Need Consult on 2-Story 3-Car Garage Studio Build

[audiofile88]

Hello all,

My name is Greg Hill of Raleigh, NC. (U.S.)

First off, thanks to all those involved in creating such a wonderful forum for all of the aspiring acoustical engineers looking for reputable information! I've amassed a TON of knowledge just within the past two weeks from this one site alone.

I'm currently in the design stages of a 2-Story, 3-Car Garage build, with 'of course' a semi-professional studio on the upper story. Budget total on the project is ($75k).
I've been in contact with a local contracting firm and have had them look over the initial details of the build. Unfortunately their experience in acoustical construction is very limited, but they assure me I've got the space to do so.

The garage itself will be 32' x 26' x10' on the first story, while the upper story will be roughly 32' x 22' x 8' with a front faced dormer on the center third of the structure. (The images below will detail this further) The dormer will be 10' 8" (1/3) of the width of the structure allowing the center depth to equal 25'.

The instruments to be recorded include Guitar (Elec/Acous), Bass, Drums (average 6 peice set), Keys, Vocals, and other digital sources.
I am attempting to alot for a Control Room, Iso/Vocal Booth, Live Room, and Bath.

Here's a look at the floor plan I've created in correspondence to the previous dimensions-



Please ignore the interior dimensions of the picture above. These drawings are completly tentative and are more than likely in need of adjustment due to optimal positioning of the rooms, and their associated ratios.

I'm instilling the 'Room within a Room" approach with both the Control Room, and Iso/ Vocal booth. The CR is the bottom center room with (my best attempt of) John's recomended geometry, and the bottom right will be the Iso/Vox. The larger rear room will act as the live room, and the smaller, bottom left corner room will be the bath. All rooms with the exception of the Bath, will employ John's construction reccomendations. double wall 2x4 timber framing, rockwool instulation, resillent channeling, drywall/fabric exterior, slat-resonators, bass traps, etc.

Here's another look at the building with the exterior walls up and accurate dimensions of the open floor plan-



Vertical dimensions are in Red, Horizontal dimensions are in Black.

The next images will illustrate the wall framing and overall layout in 3D perspective-







As indicated on the first three images, I do plan on installing two 6' wide sliding glass doors, offset at a 6 degree angle to enter/exit between the live room and Iso/Vox booth. The following two images of the wall installation show a swinging door frame which will not be used. (Sorry for the confusion)

And finally a look at what I hope to achieve upon project completion-



This image illustrates placement of acoustical treatment, and overall location of instruments/gear.

My main concern thus far is the overall size and placement of the rooms, as well as the appropriate treatment for each. I don't have picky neighbors, and will only be recording at higher db's when tracking amplifiers or drums. I monitor at the average listening level, and am doing my best to be able to hear for the next couple of years or so.

If you have a suggestion, or possibly a better layout for this size floor plan, I would be thrilled to venture the idea.

As far as materials and construction, I feel I am covered thanks to John and this site. I would just like to use this large of a space accurately, both in layout, and acoustical response.

Thanks in advanced for having made it through my ramblings. I hope I have covered the information needed to get an idea of what I'm going for. If not, I am happy to go into further detail.

I'm excited to get everyones input and get this project rolling. I will do my best to keep an updated timeline via the forum to hopefully help out others looking to build a home studio as well.

Thanks again for your time,

-Greg Hill

[xSpace]

Hi Greg.

"I'm instilling the 'Room within a Room" approach with both the Control Room, and Iso/ Vocal booth."

You mean installing, right? To my point, the only actual room in room you have is the control room. Everywhere else is, well, not room in room designed.

It's a bit of a leap, but you have to think "exploded schematics" when making these kinds of designs. Simply having two walls, as in the booth connected to the control room with the sliders, isn't room in a room, or fully decoupled as it were. If anything, it is now all interconnected and, especially any acoustical project vaulted off Mother Earth, has multiple flanking paths that lessen your collective rooms ability to isolate sound.

