upper floor load limit

I started a thread a while back asking for the pros and cons of building a small studio on an upper floor in an office building. Well, it looks like I'm about to purchase an 80 sqm space on the top floor of a building. The space is L shaped. I can provide more details if someone asks, but my early question has to do with floor leading capacities of upper level floor slabs. After some trawling, I finally was able to be peruse the architectural plans and see that the floor is 125mm condeck reinforced (with shear studs). Apparently it has the same live load strength that some of the lower floors have despite them being (older) 200mm construction. I think we calculated the load bearing capacity as being 350kg /m2. Now, of course there are many variables to consider before asking if this is sufficient for building a typical MAM structure upon it, so without being too specific, I can supply at least some of the more important info. Control Room will be around 40m2 and the live room around 25m2. Using the existing outer shell as one leaf, the inner leaf will be the usual double 16mm drywall against 90x45 studs with the ceiling being 3 layers of 16mm drywall and the floating floor composed of 3 layers of 15mm compressed cement sheet under 16mm particle board flooring all above joists upon rubber. For the control room, A 60 channel Neotek console and 2 large heavy main monitors are the heaviest items along with 4 x waist high outboard racks filled with the usual outboard. A lounge suite and some loaded shelves... thats about it apart from up to 10 people from time to time. The live room will just contain 5 or 6 amplifiers and a drum kit , a bunch of mic stands etc. So nothing out of the ordinary. Does any one know some typical weights of small studios such as this? I basically need to know if the floor is strong enough and I need to know very soon in order to not be outbid for the space. Unfortunately, the acoustic engineer needs about a week before he can find the time to get some answers.... Oh, the other related question pertains to strength vs TL at low frequency. Although the 125mm condeck reinforced slab is as strong as 200mm concrete, I'm guessing it's less efficient when it comes to isolation? I mean, it's lacking 75mm of concrete mass... I guess that's why the engineer suggests 45mm of compressed cement sheet. I'd really appreciate any thoughts chaps, I'm in a bit of a bind, time wise.... Thanks for reading!

When it comes to structural engineering and safety DO NOT rely on advice you get over the internet! Certainly not mine: I've designed a whole bunch of studios, but I'm not a structural engineer. Even though I do design structures, I still always insist that a qualified, certified structural engineer should check them over, and modify them if needed, to meet LOCAL safety regulations and building code. You should most definitely do the same. Only a structural engineer who is qualified and certified to practice in Melbourne, Australia, can tell you what is safe for YOUR build in YOUR building, and only after inspecting it in person.

I can provide more details if someone asks, but my early question has to do with floor leading capacities of upper level floor slabs.

Without knowing the dimensions of your space, it's impossible to even guess at what the load would be...

I think we calculated the load bearing capacity as being 350kg /m2.

That's not very much for a commercial or industrial building. You would not even be able to safely put a piano on that floor! An upright piano can easily weigh that much, and more. Then add the pianist... Also, inner-leaf walls are liner loads, not area loads, so you'd need to know the capability of the floor in terms of concentrated linear loads. The entire weight of all the inner-leaf walls and ceilings, is spread across an areas just a few cm wide, under the walls. A good isolation wall might well weigh 50 kg/m2, so a 2.5m high wall will weigh 125kg per linear meter. A one meter length of wall will therefore spread that load over an area of just 0.1m2 (one meter long, 10cm wide), meaning that the pressure on the actual footprint under the wall, is 1250 kg/m2... That does not take into account the additional weight of the inner-leaf ceiling, which will be transferred through the walls, into the floor.

the floating floor composed of 3 layers of 15mm compressed cement sheet under 16mm particle board flooring all above joists upon rubber.

... and you did the math to confirm that this structure actually will float? What size will each of your rubber pads be, and how will they be placed to ensure even distribution of the floor load? What are the resilient characteristics of the pads? What deflection do you need to get on those pads, in order to ensure that the floor still floats under minimum loading, and what is the resonant frequency of the floor at that load? Is it at least an octave lower than the lowest frequency you need to isolate? What is that "lowest frequency"? How much isolation do you need, in decibels? Will it still float when loaded down with ten musicians, all of their instruments, all of their equipment, your equipment, your gear, a couple of crates of beer, and a stack of pizzas? If you can't answer all of those questions, then there's a problem... Also, the weight of that "floating" floor alone is going to eat up about 1/3 of your entire load-bearing capacity... it could easily be 100 kg/m2, from the way you describe it. Maybe more...

I basically need to know if the floor is strong enough and I need to know very soon in order to not be outbid for the space. Unfortunately, the acoustic engineer needs about a week before he can find the time to get some answers....

At this stage, you don't need an acoustic engineer: you need a structural engineer. Tell him to assume that your "floating" floor comes in at about 120kg/m2 ( to be safe) that your walls will weigh 150 kg per linear meter (to be safe), that your ceiling is another 75kg/m2, plus the couple of tons extra load for your gear and people.

Although the 125mm condeck reinforced slab is as strong as 200mm concrete, I'm guessing it's less efficient when it comes to isolation?

125mm of concrete will get you about 45 dB of isolation for airborne noise, but obviously not much at all for impact noise. Maybe IIC 25 or so. - Stuart -

Stuart, thank you! This is helping me more than you imagine. Much appreciated. I'll make sure the structural engineer is across all these points. I think he and the acoustic engineer are more used to dealing with machinery noise in buildings, so I'm hoping they know what I need them to know about airborne sound such as is made by your typical indie rock band. ;)

princeplanet wrote:

Stuart, thank you! This is helping me more than you imagine. Much appreciated. I'll make sure the structural engineer is across all these points. I think he and the acoustic engineer are more used to dealing with machinery noise in buildings, so I'm hoping they know what I need them to know about airborne sound such as is made by your typical indie rock band. ;)

:thu: But don't forget impact noise: Your drums, bass cabs, and electric guitar cabs will certainly put impact noise and vibration directly into the floor (unless you isolate those too), and so will things like foot-stomping musicians keeping the beat, keyboard pedals, effects pedals, and several other things. They all go directly into the floor. Also coming the other way: Most buildings have machinery that puts impact noise into the building structure itself, such as elevators, pumps, fans, contactors, etc. As well as people walking on other floors, doors opening/closing, dropped things... You want to keep that OUT of your studio. Impact noise is a bitch... Once it is in the structure, there's no way to get it out again.... - Stuart -

OK, Had a structural engineer on the case, but something seems not quite right. He says: "The floor has been designed for a total load of 7.0kPa (700kg/m2), the proposed loads and the self-weights are in the order of 13.5kPa (1350kg/m2), I.e. the proposal nearly overloads the existing design capacity of the floor by nearly 100%. This is based on the provided information, no required factoring of load has been applied, uniform distribution of load, uniform (averaged) capacities on the existing structure and we have not independently verified the calculations/capacities. In short, we cannot support the proposal. It is not even close." By your calculations, Floating" floor comes in at about 120kg/m2 ( to be safe) , walls will weigh 150 kg per linear meter (to be safe), ceiling is another 75kg/m2, plus the couple of tons extra load for gear and people. That’s 245kg/m2 before other equipment and people are considered. What am I missing? Just need a second opinion, ....

Edit, below are the ACTUAL figures that the acoustic engineer would have liked, that the structural engineer has been updated with. see the attachment for the L shaped space, of which the long side will only go half way down. The area below does not require isolation. The corner section will be the control room, the smaller section to it's left will be the live area. -quote- [I]" Floor: 1. 15mm thick CFC sheet weighs approximately 28 kg/m2 2. 3 layers for the floor weighs 84 kg/m2 3. Insulation in the cavity will weigh around 4 to 5kg/m2 4. The purlins on top of the mounts would be steel prob 7 kg/m Wall: 1. The wall sheeting will be 2 layers of 15mm CFC sheet with 13mm plasterboard over which will be around 68kg/m2. 2. Insulation to walls nom 75mm thick 32 kg/m2. 3. Mounts at circa 450 centres will be probably around 2-3kg/mount Ceiling: 1. The ceiling will be 3 layers of 16mm fire rated plb or around 37.5 kg/m2 with 75mm thick 32 kg/m3 insulation over. 2. Penetrations etc for mech will need to be acoustically treated Entry doors recommend airlock into the room 45mm thick solid core doors with full perimeter seals both sides of door frame. The entry wall would be an additional stud wall internally not constructed off the floor with 2 layers of 16mm thick plasterboard facing the reception area" [/i] -end quote- I would have thought that support structures underneath the floor (they would be on the plans that the structural engineer has) would influence things. Nevertheless, I suppose I'd entertain halving the mass for the control room and and lessening the mass in the live area by 25%. Would that be closer?

Hmmm, I'm still thinking this through.... so, my question was to find out if this system seems too heavy for a 125 bondeck reinforced concrete slab, which has an overall strength of 700kg/m2, but a live load of only 350kg/m2. I take it that with nothing on it, the floor could take 700kg/m2, however the existing walls and ceiling probably are weighing down on this slab (surely not to the tune of 350kg/m2??). I guess he (SE) is saying that I'm left with 350kg/m2 which is meant to be the live load allowance for every day office requirements. If you have the equivalent of 32mm of plaster on the floor, ceiling and 4 walls, and you flat packed it all, then the weight is something like 480 kg/m2. Only 130kg more than the live load, but on top of that you have the equipment and humans... I'm hoping that the existing walls and ceilings are no where near 350kg/m2, even though much of it is floor to ceiling windows (8.3mm lam) so that we get a break there. One worry, however, is that the walls on the floor beneath are 1.5 metres further out than on the 7th floor (i.e., the 7th floor is a "penthouse" and is smaller with a balcony surround). Does that mean the existing walls are weighing on the slab more so than if the lowers floor's structure were directly underneath? This stuff is beyond me. AllI know that my last studio had a 200mm slab built in the '60's and on the first floor it took 4 x the weight I'm proposing for this new site, and that is why I can't believe that a newer 125 reinforced slab, which meant to be equivalent to a 200mm slab, can't take the proposed weight. Is the structural engineer being to careful? Or could there be a mistake in his calculations? After all, he said the total weight on the 700 kg/m2 would be 1350 kg -almost double- but the new structure could be around 500, the old one perhaps only 200, and the live load, well, it's a 48 channel console , some large monitors, amps, power supplies, furniture and people. much less in the live room. But I don't understand how these figures all work. Is it worse when the load is concentrated along a wall line?

