New Build In An Old Hosiery Mill

Hi guys, I've been reading and reading through these forms for quite some time now, thank you all for being here! Ok, I'm in Charlotte, NC and I have just picked up keys for a 1385sq foot space in an old mill. The total length of the rectangular space is 63ft & the width is 22ft. The ceilings are an even 12ft height throughout & there are currently no inner walls. The floors are concrete (I am sanding these down tomorrow for stain). I think it makes the most sense to get the floor stuff done 1st since there are no walls. The left wall spanning the entire 63ft length is cinder block masonry. The right wall spanning the entire 63ft length will be a staggered stud assembly w/ 2x4x12's from concrete to ceiling. This wall will be next to a 5ft hallway on the other side. The top wall spanning the 22ft width is as standard 2x4x12 stud assembly with 1/2 drywall on both sides. The bottom wall spanning the 22ft width is cinder block masonry with a steel garage lift door. I plan to divide this space into 3 main sections spanning the 22ft width: An entrance lounge split in half with an office - 22ft long x 10ft wide (basically making 2 10.5ft x 10ft rooms). A control room - 22ft long x 14ft wide. 1. The wall dividing the control room / lounge will span the 22ft width & be a single stud assembly w/ 2x4x12's from concrete floor to ceiling. Single layers of 5/8" drywall on each side. 2. The wall dividing the control room / live room will span the 22ft width will be a double stud assembly w/ 2x4x12's from concrete floor to ceiling. There will be a 12inch gap between frames. Double layers of 5/8" drywall on each room side. I'll have 6x4ft control room window & 2 nice solid-core doors between the control room & live room. A live room - 22ft long x 38ft wide. I do a lot of mixing & I will be doing some band recording in this live room, but the great majority of what I do is dealing with either 1. files 2. vocalists with music made with synth workstations & or computers. Of course, I plan to treat & basstrap, as well as using ceiling clouds to keep things in control, so my 1st question (before we get to erecting any studs) is what's your opinions on the control room size? I just ran the control room dimensions in Bob Gold's room mode calc & this is how it came up: Computed Information: Room Dimensions: Length=22 ft, Width=14 ft, Height=12 ft Room Ratio: 1 : 1.16 : 1.83 R. Walker BBC 1996: - 1.1w / h < l / h < ((4.5w / h) - 4): Fail - l < 3h & w < 3h: Pass - no integer multiple within 5%: Pass Nearest Known Ratio: - "24) A worst case scenario calculated by RPG" 1 : 1.075 : 1.868 RT60 (IEC/AEC N 12-A standard): 273 ms - ±50ms from 200Hz to 3.5kHz = 223 to 323ms - ±100ms above 3.5kHz = 173 to 373ms - <+300ms at 63hz = 573ms - 300<RT60<600ms RT60 (ITU/EBU Control Room Recommended): 253 ms - ±50ms from 200Hz to 4kHz = 203 to 303ms - <+300ms at 63hz = 553ms - 200<RT60<400ms Absorbtion to achieve ITU RT60: 713 sabins Volume: 3696 ft^3 Surface Area Total: 1480 ft^2 Surface Area Floor: 308 ft^2 Surface Area Ceiling+Floor: 616 ft^2 Surface Area Front Wall: 168 ft^2 Surface Area Front and Rear Wall: 336 ft^2 Surface Area Left Wall: 264 ft^2 Surface Area Left and Right Wall: 528 ft^2 Surface Area 4 Walls: 864 ft^2 Surface Area 4 Walls + floor: 1172 ft^2 (sabins - front wall - carpet) / Left+Right+Rear wall: 34 % (sabins - front wall) / Left+Right+Rear wall: 78 % Schroeder Fc: 93hz Frequency Regions: - No modal boost: 1hz to 25hz - Room Modes dominate: 25hz to 93hz - Diffraction and Diffusion dominate: 93hz to 372hz - Specular reflections and ray accoustics prevail: 372hz to 20000hz Count (25.6-165hz) : Axials=13, Tangentials=54, Obliques=72 Count (25.6-100hz) : Axials=7, Tangentials=11, Obliques=4 Critical Distance (direct = reverberant field): 17.10ft I posted a few quick cell phone pics to help out visually. thanks!

Hi "asylumdigital", and Welcome! :) Congrats on your purchase: Looks like a pretty good place for a studio. Several comments about things you said, some of which look like red flags to me:

The floors are concrete

Great! Good start! Good isolation, and good floor, acoustically.

(I am sanding these down tomorrow for stain).

Also great! Plain old concrete makes a great floor for a studio.

The right wall spanning the entire 63ft length will be a staggered stud assembly w/ 2x4x12's from concrete to ceiling. This wall will be next to a 5ft hallway on the other side.

I guess you mean 2x4 staggered studs on a 2x6 or 2x8 base plate? But you have the space, so why not do a proper double stud wall, for the increase in isolation? You also say that this wall will go "from concrete to ceiling", implying that it will be attached to both. If you do that, you compromise isolation. Isolation walls need to be attached to the floor, obviously, but should not be attached to any other part of the existing structure, if you want good acoustic isolation.

The top wall spanning the 22ft width is as standard 2x4x12 stud assembly with 1/2 drywall on both sides.

That wall is no good for isolation. You won't get much more than STC-thirty-something out of that, and even then with a lot of luck! 1/2" drywall is too thin to be very useful for isolation, and having it on both sides of the same studs means it is fully coupled: no isolation.

The left wall spanning the entire 63ft length is cinder block masonry.

Hollow blocks, or solid?

The bottom wall spanning the 22ft width is cinder block masonry with a steel garage lift door.

Masonry wall: good! Steel door: not so good...

