Placement of Control Room within Basement

[kywoman]

Hi,

Long time reader, first time poster. Thanks for such a great resource, and those who donate their time to help others achieve their goals.

I want to convert some of my garage to an RFZ control room. Eating the elephant one step a time, I’m hoping to receive suggestions on where to locate the room within the space. Please see the attached scenes from my SketchUp model. I’m a neophyte with SketchUp, please don’t hesitate to let me know anything you’d like to edited.

Details about the space (most relevant measurements are shown on the pics, but happy to list them here as needed.)

The garage walls have 1/2” gypsum wallboard (GWB) on 4-3/8” width studs at 24”, and a 6” depth before a 2.5 foam (XPS) sheet, then concrete. The slabs end just beyond the 1/2” GWB. North wall is built into the earth (not shown for clarity), whereas western wall is the car bays, southern wall has the door entrance.

Non-relocatable (AFAIK) limitations to the space:
Water inlet / shut off valve / filter prevent using the northwest corner of room.
HVAC runs require angled or boxed out wall along perimeter (measurements shown).
Structural posts - two shown in red. the northernmost yellow one is hypothetical (more on that in a bit!)
Structural “glulam” beam - height limiting point (4” below joists, slab to beam is 99.5”)

Potentially relocate-able items shown in green:
- A 3” DWV pipe crosses the structural support beam, and eats up an extra 4” of height on top of the 4” consumed by the structural beam (9’ 5-1/4” floor to beam as shown on model).
- Similarly, I’d need to rework the kitchen stove exhaust vent to maximize height and relocate the gas shut off valve.
- Water heater access underneath stairs

Questions I’ll ask a local structural engineer:
Calculation of live and dead loads for ceiling, calculate what weight can safely be added
Can door for water heater (underneath stairs) be relocated to south wall to maximize distance from western wall


dB measurements and TL goal
All measurements were C-weighted measurements. REW was used to see where the loudest frequencies occurred.
Garage measures 35 dB ambient when there are no significant external sources of noise, or HVAC running (HVAC adds 5-7dB). A 90 dB noise 3’ from garage walls was attenuated to 73dB at 125Hz 3’ inside the garage (6-7’ b/n mic and noise source). So the garage confers 15-20 dB TL from outside. Ideally I’d like another 50dB TL inside the studio, which would make monitoring levels (commonly around 75dB, rarely above 90dB) a non-issue for those in the floor above.


Budget
I’d prefer to keep it under $20k USD (excluding monitors and other equipment upgrades) but it’s flexible. I’ll happily DIY many parts of the build, especially all the acoustic elements.


So…

Due to the structural beam and posts, I think the most logical place for the room is with the speakers firing eastward. I could add a third post (shown in yellow) for symmetry. I’ve placed a very basic outline of the footprint of an RFZ room on the floor just to have a very rough idea of how this may occupy the space. If this is the place to put it, I’ll then look into angling the front wall to avoid the HVAC duct, wrapping the poles(?), height abnormalities, etc.

What do you think of this placement? Would you do something different?

I very much appreciate your input, thanks!

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[richroyc]

Hi there Kywoman!

I am by no means an expert, but I am in a similar place as you right now in the designing stage of a basement studio with existing overhead issues.

I have structural posts in my basement as well supporting (3) 2x10 beams which hang down 9-1/2" that I am having REMOVED! The (2) posts came out and a new steel FLUSH beam is replacing the wood beam. The result is open floor plan and full ceiling height throughout.

I know you have a tight budget (as do I) but what I once considered too expensive, I am now proceeding with. The Cost for the beam delivered and installed was $3,000.00 USD

I also had a few plumbing pipes relocated which also was not as expensive as I thought. After the plumber shut off the gas/water - I actually did the removals of the existing pipes myself (saving money) and the new pipes are flexible plastic so they go in really quick (no soldering each joint). I can't tell you how much the pipe relocation costs exactly because it was part of a larger job - but I would guess no more than $600-$1000?

These few things (although not cheap) eliminated SO MUCH headache and "building around" the existing stuff. To me it was worth it.

If you plan on keeping the columns, in I think they would need to be soffited around ( this was advice I got from Stuart as I believe he designed a studio in Canada where they had to soffit around the columns and he got good results.)


Another suggestion - looking at your sketch - is possible a corner control room design? With the rear of the control room against the southeast corner?

One strange thing I noticed n your sketch is the door location to the control room. It may be difficult to achieve symmetry with the door there because that is prime treatment area. You also show the a door swing in the TREATMENT as opposed to the rooms INNER-leaf. It may be a better idea to have the entrance in the rear of the room?





here's a link to my thread
http://www.johnlsayers.com/phpBB2/viewt ... 9&start=15

[kywoman]

Hi richroyc!

I look forward to reading your build more thoroughly. Looks like you've made a lot of progress!

