Rehearsal studio build

Hi there, This forum is a great resource - thanks. I'm a newbie with a heap of questions so here goes with some background: I currently own a single room rehearsal studio in a rented industrial unit. It was just a hobby business that I bought while I had a corporate career but also played in a band. However, business is booming and I turn down far more customers than I book each week. Hence, I've bought my own larger warehouse unit nearby and am looking to build 3 studios with the possibility of storage/tuition rooms and fourth studio on the second level. Now I know that these are just rehearsal rooms and not recording studios, but isolation and acoustics are still key to keeping customers coming back. Also, a lot of my customers do their own session recording and I may offer to provide in-room mic'ing if there is enough demand. The new unit is a warehouse with office space and a second floor above part of the area. Construction is brick exterior, concrete blocks between units (have neighbours on either side), concrete slab between floors and steel frame mezzanine extending the second floor a bit. The overhead height in the warehouse section is really high, possibly about 7.5m, haven't measured. Ceiling height below second floor section and mezzanine is 2.6m. Objectives: To build 3 studios with the best isolation I can afford, which is an upper limit of AUD $50,000 (which needs to include acoustic treatments as well). Sound measurements at my existing studio on a couple of bands shows dB ratings across high and low ranges max'ing between 95 - 120dB (eek! - I guess I'm not expecting whisper-quiet isolation between rooms, just the best within my budget). I'm no expert in building and construction. I don't mind getting my hands dirty but my experience is limited. I've been doing a lot of reading on this forum and also have the Rod Gervais book. I will be gutting the downstairs and have developed a rough floor plan for the 3 studios, which I've attached. There is some demolition of existing partitions in Studio 2 and 3 and some steel work will be required to replace thin support pillars with beams under the mezzanine (part of studio 2). So, I hope that's enough background info to move onto my long list of questions: 1) Room sizes are limited in Studio 1 & 2 with ceiling height restricted to 2.6m. Studio 1 has no height restrictions so I'm estimating that the ideal height for the room dimensions would be approx. 3.2m. However, I'm not yet sure of the cost implications for having the higher ceiling. Is the improved room ratio going to justify the extra cost (assuming I can afford it)? Any other comments regarding the room dimensions? 2) Studio 3 has parallel walls and in the diagram I've tried to include an angle, however the angles would be just short of 4 degrees off right angles - is this enough of an angle to be worth the effort or am I better off working against the perimeter walls and looking at acoustic treatments to address any deficiencies? 3) Is there any benefit to having an angled ceiling in studio 1. If so, how does one calculate the optimal shape? 4) I'm looking at double frame walls and ceilings - room in a room type setup. However, what happens against the perimeter walls? Is the wall the first 'leaf' of the wall and you construct a single frame attached to the wall with isolation clips or do you construct the double frame against the perimeter wall as well? If so, does that create a three-leaf system (Mass, Air, Mass, Air, Mass)? Also, how do you create a two-leaf ceiling where there is no existing ceiling to work with? 5) Am I starting to sound like an idiot yet? 6) How should the walls be attached to the floor (concrete slab)? I'm assuming that floating the walls is beyond my budget. 7) Speaking of floors, based on this forum and Rod's book I figured that I would not float the floors (concrete slab throughout). I thought I would just put a laminate down for aesthetics and possibly look at putting in some sand/fibre-filled drum rises in each room to absorb some of the vibration. However, the one studio builder that has come through is quite pro floating the floor and says that the floor will be the weak link if I don't - oh, what to do? 8) When gyprocking, what joint compound is used when sealing joints on the face of the wall? Also acoustic caulk? 9) Rod talks about using backer rod, then caulking all joints. Is that open or closed cell backer rod? Does it matter? 10) Studio 2 has part concrete ceiling and part mezzanine (bearers and joists - haven't pulled it apart to check the details yet). Are there any considerations with this? I'm guessing one would gyprock the mezzanine section per Rod's book and leave the concrete ceiling as is, and then construct the decoupled frame above both as normal? 11) Doors - I don't have space for large airlocks, what are my door options to avoid them being the weak link? Ok, I think that's it for now. I hope this makes sense to someone - let me know if you need more information and I'll try to be more specific. Thanks! Rob

Hi Rob, and welcome to the forum! :)

5) Am I starting to sound like an idiot yet?

That's a prerequisite! Anyone who doesn't sound like an idiot, has no business trying to design and build a studio themselves! :) So you are fully qualified, just like the rest of us. Seriously, it sounds like you have a nice space there, and a good basic plan. The only part I'd be cautions about is that possible "fourth studio on the second level". That might not be too easy. Attaining that level of isolation on an upper floor is not easy, nor cheap. But the three downstairs are certainly doable.

Also, a lot of my customers do their own session recording and I may offer to provide in-room mic'ing if there is enough demand.

If you are thinking about doing that down the line, then it would be a good idea to at least plan a small control room now (even if you don't build it yet) and install all the wiring now, since installing it later would be a major (and expensive) pain, involving some demolition and re-building of parts of your newly completed rehearsal rooms... At the very least, run conduit for future cables, and plug it in the meantime.

Sound measurements at my existing studio on a couple of bands shows dB ratings across high and low ranges max'ing between 95 - 120dB

Yup. Sounds about right. A drum kit alone can hit 115 dB easily. And of course, low frequency sound is the hardest to isolate.

