John Sayers' Recording Studio Design Forum Archive

2. I've researched multiple designs, but still haven't gotten a solid answer on the air lock. I've been getting feedback from a few venues outside of this forum and no one seems to have agreement on the airlock and if it will be a triple or quad leaf affect when there is a 46" gap between leafs.If nobody has given you a straight answer then nobody has done the math! It's that simple. There are equations for figuring this out. All you have to do is to plug in the numbers, do the math, and see what comes out.

But my question would be even more basic: Why are you wasting space with a sound-lock, when you don't need one! ? Who told you that you need a "sound lock" like that on a home studio?

In reality, you do NOT need a sound lock: A simple pair of doors, back to back, with one door in the onner leaf and one door in the outer leaf, is all that you need. Anything beyond that is wasted, or at best, over-kill.

In an earlier post, you said "I didn't really see a point because i'm not doing back to back doors.", and my answer to that would be, once again, "Why?" Why are you not doing back-to-back doors? How do you plan to get high isolation if you don't terminate the leaves correctly?

The airlock is definitely not necessary, no one told me I needed it. It was created due to the layout of the room. I'm trying to isolate the utility room as well from the bedroom and studio, but I also needed that alcove to have access to BOTH utlity room and bedroom without sacrificing more space of the bedroom. So thats why that little hallway is there, not because it was designed purposely. Doing back to back doors here only creates an issue because one of the doors would swing INTO the bedroom which I'm trying to avoid. The other option I have is to do the following and use two sets of double doors, or a super door for each (as pictured)

I also have to add: I don't even see where the door into your "Drum Room" is! I see doors into the hallway outside, and into the bathroom, and into the bedroom, but none into the drum room.... Is your access into the room through the double windows on the left? Are those actually sliding glass doors? IF that is the access path into your drum room, then why do you have a sound-lock on the bathroom and bedroom?

I guess I'm just not understanding what you are trying to achieve here... I don't see the reason for the sound lock to start with, and I don't understand the implementation either: it is not going to work with the way you are showing it so far.

There are three options really:

But you only show two of them, neither of which is correct!

c. Add a double wall around EVERY wall because this system will react as one system so using a quad leaf will ensure better isolation even though it's not the ideal 2 leaf system

That would be a mistake too.

If you really do have your heart set on a sound lock (even though you do not need it), then the correct way to implement it is the same as any other pat of a studio: two-leaf walls on all sides, with back-to-back doors in each leaf. So you would need at least six doors there....

I also forgot to mention that i'm officially going with mini splits now in each room.It is usually cheaper to go with a single ducted AHU that can handle both rooms. You can do individual units in each room if you want, but they are not 100% silent. That might or might not be a problem.

The AHUs i looked at didn't have any cooling capacity. Maybe i'm just not searching in the right place so if you have a suggestion I'm all ears. Heating is the last of my concerns considering how much heat will get produced in the room. AC and fresh air are the two major factors.

I'll be adding a SHR150 HRV for fresh air for each room as well.

My favorite question again: Why? For what purpose do you need TWO HRV's when you already have two mini-split systems? And why did you choose HRV's, instead of ERV's? Did you do the math, and prove that you will get the savings you expect, to offset the investment? Over how many years?

Also, where will your fresh air intake be for each room? And where will your stale air exhaust go? And what portion of make-up air will you be adding to the flow? How will you vary that for different room occupancy loads?

Slightly confused at your comment here. HRV does indeed bring fresh air into the room and remove stale air. I'm assuming 5 total air changes per hour which the 159 cfm of the HRV should be able to accomplish. An ERV won't be necessary as humidity should not be a problem here. As for the silencer boxes, I have seen recommended designs using both single and double baffle boxes on each vent. The common feedback is "depends on the isolation you need" yet I haven't come across any equations or calculations to help one decide if 2 or 4 are necessary per room. Any direction here would be great!

Thanks for all your feedback Stuart!