Your post came 45min before I met with a structural engineer. Looks like I get to do some sistering wherever the CR is placed... When I asked him about moving the structural columns/beams, he got pretty wide-eyed. He wasn't able to give any useful estimate on cost, other than to say "it won't be cheap."

I've done some additional layouts based on your suggestion, including angling so rear is SE, but that means two doors, one for studio access, and then a second to access the sink and workbench space 'trapped' behind it. As the NW corner has water access and the SW corner has the electrical panel, I'm thinking middle of the room may still be the best balance of space and budget. Not a 'closed' issue, of course . Thanks for the reply!

[kywoman]

I've read much on 3 vs 2 leaves, but am still uncertain on how to best approach the leaves of this design. I'm confused about distances between leaves; is there a critical distance for leaves to / to not influence the TL, especially low frequencies, in a meaningful way?

Pictured is a single leaf for the control room side walls and two leaves for front and back. Front would be the soffit, of course, and the rear would have some membrane traps and diffusors flush to interior wall. The existing garage walls have 1/2” GWB on 4-3/8” width studs at 24”, and a 6” depth before a 2.5 foam (XPS) sheet, then concrete. The doors, both small and large (car), are insulated. Note how the front wall changes to a garage door around the left front speaker.

My original plan was to do two leaves all around the room, but I'm now wondering how the existing walls affect each side.
How would you frame this room? If that's too broad of a question, would you still do two leaves on front and back?

My primary concern for TL is low frequencies.

Thanks

leaves CR walls iso.png

leaves CR inside garage.png

[Soundman2020]

Hi there "kywoman", and welcome!

Sorry for the delay in replying to your thread... there's a lot going on with the forum, and only one of me!

on 4-3/8” width studs at 24”,

4-3/8" is a strange size. Not one of the common dimensions. If it was a normal 2x4 it would be about 3-1/2", and if it was a 2x6 it would be about 5-1/2". 4-3/8"? Nothing wrong with that, of course. It's just unusual. Any idea where it came from?

The garage walls have 1/2” gypsum wallboard (GWB) on 4-3/8” width studs at 24”, and a 6” depth before a 2.5 foam (XPS) sheet, then concrete

So you already have a 2-leaf system there... Anything you add to that will make it 3-leaf. That said, it seems that this won't be an issue, as you are planning to have your CR far away from three of the walls: only one of them might be an issue. Those strange studs: Are they attached to the ceiling joists up above?

Calculation of live and dead loads for ceiling, calculate what weight can safely be added

Is there a reason why you don't want to build a proper isolated ceiling as part of the CR?

REW was used to see where the loudest frequencies occurred.

How did you calibrate REW? With a hand-held sound level meter? If so, it would be best to use that to measure your levels, instead of REW: REW is good for doing acoustic analysis, but only as accurate as the calibration you give it...

Garage measures 35 dB ambient

A or C? There's a big difference...

A 90 dB noise

What "noise" was that? And was it A or C weighted? There's a major difference between using a bass cab to provide a 90 dBC source, and playing the radio loud to provide 90dBA of an opera singer...

So the garage confers 15-20 dB TL from outside

That's about right for a typical unsealed garage, but it would be good to know more about the noise spectrum you used...

Ideally I’d like another 50dB TL inside the studio,

For a total of 65 to 70 dB? That's a real tall order. That's about the limit of what you can hope to get for a very well designed isolation system, that is very well built, in a home studio scenario. Getting more than that requires some different techniques, different materials... and a different budget! (Add a couple of zeros...). Are you SURE you need that much? Most home studio builders are happy to get 50 dB, and ecstatic if they hit 60 dB of isolation. Each time you go up 10 dB, you make it ten times harder, as you need to block ten times as much sound. Going from 20 dB to 50 dB, you need to block a thousand times as much sound, but going from there to 70 dB means blocking a hundred times more, or one hundred thousand times the original level... Big numbers. Hard to do. Big money.

I'm not saying it can't be done: I'm just saying it is hard to do, and I'm not convinced you need it at all, for just a control room, especially considering that you said... : "...

...which would make monitoring levels (commonly around 75dB, rarely above 90dB)

If you are monitoring at 75 dB, then why do you thing that you would need 70 dB of isolation? That doesn't make sense. If you told me you were going to be tracking a death-metal rock band in there at 120 dB, then I could understand it, but why do you need such extreme isolation for just a control room that you will be using at very quiet levels anyway? Is there something very loud outside that you are trying to block? Does your neighbor throw loud parties all the time, or you live next to an airport, or a zoo, or something like that? I'm intrigued about why you need such high isolation...

I could add a third post (shown in yellow) for symmetry.

... or you cold replace that beam with a steel beam, and move the posts far enough apart that the entire control room could fit between them. It sounds like a humongous major scary expensive job, but it's actually not that bad. I have done that for a couple of my customers, and several forum members have done the same thing. Richroyce is one of those guys, and he did it right. It makes things so much easier...

