gap between the control room than the existing walls?

Nope! It's the basis of how isolation works. See the diagrams above, for details.

Is it moot to have a lowered ceiling if the floor is to remain untreated?

Nope! It's a necessity! And it has nothing to do with the floor: you need that independent inner-leaf ceiling anyway, regardless of what you do to the floor. Also, we aren't talking about treatment yet: only isolation, so far. Treatment is a totally different aspect of acoustics, not related much to isolation. But you are going about it the right way: first you need to get the isolation done correctly, then worry about the treatment. You can't do it the other way! That would be like putting plants and fish in your aquarium, before putting the glass in . . .


- Stuart -

[civvie]

Thanks again Stuart for your expert insight. It's so valuable and I'm learning a lot. Acoustics can be counter-intuitive even for those who work every day with sound.

This is the concept of "room in a room":

Got it. But is it still considered a 'room in room' if you suspend a ceiling from the inner leaf walls, but don't float the floor? Why is the roof more important than the floor as far as isolation is concerned?

Excellent! So they are well sealed.... but how are the BUILT?

All drywall is the heavy acoustic 'blue board' type.

The long outer wall is metal stud frame, rockwool, and 2 staggered layers of drywall (not 3 as I thought) and then sealed, taped, plastered and painted.
The inner wall is the same but with wood studs.
There is no drywall on the inside, just airgap between the rockwool

The short wall with the 50cm airgap is similar but with all metal studs with neoprene between all points of contact with the building, Rockwool, double layer drywall on outside only, and there is apparently a heavy material 'acoustic curtain' hanging in the middle of the big airgap - apparently it's an idea taken from a BBC studio...I don't know! There are no doors on in this wall yet - the plan is to follow the designs in Rod Gervais' book. Unless there's any better door designs you can point me towards?

The other short wall (between control room) will be the same again but with all wood studs and around a 30 cm airgap and probably no curtain (unless that's a good thing?)

I beg to disagree! See above....

RE: load bearing walls. Is there a design where the inner roof load is taken from the existing cement roof. Like drywall on a light aluminium frame attached to the ceiling in a minimal and clever way which decouples it?

what's happening inside those other studios?

The other studios are photography studios, don't generate hardly any sound (they have the radio playing at low volume) and sound from our live room won't be an issue IF it's kept to a level they can have a conversation over.

That won't work.

Re: Windows as HVAC. Yes I totally agree. But we are definitely installing HVAC, it's just in the next phase when the new windows go in. - I know it's far from ideal for now. The fortunate thing is that the windows overlook a field and the ambient sound is low - wind and birds mainly

Perhaps the bigger issue is we have not planned on building an inner leaf on that wall as it is an exterior wall, it's a very solid and heavy mass build (bricks and cement) with no one to upset out side it (an nothing to upset us). BUT, now I'm thinking flanking is our concern, from the live room into the exterior wall and then transferring into the control room.

you need that independent inner-leaf ceiling anyway, regardless of what you do to the floor

RE: ceiling. This is the main point I don't 'get' yet. Why is it so important to isolate the ceiling if you're not doing the same with the floor? This doesn't seem to agree with the 'weakest link' idea. The sound will just go through the floor. I would think even MORE so than the ceiling due to bass amps or kick drums physically resting on the floor. What am I not getting here?

Thank you!

[Soundman2020]

Acoustics can be counter-intuitive even for those who work every day with sound.

Very true! There's a lot about acoustics that isn't intuitive at all, at first glance. For example, who would suspect that adding an extra layer of thick, dense mass to the middle of a wall could make it much WORSE at isolation? But it's true....

But is it still considered a 'room in room' if you suspend a ceiling from the inner leaf walls, but don't float the floor?

Yes, it is still a "room-in-a-room" if the ceiling is suspended ON ISOLATION HANGERS. Forget about floating the floor: Did you read the thread I linked you to? That explains it pretty well.

Why is the roof more important than the floor as far as isolation is concerned?