I guess I'm not expecting whisper-quiet isolation between rooms, just the best within my budget

Well, it is possible to get isolation of 100 dB between rooms... but you'll need to add a couple of zeros to your budget! Galaxy (arguably the best isolated studio on the planet) managed to get a bit over 100 dB, but it cost them millions. On the other hand, you don't need to do that! (Fortunately). OK, to put things in perspective: Each time you increase isolation by 10 dB, you need to stop ten times as much energy. So starting with a basic house wall (single stud with a layer of 10mm drywall on each side), that gives you roughly 30 dB of isolation. If you decide that 40 dB of isolation is enough (definitely not enough, but for the sake of illustration assume it is), you'd need to stop ten times as much energy as that standard house wall. 50 dB means you have to stop one hundred times as much. 60 dB is a thousand times as much. 70 db is ten thousand times. etc. You can see where this is going, and why it gets prohibitively expensive to attain very high degrees of isolation. dB is a logarithmic scale. Those super-massive, ultra-floated concrete walls at Galaxy are stopping about ten million times the amount of energy that your average house wall stops.... Which is why they cost millions to build. But if you relax the specs, the cost of construction also goes down considerably, so you can start breathing again, and pick up your jaw from the floor.... :) OK, back to reality: on your budget, 50 dB is doable, and maybe 60 dB or more, with a bit of luck and careful workmanship. 60 dB of isolation means that the 120 dB Heavy Metal Angry Gorilla Group is down to 60 dB on the other side of the wall. That's about the level of quiet conversation, so that should be acceptable. And most of that will be in the low frequency range, so what you will hear will be the muffled "thump-thump" of the drums and maybe a bit of bass. Plus, we are talking peak levels here, so average levels will be much lower. Your more gentle 95 dB band will be down to practically inaudible. That's all theoretical, of course: your millage may vary....

and some steel work will be required to replace thin support pillars with beams under the mezzanine

I don't see where the mezzanine floor is marked on the drawing. Also, make sure that those new support beams are totally outside of the studio areas: you do not want those things penetrating the rooms.

Room sizes are limited in Studio 1 & 2 with ceiling height restricted to 2.6m. Studio 1 has no height restrictions

Ummm... slight contradiction there! "Studio 1" seems to have height restrictions and also have no height restrictions! :shock: :?: Also, that 2.6 m will come down considerably with the isolation that you'll need to do.

However, I'm not yet sure of the cost implications for having the higher ceiling. Is the improved room ratio going to justify the extra cost (assuming I can afford it)? Any other comments regarding the room dimensions?

Height in a studio is a Really Good Thing! If you can figure it into your budget, it is definitely worth doing. And if you have 7 m of space, then go up as high as you can afford, within reason, and within good acoustic ratios.

Studio 3 has parallel walls and in the diagram I've tried to include an angle, however the angles would be just short of 4 degrees off right angles - is this enough of an angle to be worth the effort or am I better off working against the perimeter walls and looking at acoustic treatments to address any deficiencies?

Angling walls is useful for several things, but the normal reason for doing it in a live room is to deal with flutter echo. The minimum angle you need for that is about 12°. That can be accomplished by splaying the two opposite walls by 6° each, or 8° and 4°, or 11° and 1°, or 12° and 0°, or whatever other combination takes your fancy. As long as the total difference adds up to 12° or more, then you are OK. It can also be done by angling just part of the wall out, then angling the other part back in again, in a sort of "V" shape. And in fact you don't even really need to do it at all, since flutter echo can be dealt with in other ways... So if you don't feel like splaying, then you don't have to. Rectangular rooms can sound just fine, if treated suitably.

3) Is there any benefit to having an angled ceiling in studio 1. If so, how does one calculate the optimal shape?

Once again, angling the ceiling is useful for flutter echo, and for shifting modal response, and also because it can look cool. So first decide why you might want to do it, then figure out if you can afford to do it: Angling anything usually wastes space on the other side, which might or might not be useful. Like most things in acoustics, there are pros and cons to angling, and it all boils down to a trade-off.

4) I'm looking at double frame walls and ceilings - room in a room type setup. However, what happens against the perimeter walls? Is the wall the first 'leaf' of the wall and you construct a single frame attached to the wall with isolation clips or do you construct the double frame against the perimeter wall as well? If so, does that create a three-leaf system (Mass, Air, Mass, Air, Mass)?

OK; think of it this way: Your existing warehouse space is a shoe box. Each of your studios is a matchbox inside the shoe box. That's the basic concept. The shoe box is your outer leaf, and each match box is it's own inner-leaf. Period. So you have to build whatever wall is needed to close off the "shoe box" area that will contain the three studios, excluding the service areas (office, bathroom, chill-out room, storage, etc.). So in your case that basically means a zig-zag wall that parallels the edge of each studio. With that "shoe-box" outer-leaf shell in place, fully sealed to absolute hermetic air-tightness, you can now build each of the three "matchbox" inner-leaves. Each of those is just a single stud frame, self-supporting, with drywall on only ONE side of the studs. Done! So re-do your drawing with that concept in mind, and things will fall into place.

Also, how do you create a two-leaf ceiling where there is no existing ceiling to work with?

Simple: You build it! :) For two of your rooms, the outer leaf will be the concrete floor of the mezzanine level above (assuming that it runs wall-to-wall and is sealed to those walls), and for the other studio it will either be by the existing building roof (if it meets the needed conditions), or it will be by building a new "ceiling", built somewhat below that roof, and sealed to all the existing walls (and the new walls) that make up the outer leaf. In other words, if your "shoe-box" is missing part of the lid, then you have to build the missing part to complete the lid.

Speaking of floors, based on this forum and Rod's book I figured that I would not float the floors (concrete slab throughout).

Smart idea! :)

I thought I would just put a laminate down for aesthetics and possibly look at putting in some sand/fibre-filled drum rises in each room to absorb some of the vibration.