I’ve placed a very basic outline of the footprint of an RFZ room on the floor

Right, but that's only the inner-leaf outline I see there. You'll also need to extend the outer-leaf around the room, to isolate it properly... especially for the extreme levels of isolation you want. And your door is very much in the wrong place: you certainly don't want a door in your speaker soffit! Move it to the middle of one of the walls.

What do you think of this placement? Would you do something different?

I can't make out the dimensions on your diagram very well (nice SketchUp work, by the way!). but I suspect that you might be able to rotate that 90° to the right (so that it faces the top of the page) and fit it into the existing space, without needing to move the support posts. Did you try out that orientation?

What size control room are you looking for? How many people do you need to fit in there, max.?

What is the available height at present) (From surface of the floor to the bottom of your joists )



- Stuart -

[Soundman2020]

When I asked him about moving the structural columns/beams, he got pretty wide-eyed.

Hmmmm... a structural engineer who is afraid of structures? Hmmm.... Maybe talk to richroyc by PM, and get the contact details for his engineer... It really isn't as big a deal as it might sound. Yes, it does cost money, and yes, there's work involved, but it's not like re-building the entire house... It only involves temporarily supporting the load in other ways, taking out the wood beam, putting in the steel beam, re-attaching everything, then taking out the temporary supports. You an re-use all of those materials for the actual studio, if you work carefully....

I've read much on 3 vs 2 leaves, but am still uncertain on how to best approach the leaves of this design.

The basic concept here is that you need to build a "U" shaped wall around that area, attached to the existing wall on the fourth side, to create your outer leaf. Then you build the studio within that, as a stand-alone structure that does not touch the outer-leaf at any point.

I'm confused about distances between leaves; is there a critical distance for leaves to / to not influence the TL, especially low frequencies, in a meaningful way?

Yes. Basic rule of thumb is to never have a gap less than about 4", or the MSM gets too high. You do need to calculate that, of course, to make sure it is at least an octave lower than the lowest frequency that you need to isolate.

Pictured is a single leaf for the control room side walls and two leaves for front and back.

Why? I don't understand the reasoning for that. Why not just use a conventional design?

Front would be the soffit, of course, and the rear would have some membrane traps and diffusors flush to interior wall.

Those are not leaves, and I would not recommend using only membrane traps on your rear wall.

Note how the front wall changes to a garage door around the left front speaker.

What is your plan for dealing with that?

would you still do two leaves on front and back?

No, and what you describe are not leaves anyway!

What I would do is a conventional 2-leaf system: beef up any weak parts in the existing wall/ceiling, then build the rest of the outer leaf that will enclose your studio, then build the single inner-leaf inside that shell.

Your drawing shows your support posts inside the CR: you can't do that if you want extreme isolation. You have to get rid of them.

One other thing: you do not need to splay the side walls of your room: it wastes space, provides no real benefit, reduces room volume, makes construction more complicated, and costs you more money. Ditto for the angled section at the top of the front wall: just build a cloud. Much easier, and almost as effective.


- Stuart -

[kywoman]

4-3/8" is a strange size. Any idea where it came from?

Superior Walls XI system - http://www.superiorwalls.com/products/xiwall.php - the studs are which use #4 rebar embedded in styrofoam with a thin gauge galvanized steel facing. This facing can only hold one 1/2” GWB. If I want to add another layer of GWB, I should rip studs to size and build a box against each stud/floor/stud/ceiling, secure it, and then attach extra layers of GWB.

Those strange studs: Are they attached to the ceiling joists up above?

Indirectly? Simplest explanation is to direct you to the link above. On the page there’s a ‘click for details’ and it will show a pic that, when you mouse over a part, it highlights the feature.

Is there a reason why you don't want to build a proper isolated ceiling as part of the CR?

I thought I could maximize ceiling height this way.

(measurements....) A or C? There's a big difference...

It’s been a while now, but as best I remember, all measurements were C-weighted. Taken via https://www.minidsp.com/products/acoust ... ent/umik-1 directly into laptop with REW, and a smartphone app. Although MiniDSP claims mic profile is pre-calibrated SPL(? I don't really understand USB-mics), I calibrated the MiniDSP mic through REW prompts/procedure, which involves using a second, independent SPL meter (smartphone apps 'Decibel 10th' and 'RTA Lite'). I used both phone and REW for the measurements to make sure they were both on par, and sure enough, they were. REW allowed me to save the various measurements and a mic on stand was less of a footprint than whatever/whomever was holding the phone, so I relied on REW. Then I promptly lost all measurements about a month later in HDD issue.

What "noise" was that? And was it A or C weighted?