Your sight lines from room to room are in need of some repair as well. John has a corner control room design http://www.johnlsayers.com/phpBB2/downl ... p?id=25685, maybe that would churn up some ideas, if you viewed that.

http://www.johnlsayers.com/Pages/Projects.htm

[gullfo]

agree with Brien completely. a corner control room would be better suited for the space.

if you don't have Rod Gervais' book on building a home studio, you should definitely get a copy. you will find it a useful reference especially when you need to talk details to your contractor. Rod's 2nd edition is coming out this week http://www.amazon.com/Home-Recording-St ... 143545717X

[audiofile88]

Thanks for the quick responses guys.

I've looked over John's corner control room design and have adopted the layout with the allotted floor space of the garage.

Here's the proposed floor plan-



I definitely see the improvements in visual communication as well as isolation of the individual rooms.

The stairwell itself with have a door on the first story, closing it off from the upper story space.
Should an air lock be included at the 'foyer' of the room at the top of the steps to assist in acoustics, or is the airlock primarily used to keep sound in their respective rooms once a door has been opened?

Not indicated in this floor plan, but something worth mentioning are the angled walls to the left and right of the dormer. These two walls begin with a vertical rise of 57", then are angled at 45 degrees for an additional 3' run, as this is the roof. You can see the illustration of this in the first post, second picture down.

(I forgot to mention the details of this in the original post- The back half of the garage will make use of a hip roof, allowing a consistent height of 8')

Please let me know if you have any further recommendations for this layout, or if there is a better direction to head regarding room placement.

Also, if you may have any recommendations towards acoustic treatment within the rooms, I'd really appreciate it.

Thanks for all your help!

[gullfo]

much betterer!

[Cold]

Hi,

You may wish to rethink all of the sliding glass doors. Esthetically they would be great, but the cost to get heavy ones with enough isolation..... and their location at areas that will probably have to be treated.... A set of conventional doors to enter the cr and a smallish window into the booth may make your isolation and treatment easier to deal with.

I understand the convenience of the two entrances to the booth....

Just something to think about. My design is very similar to yours and I ended up deciding on a window.

Whether that is the right choice for your project only you can decide.

Regards,
Steve

[audiofile88]

Here it is in 3D-

You may wish to rethink all of the sliding glass doors.

I will take that into consideration. I understand that the doors can be costly and a pain to slide if they are the appropriate thickness. I might just stick with the sliding door to enter the booth in order to satisfy the sight lines. I have decided to make use of a small window between the booth and live room, a door will not fit due to the angled ceilings.

Anyone out there know if you can get Rod's book via a local book store, or must it be ordered online?

Please, keep the suggestions coming!

Thanks,

[xSpace]

In reference to Rod's book, you will most likely not find it at even the big box stores so online ordering may well be your only option.

As another option for all the sliders, you might consider installing a double slider at the primary focal position of the control room and using glass at the side walls.

[rod gervais]

My book is carried through Barnes and Noble and quite often they have it in stock, although if they do not you can order it through them.

Also, Waldenbooks, Borders, in fact - because my publisher is one of the larger global publishers you should be able to order it pretty much anywhere, including the university bookstores (heck even Target carries it). You may well find it sitting in a university library near you - it is in more than 164 university libraries worldwide.

Rod

[audiofile88]

Thanks for the reply Rod.

Just put a copy on hold at my local Barnes & Noble.

[audiofile88]

Well, as of today I have finished Rod's book, and have gone back to the drawing board in an effort to improve upon the initial layout.

As I was drawing this following image up I ran into the problem of overall isolation control...



Using Rod's method of ( 2 layers of gypsum board- Timber frame+insulation- Air- Timber frame+insulation- 2 layers of gypsum board ) I was moving along just fine until I began to think about John's design of incorporating treatment on the face of the internal wall, and gypsum board on the back.

In the original "Corner Room" floor plan, I had offset the inside walls 4". After having read Rod's book I didn't feel that 4" was necessary when including the 2 layers of GB front and back so I halved the air between the interior and exterior walls. (2")

After doing this I am unable to follow John's method where the GB would be placed in the airspace, without redoing the entire plan to allot for larger air gaps for walls that contain treatment.