Laminate floor is great, but I'd replace the "sand filled drum riser" with the drum riser design that Glenn uses: Basically just a thick layer of mineral wool with a plywood deck sitting on top. The issue with drums is not to "absorb the vibrations", but rather to prevent them from getting into the build structure. Glenn's drum riser does that. The big problem with drums is impact noise traveling down the legs of the kit and into the floor. The riser breaks that path, so the impact noise never gets into the floor. Search the forum for "drum riser", and you'll find Glenn's design somewhere.

However, the one studio builder that has come through is quite pro floating the floor and says that the floor will be the weak link if I don't - oh, what to do?

Unless you can increase your budget by quite a bit, and also blow away the mezzanine level so you can make up for the many cm of height that you will lose by correctly floating your floor, I'd go with your original plan: don't float. Rod is right. This might help you to reach the same decision: viewtopic.php?f=2&t=8173 viewtopic.php?f=2&t=8134 viewtopic.php?t=8135 And if you want to learn about all the technical details behind successful and unsuccessful laboratory tested methods of floating floors, this is the best document out there: http://www.nrc-cnrc.gc.ca/obj/irc/doc/p ... /ir802.pdf Conclusion: Don't float. Doing it right involves major cost, major mass, large springs, careful calculations, etc. And getting any of that wrong means that it won't actually float, and you wasted an awful lot of resources for a WORSE result... And no, there is no such thing as a light-weight floated floor. A bunch of rubber pucks and a dozen 2x4s does not constitute a proper floating floor, regardless of what some manufacturers try to tell you...

11) Doors - I don't have space for large airlocks, what are my door options to avoid them being the weak link?

You don't need large airlocks! All you need is one heavy door in the outer leaf, and another identical door right behind it, in the inner leaf. One door per leaf. The space between them will be about the same as the space between the leaves: just a few inches. So it is basically just a pair of doors, back-to-back, that open in opposite directions (the outer-leaf door opens outwards, the inner-leaf door opens inwards). Of course, each door needs to be massive (heavy, solid core), and have at least two complete perimeter seals around it (both sides of the jamb, and the top, and the bottom, more correctly called the "threshold"). But it doesn't have to be more complicated than that, and you don't need more space than that between the leaves. You certainly don't need large "sound locks". - Stuart -

Thanks for taking the time to provide such a detailed response, Stuart. I'm going to go through your comments carefully this evening and see if I can draw and post a graphic of your 'shoebox & matchbox' analogy to make sure I understand what you mean. Regarding the existing ceiling heights - sorry that should read : "Room sizes are limited in Studio 2 & 3 with existing ceiling height restricted to 2.6m. Studio 1 has no height restrictions" (well, obviously there are restrictions but they are not relevant!). I must be learning something as I go because I did design Studio 2 with the 2 support pillars outside the studio wall! Woo Hoo! I will try amend my diagram to show an outline of the mezzanine and first floor - I find sketchup pretty tricky to work with. Just a question re your comment about the second floor studio. Does it change your opinion at all to know that the hypothetical studio will be above studio 3, which has a concrete ceiling? It's at least 15cm thick (thicker where the concrete support beam runs through). Is there a glimmer of hope for the future? Thanks again! Rob

Does it change your opinion at all to know that the hypothetical studio will be above studio 3, which has a concrete ceiling? It's at least 15cm thick (thicker where the concrete support beam runs through). Is there a glimmer of hope for the future?

It might be possible: everything depends on your actual goal for isolation, your budget, and the existing structure of the building. The issue with building on upper floors, even if they are concrete, is that they are not damped. Building on a ground-floor slab that physically rests on the ground (often called "slab on grade") is easy, since you have the entire planet damping the slab! That's hard to beat. The earth underneath acts as a damper, sort of like hundreds of hand pressed up against the slab, that absorb the tendency of the slab to "ring" or vibrate. A slab on an upper floor does not have that: it is suspended over empty space, and is free to ring and vibrate, as much as it wants. So building a studio on an upper floor means that you need to take a lot more care in isolating your floor, and you may need to float that floor. This is one of the cases where floating is a possibility. If you don't float the floor, then your isolation is limited by simple mass law, which is not very heartening. It goes like this: TL = 20 log (f * m) - 47 dB ... where "f" is the frequency (Hz), and "m" is the mass per unit area (kg/m²). Do the calculations, and you won't like what you see. Another way of expressing mass law is that each time you double the mass , you get a 6 dB in increase in isolation for a given frequency: Implication: you need a LOT of mass. And the second part is that each time you halve the frequency, you need to double the mass just to get the SAME amount of isolation! Implication: to isolate low frequencies, you meed a huge amount of mass, twice as much as for the next octave up. Concrete weighs about 2100 kg/m3, give or take a few hundred, depending on how it is made and poured. So a 10 cm slab weighs about 210 kg/m2. At 80 Hz (fundamental kick drum frequency, roughly) you'd be getting about 37 dB of isolation. If you doubled the slab thickness to 20 cm, you'd then get a whoppingly small 6 dB increase, to 43 dB of isolation. Double again (40 cm!), and you'd get 49 dB. Double again (80cm) and you get 55 dB... Then realize that you need to increase the isolation by TEN dB just to get it to sound half as loud (subjectively) and you realize that mass law is not your friend... :) So taking your 10 cm slab and making it 40 cm thick would theoretically reduce your kick drum thump to about half as loud... and 80 cm would not even get it down to a quarter! A lot of mass for very little gain, unless you float. And the above does not even consider the possible resonances of the floor itself: A concrete slab supported at the edges and free in the middle is basically a drum head, and will vibrate naturally at certain frequencies when struck. For "struck" read: "drummer thumping his feet on the floor"... Even though the fundamental of such vibration is probably way below the audible spectrum, there can still be harmonics that are up there in the low end of normal hearing range. There are also certainly much higher frequency resonances due to the concrete itself.... Overall, not a pretty picture. Not the ideal base for having your 120 dB Heavy Metal Angry Gorilla Group going wild! The guys in the studio below trying to record soft romantic ballads might not be amused... There are solutions: you might be able to install exotic things like tuned mass dampers to help with some of that, and you might be able to cushion the surface above, with some type of riser to decouple things a bit. OR you might need to float the floor. But here's the kicker: floating that floor above a studio that already has a two-leaf ceiling, implies that you are creating a three-leaf system! :shock: You are probably already aware that, all other factors being equal, a 3-leaf system will always have worse isolation in the low frequency region, as compared to a 2-leaf system. You can compensate, of course, but compensating means increasing the mass and the size of the air gaps... Did I tell you about Murphy's Law? :) So getting back to reality: it really depends on how much isolation you need, and at what frequencies you need it. It should be possible to do something up there to get good isolation, but we get back to the exponential nature of isolation: increasing isolation by 10 dB means that you need to block 10 times more energy, and will give you a subjective decrease in perceived volume of about 50%. So the bottom line here is: how much isolation do you need, and how far can your budget stretch to getting there? Having said all that, I do know of a really good studio here in the city where I live, that was built on the second floor of an old warehouse, right above a restaurant, and operated successfully for many years: The managed to isolate it quite well, and it did not cost them a million dollars. (A few tens of thousands, I believe): It was perfectly acceptable for both their own needs and for the restaurant: no complaints on either side. So it can be done. I would not totally discard the idea of using the second floor, but do be aware of the possible issues. You should be able to get a better handle on this once the downstairs studios are built, and you can actually measure how much of that is getting up through the slab to the mezzanine level: That's the same amount of isolation as you would have going the other way: from the possible Studio #4 down to the ones below, if you do not float the floor. Based on that, you could decide if it is feasible or not. Here's a thought: you could perhaps use that mezzanine area for your future control room, which won't have any issues with impact noise from drummers and musicians thumping on the floor, and won't have such high levels as a rehearsal space anyway ("standard" listening level in a control room is 85 dB). Another option is to move your green-room, offices, and/or storage areas upstairs, to free up more space on the ground level for studio #4. Maybe you could post some photos of the actual space you have, to get a better idea? - Stuart -

