John Sayers' Recording Studio Design Forum

Hi,

We are preparing to build a rehearsal studio. We are in the design phase which is where we're facing our first problem. The problem centers around a disgreement between myself and my partner concerning the overall design.

We're expecting the rehearsal rooms to be filled with around 100-110db of noise. I obtained this number based off of other threads in the forums discussing the db levels of a regular band consiting of electric guitars, drums, and bass.

The existing space we are planning to occupy is a single floor unit, concrete foundation, 18 feet high ceilings, and enclosed on three sides by cynder brick walls. The front facing side of the building is basically all glass (glass door and windows). In my rudamentary drawing I've indicated brick walls in dark gray enclosing the space on three sides. There is a hallway that runs parallel to the north and east walls. The hallway is approximately 4 feet wide. And there is a neighbor next door on the other side of the west wall. There is no existing construction inside other than the bathroom.

Our budget for the entire project is around $50,000 USD.

I intentially left out the number of rooms planned and the dimension of the rooms because that is the root of the debate and I was hoping to get clarification. I have additional questions beyond that, but I will withhold those until I'm able to settle the first question and until I provide better details once the design disagreement is settled.

I've attached a copy of the design that my partner wants to implement. His idea is to maximize the footprint usage by cramming in as much as we can into this tiny space. Though I share his sentiment on maximizing the utilization of the floor space I disagree with the concept of cramming as much as we can while potentially sacraficing quality.

In the diagram rooms 1-4 are supposed to be normal rehearsal rooms while 5 and 6 are reserved for a potential control room, or mechanical room, for the building. He wants to put all of the rehearsal rooms as tightly against each other as possible. Isolation is necessary between the rehearsal rooms themselves, and between the rehearsal rooms and the outside world (neighbor next door). Building a 2-leaf isolation between the rooms is part of the intended design. So where rooms 1 and 2 meet they will be separated by 2x5/8" sheetrock wall, 2x4 stud framing, and a 3" air gap between the frames of the rooms. This arrangement is to be true for all rooms adjacent or not.

My concern and question is that my preference is to separate the rooms more to create more isolation. What I don't want is for a band in one room to be disturbed by what a band in a room next door is doing. My belief is that by butting up the rooms as shown in the diagram that we would be losing isolation (even with the 3" air gap, wood framing, and 2x5/8" sheet rock walls in between the rooms).

Am I correct or incorrect in believing that if I separate rooms by as much as 4 feet that the isolation for the rooms would be better? And if it is better would it even be a noticeable increase in isolation if each room eminated 100-120db of noise?

I apologize in advance if I did not supply all of the necessary details. If you need more information please let me know. Thanks.

Edit: I'm not sure if I can ask this question yet. But after thinking about it more I was wondering if we moved forward with butting the rooms up next to each other can we just layer on some more sheet rock to get more isolation?

I am not anywhere close to an expert on this, but I seriously doubt going from 3" to 4" of air gap is going to make much difference. Really to do things right I would think insulation in those walls would be the way to go. Keep your square footage up AND keep your rooms isolated. I guess the reason against this would be added cost of materials.

I apologize if my post was confusing, but I'm confused by your response. My aim is to have as much as 4' of space between practice rooms. I'll attach a copy of what I'm envisioning.

My primary concern about my design, versus my partner's design, is that the rooms are much smaller on a per sqft basis. But I feel that separating the rooms into pairs with 4' of space between them is much better for isolation purposes than just butting them up against each other as in his design (image attached to my first post).

Oh wow, I misread and thought you were increasing from 3" to 4", not 3" to 4'. The new diagram helps. Well in that case I'm sure the difference in space would help. But you still have rooms butted up next to each other, what's your plan say for between A and B?

Hi

Just looking over the pre-design floor plan, and also waiting for the experts to reply.

Although the details provided are minimal [at this point], there are design concepts presented on this forum that would be worth reading on to better plan what your requirements are.