So to sum up, Is it better to apply GB to the outside of the interior walls and allow for treatment throughout, apply GB to the interior and place treatment on top, or a combination of both?

I will be moving on to HVAC next. Again this is being built as a second story, so the handler will be located on the first story, and duct will travel up, venting from the floor.
Is this a bad idea? I know the majority of structures have HVAC venting from the ceiling as cool air sinks. Should I design it in the more common fashion, or will I be fine venting from the floor? I would assume this would also cause issues with the returns, although I'm sure they could be installed on the vertical walls.

If you have any recommendation on either subject, please feel free to reply.

Any and all help is much appreciated

[Soundman2020]

Hi Greg,

Two things: First, please follow the forum rules and reduce the size of your images to 700 pixels, so they fit on the screen easily, without forcing folks to scroll back and forth.

Second, you said: "In the original "Corner Room" floor plan, I had offset the inside walls 4". After having read Rod's book I didn't feel that 4" was necessary when including the 2 layers of GB front and back so I halved the air between the interior and exterior walls. (2")"Reducing your air gap to 2" is not a good idea. You will compromise your isolation severely like that. Or you will waste even more space in trying to compensate.

Let me explain: You read Rod's book so you probably already know that an MSM wall is a good way to isolate at low cost. It works because the wall itself is tuned to resonate at a specific frequency: At that frequency, the wall is a really lousy isolator, and in fact actually helps sound get through: it vibrates in sympathy with that frequency, really, really well, and therefore passes sound right through. (Think of it like a low pass filter). But at higher frequencies, it starts resisting the passage of sound, better and better. At roughly twice its resonant frequency, it is reasonably good isolator, and after that it just gets better and better the higher you go.

So clearly, you want to design your wall so that its resonant frequency is a long way below the lowest frequency that you need to isolate. Since human hearing runs from roughly 20 Hz to 20 kHz, you therefore want the wall to resonate at a frequency of no higher than about 10 Hz, ideally. If your MSM resonant frequency is too high, then the wall will not isolate well at low frequencies. The higher you allow the MSM resonance to go, the worse it gets.

So how do you get a good low MSM resonant frequency? The equation that describes how MSM walls behave has two main variables in it: the mass of each of the two leaves of the wall, and the distance between the two leaves. To REDUCE your resonant frequency (ie, make your wall isolate better) you can either add more mass (more layers of drywall) or you can increase the size of the air gap. Or both. And of course, the reverse is also true: To make your wall isolate WORSE, you can take mass off the leaves, or you can reduce the air gap, by bringing the leaves closer together. So you can compensate for a smaller air gap by adding more mass. Or you can compensate for lower mass by increasing your air gap. Great!

Now for the main point: The recommended minimum air gap is 4". Down to 4" the relationship between mass and air gap is roughly linear: if you double the air gap then you can halve the mass and still get the same isolation (more or less). But below 4", it stops being so linear and gets to be more and more exponential. So if you have an air gap smaller than 4" then you can still compensate by adding more mass (more layers of drywall), but now you need MORE than twice as much mass each time you halve the gap.

I didn't actually do the math (tough day, late night, feeling lazy...), but in going from a 4" gap to a 2" gap, you'd probably need not just 4 layers of drywall but something like five or maybe even six layers on each leaf (instead of just two) in order to have the same amount of isolation that you would have gotten on a 4" gap with two layers on each leaf....

Apart from the expense, you now have the issue that you are using up as much space for the extra layers of drywall, as you saved by reducing the air gap! An extra 4 layers of 5/8 drywall will take up 2 1/2 inches, so you actually LOST half an inch of wall thickness by shrinking your air gap from 4" to 2". In other words, by making your air gap thinner, you have to make the wall thicker just to get back to the same amount of isolation.

It's a situation of diminishing returns, and going from 4" to 2" takes you over the edge.