A control room - 22ft long x 14ft wide. 1. The wall dividing the control room / lounge will span the 22ft width & be a single stud assembly w/ 2x4x12's from concrete floor to ceiling. Single layers of 5/8" drywall on each side. 2. The wall dividing the control room / live room will span the 22ft width will be a double stud assembly w/ 2x4x12's from concrete floor to ceiling. There will be a 12inch gap between frames. Double layers of 5/8" drywall on each room side. I'll have 6x4ft control room window & 2 nice solid-core doors between the control room & live room.

Red flags! You are either wasting money there, or you are not isolating effective, or both! Isolating a room means building a complete system, the same all around. You cannot isolate better in one direction, and worse in another, since the entire system will only be as good as the "weaktest" side. So if you put a single stud fully coupled wall on one side of the CR, then that is what defines the isolation for the entire CR, and the double stud, double layer walls on the other side are pointless. Low frequency sound is not directional: once it gets out through that "weak" wall, then it is out and will wrap around the rest of the room, being clearly heard on the side with the "strong" wall. I always use the fish tank example: You cannot build an aquarium with glass on only one side and cardboard on the other five, then expect it will hold water! The water will leak out through the cardboard, and once it is out, it is out, and spills everywhere, regardless of which side is good of bad. In order to build an aquarium, you need glass in all six sides. Sound is like water: in order to isolate a room, you need to isolate all size sides to the same level. If not, then you wasted a lot of time and money on doing the "good" sides, since they are useless and do not contribute at all to improving overall isolation. The entire isolation of your room is defined by the weakest link: It might be a window, door, HVAC duct, electrical conduit, or a tiny gap, just 1/32" wide and 12" long under one of your walls. Any of those will seriously compromise your isolation, and that tiny gap is the worst offender of all. In other words, if you have determined that you need the level of isolation offered by a double stud wall with two layers of 5/8" drywall on each side, and a 12" air gap, then you MUST do that on ALL sides of the room (including the ceiling), or if not then you are wasting your money.

2. The wall dividing the control room / live room will span the 22ft width will be a double stud assembly w/ 2x4x12's from concrete floor to ceiling.

Once again, you mention that your walls will go from "floor to ceiling", but once again you cannot do that if you want good isolation. The concept of isolating a room is that of building a "box inside a box". In other words, you build a stud frame around the room, four walls, that ONLY rest on the floor and do not touch ANY other part of the existing building structure. There can be no mechanical links at all. On top of those wall frames, you put a ceiling frame that rests ONLY on those four new walls, once again NOT touching any part of the existing building: Then you put insulation in the stud spaces, 5/8" drywall on only ONE side of this frame, and seal the whole thing air tight. Bingo! Isolated room. If you need more isolation, then put more layers of drywall ON THE SAME of the studs (so you might have 2 or 3 layers of 5/8" drwyall, but all on top of each other on one side of the studs, and nothing at all on the other side of the studs. If you do that, then you can get excellent isolation. But there can be zero mechanical connections between that structure and the rest of the building. The only thing in common is the concrete slab. Even one single nail or screw,that accidentally bridges the gap seriously damages the isolation. The same applies to pipes, electrical conduits, and HVAC ducts: they all need to be suitably decoupled where the cross from the existing "outer leaf" to the new "inner leaf".

so my 1st question (before we get to erecting any studs) is what's your opinions on the control room size?

How big do you need it? :) "Room Dimensions: Length=22 ft, Width=14 ft, Height=12 ft Volume: 3696 ft^3" That's a decently large size, with the total volume almost right in the middle of the recommended range for both ITU and EBU. You could go smaller, or larger, if you want, depending on what you need. But the dimensions need a bot of tweaking! "Nearest Known Ratio: - "24) A worst case scenario calculated by RPG" 1 : 1.075 : 1.868" :shock: :!: :D Ummmm..... It would be good if you could post a SketchUp model of your basic existing building, plus your proposed basic layout, so we can get a better idea of what you have in mind. But you have a nice space there, with good possibilities, if you design it right! - Stuart -

Hi, thanks for the reply! There are a few things that I realize that I did not explain well. I'll get a layout picture up here very soon to help with visualization. However, I guess my primary red flag from you was - Instead of constructing room w/ in a room walls, I was trying to build dividing walls. So what you're saying is - with dividing walls, even if they are double frames w/ double 5/8 drywall on the correct sides - they will not provide adequate iso?

even if they are double frames w/ double 5/8 drywall on the correct sides - they will not provide adequate iso?

Most likely not. The issue is not the walls themselves, but the "flanking paths" around them. If you attach a wall to an existing ceiling, then the wall is not longer the limiting factor in isolation: the ceiling is. Any sound that gets into the ceiling will simply bypass the wall entirely, as though it wasn't eve there. That applies to sound that passes through the ceiling, into the space above, then back down on the other side, as well as sound that causes the ceiling itself to vibrate, since that vibration will be transmitted by the ceiling structure, causing the ceiling on the other side to vibrate, thus acting like a speaker. The same applies if you attach your new wall to an existing wall: sound will flank around it. And in addition to all of the above, sound that hits your new isolation wall and causes one side of it to vibrate will also flank around it, through the existing walls/ceiling structure, and cause the other side to vibrate. In other words, you could have the "most bestest superbest super-dooper" isolation wall on the entire planet, able to give 110 dB of TL from 10 Hz to 50 kHz, but if you attach that to a ceiling which has a flanking limit of 30 dB, then all you get from your wall is a grand total of 30 dB isolation.... Sad, but true. Your wall doesn't even exist, as far as flanking sound is concerned. It just isn't there. That's why decoupling is so important. Decoupling removes all flanking paths between "A" and "B". There can be no mechanical linkage at all between the interior of the room and the rest of the building. Not even a single nail that accidentally bridges the gap between inner-leaf and outer-leaf. - Stuart -