which has an overall strength of 700kg/m2, but a live load of only 350kg/m2. I take it that with nothing on it, the floor could take 700kg/m2,

Nope! What it means is that the current dead load is 350 mg/m2, so your variable live load is the remaining 350kg/m2. The "dead load" is the floor itself, and the underlying stricture that keeps it up. Concrete weighs around 2300 kg/m3, so a slab 125mm thick is already 287 kg/m2, plus whatever beams, columns, and other sundries are under it / attached to it. - Stuart -

I appreciate the thoughts. For those of you who have lost sleep wondering about the outcome , buying an extra coupla days meant we could reconfigure the design so we were putting walls on supporting beams from underneath- which we worked out for floor 6 plans. The structural engineer has okayed a new idea. Without going into details, the other plans had walls along unsupported parts of the floor. Also, I think now the floors are ok to be 120 kg/m2. There is new thing though, that may even warrant a new thread! :facepalm: But now that my orientation has changed (again, I'll spare you the details), I think I'll need to have my control room 4.5 M long by 6.6M wide, yes wide! With a ceiling of only 2.9M (I've always been used to over 3.4), Im wondering if anyone has ever had issues with a wide control room. I know the dimensions are Bolt-ratio approved, but am used to bass notes travelling further behind me before they bounce back. On the plus side, I prefer to face long walls in a room for aesthetic reasons (maybe even psychological). Anyone think I could get used to it?

I appreciate the thoughts. For those of you who have lost sleep wondering about the outcome , buying an extra coupla days meant we could reconfigure the design so we were putting walls on supporting beams from underneath- which we worked out for floor 6 plans. The structural engineer has okayed a new idea.

Excellent! That's good news, for sure.

Also, I think now the floors are ok to be 120 kg/m2.

Fine, but floating a floor can still be problematic. It's too late for me tonight, and I'm too tired to go into that now. More info available here: viewtopic.php?f=2&t=8173 You must be certain that it is floated properly, which isn't easy to do.

There is new thing though, that may even warrant a new thread! :facepalm: But now that my orientation has changed (again, I'll spare you the details), I think I'll need to have my control room 4.5 M long by 6.6M wide, yes wide!

:shock: :cop: Not good. I'd strongly suggest rotating your orientation 90° either left or right. With only 4.5m "length", your head is going to be very close to the rear wall.... way too close. Reflections will be arriving well inside the Haas time, thus messing up your sense of directionality, frequency, and phase. In other words, screwed up stereo image and sound-stage, and screwed up perception of tones. One of the most basic goals for a control room is to have enough space behind you such that any reflections and also the diffuse field, arrive at your ears only AFTER the Haas time. This is all about psycho-acoustics, not so much plain acoustics. Psycho-acoustics is how we perceive sound, not how the sound really is. Our ears and brains are mindbogglingly complex, and do amazing things to form our perception of the sound. But one key for all of that to work accurately and cleanly is that there can be no "copies" of the sound arriving at our ears with a delay of less than about 20 ms: the Haas time. If you hear the direct sound, then a reflection of that same sound (or a diffuse echo of it) also arrives at your ears within less than 20ms, then your brain does not have enough time to catch up and figure it all out. In simple terms, it confuses the echo as being part of the direct sound, and does not identify it as an echo at all. Instead, it assumes that the echo was actually a phase shift and frequency shift in the original sound. Long story short: it tells you that you heard a different sound, at a different frequency coming from a different direction. OK, so the effect is subtle, but it is there. That's why we take such great care to build control rooms that keep all early reflections away from the engineer's head, and only allow the diffuse field (or reverberant field, if you prefer) to get back to his ears after a delay of at least 20ms, and at a level of -20dB below the direct sound. That gives our brains enough clues to figure out true direction and frequency. So: Sound moves at very roughly 1 foot per millisecond. We need at least 20ms delay, so at least 20 feet extra path length. In other words, the sound coming from your speakers must go past your ears, then go ANOTHER 20 feet after that before returning to your ears. 20 feet is 6 meters, but it's a "there and back" path, so the rear wall of your studio needs to be at least 20 feet, (3m) behind your head. Actually, it isn't the wall that needs to be there: it is the front face of the acoustic treatment on the rear wall that needs to be that far behind you. And thus, the math does not work out for you, For that room, the mix position would need to be about 1.7m from the front wall, leaving just 2.8 m to the rear wall. But you'll need treatment in the rear wall, somewhere between 20 and 50cm deep (depending on how good you want your room acoustics to be), so you will have a distance of only 2.3m between your head and the closest reflecting surface behind you, Round trip = 4.6m = 15 feet = only 15ms delay. Well inside the Haas window. Rotate your orientation to get the 6.6m dimension as your length, not your width. There's nothing wrong with having a studio that is wider than it is long! Provided that it is also long enough to avoid the above issue.

but am used to bass notes travelling further behind me before they bounce back.

Right, but it's not just the bass notes! It's the entire sound field that is an issue. With the rear wall too close, it screws up everything. That's one of the reasons why you can't mix in a small room! And also one of the reasons why specs such as ITU BS.1116-2 and EBU TECH-3276 call for a minimum floor area of 20m2 for a critical listening room, as well as defining the allowable ratios and orientations to make sure that this is not a problem. I'm working on the design for a mastering studio right now, and it's driving me crazy, because the space is border-line too small: I've been using every trick in the book to keep the path lengths as long as I possibly can, and it's starting to work out, but its complex. And that room is a bit over 5m long. so I can tell you from immediate first hand experience that is fresh in my brain: there's no way on this planet that you'd be able to make it work with just 4.5 m length.

I prefer to face long walls in a room for aesthetic reasons (maybe even psychological).

... but not for psycho-acoustical ones! :)

Anyone think I could get used to it?

Nope. Because it's not something you can get used to! It's a physical limitation on the capacity of the ear and brain to process sound. You can't get used to it any more than you can get used to living in a room that is illuminated only by ultra-violet light; You can't get used to it, because your eye is incapable of processing it. OK, so maybe I'm overplaying this aspect a bit: it is possible to build a room that can be used to mix, in a smaller space. The issue is how good you want the room to be: If you answer that "mediocre is fine" then no problem! If all you want is mediocre acoustics in your room, then by all means make it 4.5m long. But if your answer is "excellent" or "world class" or "fantastic" or even "really good", then flip it to get 6.5m length. And if you want my opinion on mediocre rooms, then please take a look at my signature, at the bottom of every post! :) Did your acoustician already explain all of this to you? - Stuart -

Well, I know all this- I should- I've been running pro studios for 25 years and have built 2 of them already (well, had them built for me anyway). I do notice, though, that many rooms, particularly in in New York when I was there, seemed to favour wide control rooms, even looking at pictures rooms in US I notice this as well. It's hard to tell of course how DEEP these spaces are, and I would have thought 6M to be minimum dimension for depth, but then again wide rooms have the advantage of not copping so much reflection from the side. Granted, this can be dealt with, perhaps easier than a close back wall can, but are there any modern diffusion tricks or ideas re monitor placement that can perhaps mitigate certain sonic issues arising from said "wide" room? Without going into detail, there are compelling ergonomic, functional reasons that would make the wide room more comfortable for both myself and the client. If I could learn to compensate for the coloured low end, I'd certainly consider going against the grain of conventional wisdom on this.....?

Without going into detail, there are compelling ergonomic, functional reasons that would make the wide room more comfortable for both myself and the client.

If you can't go into detail, showing what the issues are, and explaining why they are a problem, then there's not much I can do to help! I'm not saying that I can fix the problem if you do explain all the boring details: it might not be fixable, as you say. But I sure can tell you that I can't fix it if I don't even know what it is! :) - Stuart -

OK - so here's a copy of what I sent out to a couple of local acoustic engineers: I’m considering a small studio build , and require a feasibility report (just a yay or nay based on the details below) leading into some detailed plans to hand over to an experienced builder. Anyway, here’s a rough layout of the new proposed usage. Its on the 7th and top floor, with a wide balcony surround. Note that the entire north and west walls (and small part of east wall) are floor to ceiling glass windows (8.3mm lam). Also remember, these dimensions are raw, and that we will probably lose 200mm space (new surfaces and cavities) from all surfaces. (Current height to hard ceiling above ceiling tiles is 3.2m if we move out HVAC and services from above ceiling tiles). (SEE ATTACHMENT FOR ROUGH DIAGRAM) The concrete floor slab is 125mm reinforced with condeck. Total load is 700kg/m2. The live load for the CR and LR is 350kg/m2. I’m assuming the point load for the walls is ok (had a structural engineer have a good look at the plans and all the walls for the 2 rooms have structural beam support below). I assume we just have the floating floor weight and equipment/ furniture /people to consider… (btw, we’re thinking of hanging as much compressed cement sheet from the existing roof as possible, for the outer ceiling leaf- less stress on the inner leaf...). A problem with this design however is : which way to face the control room? North? Or into the LR? Consider that musicians have to move from control room to live room a lot as well as into the lounge area and rest rooms (stairs down to 6th floor along the 709 wall ("Common property" is the stairs and corridor we all share). Now if CR faces into LR, then egress through a glass sliding door is possible, but I'fd like to avoid people from the CR needing to walk out into the corridor every time they need to go to the lounge/kitchen. With no room for a sound lock, this means a blast of sound getting into the common area, not to mention the extra hassle for the musicians to have to go into and out of the the corridor each time. One way to avoid this is to have a sliding door at the back of the CR that goes straight into the lounge, but as the room in narrow in this orientation, that messes up the back seating arrangement. But now consider the CR to be north facing - i.e. wide orientation - then the sliding door in the same parts of the walls become side entry. Much easier! But at the cost of a short front to back dimension. Is there a compromised solution that combines rear wall diffusion/bass trapping, monitor placement and room equalisation? If not a "world class" solution, at least a workable solution where I can still mix and master indie rock recordings at competitive levels? Importantly, I do not expect total LF isolation in both rooms. I’d be happy to record overdubs, mix and master during the day at reasonable levels without disturbing neighbours. If I must, I could always record drums after hours (when office workers go home), but it would be cool to have a heavy duty drum booth as well as 2 or 3 small amp booths for when I simply had to record during office hours. So, all up, I guess my main concerns are: Will the slab hold a serious floating floor? Which design will ensure that it actually floats properly? Is there a way to add steel bracing type reinforcement above the exiting slab (extending across to side support beams)? Regardless of how the floor is reinforced and / or constructed, can we use no more than 200mm of space including a wooden finish? Will new floor isolate down to 40hz and not annoy neighbours below and beside? After losing space to isolation treatment, will dimensions be ok? Particularly height, can I get no lower than 2.9m in height? Is that high enough for a control room? To create less weight on the slab, can the outer ceiling leaf carry much of the weight so the inner ceiling leaf need not be so heavy? Can inner ceiling -including cavity- take up no more than 200mm space? As drums are my biggest iso problem, could I build yet another raised enclosure (room with in a room within a room?) in the north east corner of the LR? Will the extra weight be a problem if it’s only 6 m2 ? Can I have some internal windows on the north facing walls of both CR and LR? How big, how many, how far away from outer windows, what type, and should they be openable for cleaning? Can i get HVAC out of the ceiling and into a wall panel? In both rooms? Where? Can I get away with a wide control room as opposed the a long one? What sort of internal treatment should I allow for (LF absorbers etc)? Power and lighting ok if in separate conduits (minimize wall perforations)? Woud I need to “star” earth? Would I need a power conditioner? Is there a way, without compromising effectiveness too much, of building these rooms with a MODULAR DESIGN where wall (and perhaps floor and ceiling) panels can be neatly demounted and re-used elsewhere years down the track? Happy to give more details… ;)