Looking at the layout along with the size of the planned rooms ... with the need for serious isolation ... the 'Room within a Room' design [that is for each room] should be studied.

Listening to the experts, there is a correlation of isolation related to 'spacing' ... but there also seems to be a distance that the effectiveness mitigates over the loss of realestate.

Just for thought ... you may consider that the wall structures would be [at least] 2x4 framing, that would follow the 'room in a room' principle. The 'inner' and 'outer' leafs would most likely hold 2 layers [minimum] of 5/8" drywall on each side of the 'room within room'. If these dual walls are separated by 2", that would space the 2 leafs some 10" apart.

I mention a this [in light detail] so that the planned number of rooms AND their dimensions will be heavily influence by the 'thickness' of the walls.

Again, just some thoughts to share as we wait on the expert replies.

Well it came down between a disagreement about the number of "large" rooms. I was telling my partner we should do three large rooms because then they would be bigger and more comfortable. He's insisting on 4 thus why the rooms are much smaller than I want and why we're kind of stuck having to butt rooms together. So I have absolutely no idea how to address the rooms that are still touching. The floorspace is limited as it is only 1950 sqft at 39.5' x 50'.

I've seen other designs online where some have been butting rooms together so I'm left wondering if they're just butting rooms together or are they taking extra steps to treat them because they are right next to each other. I don't know what to do about that. I guess I'm sort of looking for someone to tell me that it's fine and that I just have to treat the heck out of those rooms that are right next to one another.

I sort of did that on purpose because my real question from the original post was 'is it okay to butt the rooms together like in the first diagram'. I didn't want to drive anyone helping into a deeper discussion until I could get someone to answer that. Once I get a response saying it's okay or not okay then I know how to design the layout and can then create a sketchup drawing.



Yes, that is our intention. After having read the book we're deciding that 2x4 framing, with RISC clips, 2 layers of 5/8" drywall, green glue, and then spacing the frames apart by at least 3". But like I said I didn't want to burden anyone with too much analysis because I know my details are spotty. The question I really need answered is that it is okay to butt rooms as in the first diagram I posted, or it's not okay.



Hey thanks. I appreciate all the help and comments. As soon as I can get a response to my main question I can do sketchup designs and then ask the really hard questions.

Again, not an expert, but I would think that having adjoining walls would be ok if you fill them with rigid fiberglass. Preferably deeper than your standard 2x4s too.

Thanks for the reply.

So that's a new one on me. Is there something I can read on forum about rigid fiberglass?

Hi " Neoeclectic", and Welcome!

Sounds about right, but probably a bit higher: more like 115 to 118. A reasonably enthusiastic drummer can hit 115 all by himself, so by the time you add in the bass, keyboards and other stuff you can be hitting double that.

Good starting point. I guess that includes a nice thick concrete slab floor?

Excellent!

Also very good.

Not so good. Does his building actually touch yours? For example, is the wall between you and him a "party" wall, shared by both of you? Or are the separate walls, one for you and one for him, with some space between them?

Also, do you share the same foundations and slab?

Well, I guess it boils down to this: Is it more important to you guys to have a lot of rooms that produce money but sound bad, or fewer rooms that produce money and sound good? There's a basic "rule of thumb" in acoustics: small rooms sound worse than large rooms. Really small rooms sound really bad. Tiny rooms sound terrible, and are unusable. There's also the issue that small rooms need much more treatment than large rooms, exactly because you have to tryo to make them sound good again, at least to some extent.

So how big is "big", and how small is "small"? There's no real dimension that you can point to and say "Rooms more than x feet long sound good, smaller ones sound bad". It would be nice if things were that simple, but they aren't. It's a bit more complex, and depends on many factors. Everyone agree that a concert hall for a symphony orchestra and with 2,000 seats is "big" and everyone agrees that a broom close is "small", but drawing the dividing line is not simple. In fact, more than a line, it's a "grey blur".