It was a pressure washer running outside the space, 90dB measured 6” or so from the engine with the same measurement systems (phone + mic)

For a total of 65 to 70 dB? That's a real tall order... Big money!

Cancel the order! There won’t be pressure washers running immediately outside the studio I’ll be happy with modest isolation.

why do you thing that you would need 70 dB of isolation?

I don’t. Thanks for putting things in perspective!

Richroyce is one of those guys, and he did it right. It makes things so much easier...

I will revisit. In the interest of budget, my thought was to leave them as is and coat the steel posts in a damping product like this http://www.atsacoustics.com/quietcoat.html , and then possibly add a fiberglass blanket or something else… It seems like the only other option, besides what you proposed, would be to notch out an area of the glulam for some neoprene etc. decoupling between the wood beam and steel posts.

Rotate that 90° to the right (so that it faces the top of the page) and fit it into the existing space, without needing to move the support posts. Did you try out that orientation?

Yes, and unfortunately it can’t work. My wife refuses to lose both garage doors, so this is a compromise. Other issues with that orientation, but one of the biggest is losing both garage doors.

What size control room are you looking for? How many people do you need to fit in there, max.?

Nothing crazy, just want a good sounding room for mixing and mastering. Not any recording. It will be just me 80% of the time (and some dogs!), and only a couple of folks that remaining time. I just want to make the best use of the space possible. As such, here’s (http://amroc.andymel.eu/?l=17.9&w=13.48 ... ue&r60=0.6) a rough approximation of what I’d have in the interior dimensions of the room.

What is the available height at present) (From surface of the floor to the bottom of your joists )

115 (9’7”). There are some places where that isn’t available, around HVAC (front of room, main reason for splayed top of front wall!) or glulam beam.

Yes. Basic rule of thumb is to never have a gap less than about 4”.

If pink fluffy is inside GWB, that fiberglass is part of the mass, not space/gap, correct?

Pictured is a single leaf for the control room side walls and two leaves for front and back...

I wasn’t done! That is, I just wanted a basic, ahem, framework of things to post the proposed room. I was changing between independent walls, staggered stud, and nearly always in general confusion, every week it seemed liked for various reasons, so I finally just went for holding off on it until I was done. Likewise, rear wall treatments are by no means finalized. Once I get the leaves straightened out, then onto refining the other parts!

Note how the front wall changes to a garage door around the left front speaker.
What is your plan for dealing with that?

I don’t know! I am hoping for suggestions of those more learned than I, but those suggestions must respect the issues at hand, i.e., garage door has to stay, and while I can lose the motor and track away from the door, I need to keep the track so that the garage door can be raised to top of joists if needed in an emergency. The front wall area changes from concrete wall to 7’ x 8’ insulated garage door. I can’t remove the garage door and seal it with similar materials in the Superior Wall system. I realize this will compromise TL, and that’s OK. It has to be OK, because as of now there's no other option I'm allowed by the wife. She insists on the home not looking different from the outside, and we still have one functional garage bay. I'll install vertical track above so I can raise it 2’+ in an emergency, but otherwise I plan on putting various rubber jambs, blocking, silicone, etc. to ensure a water tight seal. So... how about I.e., treat the garage door itself as the concrete wall and put a 2.5" sheet of EPS or XPS against it, then frame studs at 6” depth, and add two 5/8” GWB on the studs?

The basic concept here is that you need to build a "U" shaped wall around that area, attached to the existing wall on the fourth side, to create your outer leaf. Then you build the studio with that, as a stand-alone structure that does not touch the outer-leaf at any point…

What I would do is a conventional 2-leaf system: beef up any weak parts in the existing wall/ceiling, then build the rest of the outer leaf that will enclose your studio, then build the single inner-leaf inside that shell.

So, ignoring the splayed walls and upper part of front wall, is the attached pic correctly interpreting how you’d frame this space?

The walls are not in their exact final position, note how left side by garage NW bay has a greater gap than the electrical panel side. I’m just doing a rough sketch right to see if I’ve got the correct general location. From there, I’ll get into exact symmetry et al.

As for the splayed front wall, there were a couple of reasons for that, but the gray box running through it in the first post is actually the HVAC supply that runs the perimeter of the garage. Those are all tied to points in the floor above, and, AFAIK, isn't really movable without breaking the budget. So the HVAC run will penetrate that area of the framing. Will do whatever sealing / insulation I can to minimize the TL that's compromised by this. Loose fill of insulation? GWB or OSB frame surrounding duct?

Splayed side walls: on side with electrical panel, I have to keep a 3' opening directly in front of it. On the side with the unused garage bay, I need to keep away from the garage door track that ends 9' from the front wall (shown as 'garage opener rail 9'). After those points, I have more freedom. I realize rectangle rooms are easier to predict the acoustical issues, but this way I can make as much use of the space as much as possible.


Thanks Stuart, I'm very grateful for your input and involvement!