Roof? Or ceiling? Not really the same thing. But anyway, the ceiling is NOT more important than the floor: they are all equally important, which is why they all need to be isolated and damped to the same level. Isolation is only as good as the weakest part. But take a look at the difference between a slab-on-grade floor, and a suspended drywall ceiling: The density of concrete is around 2400 kg/m3, and a building slab is typically 15cm thick. That means that each square meter of the slab weighs about 360 kg. The density of drywall is about 680 kg/m3, and a typical studio ceiling would be two layers of 16mm drywall, for a total of 3.2 cm thick. Therefore, each square meter of ceiling ceiling weighs about 22 kg. Compared to 360 kg for the floor. I think you can see the issue! The ceiling has just a tiny fraction of the mass in the floor! Why is that important? Because in order for sound to get through a massive barrier, it has to make the barrier vibrate. It's not hard to see that making 22kg vibrate is a hell of lot easier than making 360 kg vibrate...

Now for damping. In acoustics, "damping" just refers to absorbing vibrations in some manner. With the slab-on-grade, you have the entirety of Planet Earth damping the slab from below. With the ceiling, you have a few cm of insulation. It's not hard to see which damper works best!

So the floor DOES matter, absolutely, but a concrete slab-on-grade is so extremely massive, and so very well damped, that it doesn't need any extra attention. It will isolate fine just as it is. But the ceiling is a very different issue: Even though it is heavy from the human point of view, it's way, way lighter than the floor. And the damping that the ceiling gets is just a tiny fraction of what the floor gets.

The short wall with the 50cm airgap is similar but with all metal studs with neoprene between all points of contact with the building,

The neoprene won't do any harm, acoustically, but it probably isn't doing any good either. Floating a wall successfully is just as hard as floating a floor. You need to do the calculations to make sure it will actually float! It won't happen by accident or guesswork. All "springs" (including rubber) have a certain range where they can "float" the load. Think of it this way: If you take the suspension system out of a Mack truck and put it in your car, it won't work: your car does not have nearly enough mass (weight) to even move that huge spring! It does not compress the spring at all, so the "spring" basically acts as a steel rod. On the other hand, if you take the suspension system out of a motorbike and put that in your car, you have the opposite problem: Your car is way too heavy for that spring, and squashes it flat. Here, too, the "spring" basically acts as a steel rod. So you need a spring that is design to specifically to hold the weight of your car, not the weight of a truck or a bike. The spring needs to be compressed somewhere in the range of around 15% to 30% very roughly (different amounts for different materials and designs). If you only compress it 3%, it won't float. If you compress it 90% it won't float.

The same with your neoprene: If you did not calculate the load and compression, then it is not floating. You would first need to know what the optimum static deflection (compression) is for that specific type of neoprene that you used, and you would have to know what load (how many kg per square meter) would achieve that loading. Then you would have to do the math to make sure that your wall is just heavy enough, and the surface area of the neoprene was just right, to cause the neoprene to "float" the wall. If nobody did the math, then your wall is not floating. It is either over-compressing it beyond its useful range, or under-compressing so it never even gets to its useful range.

and there is apparently a heavy material 'acoustic curtain' hanging in the middle of the big airgap - apparently it's an idea taken from a BBC studio...

Limp mass. Depending on how old that wall is, the "curtain" is likely either heavy roofing felt of some type, or MLV. It can help, if built right.... in other words, if your wall is built exactly the same way that the BBC built theirs, and designed using the equations and systems they discovered and researched, then it might work. On the other hand if this construction was just "inspired by...." the BBC studio, but built in a different way, using different dimensions and different materials, then all bets are off, and it likely isn't doing anything. If you take a look at the BBC research library, you'll find hundreds of very carefully prepared papers, with great attention to detail, numerous variations of the experiments, to find out what works, why it works, and develop equations, guidelines, and systems. For every device that works, they reject dozens or hundreds that didn't work when the tested them under highly controlled conditions, in carefully designed research laboratories. Very often, there's only a small change between the device that worked best, and the one that didn't work at all. So if you DON'T use one of their designs, exactly, completely, down to the last detail, then it is rather probable that what you did build, is one of their rejects that was found to not work at all, or to work poorly. Or more sadly, one of the combinations that was found to make things WORSE than doing nothing at all! There are many of those.... Take a look through the BBC research library on acoustics: You'll probably be surprised!

There are no doors on in this wall yet - the plan is to follow the designs in Rod Gervais' book. Unless there's any better door designs you can point me towards?

There are several door designs in Rod's book. At least two basic designs: one of those is his "superdoor", which is great if you know how to build a structure that can support it well, structurally, without bending, warping, twisting, or sagging under the huge weight. The other design that Rod uses, is the typical, very common, very well tested "pair of back-to-back doors", with one door in each leaf.