But to give you a rough idea, both the ITU and the EBU recommend that a critical listening room should have a floor area of around 20 to 60 square METERS for monophonic or 2-channel stereo listening, and 30 to 70 square meters for "multichannel stereophonic reproduction". They don't say how much volume the room should have, but considering that it's hard to have a usable room with less than about 2.5m ceilings, the volume should be at least 50 cubic meters, at the very minimum, and probably more like 100 for something decent. They do say that the volume should not exceed 300 cubic meters for critical listening. There's a whole bunch of other criteria, and you can find all of those in ITU-R BS.1116-1, if you are interested.

That said, the above is really intended for control rooms and other critical listening rooms, so it isn't really applicable to your rehearsal rooms. However, when you consider that the same very knowledgeable folks also say that the control room should be SMALLER than the recording room, you can see that the above are the absolute minimums. So none of your rooms should every be smaller than about 50 cubic meters of volume and also 20 square meters of floor space. In old fashioned terms, that means not less than about 540 square feet (floor area), and no less than about 1700 cubic feet (volume).

Looking at your diagram, not one of those rooms meets the above criteria: they are all about half the minimum recommended floor area.

I'm with you 100% on that! I assume that you'll be renting out these rooms, so think of this: people will not pay much for tiny cramped rooms that sound bad! Most good musicians appreciate good sound, so you won't be attracting too many of those...

How about if you guys compromise? Make a couple of nice large, good sounding rooms, where a good sized band can practice comfortable and you can charge more, plus a couple of smaller rooms, more useful for individual artists and small groups, or for people who can't afford the big rooms, and want to pay less?

Too small for a good control room: see above for the reasons. Putting both of those areas together would almost be big enough for a small control room.

Isolation requires space and mass. For the type of isolation you need, you are talking about walls around 12 inches thick. That's the only way to get 115 dB on one side down to an acceptable level on the other side, and even more so if we are talking about drums, bass guitars and keyboards: Lots of low frequency energy in those, which is the hardest of all to stop. So you also need to account for the space required by your isolation walls, and double back-to-back doors.

You will also need one hell of a good HVAC system, to isolate rooms to that level. Fortunately, you have the ceiling height to be able to do that.

Probably not enough, if you hope to make the crazy gorilla drummer in one room inaudible to the guy practicing piccolo scales in the next room. Theoretically, that will give you maybe 65 dB of isolation (assuming that you manage to get your doors, HVAC and electrical system isolated to the same level), so your 118 dB death-metal rock band is only down to about 55 dB on the other side of the wall. That's the level of quite conversation, so it is audible. You'd need better than that in the low frequencies. Maybe add another layer of drywall on each side, and also Green Glue in between at least some of those layers.

Yup!

Well, yes, but that's going to extremes. As long as you can get around 10 inches of gap between the two leaves of the wall, with large amounts of mass on both leaves, then you should be OK. Beyond 10" you are getting into the zone of diminishing returns. More space is always better, yes, but there's a point where it no longer makes sense, and cor very massive walls that point is around 10 inches or so. 3 layers of 5/8" drywall on each side of an insulation-filled 10" gap gives you MSM resonance of around 14 Hz. That will isolate the entire spectrum pretty well.

In fact, the biggest challenge probably wont be the walls, but rather the ceilings, doors, HVAC and electrical. Walls are relatively easy (!) to isolate to 80 dB, but doors are much harder to get to that level. so is the HVAC system. So is thee electrical system.


You should be careful about defining what you mean by "butting up". The rooms can be adjacent to each other, but they CANNOT touch. No part of any room can touch any part of any other room. Each room MUST be a totally stand-alone entity that just sits on the floor. Not even a single nail, screw, electrical cable, or piece of careless dropped building debris can be allowed to bridge the air gap between any two adjacent rooms. That applies to both walls and ceilings of the rooms: the ceilings MUST be isolated just as well as the walls.

Exactly: those "extra steps" are indeed taken, and do include the above: total isolation, no touching allowed, and great care in construction to make sure the workers don't do dumb things, like "accidentally" leave some temporary 2x4 blocking in place between two rooms. Etc.

