New home studio build

[Soulshaker]

Hi All,
I'm building a home recording studio and feel blessed to have found this forum! I've spent some time learning from here and Rod Gervais's book as well. I added an addition to my existing attached garage, so far just the outer shell. I'm planning now to finish the inner section of addition which will be my tracking room and will have to finish out the control room section afterwards. I believe a 2 leaf wall system with room within a room completely decoupled from outer shell is the way to go. I have neighbors 130ft away and my attached house is bigger concern. I attached plans & pics of the build we did and the proposed plans for internal room. I'm hoping to get a confirmation from the experts here that I'm on the right path.

I'm not sure if the ceiling & walls of outer shell need sheetrock inside the studs & scissor joists against the 1/2'' OSB?

Or should I just Insulate the outer shell and then insulate my inner shell with 2 layers of sheetrock/green glue on the inside wall?

Thanks for all your time & expertise,
Jason Newcomb

[Soundman2020]

Hi there Jason, and Welcome!

Nice looking place, with lots going for it! It's great to see you did scissor trusses there, so you'll have space for all your HVAC ducting and silencer boxes and still be able to get nice high inner-leaf ceilings.

I believe a 2 leaf wall system with room within a room completely decoupled from outer shell is the way to go.

Yes, but I'm not sure you grasped the implications of "two leaf": You already HAVE one leaf in place: The shell of the building is your outer leaf. So you only need one additional leaf, which is the actual structure of each room. The term "room in a room", means that the building itself is the outer "room", so you only need to build the inner "room", which will be just simple stud-framed walls and ceiling with sheathing onl just one side of the studs. That's all. You will have one such room for your live room, and another for your control room: both of them will sit next to each other inside the shell that forms the outer leaf.

I'm not sure if the ceiling & walls of outer shell need sheetrock inside the studs & scissor joists against the 1/2'' OSB?

That depends on how much isolation you need, and what frequencies you need it at. If you only need low to moderate isolation then you can probably go with just the existing sheathing, but if you need higher isolation then it would be good to "beef up" that outer leaf with additional mass, up between the studs and rafters.

What is your target isolation level, in decibels?

Or should I just Insulate the outer shell and then insulate my inner shell with 2 layers of sheetrock/green glue on the inside wall?

You will need insulation completely filling the air gap between the outer-leaf and the inner-leaf. That's an integral part of how the MSM isolation system works. So regardless of whether of not you beef up the existing sheathing, you WILL need insulation filling the entire gap.

- Stuart -

[Soulshaker]

Stuart,
thank you for the reply! Yes I understand that the outer shell is one leaf etc..what I meant is I'm not exactly sure with the outer shell how I should go about adding mass and if I should put a layer of sheetrock in there. I did some baseline decible readings by having a drummer play in the studio inside the tracking room with 2 QSC KW153 main speakers in deep mode with a backing track of guitar & bass up to matching volume. It read 111 decibles in the room. Upstairs in my house the loudest reading I got was 82 decibels in the master bedroom which is up that main wall where the addition joins the existing house. The rest of the inside was around 50-56. Outside of my neighbors house 130 ft across the street was 75 on their front steps. My goal is to get it down to where they can't hear anything inside their house and hopefully not much inside mine. I have 11 rolls of mass loaded vinyl that was given to me that I could incorperate into this if it makes since. Also I was planning on using 2 mini-split system for the HVAC, do you see a downside to that instead of duct system?

[Soundman2020]

It read 111 decibles in the room.

With live acoustic drums plus the speakers, if you only got 111 dB I suspect that you measured on "A" weighting. You should measure on "C" weighting for loud sounds. "A" is for quiet sounds. A typical drummer can put out 115 dBC all by himself without breaking a sweat, and closer to 120 if he tries hard. Add in the speakers with the backing track, and I'd say that you were close to 120 dBC in there. Next time you measure, do make sure that your meter is set to "C" and "Slow". Also, check that it is calibrated, if you have access to a calibrator.

But anyway... "Upstairs in my house the loudest reading I got was 82 decibels". So you got about 29 dB of isolation. That's very typical of ordinary house walls and ceilings, so not surprising.