Is there a design where the inner roof load is taken from the existing cement roof. Like drywall on a light aluminium frame attached to the ceiling in a minimal and clever way which decouples it?

It is possible to do that, using acoustic isolation hangers to support the ceiling. Companies such as Mason Industries manufacturer such devices, and will help you choose the right ones for you, and help you position them correctly. And they will also ask you to pay a lot of money for that!

But yes, if you have a high budget that can afford isolation hangers and engineering services, that is an option. It would allow you to float your ceiling by suspension from the roof.... provided that the roof is actually able to support the load! You will need to hire a structural engineer to check the building structure, and make sure that the ceiling has enough remaining live load and dead load capability to be able to safely support the mass of your ceiling.

The other issue here is that the tops of the inner-leaf walls would not be correctly braced, and they could potentially "flop around", so you would need to install acoustic sway braces at several points around the edges of the inner-leaf wall top plates, to provide lateral support.

The other problem is that, since there would be no rigid connection between the ceiling and the walls, they would move independently, banging into each other, in the event of seismic disturbances, or even the movement from just opening and closing the doors, or the over-pressure from wind loading. So you will possibly also need to install seismic snubbers on both the walls and the ceiling, to prevent them from destroying each other due to moving different ways at the same time.

So yes, all of that can be done, and Mason Industries (as well as other companies) does make the devices that you need to do that. It would cost you probably a thousand dollars extra to buy the devices and get the engineering services that you would need to calculate all of that, and get the right products in the right places.

The other studios are photography studios, don't generate hardly any sound (they have the radio playing at low volume)

Thank you for proving my point! You mentioned that the "other studios in the complex built in this fashion", which is why you though you could build yours the same way. But you just showed why you CANNOT build yours the same way: because it does not work! You are aware that they play radios, since you can hear those radios... Case Closed! In other words, the way they built their places is not doing a very good job of isolating...

and sound from our live room won't be an issue IF it's kept to a level they can have a conversation over.

Bingo! There's the problem. That "IF" is a very, very big "IF"! You said your studio "... will be used for mostly drums and grand piano.". Drums are among the loudest instruments that exist, and certainly the loudest in a typical modern band. A drum kit played moderately can put out 110 dBC easily. Played fairly hard, it can put out 115 dBC, and really smashed by a heavy handed gorilla, it can hit 120 dBC. That is LOUD!!!! And you need to get that down to the " level they can have a conversation over.". Do the math: Normal human conversation is around 65 dBC, roughly. (60-70). So in order for your neighbors to have a conversation over the drums, that means the drums would have to be quieter, or at least no louder than the lowest level. Therefore, you need to get about 60 dB of isolation.

So take a seat, take a deep breath, and read through this:

A typical house wall (wood studs with drywall on both sides and insulation in the middle) gets around 30 dB of isolation. You need 60. Which means you need to block one thousand times more sound energy than the typical house wall. No, I'm not making up that number to scare you: it's the real number! The decibel scale is logarithmic, not linear. Every time you go up ten decibels, that implies ten times more acoustic intensity. So going from 30 to 40 is ten times, going from 40 to 50 is another ten times (total of 100: because 10x10=100), and going up from 5o to 60 is yet another ten times, for a total of one thousand times, because 10 x 10 x 10 = 1000. So you need to block a thousand times more than a typical house wall, in order to meet your own specification, of only having enough isolation such that your neighbors can talk to each other over the sound of your studio, without having to yell. At 60 dBC, they would still be able to hear your music, rather loud. You would have to get it down to 30 dBC in order for them to not be able to hear it at all....

So, you have set yourself a very, very high goal. 60 dB of isolation is NOT easy to achieve.

we are definitely installing HVAC, it's just in the next phase when the new windows go in.

OK great... But the isolation system for your HVAC needs to go in now, as you build the walls and ceiling. If you try to add that later, you'll have to tear down parts of your walls and/or ceiling in order to be able to install the ducts and silencers, then re-build the walls.... Probably not a smart plan! You need to design the HVAC system now, and at the very least install the silencers and ducts now, even if you don't connect them up yet.