For the level of isolation you are talking about, you need extreme measures and extreme care.

Treatment does not stop sound: isolation stops sound, treatment makes rooms sound good. There is nothing you can do with treatment inside a finished room to make it isolate any better. Isolation and treatment are two totally different, and even opposite, parts of acoustics. Isolation stops sound getting out, which means that the sound stays in. If it stays in, that makes the room sound bad. Treatment tries to make it sound good again.

Yes and no, as I mentioned above: Yes, you can have rooms next to each other, as long as they do not touch at any point. The only common factor is the concrete slab that all of the rooms sit on. Apart from that, they have nothing in common at all: no mechanical connections. For the level of isolation you are looking for, this is critical. You will probably be getting up to the flanking limit of the concrete itself, so that will be your overall limit on isolation.

If you have two separate 2x4 frames (one for each leaf), then you do not also need RSIC clips. The purpose of RSIC clips is to decouple the leaves. The purpose of separate stud frames is to decouple the leaves. So you don't need to do both: once you are fully decoupled, then you are fully decoupled, and you get no further gain by trying to decouple even more. If you are sitting on the bottom of a swimming pool you cannot get any wetter by taking a hose pipe down with you! You are already totally wet. Same concept.

Semi-rigid fiberglass, such as OC-703 is good for treatment inside the room, but for your levels of isolation you would be better off filling those wall cavities with ordinary pink fluffy fiberglass, or mineral wool. Fill them as much as your building code allows.

Hope that helps a bit!


- Stuart -

_________________
I want this studio to amaze people. "That'll do" doesn't amaze people.

Thanks a bunch for the reply, Soundman. You've given me a lot of things to think about but I feel like I have enough to start a sketchup design now although I have more questions based off of your comments.



I double checked and it turns out it's slab and not a foundation. I originally assumed it was a foundation because I was sure the plumbing was coming from up underneath.

Also the cinder brick wall that divides us is a party wall. So the neighbor and us share it along with the slab we're sitting on.



Since we share a party wall which is cinder brick with the neighbor would it make sense to use RSIC clips on the side that our neighbor is on? I ask because my original plan was to allow that cinder brick wall between us and the neighbor to act as a leaf. But it sounds like that's not such a good idea.



I'm with you on that. I think in this case bigger is better. But it'll be tough only having 1950 sqft to work with and a bathroom that can't move.



I think at this stage I should do some sketchup diagrams. I'm just now learning how to do it so it will take me a while. But you say to use Green Glue on at least some of those layers. Shouldn't we be using Green Glue on all of the layers? At least that's what I was intending to do.



Is that 10" measured between the leaves or between the edges of the wall frame? I've been reading that if building a double wall that a 3" gap should be placed between the wall frames to get the STC 63. Simple math is telling me that since a 2x4 is 3.5" that (2x3.5)+3=10. So we're measuring between the surface of the leafs right? If I understand correctly a total gap of more than 10" something like 12"-16" probably wouldn't help much? But if I had another 6" or so to space them apart should I just do it anyway?



I'm sorry. You're right I didn't mean they would actually be touching. Poor choice of words on my part. There would be a gap between all rooms but as in my previous question I'm wondering how much I could get away with now.

Thanks very much for your insight. I'm going to be spending some time doing a drawing in sketchup and I'll post it here with my follow up questions and for criticism. Thanks!

OK. I guess you mean slab on grade? As in the entire floor is poured on top of Mother Earth, with no air gaps?

That's what I feared. So probably your biggest issues are going to be the flanking limit through the slab itself, and impact noise/vibration getting into the slab/cinder block. In my crystal ball, I see some drum risers and amp cabinet risers in your future...

You mean on HIS side of the wall or on YOUR side? You should try to check what he already has on his side. For example, if he has lath and drywall on his side, then that's a potential three-leaf problem. Hopefully, he just has the cinder block wall there, with no other leaves.