Soundman2020 wrote:

Due to the negligence of my initial builders of my home, I decided to build a separate 2x4 stud wall 1" away from the pre-existing one that is touch the concrete.

One more thing here: are thos "walls" load-bearing? Ie, are they structural? Holding up something above? Get a structural engineer in to examine them, and tell you for sure. If they are NOT load bearing, them take them out! They serve no useful purpose like that. Just wasting space... To me, it looks like they are merely framed up ready for drywall. If you can take them down, then do so carefully so you can re-use the wood.

- Stuart -

The walls appear to be bearing the load against one wall. On top of that, my contractor said it will be more expensive to demo the existing wall instead of just building another one. That was the reason for doing seperate walls

Also, regarding your question on the entrance to the drum studio, those are sliding doors marked by "7065 SL" Not sure if the nomenclature or abbreviations are different in other parts of the world, but I've always known that to be 7'0" x 6'5" Slider. I will be using two of these back to back as outlined in many of John's designs.

Hope that helps explain the current status a little better!

I'm still trying to get a handle on what you want to do here, since the diagrams don't seem to match what you are saying. So let's start with an even easier diagram, color coded: So, to clarify: the actual "studio" part is the drum room, at the top, colored blue. There is NO access to this room through the sound-lock. The ONLY access is through the purple doors, and that leads to the yellow area, which I am assuming is just part of the house, and is not isolated.

Is that it?

So the sound-lock is for the BEDROOM (colored red here), and is NOT for the studio. Correct?

And what you are calling the "utlity room" is the part marked in green, which is actually labeled "bathroom" on the drawings. Correct?

Why do these rooms need to be isolated? Will there be something very loud going on in the bedroom that you need to keep out of the rest of the house? What is going to be in there, that needs to be isolated?

Ditto for the bathroom/utility room: Will there be something very loud going on in there that needs to be isolated from the rest of the house, including the bedroom and the studio?

because one of the doors would swing INTO the bedroom which I'm trying to avoid.

Why? For what reason do you prefer to not have doors opening into your bedroom? It is normal practice that doors open into bedrooms, not out of them. It an be done both ways, of course, but it is far more common to have doors opening into rooms.

The other option I have is to do the following and use two sets of double doors, or a super door for each (as pictured)

That's the best option I have seen so far! It's the only one that has the isolation envelopes complete.

The AHUs i looked at didn't have any cooling capacity. Maybe i'm just not searching in the right place

Definitely not looking in the right place! A ducted mini-split AHU is practically identical to a non-ducted unit, except for the housing. This is one I spec'd for a studio in Nashville last year: That's far too big for what you need, but it gives you an idea of what they look like and how they work. It's basically just an ordinary mini-split with duct flanges and no pretty casing around it.


Do a google search for "LG EM_MultiV_Ducted_IndoorUnits" and donwload the entire PDF catalogue, with all the models. Other manufacturers have equivalent models (Mitsubishi, Carrier, etc.)

Heating is the last of my concerns considering how much heat will get produced in the room. AC and fresh air are the two major factors.

Exactly. You were probably looking for furnace AHU's, not A/C AHU's.

where will your fresh air intake be for each room? And where will your stale air exhaust go?

Slightly confused at your comment here. HRV does indeed bring fresh air into the room and remove stale air.

You are missing the point entirely: the question is not about what unit or fan you will use, but WHERE you will get that air from. In other words, where is the physical air intake register on the outside wall of the building? You say you plan to have two HRV's, so you will need TWO such intake registers, and they cannot be physically close to the exhaust registers on the outside wall of the building, where you will be dumping the stale air.

As for the silencer boxes, I have seen recommended designs using both single and double baffle boxes on each vent. The common feedback is "depends on the isolation you need" yet I haven't come across any equations or calculations to help one decide if 2 or 4 are necessary per room. Any direction here would be great!