Challenge accepted! :) And you can keep your CR facing the LR, oriented in the normal manner.... It is possible.... without needing any doors at all to the common area, from either the LR or the CR... :)

Will the slab hold a serious floating floor? Which design will ensure that it actually floats properly?

With only 350 kg/m3 live load capacity to play with, that is "iffy". I would consider doing a "damped deck" style floor instead. It is not a true floated floor, but it can provide quite a bit of isolation, especially for impact noise. I do foresee a potential issue with your console, though. A 60 channel Neotek is a monster. It probably weighs 600 kg, at least. Spreading that over a small area is going to be an issue. Is the console a "deal-breaker"? Do you absolutely have to have that thing? It's going to be an interesting exercise to spread that weight over a large enough area to not overload the floor. It might be doable, but it's going to take some interesting design....

Is there a way to add steel bracing type reinforcement above the exiting slab (extending across to side support beams)?

It may be possible, but only your structural engineer can say for sure. I would guess that RSJ's would be the solution, but they would take up a lot of room height. Probably not the best solution. I would look into the possibility of reinforcing the existing slab by adding more thickness to it, with suitable internal structural bracing (rebar, steel mesh). If you make it thick enough, and do it well enough, then it will be able to carry more load (including its own increased dead load).

Regardless of how the floor is reinforced and / or constructed, can we use no more than 200mm of space including a wooden finish?

Yes. But a qualified "yes". It can be done assuming that one of the following conditions is true: 1) You do not need excessively huge isolation, or 2) If you do need excessively huge isolation, then you have a substantial budget that will allow you to get it with low-profile walls. You need the higher budget due to the need for more exotic (and more expensive) building materials. So assuming that either 1) or 2) is true, then yes you can have isolation walls in 20cm or less.

Will new floor isolate down to 40hz and not annoy neighbours below and beside?

Potentially, yes, but you will need to define "not annoy" in terms of decibels of isolation. You should do some extensive testing, with the cooperation of said neighbours, to find out what THEY consider to be "not annoying", measure how much isolation actually needs, and set that as your goal. Then define your construction budget based on that. With such a complex situation you cannot start out by defining your budget, then try to make it get the isolation you need: you must approach this form the other angle: Define what you need to do, then figure out the budget that will be needed to get there.

After losing space to isolation treatment, will dimensions be ok? Particularly height, can I get no lower than 2.9m in height? Is that high enough for a control room?

That's three questions in one! Let me split them out for you:

1) After losing space to isolation treatment, will dimensions be ok?

Assuming you mean "OK" as in "potentially world class acoustics in the control room", then yes, that is absolutely and certain feasible! The CR is not an issue. But assuming you mean "Abbey Road class acoustics in the Live Room", then no, that is not possible, because the main studio at Abbey Road is many times the height, width, length and volume of your LR. However, if you mean "OK" as in "A reasonably decent place to track, perform and rehearse for typical bands under the majority of circumstances", then the answer is "yes". 34 m3 is not large for a live room, but it is large enough to get a typical band in. It's not large acoustically either (in terms of wavelengths), but it's large enough that it can have a nice "character" to it, especially so, considering the high ceiling.

2) Particularly height, can I get no lower than 2.9m in height? ... (Current height to hard ceiling above ceiling tiles is 3.2m...)

Assuming that you mean the acoustic ceiling, then yes, it is certainly possible. I use a technique that would allow you to have your acoustic ceiling at around 3.1 m, or maybe a bit lower, but certainly no lower than 3.0m. But that's the height of the actual acoustic ceiling: there will be structural support members below that. They could be made visible, if you wanted that look, o they could be hidden. The lowest part of the visible ceiling could still be at or above 2.8 m, in all probability. It might even get close to 2.9m, with careful design, and a high budget to allow for exotic materials. Of course, all of the above is with reference to the existing floor: It does not yet consider the height you will lose if you decide to float your floor, in some fashion. I can't take that into account, since we don't yet know how much room that would take, as it depends on may factors that are not known yet. But if you go with the "damped deck" proposal, your floor should take up no more than about 10cm. A properly floated concrete slab would take up maybe 15cm. (On the other hand, a floor incorrectly floated on rubber pucks and framing with layers of plywood decking, as you typically see on YouTube, could lose you as much as 25cm, and be very ineffective, or likely even make matters worse).

3) Is that high enough for a control room?

Plenty. More than enough. The toughest specs for world-class "critical listening rooms" calls for a floor area of at least 20m2 for stereo rooms, 30 m2 for multi-channel, and the classic "standard" acoustic response is referenced to a hypothetical room that has 100m3 of volume. Your CR has a floor area of around 34m2, and acoustic ceiling height of 3.1m. That's 106 m3 room volume. You hit all the key points very nicely. Your room ratio is within the Bolt area, and is rather nice, actually, with good modal spread, and a nice smooth Bonello chart. I see no reason why you cannot have a room that is every bit as good as this one: viewtopic.php?f=2&t=20471 (Provided that it is designed as well as that one was, and built with as much care as that one was).

To create less weight on the slab, can the outer ceiling leaf carry much of the weight so the inner ceiling leaf need not be so heavy?

Assuming that there is available live load capacity in the existing ceiling above you, then it is feasible that it could carry the entire ceiling weight for both of your rooms. EDITED! On re-reading this, I realized that you were saying something else, and I didn't really answer that. So about an hour later, I edited this post to add the following information: You were asking if it is feasible to have a two-leaf system where most of the mass is on only one leaf, with very little on the other. Yes it is possible, but it is not very effective. The best configuration (see the Wyle report paper from 1973) is when you have roughly equal mass on each leaf. That gives you the highest isolation for the lowest mass and air gap (and therefore, for the lowest cost). Also, assuming that your current outer-leaf ceiling is a concrete slab, then trying to increase the mass of that by adding a few layers of fiber-cement boards to it, is not going to have much effect. Assuming that the ceiling is similar to the floor, the surface density is around 350 kg/2. Fiber-cement board weighs around 1550 kg/m3, so a 10mm sheet has a surface density of roughly 15 kg/m2. In order t get an increase if 6 dB in the isolation of your single-leaf slab ceiling, you need to double the mass. So you would need a thickness of twenty four sheets of fiber-cement-board to do that! That would be 230mm thick... and would likely overload the ceiling capacity anyway.... and all of that to get you just 6 dB extra. Not practical, not effective, and not cheap. My suggestion was not related to that. What I was suggesting is that you leave the outer-leaf ceiling slab exactly as it is, but hang the inner-leaf ceiling weight from it, using suitable acoustic isolation hangers tuned to the correct frequency, along with suitable sway braces on the tops of your walls. That way, the weight of the inner-leaf ceiling would NOT rest on your floor. It would be supported by the outer-leaf ceiling. So that load capacity of your floor would be spared, and available for other loads. The only weight on your floor in this case, would be the walls, and the floating floor, or the damped-deck floor if you decided to go that way, as well as your gear and musicians. With a 600+ kg console, 8 musicians at 80 kg each, and another couple of hundred kg in their gear and instruments, you are going to need to free up all the load capacity you can. Consider this "freebie" to be my most valuable contribution to saving your project from the trash bin.... :)

Can inner ceiling -including cavity- take up no more than 200mm space?

Yes. See above.

As drums are my biggest iso problem, could I build yet another raised enclosure (room with in a room within a room?) in the north east corner of the LR?

That would be a three-leaf system! It has potentially WORSE isolation for low frequencies (read: kick, toms, snare....). Here's why: I can go into more technical details on that if you wish, to explain why that happens, but there's the proof in real-world, understandable graphs. 3-leaf is great if you only need to isolate high frequencies, but not-so-great at all for lows.

Will the extra weight be a problem if it’s only 6 m2 ?

Probably, plus you would lose even more ceiling height... inside a drum booth! Drums need height to sound good. Not a smart idea to put them in a room with a low ceiling.

Can I have some internal windows on the north facing walls of both CR and LR?

Yes, you sure can!

How big, how many, how far away from outer windows, what type,

How big do you want them, and how much money do you have! :) They go together. The windows can be as big as your budget allows, and as big as the floor will support. There are also some acoustic restrictions on where the windows can be in each room, of course, but money is probably the bigger issue here, along with floor loading. Large sheets of thick laminated glass are heavy, and expensive.

and should they be openable for cleaning?

No, definitely not. And they won't need cleaning on the cavity side, if they (and the room) are built correctly. They need to be sealed in order to provide good isolation. I'm assuming that the building itself provides cleaning of the exterior windows, from the outside. The surfaces of the glass that face the wall cavity will not ever need cleaning. The only window surface that will need cleaning, is the surface that faces the room, which is easy to access.