That makes sense. I think your suggestion to wait and see what dB readings we get once studio 3 is built, is a good one. Either way, I don't have the budget to work on that level for a while! I might just use it for storage in the mean time for those guys prepared to lug there gear up and down stairs. I think I understand your shoebox analogy now and yes, it's all starting to make sense now. I've attached another diagram, just ignore some of the line gaps. They aren't there when you zoom into the diagram but I can't for the life of me get rid of them when the floorplan is smaller. One further question it's raised for me is if I have different ceiling heights, lets say studio 1 is 3.2m and Studio 2 is 2.6m, how do maintain the two leaf structure for the .6m that does not have a second frame against it? Do I build the second frame up off the outer ceiling of Studio 2? The area in the bottom right of the floor plan includes toilets, kitchen and small storage room. Upstairs there is the room (with the concrete slab) that covers all the space to the right of the stairs above studio 3 and the amenities and the mezzanine is on the left of the stairs, a rectangle that extends to just beyond the support pillars (that will be the recreation space). I will post some pics later this week. Cheers Rob

I've attached another diagram,

Yup! You got it. That's the basic concept. Each room stands on its own, consisting of a single leaf, and all of them are inside the common outer-leaf. So between any two rooms there are two leaves, and between any room and the outside world there are also two leaves.

One further question it's raised for me is if I have different ceiling heights, lets say studio 1 is 3.2m and Studio 2 is 2.6m, how do maintain the two leaf structure for the .6m that does not have a second frame against it? Do I build the second frame up off the outer ceiling of Studio 2?

For the outer leaf, yes. So where the mezzanine slab ends above #2, you'll have to build a vertical section of "ceiling" (actually a wall) that goes up as high as you need to join the ceiling (roof?) above #3. So you complete the outer shell like that. Looking forward to seeing those pics! - Stuart -

Well, after working through the details with a few contractors I've had to come back to reality regarding the design and budget. Gees, all that gyprock adds up! The floor plan will stay as is, but I've reluctantly scrapped the extra ceiling heigh in studio 1. So now all studios will have an external ceiling height of 2.6m. Not sure how that's going to affect the sound in terms of room ratios but will just have to deal with that when the rooms get treated. So, now I very quickly need to clue myself up on how to tackle the electricity/cabling requirements and airconditioning (split-systems in each room). If all goes to plan, demolition of the existing partitions may start as early as Monday! Will try to get some pics up this weekend so that I can keep a photo diary of progress. Cheers Rob

Gees, all that gyprock adds up!

Yup! Sure does! But is there a cheaper option? Mass is mass, and sound waves don't care how much you pay for it. So look around: Alternatives are OSB, MDF, and plywood, all in roughly the same density range. You might get lucky and found something less expensive. Or maybe not... But if you find 5/8" OSB or plywood at a good price, that is a great option: gives you amazing extra structural integrity (in sheer, at least), and also gives you a nailing surface around the entire room! So any place you want you can hang anything you need, such as treatment, lights, etc. One other possibility is fiber cement panels, which are much more expensive but twice as dense, so you only need half the thickness... :) It is worth considering these alternatives. One more option: I once got a pallet of drywall that had been damaged by a careless forklift driver at a great discount. Every sheet was damaged, but only on one corner. I trimmed off the damaged section, and got very usable but slightly smaller than normal sheets. Needed some creative hanging, but saved a bundle...