If that's the case, then that cinder block party wall is, indeed, your outer leaf. All you need to do is to seal the surface well (render, plaster, stucco, or even just a good quality masonry sealant), and you are done. You have to make that entire wall air-tight, totally hermetic, between you and him. Slab to roof, along the entire length, there can be no gaps at all. The wall must be tightly sealed. If there's any gap at all where air can get through, then so can sound.

.Your original idea is correct! That is your outer leaf.

Not necessarily... with careful design, I think you should be able to get some decent rooms in there.

:) Yup! SketchUp does take some getting use to. But once things start to "click" and you understand their unusual concepts, then it turns out to be a great tool for studio design.

You certainly can if you want, and if you have the budget! GG is not cheap, and as long as you have one complete layer all around the room you should be doing pretty good. But there's no harm in doing two layers (the only harm is to your bank account... ).

Between the facing surfaces of drywall. In other words, if you could get a tape measure inside the wall cavity, that's the distance you would measure between the face of the outer leaf and the face of the inner leaf.

Correct!

It would help, for sure, but the relationship is not linear: it's more of a gentle curve, so you are starting to get past the point where increasing the gap by a small amount makes a big difference. It still makes a difference: just not as much. For example, adding one inch to go from a 4" air space to a 5" airs pace makes a big difference (assuming one side of the wall is inside-out, of course), but adding one inch to go from a 14" gap to a 15" gap does not have nearly as much benefit (all other things being equal).

If you can spare the space, and really do need totally maxed out isolation, then it will help a bit. But can you afford to lose so much floor space? If you add six inches air gap to a wall ten feet long, you lose 5 square feet of floor area. If your room was going to be (for example) 10' x 12', but now went down to 9'6 x 11'6, then your floor area went down from 120 ft2 to 109 ft2. You lost nearly ten percent of your floor area by doing that. Can you afford that?

- Stuart -

_________________
I want this studio to amaze people. "That'll do" doesn't amaze people.

Yes.


I was thinking the same thing, but haven't gotten far enough into the evolution to think too deeply about those. I read what you said about fitting things into small spaces. So it inspired me to come up with the new diagram attached to this post.

Can you take a look and comment if you think it's a better idea than the two previous ones I posted earlier? I like this better because we'll be using more of the floor space to create larger rooms. What I don't like about it is that I'm still concerned about the neighbor to the left, and very concerned about noise getting through the front of the building. The front of the building is all glass from top to bottom and left to right.


I'll have to double check this and get back to you. When I looked inside his store I didn't actually pay attention to how his side of the wall was built. Next time I'm out there I'll be sure to take a look.

I have a question about doors.

I was looking at STC ratings for doors whether manufactured or self-built. The rating I see on average is STC 57 on a perfectly well built door. So my question is if the room is built with a STC 63 design but the door is only rated at STC 57 does that effectively make the overall STC rating of a room 57 because of the door?

Exactly. The overall isolation is only as good as the weakest point, and if that happens to be the door, then that's where the most sound will escape.

That said, a single door rated at STC-57 seems a bit optimistic. Getting that level of isolation from a single door by itself would mean that the door is very, very massive, with excellent seals.

Also, even if the door can get STC-57, and assuming that wall/floor/ceiling can also get STC-63, it will most likely turn out that neither of them defines the final isolation of the room. It is more probable that the HVAC system and/or electrical system will be the defining factors, unless they too have been designed for high levels of isolation.

And of course, the usual caveat applies: Looking at the STC rating of designs is lousy way of judging isolation for a studio, since STC tells you nothing at all about the ability to isolate low frequencies, which are the hardest of all to isolate. Low frequencies (bass, drums, keyboards, etc.) are simply not considered on the STC calculations. So it would be better to look at the full Transmission Loss curves for the designs and/or products you have in mind. TL gives you a much more realistic picture of how something will perform in isolating a studio.


- Stuart -

_________________
I want this studio to amaze people. "That'll do" doesn't amaze people.