So you have answered one of the two key questions here: "How loud are you?". The other question that you still need to put a number to is "How quiet do you need to be?" You can estimate that using your meter, by measuring the ambient levels in the target location you mentioned, late at night when it is very quiet, and there's no noise going on anywhere. Measure in the same places as you did here, to get that lowest level, then subtract that from the higher levels, and the difference is how much isolation you need.

The rest of the inside was around 50-56.

Still pretty high. Very audible, and probably annoying. Most people judge that something like 35 dBC is acceptably inaudible, or maybe 40 or even 45 dB if the ambient level is a bit higher. So your levels are 15 to 20 dB higher, which makes them "not very quiet".

Outside of my neighbors house 130 ft across the street was 75 on their front steps

Also pretty loud! Drums at 75 dB would not be something I'd want to hear from my neighbors, and I'd be very tempted to have a chat with the cops about that, if it happened regularly!

My goal is to get it down to where they can't hear anything inside their house and hopefully not much inside mine.

So very roughly, you would need an additional 40 dB of isolation, above and beyond what you already have, to achieve that goal. You already have 20-something, so we are looking at a total upwards of 65 dB isolation. That's do-able, but not easy, and not cheap. The practical limit for home studios is around 70 dB: getting more than that is VERY hard to do. Most home studios get around 50 dB isolation, maybe 60. That would be realistic.

You didn't mention budget, but that's an important issue. The higher you go in isolation numbers, the higher and HIGHER you go in cost. Exponentially. The reason is not hard to understand: The decibel scale is already logarithmic: each time you go up ten points on the scale you are MULTIPLYING the energy levels by ten. To put that in perspective, to get from 30 dB of isolation to 40 dB, you need to block ten times more energy. To get from 30 dB to 50 dB, that's two "steps of ten", so you need to block 10 x 10 = one hundred times more. To get from 30 dB to 60 dB, you need to block 10x10x10 = one thousand times more energy. And from 30 to 70 dB you would need to block ten thousand times more energy. That's scary, when you look at it from pure math numbers. And it pans out in real life, not just on paper. Fortunately, there are some things you can do to increase isolation without going to extreme expense, but for high levels, it gets expensive.

Not trying to scare you! Just pointing out reality.

I have 11 rolls of mass loaded vinyl that was given to me that I could incorporate into this if it makes since.

If you have it, then you might as well use it. Especially if you got it for free. But it's not something that studio designers and acousticians normally recommend for home studios. It works, yes, because it has mass, and mass is what stops sound. But MLV is very expensive mass, and sound waves really don't care what the price tag was for the mass. They just react to the mass, not the price. So it makes sense to get the least expensive mass that will do the job, and usually that is plain old 5/8" drywall. Now, 11 rolls won't go very far, so I would save that for the toughest spots, and just use ordinary dyrwall, MDF, OSB, plywood, and similar products for most of your mass.

Also I was planning on using 2 mini-split system for the HVAC, do you see a downside to that instead of duct system?

You still need ducts! You need to get fresh air into the room and remove the stale air, so you have to have ducts and silencers and fans. That's a given for studios. So there's not a lot of difference between using a ducted mini-split or a non-ducted mini-split. The only thing that changes, is where you mount it. T There are pros and cons both ways, but for the majority of studios that I design, I put a ducted mini-split outside the isolated area of the studio, and that feeds into a duct system, into the rooms. I do this to keep all the noise outside, and also for other reasons, such as simple access for cleaning, maintenance, repairs, replacement. But sometimes I do non-ducted or "ductless" mini-splits inside the room, when there's no other easy options. Both can work.

- Stuart -

[SGleason]

The decibel scale is already logarithmic: each time you go up ten points on the scale you are MULTIPLYING the energy levels by ten.

Excellent explanation of logarithmic as it relates to sound control.....a very important concept but one lots of folks I speak with can't quite wrap their heads around.

Nice looking space, Soulshaker. I'll be following the build.