So that's just my long and convoluted way of saying that you might want to re-think your 2" air gap!

Stick with at least 4" for your air gap.


- Stuart -

[audiofile88]

Thanks for the reply Stuart.

Image has been fixed.

I understand that decreasing air space will result in less isolation, and I felt with the previous drawing things were not the way they needed to be... not even close.

In implementing Rod's design I was under the impression I could eat up some air space due to the amount of GB (mass) illustrated in his drawings. I can see where that would cause the issues you described.

As far as the bare minimum being a 4" air space, is this also true with John's design I've implemented within this drawing?



I found this information on Johns site here- http://johnlsayers.com/Recmanual/Titles/Acoustics3.htm
Within his illustrations he appears to have only a 1" air space between the existing wall and the new interior wall.
I'm treating the exterior walls of the garage as "existing walls", although they have not been built yet.

Should I still allot for a 4" air space even within this design?

Also, is there a particular way to treat the exterior walls of the structure as they are being built, rather than normal residential practices?

[Soundman2020]

Within his illustrations he appears to have only a 1" air space between the existing wall and the new interior wall.

A couple of comments about John's Recording Manual:

1. He originally wrote that a long time ago. Since then, things have changed: acoustics has advanced as a science, ideas and fads come and go, he has come up with new and better techniques, etc. The exact same principles still apply that John mentions in the manual, but some of the details aren't the same. So the manual is a good foundation for learning the basis of how to isolate your room, but you should still follow up and check on modern techniques. Don't get me wrong: The manual is great, and there is nothing WRONG with it: Just that things change over time.

2. The drawings in John's manual are not necessarily to scale! What LOOKS like one inch might not actually BE one inch. John normally provides accurate measurements in the text when he is describing actual treatment, but sometimes his drawings are only meant to illustrate a point, so they don't have dimensions. On the page you mention, he's talking about basic principles, not giving measurements for actually building a wall.

Then there is the issue of terminology: A lot of people get confused with the term "air gap", thinking that it just refers to the gap between the studs on the inner leaf and the outer leaf. Not so. The air gap is the space between the SURFACES of the inner leaf and outer leaf, regardless of where the studs go, and regardless of how much insulation you put in it. The insulation is PART of the air gap. Try to imagine your wall as just the surfaces standing up in space all by themselves, with no studs or insulation or anything else present: The gap between them is the air gap. That is what sound waves "see" as they interact with the wall. That is what the equations deal with. It is the actual total distance between the two hard surfaces that face each other, inside the wall. The only way you could get a 2" air gap with stud walls is to build BOTH leaves inside out: If you build even one of them normally, then the depth of the studs themselves means that you cannot have an air gap of less than about 4". Or you could also get a 2" gap if one leaf is a solid brick or concrete wall, and the other is inside out studs.

So, what John shows on that diagram, is air gaps of at least 4" (assuming the studs are 2x4s, plus a 1/2" extra.

Should I still allot for a 4" air space even within this design?

Yup. The physics of the wall remains exactly the same, regardless of how you support the leaves. John and Rod are saying the exact same thing: you need at least a 4" gap between the inner leaf surface and the outer leaf surface, regardless of which side you put the studs on.

Also, is there a particular way to treat the exterior walls of the structure as they are being built, rather than normal residential practices?

The basics are still the wyay John describes them in his manual: Lots of mass on each leaf, a total airtight seal on each leaf, an air gap between the leaves, insulation in the air gap, and total decoupling: nothing at all can bridge the gap between the leaves, not even a single nail.

That's the basis, but the details vary depending on materials: What materials are you going to use for your outer leaf? Stud wall with siding? Brick? Concrete? Blocks? Something else? Right now you show 2x4 studs for the outer leaf, so I'm assuming that's what it will be, but what are out planning to put on the outside of that?

- Stuart -

[audiofile88]

The outer leaf will be built to match the house on the property.

Standard 2x4 stud framing, particle board, and siding.

Should I even consider installing GB on the inner wall of the outer leaf or will this create a 3 leaf system limiting the air gap distance?