So, now I very quickly need to clue myself up on how to tackle the electricity

Everything must be surface mount (plugs, lights, ducts, etc,), only one single drywall penetration is permitted per room, careful decoupling and sealing where that single penetration happens, star grounding. That's your crash course in the absolute minimum, non-negotiable requirements. I can add more to that, but none of those can be taken away.

cabling requirements

Signal cables (mic-level, line-level, headphones, CAT-5, telephone, etc. should all be run low, against the bottom of the walls, electrical power should always be run high, against the tops of the walls, and the two shall never meet or cross. Where they absolutely have to meet, they must cross over only at 90° angles. Do yourself a big favor, and run ALL of your cabling in suitable conduit: You'll thank me later for that. And once again, the rule is only one single wall penetration per room, for all of the signal cables. No exceptions.

airconditioning (split-systems in each room).

A split system is only ONE part of your HVAC system. It is the "H" and the "AC", but not the "V", and the "V" is critically important: It means "ventilation". It means bringing in fresh air to each room, so that your customers don't die on you from lack of oxygen! It means exhausting the stale air from each room so that the musicians can actually stand being around each other as the work up a sweat... and it mans doing all that through silencer boxes, in order to retain the isolation between rooms. Not an easy task...

If all goes to plan, demolition of the existing partitions may start as early as Monday!

demo is fine, but construction is not! You ain't ready yet, not by a long shot. There's stacks more you need to do before you start building, and all of it is called "design". It makes no sense at all to start building if you don't have a full design ready! - Stuart -

I hear you! I'm going to start by reading Chapters 6 & 7 of Rod's book (which I hadn't got to yet) and then go over Chapter 10 again and enhance my design. I'm sure my list of questions will grow again. I will also do a bit of research on alternatives to Gyprock to see if it can save me some $'s. It's the major expense on the job given I need over 1000 sqm. Thanks again for your help. I've been told I'm crazy for trying to go this alone (with the help of contractors working to my exact specifications) and not relying on a professional. I have moments when I feel like the knowledge is all starting to come together and then I have times when I get that 'what the hell am I doing' feeling!

Ok, so I've been doing a lot of reading on my HVAC options. At this stage it looks like split systems in each studio for cooling and flexiduct with in-line fans & silencer boxes for air. I've had a look at all the silencer box designs on the forum and in Rod's book and I'm a bit concerned (and I know this has been raised before). So I seal these rooms up so tight that oxygen becomes an issue, yet I go and put 6 great big holes in the ceilings and JOIN them (3 for inflow, 3 for outflow). Even with silencer boxes, all I see here is I've made a nifty little channel for sound to travel between the 3 rooms I want to isolate from each other! Let's say I manage to achieve 60dB TL between rooms if I get everything right with the build - has there been any lab testing that indicates what sort of TL these silencer boxes achieve? Of course, I could have 3 independent inflows/outflows with fans but that's just not going to cut it budget-wise. Can anyone share their experience of utilising these silencer boxes and the impact on TL in a multi-room scenario? I'm going to look at how include the ducting and boxes into the design but I'm a bit dubious. I'm meeting the air-con guy next week and hopefully he has some experience on the ventilation side of things so I can pick his brains.

I'm really struggling to find the right ventilation solution, which isn't helped by my terrible sketchup skills. I have spent hours upon hours trying to improve my model in 3D and I end up botching it up or on my last effort, losing the damn model on the screen - no manner of view changes or perspective changes, camera changes would bring it back. So, I'm giving up and just trying to get back to basics. Based on all the reading I've done it looks like getting the ducting out of the MAM structure asap is a good thing. I have a lot of airspace above Studio 1 and part of Studio 2. Is a viable option having the room inlets/outlets go into silencer boxes (attached to the inner leaf frame? I've seen pictures like this on the forum but this contradicts some other advice provided) and then via flexduct (suspended from the outer leaf ceiling frame?) breaking through the outer leaf via a suitably sealed (caulked) join. Does it matter what I do to the ducting then in terms of what it attaches to? I'm thinking I could attach to the perimeter wall (above and not attached to the the outer ceiling) and create a housing along the wall and take it to wherever it needs to go? I'm starting to feel like this is a puzzle I'm not going to be able to solve. I think if I just get the do's and don't right about what the ducting should attach to at it's various points, and how it's decoupled from the frames, I will have a better chance of coming up with a suitable solution with the help of my builder and HVAC guy (neither of which can help from an isolation point of view). Can anyone help?

I think I've addressed the ventilation issue. One thing I have a lot of is space above the outer leaf of the ceiling so I've decided to borrow Native's design for the placement of the silencer boxes and inlet/outlets in the rooms. I will have 3 separate systems with in-line fans so each room can be operated independently. Cost-wise if you factor in the fan sizes and ducting required for each room vs. 2 large fans, branch ducts etc. for a single system, I should still be ahead going with 3 separate systems. Next focus item - electricity and lighting. The only equipment I will have in the rooms are PA's (and gear that the customers bring in) so I don't think it should be very complicated. So single entry point for power and I'm thinking LED track lights. I might look at getting some conduit in just in case we wanted to set up a control room one day. I know I keep promising, but pics will follow shortly (left the camera on site). The demolition has been finished so the downstairs is now cleared. Next step is putting up the support beams for the old mezzanine so we can remove the 6 (!!) support posts.

Let's say I manage to achieve 60dB TL between rooms if I get everything right with the build - has there been any lab testing that indicates what sort of TL these silencer boxes achieve?

I don't have much in the way of actual independent lab testing of specific products, but there is plenty of useful stuff about HVAC and acoustics on the ASHRAE web site.