Steve

[Soulshaker]

Thanks again for your expertise. I Really missed the boat on the HVAC, I was completely ignorant of how the mini split system works and didn't account for fresh air. I'm going to look into this and the options but I'm scheduled to frame & sheetrock the inner shell soon. My HVAC guy was going to install the mini split after that so do you think its still doable to do HVAC work afterwards and add a way to get fresh air? Is there anything other than a layer of sheetrock & regular pink insulation that should go up into outer shell ceiling? I'm talking about adding 5/8" sheetrock layer up against the OSB at top of ceiling. Also I'm not sure if I should fill more insulation where it gets deeper in scissors joists or keep it all 1 layer throughout.

[Soulshaker]

It read 111 decibles in the room.

With live acoustic drums plus the speakers, if you only got 111 dB I suspect that you measured on "A" weighting. You should measure on "C" weighting for loud sounds. "A" is for quiet sounds. A typical drummer can put out 115 dBC all by himself without breaking a sweat, and closer to 120 if he tries hard. Add in the speakers with the backing track, and I'd say that you were close to 120 dBC in there. Next time you measure, do make sure that your meter is set to "C" and "Slow". Also, check that it is calibrated, if you have access to a calibrator.

I ran another decible test using C weighting/slow with my QSC mains sans drummer. I could only get up to 117 db in the room because of system limitation. My closet neigbors read 78db and my loudest room in my house was 85. Seems to be inline with what your saying. My budget right now is $13,000. I realize I will need more $ to completely finish. I have enough to add a layer of sheetrock to the OSB in outer shell & insulate. Frame inner shell, insulate, 2 layers of 5/8' sheetrock with green glue. install mini split system. A friend who is an electrician is doing all electrical for trade. I'm reading up on the fresh air dilemma in Rod Gervais's book and it is somewhat over my head. I'm going to get HVAC guy to read as well. In my region building guidelines call for R30-60 attics & R13-15 for walls. I'm not sure exactly what to use in the outer & inner walls & ceilings.

[Soulshaker]

You need to get fresh air into the room and remove the stale air, so you have to have ducts and silencers and fans. That's a given for studios. So there's not a lot of difference between using a ducted mini-split or a non-ducted mini-split. The only thing that changes, is where you mount it. T There are pros and cons both ways, but for the majority of studios that I design, I put a ducted mini-split outside the isolated area of the studio, and that feeds into a duct system, into the rooms. I do this to keep all the noise outside, and also for other reasons, such as simple access for cleaning, maintenance, repairs, replacement. But sometimes I do non-ducted or "ductless" mini-splits inside the room, when there's no other easy options. Both can work.

- Stuart -

I've spent the last few days researching in this forum and Rods book as well. If I do use the ductless mini-split system would this be inline with what I would use for fresh air?
https://www.amazon.co.uk/Recovery-Venti ... l_huc_item

[Soundman2020]

I've spent the last few days researching in this forum and Rods book as well. If I do use the ductless mini-split system would this be inline with what I would use for fresh air?

Mini-split systems provide only cooling, heating, and dehumidification. They do not provide fresh air. That applies to both ducted systems, and also non-ducted (ductless). In both cases, you still need ducts to provide the fresh air, and to remove the stale air.

- Stuart -

[Soulshaker]

What I meant was if I'm using ductless mini-split system would I also add a separate HRV or ERV system? I was speaking of this attachment.

https://www.amazon.co.uk/Recovery-Venti ... l_huc_item

[Soundman2020]

What I meant was if I'm using ductless mini-split system would I also add a separate HRV or ERV system? I was speaking of this attachment.

Ahh! OK. Now I get it. I missed the link.

HRV's can save you on cooling costs if there is a fairly large difference between indoor temperature and outdoor temperature. ERVs do the same, but the also deal with humidity, so if there is a large difference between indoor humidity and outdoor humidity, then an ERV might be a better option than an HRV. If humidity levels are similar, then just an HRV would be fine. And if your climate is mild, without large differences in temperature between indoors and outdoors, then you don't even need the HRV. All they do is save you on cooling or heating costs, because they can recover some of the heat in the incoming fresh air or outgoing stale air, and transfer it to the other stream.