Can i get HVAC out of the ceiling and into a wall panel?

You could, but why do you want it in a wall panel???? Studio HVAC registers (both supply and return) usually go in the ceiling, or at the tops of the walls. What is the reason for wanting to have the registers in the walls?

In both rooms?

Yes.

Where?

Wherever it is needed in order to provide the correct flow rate (volume) at the correct flow velocity (speed) for the occupancy situation of the room at any given time (number of people, amount of heat generated by gear, etc.), and the outside climate at any given time. In other words, the HVAC system must be designed such that it can can control the temperature and humidity, and provide enough air to keep everyone alive and feeling well, while removing enough CO2 and other nasty gasses, when the live room is full of crazily jamming musicians at the maximum planned/legal occupancy number, and the control room is also full of wildly partying people at the maximum planned/legal occupancy, on the hottest, most humid day of mid summer, without being overwhelmed, while also being able to do the same for one single calm musician playing lightly, with one single calm engineer in the CR, on a cool dry day, without freezing everyone. And it also has to be able to do that while not allowing any noise to get in or out. It's not s easy to do that! Tall order! You can't just place any old register wherever you feel like it, and hook it up to any old AHU or ERV, or whatever. HVAC is a huge part of studio design. I often spend as much time on designing the HVAC system, as I do on the entire rest of the studio!

Can I get away with a wide control room as opposed the a long one?

Perhaps, but with only 4.9m to play with, it certainly won't have world-class acoustics. You have a huge console, which will force the mix position to be way too far back in the room for good acoustics. Probably near the middle of the room, as far as I can figure. And there's also no need to do that! As I mentioned above, there are options available to you that would allow you to have your CR facing the LR, without needing to have any doors at all into the common area (although you could if you wanted too). Whoever is telling you otherwise is not very creative, or not very experienced in studio design. The ONLY issue that might be problematic is the size of your monster console: whichever way you lay out the room, it's a problem. I'm surprised nobody has mentioned this yet, as that's one of the biggest issues I see for your CR. With your enormous console size, I would shoot or even thinner walls that what you mentioned: you'll need the space to just to fit the console into the room, resonantly comfortably, with reasonable access around it, in a reasonable location, and with reasonable acoustics. Large consoles in small rooms are an acoustic nightmare.... However, I would suggest flipping your CR with your LR: I would have the LR abutting the green room ("lounge/reception/kitchenette"), and the CR at the East end, facing west (into the LR). There are many reasons I would suggest doing that, but I'd prefer to not to reveal all my secrets in public! :)

What sort of internal treatment should I allow for (LF absorbers etc)?

For which room? The CR would need carefully designed treatment to achieve ITU and EBU acoustic response specs, such as the room in the link I gave you above. It could be done, or at least it could get very close to that. Once again, asking for specific treatment gets into the realm of proprietary custom acoustic design, and "I'd prefer to not to reveal all my secrets in public!" :) Suffice it to say, I'd treat that room in the normal way that I treat all high-quality rooms...

Power and lighting ok if in separate conduits (minimize wall perforations)?

Yes, but power and lighting can actually run in the same conduit, as long as that is permitted by building code. There's no reason why it shouldn't be allowed. But you do need separate conduit for your audio signal cables, and perhaps also for other wiring that you might need, such as alarm, CCTV, internet, telephones, intercom, etc. And yes, you will need to take care with wall penetrations, to retain the level of isolation that you need.

Woud I need to “star” earth?

I always suggest that star grounding should be used in a studio. It's one extra level of protection against ground-loops and other unwanted electrical noise.

Would I need a power conditioner?

Perhaps, but probably not, assuming that the power feed assigned to your area is stable and clean. You would only need power conditioning if there are known existing issues with the power feed, such as voltage swings, frequent brownouts, or electrical noise induced from building equipment, such as elevators, pumps, fans, etc. Hire an electrician to hook up a real-time line analyzer/recorder to your power feed for a few days, and monitor the conditions. If his report says there are issues, and they are serious, then consider getting a power conditioner, or SPS, or even a true UPS. Of course, if blackouts are frequent, then you will probably need a good UPS anyway. And if you need to run your studio at times when the building power or building HVAC is cut off (eg, nights, weekends, holidays, etc.) then you might also need a generator. That's big money! Hopefully not needed.

Is there a way, without compromising effectiveness too much, of building these rooms with a MODULAR DESIGN where wall (and perhaps floor and ceiling) panels can be neatly demounted and re-used elsewhere years down the track?

We keep on getting requests for modular rooms hereon the forum! It seems to be the latest fashion... :) Short answer: Yes, it can be done. Medium answer: ... provided that you have some extra money to throw away. Long answer: It is possible to design and build the studio as a series of sections, segments, or modules that can be bolted together, without compromising isolation or acoustics. However, that increases the complexity of the build slightly (as you need to seal all of the joints between modules such that they are air-tight), and thus also increases the cost (bolts, nuts, and washers are not cheap, when you need hundreds of them, and to pay the guys to sit there for hours and hours, tighten all of them correctly, and sealing the gaps, plus the sealant... ). Then there's the issue of re-assembly elsewhere: you could certainly re-assemble the exact same pieces in other location... provided that the "other location" is the same size (or larger), and the same shape, with doors and windows in perfectly identical matching positions! If not, then you'd have to modify the design in any case. And there will always be some damage, when you try to take apart a building assembly. It wont' come apart perfectly, it won't be loaded onto the trucks perfectly, it won't transport perfectly and there will be issues when you try to reassemble it.

Happy to give more details…

Me too! But not on-line... :) Suffice it to say that I'm a bit surprised that you have already been talking to studio designers, and they have not come up with all of the above. There's nothing excessively complex or terribly out of the ordinary here, apart from the load limit. All of the other stuff you brought up can be dealt with, in ways that are commonly used when designing studios.

I’m considering a small studio build , and require a feasibility report (just a yay or nay based on the details below)

My response: "Yay, with caveats". PM me, for more info, if you are interested. - Stuart -

Another incredibly generous and detailed response! And I will indeed PM you, but I need to clarify and update some important details... First, unfortunately - and I hope this is not a deal breaker - some detail about my existing ceiling. I went in again today to take some measurements, and the news is not good. Remember, it's an office, so there are office ceiling tiles when you look up. These are 2.67 m from the floor carpet. Above the ceiling tiles are all the services, large steel boxes and wide ducts for HVAC, wires galore and some 90mm PVC pipes (not for water) probably for more wires. Obviously we're looking at moving all the services out of there (not sure where to, maybe a rear part of the ceiling, or in a deep wall panel?). Once the ceiling is cleared of ceiling tiles and all services, then we find a drywall ceiling which is under the actual roof of the building as we are on the TOP FLOOR. The roof appears to be tin, and has a slight slope south to north for rain runoff. The drywall beneath, presumably fastened to battens, follows the same angle, and it indeed loses 12 cm height from south to north. Consequently, on the south side of both rooms, the carpet to drywall ceiling height is 3.16m, but on the north side only 3.04m. There may indeed be a few centimetres between the ceiling drywall and the tin roof, and one idea might be to remove the drywall and stuff some dense material as high as possible between the battens, right up against the tin roof maybe. I have a hundred metres of 50mm compressed strawboard which could do the job if cut neatly... So the ceiling slopes. The question is, does the CR finished ceiling need to slope as well? Or should it be flat, meaning the cavity above will be thinner at one end? How much cavity will we need? Now, what you suggest re hanging some ceiling weight of the existing roof was interesting, BUT, you gave the impression you were under the misunderstanding that the ceiling was a concrete slab! It's a tin roof, albeit with some steel support, and is probably no where near as strong as a slab. My idea was that seeing we need a 2 leaf ceiling, we might hang as much as possible off the roof for the outer leaf. But you respond that both leafs need to be equal in mass. So, as an example, if we are adding 15mm of FC to the drywall off the roof, and 30mm of FC for the inner leaf, and leave a 100m cavity, then we have lost 145mm from the ceiling before internal treatments. So 3.015m at the high end, and 2.895m at the other end (BEFORE raising the floor!). Not the most mass dense or wide cavity ceiling, but perhaps it doesn't need to be, after all, there's no one above, and the balcony is 3 m deep all around before sound gets down and around to the lower neighbours. As for leakage through the ceiling to other neighbours on my floor, it is mainly an issue with the office next to the LR, which will need an extra barrier wall for further isolation. Not sure what else can be done there. Luckily people aren't often in that office! . Now getting back to your idea (when you thought the roof was a slab), I think you meant that we could fatten the roof/ceiling leaf without the need for an inner ceiling leaf.(I could be wrong, but let's go with it for a bit...) That would be great, because we wouldn't need a cavity, so my ceiling could be even higher! But surely there is a limit to how many layers of FC the roof will hold?? Perhaps the plans can tell us.... By stacking a single ceiling leaf (including in between the battens), then at best we may win back 100mm or so from the ceiling, THEN, if we can find a way to lose only 150mm from the floor, then we win another 50mm back, and that gives us a finished space of approx 2.95 at one end and 2.8 at the other. And I call that absolute minimum height I'm prepared to work under! So notwithstanding the ceiling challenge, we have the, perhaps more critical, floor challenge. I'm assuming the best way to maximise T/L for the floor in 150mm or less is 10 layers of 15mm FC ! No pads, no cavity, no float... Surely the resonant frequency of that floor would be pretty low, problem is the weight, of course. Would be interesting to know what the best compromise is. A poured slab on springs I think will be too expensive, but happy to consider 150mm options that will be effective. I get the feeling a damped deck approach will not do enough... So, single slab floor and single slab ceiling, more mass instead of cavity because we are space poor. Obviously weight is an issue, but what about the way that the double decoupled walls need to stay decoupled at the floor and ceiling? A slab on top and bottom "short circuits" the inner and outer leafs of the walls. So I am assuming that if the floor is a solid built up slab, then the walls would "float" on top of the floor via rubber decoupling?? Similarly, would the "slab" ceiling, which is hung off the roof structure, be made to "float" above the inner wall leaf with something like neoprene serving to decouple? Or could the walls also just be "slab" like as well, no cavity, just thick mass. A designer in Melbourne likes to insist that 2 x 50mm compressed strawboard stuck to each other beats a cavity wall for LF T/L. I wish that was true, then my walls only lose 100mm instead of the 200mm I allowed for. BTW, the dimensions in the diagram have NOT allowed for any inner walls, so I hope the workable room dimensions you referred to took this into account.... OK, onto other matters needing clearing up, the Neotek console is in fact 40 mono channels with 12 stereo channels, and weighs, I think only around 450 kgs. It's 3.2m wide and around 1.3 deep. So probably not as long or as heavy as you thought, but still too long for the narrow version of the CR as opposed to the wide, which I'm pretty set on. But I will PM you on your idea to have the CR at the end, sounds crazy to me! Triple leaf effect, I get it, but if the roof is tin, and we build either an outer leaf of single slab leaf right against it, then there's essentially no triple effect, no? As for internal treatment, particularly LF absorbers in the back wall, what is wrong with the idea of a wall of diaphragmatic absorbers built into the back wall? It's a two-for-one in that it's a wall as well as an absorber. Can't be wasting no space with add-on absorbers inside the finished walls... ;) HVAC- school me! Both my other studios had split systems, so I have no idea (not that I have any idea about the rest of this stuff, I'm just riffin'... :) ). How much ceiling space do I need, at minimum, to give up to HVAC per room? And where? the front? back? the side? Lastly, the MODULAR idea. Yes very appealing for obvious reasons. Here I must say that, after having just torn down my last studio, the idea of dismantling modular wall units would be a very clean alternative to the very messy job of smashing walls to bits and carting them away in bin skips. It took 4 people a month, it was expensive, dusty and dangerous. Not to mention wasteful! Unscrewing wall modules would take less time, have no waste costs, be much cleaner and safer, and be re-useable!!. I really, really wish my last place was built that way. Problem is, and I should have mentioned this earlier, that there are only people lifts, not goods lifts in the building. Only 2.2m high! Not only that, but the lifts only go to the 6th floor, I gotta climb a flight of stairs to get to 7th heaven (hmmm, not a bad name for the new studio....). Sooo, I was gonna ask if it's unheard of to construct modular wall units of say, 1.5m2 each. Not only would they be easy to carry, but they would fit in my lift! ;) A double staggered stack can constitute a wall except for where the doors and windows go. Just gotta seal them and cover with pretty panels. I could even have the modules made off site, so as not to disturb the office neighbours as much during construction. Thoughts?? I'll leave it there for now and look forward to any response. Then I'd be only to happy to PM about taking this to another level where we can talk $$$ ;) Cheers! pp