Cost-wise if you factor in the fan sizes and ducting required for each room vs. 2 large fans, branch ducts etc. for a single system, I should still be ahead going with 3 separate systems.

When sizing your fans, don't forget that you will never actually get the rated flow, when the fan is installed and operating. The ducts, rooms, silencers, dampers, etc. all provide some resistance to the flow of air, so a 250 CFM fan will not actually cause 250 cubic feet of air to move through the room each minute. Also, don't forget to oversize your ducts and registers, beyond what would be normal for a similar sized room that is not a studio: You want to get your flow velocity down as low as possible to reduce noise made by the air itself.

Does it matter what I do to the ducting then in terms of what it attaches to?

Oh yes! Especially if it is sheet metal ducts (not so much for flexduct). For maximum isolation, the ducting should be hung form proper isolation hangers, and have flexible joints wherever it could pass vibrations through to/from an isolated area.

Next focus item - electricity and lighting. The only equipment I will have in the rooms are PA's (and gear that the customers bring in) so I don't think it should be very complicated. So single entry point for power and I'm thinking LED track lights. I might look at getting some conduit in just in case we wanted to set up a control room one day.

One other point: star grounding. All of the studio wiring should be done with start grounding.

I know I keep promising, but pics will follow shortly

Yeah, yeah, yeah, promises, promises... :) :shot: - Stuart -

Here are some long awaited photos - I finally remembered to bring the camera home. What a week! It's been really tough getting the completely decoupled concept across to the builders. They get it, but then forget when it comes to details so there is a lot of pressure to pay attention to every tiny detail. There have been a few compromises on my ideal plan because of budget constraints, such as having two timber support pillars and an existing concrete pillar within the two leaves between studios (but not touching either leaf) attaching to the outer ceiling (first floor). A bulkhead to accomodate a new support beam between the middle of studio 2. The biggest compromise is going to be the mass on the new outer ceiling (floor) which will extend from the existing mezzanine over studio 1 and part of studio 2. I'm going to have to live with two layers of particle board over the top - the cost of doing additional layering of gyprock between joists exceeds my budget. The independent inner ceilings and walls will still get 2 layers of 16mm Gyprock as well as Rockwool within all the frames. I was hoping to do more insulation in the space between frames and also against the brickwork, but that will also push the budget too far. I'm travelling that not-so-delicate line between theory and harsh reality!

It's been really tough getting the completely decoupled concept across to the builders. They get it, but then forget when it comes to details

That seems to be the big issue with using non-specialist builders: they are so used to doing things another way, that it's hard for them to "unlearn" their habits, even though they do understand. It takes a while to re-program their auto-pilot function...

such as having two timber support pillars and an existing concrete pillar within the two leaves between studios (but not touching either leaf)

That's fine, and is not a compromise, if I understand you correctly: you are saying that these pillars are in the air cavity between the walls of two studios? Not inside either studio? If so, then that's fine. No problem.

A bulkhead to accomodate a new support beam between the middle of studio 2.

Not sure what you mean there... Maybe you could update your diagram to show that?

The biggest compromise is going to be the mass on the new outer ceiling (floor) which will extend from the existing mezzanine over studio 1 and part of studio 2. I'm going to have to live with two layers of particle board over the top

Then increase the air gap under neat that floor, down to the ceiling below! An isolation wall is a tuned system, and there are two ways you can tune it: change the mass, or change the size of the air gap. If you decrease the mass, then you can compensate by increasing the air gap.

I was hoping to do more insulation in the space between frames and also against the brickwork, but that will also push the budget too far.

I would carefully, carefully re-consider that decision. The insulation in the air cavity is part of the tuned system. It acts as a damper on the resonance, and also does many other things. Leaving that out will cost you a LOT of isolation. At least 10 decibels, and possibly as much as 15 decibels. That's a huge, major difference. That will make things about TWICE as loud between rooms, and perhaps even three times as loud. Most people don't understand the role that insulation plays in the walls, and think that it is just there to absorb some sound, but in reality it does far more than that. It damps the MSM resonance, damps internal resonances at higher frequencies, absorbs some sound (not much), drives down the resonant frequency of the wall, adds some mass (not much) and a few other things. It makes a big difference. At the very least, make sure that you have at least 4" of insulation in EVERY wall cavity, on all sides of all rooms, including the ceiling, and make sure you are using the optimum stuff: if it is fiberglass then use only insulation with a density of around30 kg/m3 (about 2 psf), and if it is mineral wool, then make sure the density is around 50 kg/m3 (about 3 psf). Do not get stuff that is much higher or lower in density, and do not substitute for other types of insulation. Then, if you can stretch that budget just a bit further, add a second layer of insulation inside all the cavities, for a total of 8". This is a big deal, and worth scrimping somewhere else to get it right.

I'm travelling that not-so-delicate line between theory and harsh reality!

Unfortunately, the harsh reality will be that you get lousy isolation if you skimp in the wrong places! Skimp where you can fix it later easily, as funds become available, not in places that can't be fixed, such as inside the wall cavities. For example, do one of the studios with a single layer of drywall on the inside right now, realizing that it will have reduced isolation, and use the money you save on that drywall to put plenty of insulation in ALL of the the wall cavities. Then, when money comes in, you can add the second layer of drywall to that studio without too much hassle. Etc. I would skimp where it can be fixed easily, not where it can never be fixed, and skimp on things that aren't so important initially. - Stuart -

That's fine, and is not a compromise, if I understand you correctly: you are saying that these pillars are in the air cavity between the walls of two studios? Not inside either studio? If so, then that's fine. No problem.

That's correct. I'm pleased to hear it's not a compromise. Logic was telling me it was ok, but I am no expert!