For example, if it is hot outside, then dumping the cool indoor air (which you spent money to cool) seems like a waste, when you are going to replace it with hot air from outside that then needs cooling. An HRV transfers some of that incoming heat to the outgoing air, so the incoming air gets cooler, and the outgoing air gets hotter. Viewed from a different perspective, you transferred some of the "coldness" of the stale air back into the fresh air, so the "coldness" isn't wasted. But an HRV is only efficient of the temperatures are very different, such as maybe 21°C inside but 35°C outside. If it is 21°C inside and just 23°C outside, you don't get much heat transfer, so it isn't worth it.

So, depending on your climate, you might not need any HRV, or it might help you a lot. The same applies to an ERV if you also have large humidity differences between indoor air and outdoor air.

- Stuart -

[Soulshaker]

What I meant was if I'm using ductless mini-split system would I also add a separate HRV or ERV system? I was speaking of this attachment.

Ahh! OK. Now I get it. I missed the link.
- Stuart -

I live in Virginia. Here is the yearly temperature & humidity averages. June through August does get humid. Do you feel like an ERV system is warranted in these conditions?

[Soulshaker]

Hi all, I wanted to double check that the 2 leaf system I am building is correct. My layers of wall build going from outside of my shell to inner walls is-

OUTSIDE SHELL SITTING ON CINDERBLOCK FOOTINGS
vinyl siding /1/2" OSB / 2x4 studs / 5/8' drywall in-between studs with backer rod & caulk / R-13/insulation / 2" air gap

INSIDE SHELL SITTING ON CONCRETE SLAB
2x4 studs / R13 insulation / 5/8' drywall / green glue / 5/8' drywall


On my ceiling of outer shell I don't see how I could put drywall between the studs to add mass as Im doing on walls because there are roofing nails sticking through the OSB. I was going to grind them flush but was advised by a roofer not to because it weakens shingles. I have 11 rolls of mass loaded vinyl that would be enough for ceiling. Could I put strips of MLV on furring strips in-between the scissor joists on OSB to add mass?

[Gregwor]

It looks like your "attic" need to breathe. So your outer leaf would be inside out modules that slide up in between your joists. Insulate above those like a normal attic. I could be wrong here, but that would make the most sense to me and is how I will be doing my live room.

Greg

[Soundman2020]

there are roofing nails sticking through the OSB. I was going to grind them flush but was advised by a roofer not to because it weakens shingles.

Right! Never, ever grind or cut protruding nails in roof decks. What you could do if you want to "beef up" the mass (and assuming that your ceiling is not vented-deck, and that the trusses have the load bearing capacity to support it) is to press Styrofoam panels of just the right thickness over the nails, then beef up over that in the normal way.

R-13/insulation / 2" air gap

Fill your air gap with insulation too, not just the framing. Completely filling the entire cavity is necessary to get maximum damping and maximum reduction in speed of sound, and therefore maximum reduction in MSM resonant frequency, which maximizes isolation.

Could I put strips of MLV on furring strips in-between the scissor joists on OSB to add mass?

I doubt that would work. How would you keep it in place? How would you seal the joints and the edges? Air-tight seals are critical for isolation. I would save your MLV for tuned traps and beefing up the speaker soffits, for example. Or return it to the store for refund.

It looks like your "attic" need to breathe.

Very likely. That looks like a ventilated deck roof, probably with air inlets under the eaves and a ridge vent on top. That has to breathe. And therefore cannot be the outer-leaf of the MSM system. Sometimes you just have to go three-leaf.

So your outer leaf would be inside out modules that slide up in between your joists.

That would work, but it would be complicated to do with scissor trusses, due to the the angels of the various components. The modules would have to be strange shapes and sizes, with tapered framing. It would be easier / cheaper / faster to just put up OSB and a couple of layers of drywall directly on the bottom of the trusses, and seal that to the walls. That leaves the entire attic space free to ventilate, then you can build the complete inner-leaf room within that "shell". With an inside-out inner-leaf ceiling there would still be plenty of ceiling height.

- Stuart -