So the ceiling slopes. The question is, does the CR finished ceiling need to slope as well? Or should it be flat, meaning the cavity above will be thinner at one end? How much cavity will we need?

The inner-leaf ceiling does not need to slope, but it can if you want it to. It might be beneficial, if it happens to slope in the correct direction. If not, then it might be better to keep it flat, although the slope is not huge. I'd have to do the math and see what makes more sense. But to answer your question, there is no requirement that the inner-leaf ceiling must be parallel to the outer-leaf ceiling (or rather, the "middle-leaf ceiling" in this case... you have a 3-leaf ceiling!) Having said that, I'd still check with your structural guy to see if you can hang any extra weight form that existing ceiling.

albeit with some steel support, and is probably no where near as strong as a slab

Steel is pretty strong... :) In fact, concrete has terrible reaction to tensile loads: It is fantastic for compressive loads, but bad for tensile. That's the reason for having all the steel inside concrete slabs, walls, bridges, etc.: the steel is fantastic with tension loads, but lousy for compressive, while the cement is lousy with tension loads, but fantastic for compressive,. Together, steel and concrete are unbeatable, as each complements the other with what it lacks. So if you have steel up there, that's not a bad thing! If it is arranged in the right way, and would be supporting your ceiling in tension, not compression, then it can probably take a pretty decent load....

But you respond that both leafs need to be equal in mass.

For a 2-leaf barrier, yes, but not for a 3-leaf. The best performance in a 3-leaf is when the middle leaf has as much mass as both of the other two combined. In other words: M2 = M1 + M3.

So, as an example, if we are adding 15mm of FC to the drywall off the roof, and 30mm of FC for the inner leaf,

The ceiling, as you describe it, is already two-leaf. It is fully coupled, yes, but still two-leaf. Adding your inner-leaf ceiling will make it three-leaf.

...and leave a 100m cavity, then we have lost 145mm from the ceiling before internal treatments.

Nope! Not if you use my method... :)

but perhaps it doesn't need to be, after all, there's no one above,

You are not seeing the big picture here: Isolation is all about the full envelope, all around your room, not just parts of it by themselves. It is only as good as the weakest part. If you have walls, floor, doors, and windows all built for 70 dB of isolation, but your ceiling is only built for 30 dB, then your total isolation is around 30 dB. The rest that is built for 70 is wasted. You need to aim for the same isolation on all sides. Sound is like water: one it gets out, it "splashes around all over", following the easiest path. It does not just go in straight lines directly perpendicular to the surface: it wraps around, and goes in all directions. So if your walls are great but your ceiling is lousy, the sound will still get around to being outside your walls....

As for leakage through the ceiling to other neighbours on my floor, it is mainly an issue with the office next to the LR, which will need an extra barrier wall for further isolation.

Not rally. It's the same as above: If you build that wall fantastic but neglect another wall, or the floor, or a window, or the HVAC system, then your neighbors will still hear you. Studio isolation is "all or nothing". You need to think of the entire set of walls, floors, ceilings, windows, doors, HVAC system, etc as one single whole unit that all works together. It is not a set of individual parts that work each by itself. Yes, the individual parts do play a role, but they play an even bigger role as part of the entire system. Your room has only one single isolation system around it, not individual walls. In all directions, that isolation is only as good as the weakest part.

I think you meant that we could fatten the roof/ceiling leaf without the need for an inner ceiling leaf.

Nope! You still need an inner leaf. I guess I didn't explain that too well. I was just proposing to hang that from the outer-leaf, but NOT to eliminate it. You can't leave out the inner-leaf ceiling! That's like leaving the right side wheels off your car, because you only ever plan to turn left...

But surely there is a limit to how many layers of FC the roof will hold??

Yes, and the limit is far, far less than what you would need to create a single-leaf ceiling! (Or a coupled two-leaf, which is similar in many ways...)

I'm assuming the best way to maximise T/L for the floor in 150mm or less is 10 layers of 15mm FC No pads, no cavity, no float...

Nope! That would weigh around 230 kg/m2 (which is 66% of your total load capacity) and it would increase your isolation by roughly 3 dB. Yup. I do mean three decibels. The reason is simple: "Mass Law". That's the equation that governs how single-leaf barriers work. Basically it says that when you DOUBLE the mass of a single-leaf barrier, you get an increase of 6 dB in isolation. But that's in a perfect world: in the real world, you get an increase of a bit less than that, each time you double the mass. But adding ten layers of 15mm FC isn't even double the mass. I would estimate about 3 dB increase. Hardly even noticeable. Plus, you would not solve the problem of impact noise.... If the FC rests directly on the slab, then there's still a direct flanking path....

Surely the resonant frequency of that floor would be pretty low,

The resonant frequency of a single-leaf floor is not really relevant to the issue of isolation. It only becomes relevant in 2-leaf or 3-leaf barriers.

I get the feeling a damped deck approach will not do enough...

Really? Why? :)

but what about the way that the double decoupled walls need to stay decoupled at the floor and ceiling?

The walls only need to be decoupled at the ceiling, not the floor. You can try to decouple them at the floor too if you want, but it isn't necessary. If you do decide to do that, here's what you need: You could try to do the math yourself, and figure out how to make another type of rubber float, but it's a LOT easier to just buy the correct product.

A slab on top and bottom "short circuits" the inner and outer leafs of the walls.

The inner-leaf walls do not touch the ceiling at all. There's a gap up there. No contact.

Or could the walls also just be "slab" like as well, no cavity, just thick mass.

If there is no cavity, then you have a single-leaf wall. If you have a single leaf wall, then it is subject to Mass Law. See above. There's no getting around the laws of physics: they are the same everywhere in the universe. Mass Law is well understood. It goes like this: TL(dB)= 20log(W) + 20log(f) -47.2 Where: W is the surface density of the panel, and f is the frequency. You can do the math yourself, and calculate the isolation for any frequency, and any wall. As long as you know the surface density of the wall (or floor or ceiling, or window) then you can work out how much it will isolate for each frequency. This law is know to be correct for all single-leaf barriers made from typical construction materials.

A designer in Melbourne likes to insist that 2 x 50mm compressed strawboard stuck to each other beats a cavity wall for LF T/L.

Really? :) I'd like to see the proof of that! Does he have evidence from respected acoustic laboratory tests to back up that claim? Does he have equations to show how it works, and predict the outcome? :) In reality, the information I have does not agree with his claims... not in the least! : STC-17! : :shock: Seventeen. That's all Not very encouraging.... :) That's real data from real acoustic tests, not unsupported claims out of nowhere.... The full report is freely available on-line: The note on this specific result says: "Sound Transmission Loss: These results measure the reduction in sound transmission through the [50mm strawboard] when used as a wall or other form of sound barrier." So there you have it. One panel will give you about the same isolation as a cardboard box, and two panels glued together would give you above HALF the isolation of a typical stud wall. I'd say that perhaps you are not talking to the right people, and would probably not want anyone who makes claims like that to be designing your place.... You can probably ignore any other "advice" you got from that person.

I wish that was true

So do I! But the manufacturer himself says that is is NOT true! The manufacturer publishes the real data, and makes no such claims.... Because any such claim is ridiculous: it defies the laws of physics. It just is not even vaguely close to reality.

the Neotek console is in fact 40 mono channels with 12 stereo channels, and weighs, I think only around 450 kgs. It's 3.2m wide and around 1.3 deep. So probably not as long or as heavy as you thought,

OK, but it's still a monster! :) But it can probably fit in, if that's the case.

but still too long for the narrow version of the CR as opposed to the wide,

Not really. You have 4.9 m width. Lose 15cm off each side for isolation, leaves you with 4.6m The console is 3.2. So there will be 1.4m of space. Split two ways, on either side of the console, you will have 70 cm. That's PLENTY. That's about the width of a typical doorway (just a bit less).

as opposed to the wide, which I'm pretty set on.