Not sure what you mean there... Maybe you could update your diagram to show that?

I think a bulkhead is a soffit? The inner-leaf ceiling frame is dropped down a bit and then back up to create a 'box' around the beam whilst remaining decoupled from the beam (which attaches to the outer-leaf floor and perimeter walls/frame). My concern is more about the effect it will have on acoustics as it runs through the middle of studio 2 ceiling. These are all live rooms and I'm hoping these sorts of issues can be ironed out with room treatments once the rooms are tested after build. Isolation is priority 1, acoustics priority 2.

Then increase the air gap under neat that floor, down to the ceiling below! An isolation wall is a tuned system, and there are two ways you can tune it: change the mass, or change the size of the air gap. If you decrease the mass, then you can compensate by increasing the air gap.

There will be a larger air gap than the minimum of 100mm. Under the mezzanine we have no option but to run the ceiling joists perpendicular to the existing floor joists (which I forgot to mention is another compromise which I'm hoping does not have negative consequences) so we are losing more height than we would like but it sounds like the downside of a lower ceiling might balance off with the upside of a larger air gap between ceiling and first floor. Where we are constructing the floor (outer ceiling) from scratch, we have more leeway and the good news is ceiling height in studio 1 has gone up to 2.7m (less 32mm) at no extra cost (size of timber makes it less labour than cutting timber to match ceiling height of studio 2).

At the very least, make sure that you have at least 4" of insulation in EVERY wall cavity, on all sides of all rooms, including the ceiling, and make sure you are using the optimum stuff: if it is fiberglass then use only insulation with a density of around30 kg/m3 (about 2 psf), and if it is mineral wool, then make sure the density is around 50 kg/m3 (about 3 psf). Do not get stuff that is much higher or lower in density, and do not substitute for other types of insulation. Then, if you can stretch that budget just a bit further, add a second layer of insulation inside all the cavities, for a total of 8".

Sorry Stuart, I don't think I was clear with my comments re the insulation. What I meant was I don't feel I can stretch the budget to include the second layer of insulation inside all the cavities as you've mentioned above. I have definitely included insulation within every frame of walls and ceilings (so will be 2 layers between studios and in ceiling). However, the Rockwool I've settled on has a density of 40kg/m3, which I'm aware is on the lighter side of what you and others on this forum recommend. To be honest, I struggled finding something higher that didn't include some form of wrapping, like a foil or paper, which I've read is a no-no. If I can find something with a density of 48-50kg/m3, is there any benefit in just using it in strategic places (perhaps in the first floor/outer ceiling where I'm light on mass or just the walls between studios), or is it an all or nothing type situation were you're only as strong as your weakest link.

Unfortunately, the harsh reality will be that you get lousy isolation if you skimp in the wrong places! Skimp where you can fix it later easily, as funds become available, not in places that can't be fixed, such as inside the wall cavities. For example, do one of the studios with a single layer of drywall on the inside right now, realizing that it will have reduced isolation, and use the money you save on that drywall to put plenty of insulation in ALL of the the wall cavities. Then, when money comes in, you can add the second layer of drywall to that studio without too much hassle. Etc. I would skimp where it can be fixed easily, not where it can never be fixed, and skimp on things that aren't so important initially.

This was my thinking with the first floor (outer ceiling). Because I have clear access to it, I could always beef it up further from the outside. But I do need to think more about the insulation, which has been bothering me all week. Now, I have lots of reading to do on star grounding and other electricity considerations - next week I'm meeting the electrician to discuss requirements. Thanks!

I think a bulkhead is a soffit? The inner-leaf ceiling frame is dropped down a bit and then back up to create a 'box' around the beam whilst remaining decoupled from the beam (which attaches to the outer-leaf floor and perimeter walls/frame).

Yeah, that's the idea. Work around it without touching it.

My concern is more about the effect it will have on acoustics as it runs through the middle of studio 2 ceiling.

Well, you don't have a lot of choice in the matter so it has to be there! But it won't affect things too badly, as you'll be putting a boat load of acoustic treatment up there anyway. I wouldn't seat it to much. Probably the worst problem is the reduced room height, and right where you need your drum riser.... So you should only rent that room to really short drummers! :shot: :lol: :!:

What I meant was I don't feel I can stretch the budget to include the second layer of insulation inside all the cavities as you've mentioned above. I have definitely included insulation within every frame of walls and ceilings (so will be 2 layers between studios and in ceiling).

OK, that will be good. So just to clarify, there is at least three inches on each surface? In other words, if I take a cross section through the wall, I would see drywall, then 3 inches of insulation, then empty air, then another 3" of insulation, then the drywall on teh other side? Is that it? If so, then you are doing fine.

However, the Rockwool I've settled on has a density of 40kg/m3, which I'm aware is on the lighter side of what you and others on this forum recommend.

It's not ideal, but it is fine too. It will do the job. In fact, less dense insulation is a bit better with low frequencies, just not so good with highs. But lows is where your problems will be, so I would not sweat it. If 40 kg/m3 is all you can get, then that's fine.

If I can find something with a density of 48-50kg/m3, is there any benefit in just using it in strategic places (perhaps in the first floor/outer ceiling where I'm light on mass or just the walls between studios), or is it an all or nothing type situation were you're only as strong as your weakest link.

If you can find the more dense stuff, then do one leaf with that and one leaf with the lighter stuff. In other words, wrap Studio #2 with the good stuff, and do #1 and #3 with the lighter stuff. The purpose of the insulation is not to actually isolate by itself: insulation is a really lousy acoustic isolator. What it is there for mostly is to damp resonance in the cavity, and it's pretty good at doing that. So as long as every surface is covered with at least something, you are good. - Stuart -

OK, that will be good. So just to clarify, there is at least three inches on each surface? In other words, if I take a cross section through the wall, I would see drywall, then 3 inches of insulation, then empty air, then another 3" of insulation, then the drywall on teh other side? Is that it? If so, then you are doing fine.