Have you defined how much isolation you need, in decibels? I would say that anything over about 40 dB or so will need a box on each leaf penetration. You MIGHT be able to push that to 45 or so, but I can't see it being possible beyond that.

my contractor said it will be more expensive to demo the existing wall instead of just building another one.

Maybe you need a new contractor! Give me half an hour with a good sawzall, and I'll have that out! It is just FRAMING... And very poorly done framing, at that. Do not trust your contractor to give you answers on structural issues: call in a structural engineer, pay his fee, and ask him all the questions you need to ask him. He's the only guy qualified to tell you if that is load-bearing or not. There is only a single top plate on there, the nailing is not up to par, and I doubt it meets code or passed inspection. To me, it does not seem to be load-bearing, but I'm not there to examine it properly, and I'm not a certified structural engineer in your city in any case...

If that were my room, I would call in the engineer, find out if it is load.bearing or not, and if so, I'd spend a few minutes with some basic wood working tools ripping it out, but carefully so that I can re-use the wood later. Then I'd re-design the room as big as possible, without losing all those dozens of square feet of very precious room volume.

7'0" x 6'5" Slider. I will be using two of these back to back as outlined in many of John's designs.

John uses ACOUSTIC rated sliding glass doors, not the type you buy in Home Depot. That's a drum room, drums are loud, and I'm assuming you want high isolation to the rest of the house. Have you quoted acoustic-rated sliding glass doors yet? They are not cheap.

We're getting there, towards a plan for your studio, but there's lots of stuff that is still up in the air...

- Stuart -

I'm still trying to get a handle on what you want to do here, since the diagrams don't seem to match what you are saying. So let's start with an even easier diagram, color coded:

Basic-layout-2.jpg

So, to clarify: the actual "studio" part is the drum room, at the top, colored blue. There is NO access to this room through the sound-lock. The ONLY access is through the purple doors, and that leads to the yellow area, which I am assuming is just part of the house, and is not isolated.

Is that it?

So the sound-lock is for the BEDROOM (colored red here), and is NOT for the studio. Correct?

And what you are calling the "utlity room" is the part marked in green, which is actually labeled "bathroom" on the drawings. Correct?

Why do these rooms need to be isolated? Will there be something very loud going on in the bedroom that you need to keep out of the rest of the house? What is going to be in there, that needs to be isolated?

Ditto for the bathroom/utility room: Will there be something very loud going on in there that needs to be isolated from the rest of the house, including the bedroom and the studio?

NOW we are rockin' the same language! LOL yes on everything you said. YELLOW goes out to the rest of the basement, partially finished. BLUE is the drum studio, and GREEN is the utility room with two furnaces and a water heater. RED is a bedroom, but also designed for a 2nd tracking room, or even a vocal/instrument booth if you will. The idea was this room wouldn't need the same isolation compared to the drum room that would be blasting at 110-120 dB SPL when a trained singing voice gets more in the 80-90 dB SPL range. The cost for me to sound proof this was a minimal adder, really the studio glass window was the only large expense, but worth it for planning ahead.

For the GREEN utility room area, there is a roughed in bathroom next to it, but not completed, just roughed in plumbing, which I'm sure caused some of the confusion on what exactly that area was. Even so, I figured it be best to isolate it from the RED tracking/bed room and BLUE studio as when I checked the noise levels from both furnaces running, it came in around 65-70 dB SPL on my meter.

BTW... LOVE the irony of you coloring the bedroom RED and then asking me "Will there be something very loud going on in the bedroom that you need to keep out of the rest of the house?" LOL Maybe... if she can pull me out of the studio and out from behind my drum kit

because one of the doors would swing INTO the bedroom which I'm trying to avoid.Why? For what reason do you prefer to not have doors opening into your bedroom? It is normal practice that doors open into bedrooms, not out of them. It an be done both ways, of course, but it is far more common to have doors opening into rooms.

The only reason to avoid that in the option 1 and 2 designs was to save floor space if I wanted to put a mixing desk or other equipment again the wall under the window. I definitely don't plan to use this as a mastering room, but having a little flexibility in layout for equipment is never a bad thing.