So you don't want to have a control room with good acoustics? That's fine, but I'm not sure that I would invest all of that money, time, and effort into a place that can only be mediocre at best. But it's your money! If you want to do that, then that's your decision.

Triple leaf effect, I get it, but if the roof is tin, and we build either an outer leaf of single slab leaf right against it, then there's essentially no triple effect, no?

That's probably illegal, and would be rather silly. Tin roofing needs air under it. Tin roofing needs to be ventilated. Or insulated. Check your local building code to find out what is allowable, and what is not.

As for internal treatment, particularly LF absorbers in the back wall, what is wrong with the idea of a wall of diaphragmatic absorbers built into the back wall?

:roll: Ummm.... I wish treating a room were that simple! I really do! But it if were, I would be out of a job... :) However, I still have a job, because designing studios and their treatment is a lot more complex than people think. A diaphragmatic absorber (or "membrane trap") will treat one single frequency, period. You will have MANY frequencies that need treating. You will have at least nine axial modes that require treatment, a dozen or more tangential modes, and probably a couple of oblique modes as well, all below the Schroeder frequency for your room. The rear wall can only treat about one third of those, because the others do not ever even reach the rear wall! Putting a diaphragmatic absorber on the rear wall to try to treat your 0,1,0 mode would be rather silly, for example... The 0,0,1 mode does not involve the rear wall at all. It can be treated in the rear CORNERS, but not on the rear wall. But you can't put a diaphragmatic absorber in the corner.... In addition, a diaphragmatic absorber needs a lot of depth, and a lot of area, and is not very efficient anyway. The space used up by one such trap treats ONLY one single frequency, and that space cannot be used to treat any other frequency. On the other hand, the type of trap I use on the rear wall will treat ALL problematic frequencies at once, across the entire wall. So the square meter that treats the 1,0,0 mode will also treat the 2,0,0, and the 3,0,0 mode, and the 1,0,1 mode, and the 1,1,1 mode, and the 1,2,1 mode, and the 1,2,2 mode, and the 2,2,2 mode, and all of the others, It will treat every single mode that involves the back wall, regardless of frequency. That is efficiency.

Can't be wasting no space with add-on absorbers inside the finished walls...

:shock: It is not wasted space if it does its job! That's like saying "we cant be wasting space to put an engine in the car"! :) And no, there is not enough depth or space on the rear wall to successfully treat it only with membrane traps. I only ever used membrane traps a last resort, for particularly stubborn, problematic modes. And a membrane trap won't help at all for SBIR.... :) But the type of rear wall treatment that I do, will. The goal with a control room is to have totally neutral response across the entire spectrum, in both frequency and time domains, as well as in phase. It CANNOT be achieved if you put membrane traps across the entire rear wall, because the rear wall is needed for many other things at the some time. For example, it is a large part of creating the ITDG, then following it with the diffuse field at -20 db and +20ms delay. You cannot achieve that if the rear wall is a bunch of tuned reflective devices! Sorry, but your plan is just not realistic if you want food acoustics in your room.

HVAC- school me! Both my other studios had split systems, so I have no idea ... .

A split system is not HVAC! It is a part of HVAC, but it does not provide any ventilation. It only provides the cooling and heating. You can still use split systems in these two rooms if you want, but in addition to that, you also need ventilation. Well, you need it if you want to have enough oxygen to stay alive.... :)

How much ceiling space do I need, at minimum, to give up to HVAC per room? And where? the front? back? the side?

The biggest issue is the silencer boxes. They take up a lot of space. I normally put those in the ceiling cavity, or in the wall cavities, or build them into the speaker soffits. The size will be determined from the HVAC calculations. You first need to know how many room changes per hour you will need in each room, based on occupancy and building code. With that, you use the room volume to figure out what air flow rate you need. Based on that, and using the rules of thumb for air flow velocity, you can calculate what the diameter of your HVAC ducts will be, and what size your registers will need to be. Based on that, you design your silencer boxes such that the international cross-sectional area changes by a factor of at least 2, at both the entry and exit points. Add to that the thickness of the duct liner, and the thickness of the silencer box walls (which you calculate based on the surface density of your walls), and you arrive at the minimum height and width of the box. Then based on how much insertion loss you need, you can figure out how many baffles you will need, and thus arrive at the minimum length of the box.

I was gonna ask if it's unheard of to construct modular wall units of say, 1.5m2 each.

I guess it is feasible, if you have the budget to do that... but how are yo going to get the doors in? And most of all, how are you going to get the console in? If the console frame is 3.2m long, and the elevator is only 2.2m high... it ain't gonna fit! Sure, you can take the guts out of the console in pieces, but the frame itself ... ??? Also what is the weight capacity of the elevator? Can it handle the type of loads you are thinking of? I'm also wondering about how happy your musician customers will be, at having to drag drum kits, guitar cabs, amps, and road cases up a flight of stairs, then drag them down again after the session....

A double staggered stack can constitute a wall

I'm not sure what you mean by "double staggered stack": If you build your inner-leaf walls correctly, the will be single stud frames with sheathing on only one side.....

I could even have the modules made off site, so as not to disturb the office neighbours as much during construction. Thoughts??

It is possible, yes, as long as you have the money to cover the extra cost of that. Personally, I think it would be cheaper and easier to pop out some windows and use crane to get larger pieces in and out, but that's just me... :) - Stuart -

Oh, and another thought that makes me consider the "long" aspect for the CR, maybe if I didn't position the console in the middle but shifted to the right 70 cm ( with the side against the wall), then it's much easier for musicians to walk in an out of the LR and I'd be happy with that. Not ideal given the unbalanced reflective symmetry, but surely that is the lesser evil...? To be clear, the entry door to the studio is from the common area to the reception/lounge. Then from there there should be a door in the middle of the CR's back wall, and another between the soffit mounted monitors at the front of the CR to the LR. The other thing is, I really don't want to lose much more internal space to absorbers and treatment. Obviously the corners will need work, and maybe some shallow absorption else where, but nothing bulky. I'd rather have a few peaks and dips in the room than have it feel like a padded cell... Besides, the ratios are good - Bolt approved! ;) ...

Oh, and another thought that makes me consider the "long" aspect for the CR, maybe if I didn't position the console in the middle but shifted to the right 70 cm ( with the side against the wall), then it's much easier for musicians to walk in an out of the LR and I'd be happy with that. Not ideal given the unbalanced reflective symmetry, but surely that is the lesser evil...?

Depending on how your walls are designed and built (materials, techniques), you might have a bit more than 70cm on each side. It might be possible to move the console over slightly to one side, but I would not move it over completely. Symmetry is critical for a control room. The left ear needs to hear the same acoustic "signature" as the right ear. If not, then the engineer will subconsciously "compensate" in the mix, so the mixes will be slightly "skewed", and sound strange elsewhere.

To be clear, the entry door to the studio is from the common area to the reception/lounge. Then from there there should be a door in the middle of the CR's back wall, and another between the soffit mounted monitors at the front of the CR to the LR.

That's not the way I would lay it out! I already mentioned that there's a much better layout that I would use...

The other thing is, I really don't want to lose much more internal space to absorbers and treatment.

You won't need to, if the room is designed and built properly. The only part that needs a lot of space, is the rear wall, and that is unavoidable in any studio. You will lose roughly 50cm on the back wall, regardless of how it is treated. You have no choice, if you want a usable studio. The back wall is always, without any doubt at all, the source of the majority of biggest problems, including the lowest modal ringing, SBIR, and the diffuse sound field after the ITDG. If you don't treat the back wall suitably, you might as well not have a studio at all!

Obviously the corners will need work, and maybe some shallow absorption else where, but nothing bulky. I'd rather have a few peaks and dips in the room than have it feel like a padded cell...

So you don't actually want a studio: You want a pretty room with speakers and a console in it, and you don't care if it is actually usable as a studio? :shock: :?: That's a strange position to take! You also seem to be misunderstanding what studio treatment is all about. The first, most basic, and biggest priority of a control room, is neutral acoustics. Take a look at ITU BS.1116-2 and EBU TECH-3276. They define the technical specifications that a room MUST meet in order to usable as a critical listening room. If your room does not meet, or at least get close to, those specs, then it won't be much use a world-class control room. If you do not have neutral acoustics and a symmetrical room, then your mixes will not "translate" well. They will sound great in your room.... but not so great when played back on the radio, in a car, on iPhone ear buds, in a club or church, on a home stereo system, on a "boom box" or anywhere else. The ONLY place they will sound good, is in your room. The way to avoid that is very simple: make the room neutral, acoustically, and symmetrical. And there are very specific ways of doing that. But don't get me wrong! That does NOT mean that the room has to look bad! A good studio designer will make the room look fantastic, visually, aesthetically, as well as performing excellently, acoustically. Take a look at the rooms that John has designed: I don't think you could say that any of those are "padded cells"! First priority in a studio has to be acoustics. A close second has to be aesthetics. And right up there with those two, in very close third place, is functionality: the room must have good access paths, good traffic flow, good sight-lines, be comfortable to work in, etc. If your room does not meet those three needs ( #1 acoustics, #2 aesthetics, #3 functionality) then it isn't a studio: it's just a bunch of rooms where people do things, trying to make mediocre music. In fact, some people would switch around #2 and #3, putting functionality above aesthetics. I would not argue with that....

Besides, the ratios are good - Bolt approved!

You seem to be missing the point of what room ratios are all about. Having a good ratio does not mean that you won't have modal problems: It only means that your modal problems will be evenly spaced! They will still be there, just as big as in a room that does not have a good ratio, but they will be spaced around the bottom end of the spectrum more evenly. That's it. Nothing more. A ratio inside the Bolt area does not guarantee a good room. It just means that it will be "less bad" than it would have been. A good ratio does not affect the treatment much. You will still need substantial treatment for the modal issues, regardless of what the ratio is. Therefor, your modes will still need treating, just the same as in any other room... So will your SBIR, and diffuse field, and flutter echo, and decay times, and curve shape due to Schroeder frequency, floor bounce, ceiling bounce, etc. If you want a studio that actually works like a studio should, then you need to have it designed and built like a studio should be designed and built. Did you look at the studio in the link I gave you a couple of days ago, including the acoustic response graphs? If not, here it is again: viewtopic.php?f=2&t=20471 - Stuart -

PM'd you.

Um, not sure if anyone is still watching this space, but I feel a little embarrassed to update this sorry saga with, erm, some good news! :D (well, for me anyway...). i Get the feeling my structural engineer was preparing me for the worst, hence my alarmist posts, and my desperate attempts to shore up hope for an impossible build on a light weight floor. So here we are now in this 3rd and hopefully final stanza of this little "feasibility" adventure, with the news that the structure can support 900kg/m2, and that my floor can actually support 500kg/m2 !! :) And yes, this is on a 125mm slab on the 7th (and top) floor! My engineer seemed as surprised as I was to find the structural beam support to be as over engineered as it is. So this of course opens up an entirely different realm of possibilities, and I invite you all, even the nay sayers, to help me explore them. Yes, I have been reading up and even talking to various acoustic folk, but this project just might need some "out of the box" ideas. Main reason is that there is no goods lift, and the lift in service is only 2.2 M high and stops at the 6th floor! A poured concrete slab is surely out of the question, so I must consider the heaviest options that take up the least space that I can get up there. I'm thinking of steel springs under 7 layers of 15mm FC with a 100mm insulation filled air gap. But what would be great is if I can get the whole added floor system down to just 150mm. Same deal for the ceiling, a loss of only 150 mm means I can have a finished room height of 2.86 m sloping down to around 2,75 m. Not great, but perhaps only just workable? I don't think I can get carried away and start thinking of using steel plates on the floor (or can I?). I read of such floors where structural support was no issue, but space was. Nice solution. Any other suggestions?

So here we are now in this 3rd and hopefully final stanza of this little "feasibility" adventure, with the news that the structure can support 900kg/m2, and that my floor can actually support 500kg/m2 !!

Great! That is, indeed, good news. It does, indeed, opens up some additional possibilities.

and I invite you all, even the nay sayers, to help me explore them.

:shock: :shot:

Main reason is that there is no goods lift, and the lift in service is only 2.2 M high and stops at the 6th floor! A poured concrete slab is surely out of the question,

Why? There is no problem getting concrete poured at that level: This is a very common situation: needing to get concrete from the truck at street level up to a higher floor, just is not a problem. Simple, fast, effective. Just pop out a window, and they can pour your slab in a couple of hours. Problem solved. Talk to these guys: http://www.meales.com.au/highrise.html Renting a pump truck for a couple of hours is going to be far cheaper than hiring a crew of workmen for a couple of days to carry the fiber-cement board up the stairs, even assuming that the building administrators would allow you to commandeer the one and only elevator 100% of the time... That's about two hundred standard sheets of FC you'd need to bring up the elevator, then carry up the stairs. Each one weighs 26 kg. Assume that a pair or workmen can carry two board at a time between them, that's a hundred trips. Assume that a round trip (down to street level in the elevator, load up, ride to the sixth floor, then carry up the stairs, put in place, repeat) takes ten minutes, that's a thousand minutes, which is 17 hours. Consider 6 hour work day (allowing for breaks), that's three days work, three days constant use of the elevator.... Not to mention the minor detail that a standard sheet of FC is 2.4m long, but your elevator can only fit something 2.2m...

I'm thinking of steel springs

What springs? What resilience? How much do those springs need to compress in order to float your FC deck? What resonant frequency will the deck have? How many springs? How will you account for the need for more springs / different springs under high-load areas, such as under your console, vs low.load areas, such as empty floor space with nothing on it? You seem to think I'm being a "nay-sayer" by pointing out all the negative aspects of your plan, but you are totally wrong about that. I'm merely pointing out things that you likely ave not yet taken into account! You seem to think that my purpose is to put you down: Wrong there too! My purpose is to help you do it right, rather than waste many tens of thousands f dollars on doing it wrong. Floating a floor is not a project that you can take on lightly. It's a big deal. It is complex, it is expensive, and it involves a lot of math and knowledge. You don't seem to have that knowledge (if you did, you wouldn't be asking for it here on the forum! :) ) But you also don't seem to like the advise you are getting here. You can't have it both ways! I keep on pointing out glaring issues with your plan, and I keep on showing you better ways to do what you want to do, and you keep on ignoring that advice. So I'm sort of at a loss here, as to why you keep on asking! I'm not sure if you have read this thread, but even if you have, it's probably a good idea for you to go over it again: viewtopic.php?f=2&t=8173

I'm thinking of steel springs under 7 layers of 15mm FC with a 100mm insulation filled air gap.

Have you done the math? That will give you a surface density of around 160 kg/m2. Over a 100mm air cavity, what is your resonant frequency? At what frequency does the floor isolate? How much isolation do you get, in decibels? Is that enough? What type of frame will you have under your FC to support it? FC is fragile: it is brittle, and cracks easily. How will you prevent that from happening? Can you afford the 29cm of lost height? Or did you forget to account for the framing that is needed to support your FC, when you figured the height loss? So many questions, so few answers....

But what would be great is if I can get the whole added floor system down to just 150mm.

A 75mm concrete slab over a 75mm damped air gap would get you a resonant frequency of around 15 Hz. The floor would isolate well from around 28 Hz upwards. Isolation would be around 65 dB. Mason Industries FSN jack-up isolation mounts would do the job nicely. That's 150mm, plus underlay, plus 8mm laminated flooring, and you lose only a tad over 160mm for your complete finished floor

Same deal for the ceiling, a loss of only 150 mm means I can have a finished room height of 2.86 m sloping down to around 2,75 m. Not great, but perhaps only just workable?

You have 320cm total, slab to ceiling. You will lose 16cm for the floor with my method (above), leaving 304 clear height. With my method for the ceiling, making some typical "rule-of-thumb" assumptions, you can lose no more than about 14cm there. That leaves you 290 cm as the acoustic height of your ceiling, and perhaps 270 to 275 visual ceiling height. That's pretty good for a control room, sort of reasonable for a live room. Allowing for typical builder error, measurement error, unforeseen problems, Murphy's law, etc. I would estimate that you can realistically expect a visual ceiling height of around 265 cm, and an acoustic height of maybe 285.

I don't think I can get carried away and start thinking of using steel plates on the floor (or can I?).

From what I can see so far, budget is not a problem here, and there is plenty of money to do whatever it takes. So if you are considering exotic materials and techniques, you could lay some sheet lead and use far fewer layers of FC. Lead is about 8 times more dense the FC, so in theory you could have one layer of 15mm FC, two layers of 5mm lead, and another layer of 15mm FC, which would give your roughly the same mass as seven layers of FC, but in only 40mm thickness, vs. 105mm thickness. Of course, you might have problems trying to get that approved by your local authorities, but it would work wonderfully. That's about it. You don't have many more realistic options. - Stuart -

Soundman2020 wrote:

So here we are now in this 3rd and hopefully final stanza of this little "feasibility" adventure, with the news that the structure can support 900kg/m2, and that my floor can actually support 500kg/m2 !!

Great! That is, indeed, good news. It does, indeed, opens up some additional possibilities.

and I invite you all, even the nay sayers, to help me explore them.

:shock: :shot:

Main reason is that there is no goods lift, and the lift in service is only 2.2 M high and stops at the 6th floor! A poured concrete slab is surely out of the question,

Why? There is no problem getting concrete poured at that level:

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This is a very common situation: needing to get concrete from the truck at street level up to a higher floor, just is not a problem. Simple, fast, effective. Just pop out a window, and they can pour your slab in a couple of hours. Problem solved. Talk to these guys: http://www.meales.com.au/highrise.html Renting a pump truck for a couple of hours is going to be far cheaper than hiring a crew of workmen for a couple of days to carry the fiber-cement board up the stairs, even assuming that the building administrators would allow you to commandeer the one and only elevator 100% of the time... That's about two hundred standard sheets of FC you'd need to bring up the elevator, then carry up the stairs. Each one weighs 26 kg. Assume that a pair or workmen can carry two board at a time between them, that's a hundred trips. Assume that a round trip (down to street level in the elevator, load up, ride to the sixth floor, then carry up the stairs, put in place, repeat) takes ten minutes, that's a thousand minutes, which is 17 hours. Consider 6 hour work day (allowing for breaks), that's three days work, three days constant use of the elevator.... Not to mention the minor detail that a standard sheet of FC is 2.4m long, but your elevator can only fit something 2.2m...

I'm thinking of steel springs

What springs? What resilience? How much do those springs need to compress in order to float your FC deck? What resonant frequency will the deck have? How many springs? How will you account for the need for more springs / different springs under high-load areas, such as under your console, vs low.load areas, such as empty floor space with nothing on it? You seem to think I'm being a "nay-sayer" by pointing out all the negative aspects of your plan, but you are totally wrong about that. I'm merely pointing out things that you likely ave not yet taken into account! You seem to think that my purpose is to put you down: Wrong there too! My purpose is to help you do it right, rather than waste many tens of thousands f dollars on doing it wrong. Floating a floor is not a project that you can take on lightly. It's a big deal. It is complex, it is expensive, and it involves a lot of math and knowledge. You don't seem to have that knowledge (if you did, you wouldn't be asking for it here on the forum! :) ) But you also don't seem to like the advise you are getting here. You can't have it both ways! I keep on pointing out glaring issues with your plan, and I keep on showing you better ways to do what you want to do, and you keep on ignoring that advice. So I'm sort of at a loss here, as to why you keep on asking! I'm not sure if you have read this thread, but even if you have, it's probably a good idea for you to go over it again: viewtopic.php?f=2&t=8173

I'm thinking of steel springs under 7 layers of 15mm FC with a 100mm insulation filled air gap.

Have you done the math? That will give you a surface density of around 160 kg/m2. Over a 100mm air cavity, what is your resonant frequency? At what frequency does the floor isolate? How much isolation do you get, in decibels? Is that enough? What type of frame will you have under your FC to support it? FC is fragile: it is brittle, and cracks easily. How will you prevent that from happening? Can you afford the 29cm of lost height? Or did you forget to account for the framing that is needed to support your FC, when you figured the height loss? So many questions, so few answers....

But what would be great is if I can get the whole added floor system down to just 150mm.

A 75mm concrete slab over a 75mm damped air gap would get you a resonant frequency of around 15 Hz. The floor would isolate well from around 28 Hz upwards. Isolation would be around 65 dB. Mason Industries FSN jack-up isolation mounts would do the job nicely. That's 150mm, plus underlay, plus 8mm laminated flooring, and you lose only a tad over 160mm for your complete finished floor

Same deal for the ceiling, a loss of only 150 mm means I can have a finished room height of 2.86 m sloping down to around 2,75 m. Not great, but perhaps only just workable?

You have 320cm total, slab to ceiling. You will lose 16cm for the floor with my method (above), leaving 304 clear height. With my method for the ceiling, making some typical "rule-of-thumb" assumptions, you can lose no more than about 14cm there. That leaves you 290 cm as the acoustic height of your ceiling, and perhaps 270 to 275 visual ceiling height. That's pretty good for a control room, sort of reasonable for a live room. Allowing for typical builder error, measurement error, unforeseen problems, Murphy's law, etc. I would estimate that you can realistically expect a visual ceiling height of around 265 cm, and an acoustic height of maybe 285.

I don't think I can get carried away and start thinking of using steel plates on the floor (or can I?).

From what I can see so far, budget is not a problem here, and there is plenty of money to do whatever it takes. So if you are considering exotic materials and techniques, you could lay some sheet lead and use far fewer layers of FC. Lead is about 8 times more dense the FC, so in theory you could have one layer of 15mm FC, two layers of 5mm lead, and another layer of 15mm FC, which would give your roughly the same mass as seven layers of FC, but in only 40mm thickness, vs. 105mm thickness. Of course, you might have problems trying to get that approved by your local authorities, but it would work wonderfully. That's about it. You don't have many more realistic options. - Stuart -

My last post was also posted at Gearslutz and was copied over here. The "nay sayers" were on that forum, not here, sorry! Not sure how I gave the impression that budget is not a problem, because it is! For example, how much will it cost to get concrete pumped up to the 7th floor for 68 m2, including truck hire, labour and materials? Should I consider only doing this for the Live room and something cheaper for the CR? And as for the lead sheet, surely that's illegal? And if not, too expensive, not to mention toxic?? Are there no other safer, legal and affordable metals? If so, what sizes could they be? Beams or plates? And what exactly is your method for the ceiling that will lose only 140cm? (or shall I PM for that?). Lastly, with the floor TL you have in mind, will that be greater than the wall and ceiling TL? If so, does it matter in my particular instance (no one above me, but someone directly beside the LR and others directly below?). Also, now that this whole thing starts to seem feasible, I'm now most worried about the office adjacent to the LR, despite a serious decoupled floor, I just cannot imagine enough isolation through the wall there. Why couldn't I consider something like a 1 metre wide 'barrier" wall (along the 7m length) that I could also use as a bass trap / storage area?

My last post was also posted at Gearslutz and was copied over here. The "nay sayers" were on that forum, not here, sorry!

Ahhh! OK. Yes, they do seem to have some of those over there, don't they? :) The have a few good guys over there, for sure, but some of them seem to be a bit too quick on the trigger, with the "You can't do that" comments, without first getting all the facts... (I'm sometimes probably guilty of that myself, but hopeful not at the same level ...)

For example, how much will it cost to get concrete pumped up to the 7th floor for 68 m2, including truck hire, labour and materials?

Not sure... But how about if you get a quote, so you know for certain? Call the guys in the link I gave you, or their competitors. I found them in a couple of minutes, using Google, so I'm sure you'll be able to find many more if you look harder than I did. Call a few of them, and ask for a quote. Then you'll know if this is feasible or not. And also call your local hardware store, to fund out how much 200 sheets of 15mm fiber-cement board will cost, including delivery to the seventh floor by manually carrying each board up all seven flights of stairs, because the 2.4m boards won't fit in the 2.2 elevator... Compare the two prices, and see which better fits your budget.

Should I consider only doing this for the Live room and something cheaper for the CR?

It might be feasible to do a lower mass system for the CR, yes. I don't know if it would be cheaper, because the cost of carrying every stud, panel, and roll of any type of material that is bigger then 2.2m, up seven flights of stairs, might add up fast.

And as for the lead sheet, surely that's illegal?

Probably, yes. Which is why I wished you luck in getting it approved by your local authorities! :) But it might be worth checking. It may be allowed, if it is handled properly and encased suitably. After all, it is widely used still in medical radiography, because there's not much else that blocks x-rays and other forms of radiation used in medical procedures. So there must be conditions under which it is allowed. Get a copy of the building code applicable to your area for commercial buildings, and also call your local municipal building inspection office, to chat to the inspector who will be inspecting your place anyway as you progress, to sign off on each stage.

not to mention toxic??

Well, as long as you don't plan to eat your walls, you should be OK on that account! :)

Are there no other safer, legal and affordable metals?

Next best would be steel plate, followed by aluminium plate, followed by MLV, followed by fiber-cement board, then MDF, drywall, OSB and plywood, in that specific order. That goes from highest density to lowest. Perspective: Lead is twenty two TIMES more dense than plywood. You would need 22 cm thickness of plywood to do the same as one cm of lead. Take that into account when you compare prices. It's not just the cost of one sheet that mattes: it's the cost per kg. If a sheet of lead 10mm thick is "only" twenty times more expensive than a sheet of plywood 10mm, thick, then the lead is actually cheaper.

If so, what sizes could they be? Beams or plates?

Lead foil usually comes on the form of rolls for the thinner stuff, or plates for thicker stuff. MLV always comes in rolls. The rest in sheets. Standard sheet size for many things (OSB, MDF, plywood, drywall, etc.) is 1.2m x 2.4m Other sizes are available, but 2.2m is not a common size.

And what exactly is your method for the ceiling that will lose only 140cm? (or shall I PM for that?)

The concept is not a secret: inside-out construction. But the actual method that I have developed is not something I'd be happy to throw out in public, for free... :) It has taken a lot of hard work and careful refinement to get it optimized.

Lastly, with the floor TL you have in mind, will that be greater than the wall and ceiling TL?

I would try to make it similar all around. The big problem will be the ceiling, and the HVAC system, not so much the floor or the walls.

If so, does it matter in my particular instance (no one above me, but someone directly beside the LR and others directly below?)

Let me answer your question with a question: If you are in traffic, stopped next to a guy who seems to have the entire sound system for a Grateful Dead concert running in his back seat, and is belting out "music" really loud, and you then open the window on the OPPOSITE side of your car (the side facing away from his car): can you hear the "music" like that? Or can you only hear it when you open the window on the side directly facing his car? Now, with that answer in mind: does it matter much which side of your studio you have neighbors? Will the one below you still hear the "music" that comes out the poorly isolated ceiling above you?

I'm now most worried about the office adjacent to the LR,

Once again, if you do the layout I have in mind, there won't be any office adjacent to your LR...

I'm now most worried about the office adjacent to the LR, despite a serious decoupled floor, I just cannot imagine enough isolation through the wall there.

Why not? The math doesn't lie.... But I would avoid that layout in any case (see above), and get the noisy part to another location.... :)

Why couldn't I consider something like a 1 metre wide 'barrier" wall (along the 7m length) that I could also use as a bass trap / storage area?

You could if you wanted to, .... if you had enough room to waste! But you don't. Neither of your rooms can afford to lose one meter off the side. - Stuart -

OK, I worked out materials cost without labour- all materials calculated to be equivalent in mass to 100mm concrete: 12 kg/m3 gyprock - 200 mm 16mm @ 3.6m2 = $53 divided by 3.6 = $14,7 = $184 m2 17 kg/m3 FC - 150 mm 15mm @ 2.7 m7 = $147 divided by 2.7 = $ 54.4 m2 x 10 = $ 544 m2 24 kg/m3 concrete - 100mm = $ 120 m2 25 kg/m3 glass - 100 mm $109 (12.5mm) m2 x 8 = $ 872 m2 78 kg/m3 steel - 33 mm 14.4m2 x 16mm = $ 2,769 = $ 384 m2 117 kg/m3 lead - 20 mm $145 m2 @ 1.8mm = $1595 m2 ..... so yeah, concrete wins! But if I wanna save 67mm in space for the equivalent mass in steel plate, then for 3 times the price steel plate wins. Not sure how you deal with the gaps when laying steel plates? Also, would you expect "ringing" with the steel? Can it sit atop the rubber or metal springs ok? Or does it need a damping material under or over it? This would of course lessen the space advantage...

It looks like there might be errors in some of your base numbers there. Firstly, all your numbers are off by two orders of magnitude: concrete, for example, is around 2400 kg/m3, not 24 kg/m3. But there are also a couple of numbers that don't jibe at all, even allowing for the two missing zeros. Here are the actual typical densities that I use for my rough calculations: DRYWALL 685 kg/m3 FIBER-CEMENT 1550 kg/m3 CONCRETE 2400 kg/m3 GLASS 2500 kg/m3 STEEL 7850 kg/m3 LEAD 12000 kg/m3 So it looks like drywall is way off, and your FC is slightly off. The rest are close enough.

..... so yeah, concrete wins!

Yup! Glad you did the math, and arrived at the same conclusion I've been trying to tell you! :)

then for 3 times the price steel plate wins.

Yep!

Not sure how you deal with the gaps when laying steel plates?

You weld them.... which kind of makes disassembly hard in the future...

Also, would you expect "ringing" with the steel?

If I had a steel floor, I would damp it with a layer of suitable rubber matting, then a layer of OSB, and put the final flooring on that. So do consider that in your thickness calculations. You'd still be ahead, but not as much as you are thinking.

Can it sit atop the rubber or metal springs ok?

I would put neoprene pads between the springs and the steel. Steel springs are good for low frequency isolation, but not so much for high frequency. Neoprene is good for high frequencies, not so much for lows. But don't forget that the actual, real "spring" in any floated floor, is the air, not the resilient material. They work in parallel, but the resilient support reduces the total isolation effect. It does not increase it, as some people seem to think. It's the air that does the magic.

Or does it need a damping material under or over it?

Neoprene pad between spring and floor deck (regardless of material). Rubber matting on top of deck (in the case of steel). The rubber matting and extra layer of OSB are only needed for steel, not for concrete. - Stuart -