The fortunate thing is that the windows overlook a field and the ambient sound is low -

But you are missing the point here: If you open the window, the very loud sound of your drums and piano, will be going out the open window.... and then back in to your neighbour's studios, through their un-isolated walls and windows! As well as disturbing anyone else that is out there, with a fairly large distance...

Perhaps the bigger issue is we have not planned on building an inner leaf on that wall as it is an exterior wall,

Have you taken a look at the principle of physics called "mass law"? If not, they you should. That's the law that governs how a single-leaf partition (or coupled two-leaf partition) works to isolate sound. It's very simple, and goes like this:

TL(dB)= 20log(M) + 20log(f) -47.2

Where:
M is the surface density of the panel (mass per unit area (kg/m²) ), and
f is the center frequency of the third-octave measurement band.

Do the math, and you'll understand why studios are never designed with single-leaf walls...

BUT, now I'm thinking flanking is our concern, from the live room into the exterior wall and then transferring into the control room.

Exactly. That is one of the issues, for sure. Another one is the poor isolation from a single-leaf wall (mass law)...

Why is it so important to isolate the ceiling if you're not doing the same with the floor?

Because the floor has about ten to twenty TIMES as much mass as the ceiling, and much better damping. It is also far more rigid, and the coincidence dip frequency is considerably higher. The concrete slab on grade floor is already pretty well isolated, and doesn't need much more attention. The ceiling is very different.

The sound will just go through the floor.

Why? The slab is massive: hugely massive. It is also extremely well damped by the ground underneath. Why would sound go through that? And if it did, where would it go?

I would think even MORE so than the ceiling due to bass amps or kick drums physically resting on the floor.

Yes, it is possible that you could have a problem with impact noise getting into your slab from the drums, piano or bass amp, but that is very simple to deal with: just build a drum riser to isolate it from the floor:

GLENN-example drum riser 1.jpg

GLENN-example drum riser 2.jpg

Simple. Cheap. Effective. That's a design created by Glenn, one of the other major contributors here on the forum.

Preventing impact noise from getting into the floor structure is relatively easy. Preventing airborne sound from getting through the walls and ceiling is not.


- Stuart -

[civvie]

Thanks again Stuart.

You've made a bunch of good points and I have some reading to do now!

But I just wanted to say quickly, I think you missed the bit in my first post about the ceiling in this building being essentially the same construction as the floor. It is a huge old thick cement industrial factory ceiling. On the other side is the outside London sky (not another floor). It is therefore, I would think, a very different calculation and that's why I ask ' Why isolate a ceiling like this if we are not bothering with the floor' because the ceiling in this case is built much like the floor.

How does this information change what you would advise? (again, given a tight budget)


Also, I know about the radios and noise in the other rooms because I manage them and have been in them a lot. The sound isolation in those rooms is actually very good.

[Soundman2020]

because the ceiling in this case is built much like the floor.

So you have another Planet Earth sitting on top of your ceiling, providing all the damping and extra mass?

- Stuart -

[civvie]

So you have another Planet Earth sitting on top of your ceiling?

Haha. No! But neither does the floor, as we are one floor up.
Downstairs is storage and doesn't make much noise.

Am I right in thinking this makes the floor and ceiling pretty equal?

[Soundman2020]

Haha. No! But neither does the floor, as we are one floor up.

So your original post was also incorrect? When you said : "Floor: Very old and hard parquet floor on cement foundation.", it's not actually on the foundation?

- Stuart -

[civvie]

So your original post was also incorrect?

I'm afraid so. Sorry I'm pretty new to building terminology. We are on the 1st floor of a 2 storey warehouse.
So does this make our ceiling much like our floor?

And thanks for the drum riser plans! Definitely going to build one of them.

[Soundman2020]

I'm afraid so. Sorry I'm pretty new to building terminology. We are on the 1st floor of a 2 storey warehouse.
So does this make our ceiling much like our floor?

A little bit, but it also makes the floor more like a drum, and much, much harder to isolate your room than you thought. The slab is an un-damped membrane, stretched across a frame, with a resonant cavity on the other side. Just like a drum, that system will resonate at several frequencies, and with several modes. This is the reason why studios are normally built on the ground floor, seldom on upper floors. The ones that are built on upper floors need much higher budgets, to either damp the floor slab, create a partially decoupled "fake" floating floor, or build a proper floating floor.


- Stuart -