The AHUs i looked at didn't have any cooling capacity. Maybe i'm just not searching in the right place
Definitely not looking in the right place! A ducted mini-split AHU is practically identical to a non-ducted unit, except for the housing. This is one I spec'd for a studio in Nashville last year:
That's far too big for what you need, but it gives you an idea of what they look like and how they work. It's basically just an ordinary mini-split with duct flanges and no pretty casing around it.

Already searching... and I think your assessment was correct, I was only getting furnace AHUs instead of cooling ones

where will your fresh air intake be for each room? And where will your stale air exhaust go?
Slightly confused at your comment here. HRV does indeed bring fresh air into the room and remove stale air.
You are missing the point entirely: the question is not about what unit or fan you will use, but WHERE you will get that air from. In other words, where is the physical air intake register on the outside wall of the building? You say you plan to have two HRV's, so you will need TWO such intake registers, and they cannot be physically close to the exhaust registers on the outside wall of the building, where you will be dumping the stale air.

AH! Now I understand your comment. I already had it designed to pull air from outside along the concrete wall in the RED bedroom. This is where my other intakes are for the furnaces. The exhaust would be on the other side of the house with my two other exhaust pipes. Although looking at the installation manual for the SER 150 said you only need about 6 feet of separation, but even that seemed a little small to me.

As for the silencer boxes, I have seen recommended designs using both single and double baffle boxes on each vent.
The common feedback is "depends on the isolation you need" yet I haven't come across any equations or calculations to help one decide if 2 or 4 are necessary per room. Any direction here would be great!Have you defined how much isolation you need, in decibels? I would say that anything over about 40 dB or so will need a box on each leaf penetration. You MIGHT be able to push that to 45 or so, but I can't see it being possible beyond that.

Understood, and appreciate that direction. I'll definitely want more isolation than 40dB so I'll need to do two silencers per duct. I should have plenty of room inbetween my 2x6s and floor joists to do this, but I'll take some measurements and figure out placement tonight.

my contractor said it will be more expensive to demo the existing wall instead of just building another one. Maybe you need a new contractor! Give me half an hour with a good sawzall, and I'll have that out! It is just FRAMING... And very poorly done framing, at that. Do not trust your contractor to give you answers on structural issues: call in a structural engineer, pay his fee, and ask him all the questions you need to ask him. He's the only guy qualified to tell you if that is load-bearing or not. There is only a single top plate on there, the nailing is not up to par, and I doubt it meets code or passed inspection. To me, it does not seem to be load-bearing, but I'm not there to examine it properly, and I'm not a certified structural engineer in your city in any case...

Unfortunately it did pass inspection when the house was built. I'll be honest, our inspectors in Chicago are just as crooked as our politicians...and our contractors. You wouldn't believe the stories I have from building my house 5 years ago... Either way, I did have an architectural engineer come out and take a look. He agreed that it was questionable at best, but it would be safer just to leave it and build around. I wasn't happy with the news either, but in reality I'm not losing all that much square footage because I extended the studio into the YELLOW area to make up for the lost space. It came out to be about a 5-6 sq foot reduction.

7'0" x 6'5" Slider. I will be using two of these back to back as outlined in many of John's designs.

John uses ACOUSTIC rated sliding glass doors, not the type you buy in Home Depot. That's a drum room, drums are loud, and I'm assuming you want high isolation to the rest of the house. Have you quoted acoustic-rated sliding glass doors yet? They are not cheap. [/quote]

Agreed with you 100%... which is why i over-paid for studio sliding doors from a popular vendor that will do 65 STC, but more importantly about 40dB of isolation down at 100Hz. To be fair though, after pricing sliding doors from Veka, Pella, Anderson, Milguard, and Jeld-wen... the studio sliding doors were on par with all the others by the time I added in our insane sales tax here. So expensive, yes. Worth it? absolutely!