That's right - drywall, insulation, air, insulation and drywall, except the 3 perimeter walls which are brick/concrete, air, insulation, drywall. Here are a few more pics from week 2. Air con and ventilation is the focus now. An existing air con unit needs to be moved, and piping done for all 3 studios. Duct work for ventilation also needs to be finalised. Sourced the duct lining so will be busy building silencer boxes for a while! Just a question regarding the drywall. I'm sure I read somewhere that adhesive should not be applied to the frame for the first layer of drywall (standard practice here before screwing the drywall to the studs). I've struggled to find a reference to it again so can someone please confirm? I know that adhesives should not be used to join the second and/or subsequent layers to each other, just not sure on the first layer to the frame. Thanks.

I hope it's not too late, but a couple of changes I would suggest about the framing. First, is to use double top plates, instead of just one. That's a lot of load you are going to be carrying up their, and with just one top plate, you run the risk of sagging over time... The other is the rough framing for the doors: You are showing only one stud on each side! :shock: :!: The doors are going to be massively heavy, and one stud alone is not going to be able to keep things aligned as you open and close that door all the time. Use three studs on each side of the rough frame, or at the very least use three on the hinge side and two on the handle side. And the door headers you are showing are inadequate as well: At the very least put a couple of 2x4s on edge, side by side, instead of just one flat, but 2x6s on edge would be better. Why? Because your door seals are critical to maintaining isolation, so you want to minimize any possibility that the framing might sag, warp, twist or otherwise change position over time, due either to the load of the door itself or to the load being carried by the header. If there is movement there, then your seals might shift just enough to "unseal", and BANG! there goes your isolation... Finally, is blocking: I don't see any! You are probably required to have it for fire code, but even if it is not required I would still do it, simply from the point of view of adding a bit of strength and rigidity to the framing, and having the extra nailing surfaces for the drywall. If you have not started dry-walling yet then it is still easy to change all of these. Maybe Brien might have more comments on your framing, but those were the three I noticed. One other point: It is hard to see in the photos, but I don't see any signs that the sole plates have acoustic caulk under them. Was that done correctly? Once again: air-tight, totally hermetic seals are critical to isolation. Even a tiny crack under a wall somewhere can seriously damage your isolation, so you need to take extra care that there are no such cracks, and never can be. So if they were not sealed when they went in (there should have been 3 separate beads run under each), now is a good time to at least do a bead along each edge of each sole plate, then an additional bead under each layer of drywall, after it is in place. And do make sure that the workers clean the floor properly before applying the caulk! Caulk over dirt and sawdust is not going to get you a good seal.... - Stuart -

I hope it's not too late, but a couple of changes I would suggest about the framing. First, is to use double top plates, instead of just one. That's a lot of load you are going to be carrying up their, and with just one top plate, you run the risk of sagging over time...

Thanks Stuart. It's too late for double top plates but I noticed that as they're finishing off the framing in each studio (working back from studio 3), they have added another layer of timber under and against the top plate between studs - I'm hoping that's going to address your concern re sagging over time.

The other is the rough framing for the doors: You are showing only one stud on each side! The doors are going to be massively heavy, and one stud alone is not going to be able to keep things aligned as you open and close that door all the time. Use three studs on each side of the rough frame, or at the very least use three on the hinge side and two on the handle side. And the door headers you are showing are inadequate as well: At the very least put a couple of 2x4s on edge, side by side, instead of just one flat, but 2x6s on edge would be better. Why? Because your door seals are critical to maintaining isolation, so you want to minimize any possibility that the framing might sag, warp, twist or otherwise change position over time, due either to the load of the door itself or to the load being carried by the header. If there is movement there, then your seals might shift just enough to "unseal", and BANG! there goes your isolation...

The framing for the door and wall in studio 1 was not completed when the picture was taken, but having said that, I'm quite sure there are only 2 studs on either side. I know the door headers were beefed up but I think they were done flat. I will need to take another look this afternoon. Won't be drywalling for a few more days (at least!) so there is still time to address.

Finally, is blocking: I don't see any! You are probably required to have it for fire code, but even if it is not required I would still do it, simply from the point of view of adding a bit of strength and rigidity to the framing, and having the extra nailing surfaces for the drywall.

I raised this with the builders and they assured me it was not a requirement but I will take it up with them again.

One other point: It is hard to see in the photos, but I don't see any signs that the sole plates have acoustic caulk under them. Was that done correctly? Once again: air-tight, totally hermetic seals are critical to isolation. Even a tiny crack under a wall somewhere can seriously damage your isolation, so you need to take extra care that there are no such cracks, and never can be. So if they were not sealed when they went in (there should have been 3 separate beads run under each), now is a good time to at least do a bead along each edge of each sole plate, then an additional bead under each layer of drywall, after it is in place. And do make sure that the workers clean the floor properly before applying the caulk! Caulk over dirt and sawdust is not going to get you a good seal....

They did not run 3 separate beads under each sole plate but they will definitely be caulked well before the drywall starts going up. Thanks again Stuart, your comments have been very valuable.

Hi Rob Me and my husband are thinking of buying a warehouse in New Zealand and doing the same thing - 3 rehearsal rooms etc. We are pretty confident we can get the rooms fully booked out within a short period of time. Im interested to know how long the build/conversion process took you and also how much it cost you in the end and also if you would do it all over again what would you change?? thanks for any help. :-) - Sarah :shot: