First, I'm new to this forum. What a great resource!! Thanks for your work in putting this together!
I'm building a reasonably elaborate home studio in California (near San Francisco). I'm converting an existing 2.5 car garage (with extra high ceiling) into a 3-room studio (Main Room, Iso, Control Room). I'm also setting up the Sound Lock as a 4th tracking space. The Main Room outer shell is 19'-1" (5.8m) wide x 21'-5" (6.5m) long x 13' 4" (4m) high. The main focus of the studio is tracking (I don't like to mix), so the Control Room is reduced in size to allow for me to bring in an engineer for the purpose of getting good stuff on tape, then taking tracks elsewhere to mix. The main focus of the studio is a great sounding Main Room with significant isolation as it will be used for live rehearsing as well as live ensemble recording (with reasonably loud bass guitar). There are some neighbor issues on one side and an unbelievably loud frog pond on the other (loudest frogs you've ever heard!).
Current status of the project is that the outer shell is now built (except windows and doors), and we'll be starting in on the inner shell (room within a room) in the first week of May.
That's the good part. The bummer is that I hired a local studio designer that has made some bad recommendations. I started doubting his skill level a month ago and began educating myself. Now after reading several books and scouring sites like this one, I know that some major mistakes have been made and I'm now taking over the design and management of the project myself.
The biggest problem (that I've identified) is that the now completed outer shell includes a triple leaf construction AND we haven't even built the inner room yet. See the attached file (Exterior Wall Detail.png):
Though the original recommendation was to put sheet rock on the backside of the inner wall (creating a 5-leaf wall system), I'm obviously not going to do that now. But I am basically stuck (for budget reasons) with the exterior wall as it is shown in the drawing. Given the fact that the Main Room is quite large, my hope now is that the interior walls, which will be canted relative to the outer wall can be placed far enough inward to minimize the negative effects of the quadruple leaf system that seems impossible to avoid at this point. See my proposed detail for the interior wall (Interior Wall Detail.png) attached:
There has been no work done to construct the Interior Wall, so I want to get this one right and hopefully get this project back on track.
So, given my situation, here are my questions:
1) Does my proposed Interior Wall Detail look good given that the exterior wall is currently installed and not easily changed?
2) The canted interior walls can range from 1 inch to 3 feet away from the exterior wall, so can you recommend a minimum distance between the two walls to ensure that the airspace between is large enough to prevent any significant transmission of bass frequencies?
3) Should I cover the now existing innermost sheet rock as shown on the Exterior Wall Detail with an absorbent material (sound board or similar) to minimize reflections between the two walls?
4) The floor now is the existing garage's concrete slab, and the design for it is still up in the air. I want to create as much isolation from the slab as possible, but ideally don't want to rip it up. The most attractive floor detail that I've seen to date is the one given by Rod Gervais on page 269-270 of his book Home Recording Studio (2nd edition). He shows two pieces of plywood semi "floating" on a layer of 703 rigid fiberglass. Has anyone tried this? How does it work?
5) My existing concrete slab is not level (out by up to 1 inch), so if I use Rod's detail, any ideas on how to level the floor?
Any help will be hugely appreciated, and I'm happy to post photos and more info if anyone would like to learn more.
Thanks ahead of time!!!
New Studio in CA - Questions
Originally posted at johnlsayers.com, topic 15849.
"I started doubting his skill level a month ago and began educating myself. Now after reading several books and scouring sites like this one, I know that some major mistakes have been made and I'm now taking over the design and management of the project myself."
From the negative comes the positive, good for you!
Your interior wall only need be a frame with the mass added directly to the frame. The clips and hat track which are designed to "decouple" the mass, are not required since by virtue of the single frame that is not attached to anything...the wall is already decoupled:)
In order to overcome the existing exterior wall you will need to have a larger air space in between it and the interior frame. So the question is, what kind of isolation does the current wall configuration provide...is it adequate for your needs?
Thanks for this tip. Unfortunately the extra hat and clips have already been purchased...so I can't save any money by your excellent suggestion...Your interior wall only need be a frame with the mass added directly to the frame. The clips and hat track which are designed to "decouple" the mass, are not required since by virtue of the single frame that is not attached to anything...the wall is already decoupled:)
No, I don't believe that this wall will be adequate. Plus I must build the interior wall in order to create isolation between various rooms (Iso, Control Room) as opposed to just the outside world. Can you direct me to a formula or some kind of math that can help me arrive at the correct spacing between the interior and exterior walls?what kind of isolation does the current wall configuration provide...is it adequate for your needs?
"Thanks for this tip. Unfortunately the extra hat and clips have already been purchased...so I can't save any money by your excellent suggestion..."
I didn't bring up saving money. It isn't important, assuming you already own the material. The assembly, a mass/spring/mass that you are wanting to do does not require a framed wall with clips and hat track on any of the frames.
The mass/spring/mass is a simple image but a difficult to understand process.
The process of decoupling is as simple as this.
One hard boundary (usually exterior brick or OSB, etc) attached to a framed assembly. Then there is the air space:) Then the next framed assembly with an interior hard boundary usually sheetrock).
Currently you have a decoupled mass/spring/mass with the exterior wall assembly.
NOW...you want to, just because you have it, install clips and hat track on the interior assembly.
If you review the data on clips and track you will see that that TL(transmission loss) suffers in the low end and the low frequency area is where you want to get the most support.
So if we look at your current, plus the pending...we see that the lose in low end frequency isolation is multiplied by two basically making all the work you are doing and all the money you are spending...useless to your goal.
Got it. I'll lose the clips. But I'm still confused on how far to separate the two walls. For example, I was thinking of doing walls that cant at 5-10º, which means that these two walls that I've shown here will be up to 4' apart in some places. Does the mass/spring/mass concept apply to walls that are 4' apart? If not, what is that critical distance, below which the mass/spring/mass rule applies? Also, any input that you or anyone else could provide on my questions #3-5 in the original post would also be much appreciated. Thanks!If you review the data on clips and track you will see that that TL(transmission loss) suffers in the low end and the low frequency area is where you want to get the most support.
the air gap should be roughly 8"-12" between the mass layers. if you're angling walls and losing 4' of space, you might re-consider the rationale for angles on the isolation walls and instead build them straight then add a set of slat walls inside the isolation space to create the needed angles and provide usable absorption and diffusion.
Thanks for this tip. This is exactly what I was looking for. I will be sure to maintain a min of 8-12" between mass layers.the air gap should be roughly 8"-12" between the mass layers.
Really cool idea! I'll do some more studying on absorption and diffusion to see how this could work in my case. I'll post a floor plan to this thread later in the week that hopefully brings all this together into a design that works.if you're angling walls and losing 4' of space, you might re-consider the rationale for angles on the isolation walls and instead build them straight then add a set of slat walls inside the isolation space to create the needed angles and provide usable absorption and diffusion.
Well...the issue you have is that you already have an existing basic decoupled wall assembly. So there is no "standard" that can be suggested. The above is a best guess and will most likely fail in the area of isolation. Having nothing more to go on then what you have presented...which is all in hindsight anyway...you need about 36 inches to overcome the existing assembly.Thanks for this tip. This is exactly what I was looking for. I will be sure to maintain a min of 8-12" between mass layers.the air gap should be roughly 8"-12" between the mass layers.
the air gap should be roughly 8"-12" between the mass layers.
Hmmm...I'm hearing 12" and I'm hearing 36". Can either of ya'll provide a little more explanation (and preferably some math) as you are both clearly experts and you are not saying the same thing here... To make sure we're all on the same page, I want to achieve significant isolation for rock/jazz band levels which includes an amplified bass player and a drummer. The space is about 19' x 21' and I was planning on building canted interior walls (just inside the existing exterior wall detail shown in my original post). Thus, the interior walls will never be parallel with the exterior wall. These angled interior walls then will only be close to the exterior wall in a few places. So, the question is: what is the minimum distance between the canted interior wall and the exterior wall at those places where the two are closest together?you need about 36 inches to overcome the existing assembly.
You are wanting to overcome an existing triple leaf correct? What Glenn mentioned, the 8"-12" will work...but, in order to really get over this 3 leaf, you need more distance.
3 leaf assemblies exist everywhere like the floor/ceiling/roof hard boundaries, yep cant get away from them:).
Or like in a hotel corridor, which some might call a four leaf. But the thing that makes it work is the huge distance between wall assemblies. So while the 8"-12" will work...if you can get more you NEED to get more space in between the existing triple and the next hard boundary.
Brien is right in that to be fully effective on a triple leaf or quad leaf you need more space. that said, looking at your exterior construction and the 2x drywall you already have there with the "third" leaf the sheathing and stucco, i think that if you can go 8-12" i think you'll be OK because the outer leaf materials are different and the resonant frequencies are different. as just a rough calculation, the inner walls to the drywall on the exterior is over 20db greater than the exterior wall itself on 8" and 23db on 12". and your exterior wall calculates to around 40db TL. of course doing a proper sound level test on the existing structure would make all the difference...
Excellent. Now this is starting to come together for me. Thank you both for your replies.
We are putting the windows and doors in the exterior walls in about 3 weeks. Once those are in, then I should be able to take some measurements to see how the exterior wall is performing. I just bought a digital sound level meter. Can you direct me to some instructions on how to run a "proper sound level test"? If it's something that I can do with my meter, then I'd be happy to take measurements and post so we can have some data to help contribute to the knowledge base here.of course doing a proper sound level test on the existing structure would make all the difference...
What type of windows and especially doors are you using?
The exterior wall includes one window and 2 doors. The window is 73" x 46", looks out onto a scenic marsh/pond and includes 2 pieces of 1/4" laminated glass with about 6" gap between (both mounted in the exterior wall). I plan to put in a third piece of 1/2" laminated glass mounted in the interior wall 12" away from the exterior wall (according to y'all's recommendations in this thread). The 1/4" glass was a design decision that my now former studio designer made, but knowing what I know now I probably would have just put one heavy piece of say 1/2" or thicker glass in the exterior wall, but it is done and paid for... I'm planning to use the "super door" detail that Rod Gervais gives on page 106 of the 2nd Ed., except I'm not a big fan of lead, so I was thinking about using a slab of 3/16" steel instead of the 1/8" lead that he shows. Doing the math, 3/16" steel is about the same weight as 1/8" lead and it's quite cheap at a local metal shop. Unfortunately, again, the doors were already purchased before I stepped in to take over the design. While the doors are basically fine (solid core, etc.), they were ordered with standard holes cut out for the door knobs. Should I just plug those holes and go with a surface mounted handle to prevent sound loss through the door knob? If so, any ideas on the best material to plug the holes with?What type of windows and especially doors are you using?
That sounds like a good way to go, overall :)
The door hole, assuming you are going to paint the door, you can boor a piece of milled material with a holesaw of the same size as the existing hole, should be 2 3/8". Glue that plug into the hole, let it dry, and use whatever you have handy, water putty or all purpose bondo to slick it and fill it up smooth.
for testing - using sine sweeps and bass-drum mixes played around 110db inside and using a sound level meter checking around the perimeter and at the edge of the property will give you a decent idea about your isolation. secondary - using REW to check the room acoustics and determine what problem frequencies you might have.
Thanks gullfo. Will do and report back with data in a few weeks once I get the doors in.
To overcome a triple leaf issue, the extended air cavity is certainly a good idea. Similarly, having the extreme outer leaves as massive and as damped as possible will also work. The larger the cavity and the more mass the extreme outer leaves have, the less severe the effects of the dual air cavities (triple leaf) will be.
Based on input from all above (and other sources) I'm mostly done with the re-design effort. Here are some photos showing the current status. The triple leaf outer wall assembly is completed. Here's the whole Main Room and a close of the triple leaf construction (this is at exterior window so insulation stuff in the gap between leaves):
In the first photo you can also see the that Control Room walls had been constructed incorrectly as well, but these did not have the full triple leaf installed yet, so I had the contractor remove the sheetrock from the inner portion of these walls (part facing main Studio Rm). Thus, the room-to-room iso should be pretty good; it's just the studio to outside world that has the triple leaf. Here's the Control Room now with the sheet rock ripped back off (cellulose insulation exposed), then the cellulose covered with landscape fabric to keep it in place):
Here's the plan that my "designer" had done originally. His concept was to cant the isolation walls for the Main Room:
Based on Glenn's input above, here's my current plan showing parallel iso walls, then a a few lines indicating that I'll add angles via treatments of some sort (not defined yet). Also, note that the right wall in plan view is shared with the Main House, but everything else is free standing (originally asa 3-car garage):
Here's the current design in 3D (walls chopped down for easier viewing of the interior space):
Here's a few more views showing how I've got some nice tall walls due to the sloped roof (thereby giving me a decent amount of volume to the main room):
One thing that you'll note with my studio design is that I've designed it to have a multi-purpose large main room plus a very reduced Control Room. I am a jazz musician and the primary purpose for this studio is to track records (and rehearse) live. I won't be doing any final mixes or mastering here. The only purpose for the Control Room is to have an engineer brought in during sessions to get good stuff on tape (actually hard drive...but that doesn't sound as hip!). I've created some symmetry on the south wall of the Main Studio so I can do rough mixes from there. The Control Room will also double as a second iso for tracking larger bands and the sound lock (upper left of plan view) will also serve as a third iso room.
Based on the above, my current questions are:
1) Does it make sense to run the iso walls for the main room parallel (instead of canting)?
2) If so, what should I do to create slat walls (as Glenn suggests) and/or other treatments to make the Main Studio room sound as good as possible? As shown with iso walls the room is 17' x 18' x 16' high at the peak of the roof.
3) Given the triple leaf exterior walls that are now constructed, how should I construct the inner shell for the Main Studio and Iso Room (they are not built yet)? I want maximum isolation to the outside world as I have an uptight neighbor and I play bass loud.
The inner walls will be constructed next week, so any input would be much appreciated.
I made a few minor changes to the design. Here are a few more images:
looking at the plan view, why not bring out the isolation walls in the top and bottom left to be square to the exterior walls and then angle on hard treatments like slats? is the upper left a small air lock?
The upper left is a sound lock that goes out to the driveway. That door is 4' wide for load in. Since the sound lock ended being so big to accommodate the door, I thought that it would be nice to be able to occasionally use that space as a second iso room for a vocalist or horn player (I like to do live trio and quartet recordings since the music is jazz and it really benefits from the live interaction). While this area does need to be a sound lock (the exterior door is already installed), the exact shape is still negotiable, so let me know if you have other ideas on the shape for this sound lock. The lower left is not built at all yet, so we could still do anything here. The reason I showed it this way was that I want that end of the live room to also double as a rough mix work station, and general playback listening station when I'm recording solo or overdubbing (note the speaker positions). Thus, I thought that some symmetry would be good and that angle is the same angle as the opposing wall with the sliding glass door. Since the slider is reflective, I was contemplating making that angled wall out of stone. Does this make sense? Any other ideas on how to create symmetry on that end of the room while running the isolation walls fully parallel as you suggest?looking at the plan view, why not bring out the isolation walls in the top and bottom left to be square to the exterior walls and then angle on hard treatments like slats? is the upper left a small air lock?
using slats on the front - inside out walls on the left side (to the iso booth) and regular walls on the right (where you have the angle now) will give you the angles, some absorption, and some diffusion., i'd probably expand the air lock then a bit to make it useful as a booth, or eliminate it.
Good ideas, Glenn. I'm trying to finalize the design for all of my walls soon. Are you available for some hourly consulting? If not, got any recommendations? I probably just need 5-10 hours of someone's time to review things and provide some detailed advice.using slats on the front - inside out walls on the left side (to the iso booth) and regular walls on the right (where you have the angle now) will give you the angles, some absorption, and some diffusion., i'd probably expand the air lock then a bit to make it useful as a booth, or eliminate it.
Here's another crack at the layout based on Glenn's recent input. Glenn is this more what you were thinking? I enlarged the sound lock and turned it into a proper second iso. It's now about 5'x5'. I'm thinking that maybe I won't go all the way to the ceiling with it, but rather put its ceiling lower than the main room and use it for storage or treatments, etc. Thoughts?
Also, the lower left in plan view is now shown with a slat wall (brown). Is this what you were recommending?