New Drum/Live Room Design in Chicago, IL

[Gregwor]

I agree, that is flanking.

I JUST posted before you here with basically the same question as you regarding inside out walls. It looks like a LOT more work with a ton of expensive caulking involved. However, it would be your ultimate solution. If you only leave a 1/2" gap between your inner leaf drywall you're only really losing 1/2" more than you originally had! Either that, or do a normal style wall and actually lose an extra 4" (3.5 for lumber plus 1/2" gap.

Greg

[nmk85roll]

Gregwor,

Do you have a link to your thread? That way I can monitor the feedback you get as well...

I thought about this a little more tonight, and I'm thinking maybe a good option is to go back to isolation clamps and channels on the concrete couples walls, and then continue to use the double stud walls for the wall with the sliding door and studio window as the isolation will be a little better with the glass. Do I need to worry about any impedence mismatches between a double stud wall and single stud wall will channels?

My other major concern with this approach would be decopuling my ceiling. The 2x6 beams will lay on a constructed shelf within the 2x4 wall on the right side of the diagram. Although that wall still has a decent airgap from the concrete, in some places the framing is touching the floor joists above, even though not supporting. My concern is that even though its touching slightly, I'll have another flanking path to the floor above. is this a true concern or pure paranoia on my part?

2x4touchingjoist.jpg

Studio15finalb-Model.jpg

[Gregwor]

Here's my thread you asked for. It's been a big learning curve!

http://www.johnlsayers.com/phpBB2/viewt ... =1&t=21355

I'm not the one to answer your question about impedance mismatches regarding different wall design. Sorry. Hopefully someone answers because that's a new topic I would love to learn about!

Greg

[nmk85roll]

Here is the rendering of adding a total double wall would look like. Basically, I go from 230 sq ft to 223 sq ft. The entire new wall would be added with a 0.75" airgap from the pre-existing 2x4 framing with insulation. That would bring my TOTAL air gap, between the concrete wall to the interior drywall to around 8".

Again, really trying to decide if I should do clips on two walls like the previous rendering or go with a full double wall approach as shown below.

Studio15fina_double-Model.jpg

[nmk85roll]

bump for some feedback on the proper airlock design....

[Gregwor]

Sorry I missed this. It's weird. I check this sucker every day and then a post will pop up that seems like it disappeared for a bit until it gets bumped. So strange.

Anyway, I see a lot of flanking going on in the bottom right hand side of your picture.

Screen Shot 2018-02-07 at 3.38.24 AM.png

IMO, do the full double wall thing. It's probably easier in the end, and ultimately better. Period. Just don't have flanking anywhere. It's that simple

I hope that helps a bit. I must sleep.

Greg

[nmk85roll]

didn't see your picture at first, see my next post...

[nmk85roll]

Sorry I missed this. It's weird. I check this sucker every day and then a post will pop up that seems like it disappeared for a bit until it gets bumped. So strange.

Anyway, I see a lot of flanking going on in the bottom right hand side of your picture.

Screen Shot 2018-02-07 at 3.38.24 AM.png

IMO, do the full double wall thing. It's probably easier in the end, and ultimately better. Period. Just don't have flanking anywhere. It's that simple

I hope that helps a bit. I must sleep.

Greg

Greg, I'm not concerned with the closet actually, that will be completely separate from the actual sound proofed walls so this is almost a "freestanding" wall that will be clamped into the double dry wall. That make sense? The airlock i'm referring to is the one between the 3 doors of the utility room, bedroom, and open basement area. If I do a double wall, it would be a quad leaf system now, but not sure if the 38" distance between the leaf makes it act as a separate system where I wouldn't need to worry about it.

[Gregwor]

Here is the connection point I'm worried about.

Screen Shot 2018-02-07 at 2.43.15 PM.png

Greg

[nmk85roll]

AH!!! Yes, that was me just being lazy with autocad... But a good find none the less! Here is how it should be:

greg.jpg

[nmk85roll]

A little update... 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. As discussed earlier, this gives me an 8" air gap between my concrete mass and my inner double 5/8" drywall with green glue. The inner room ceiling framing will be supported everywhere on this new 2x4 wall. In my area, it was fairly cheap to upgrade to 2.2E 2x6s so I went with those even tough I only needed 1.8E for my 14' span.

One overall comment I have from doing tons of research on here and other forums. It seems that we are all obsessed with the inner leafs and sealing them properly, yet I see maybe 10% of design threads even mention sealing the outer leaf properly! Maybe my basement wasn't as straight forward as everyone elses, but I can't imagine everyone already had a nice sealed up outer leaf. Hopefully we all aren't overlooking this! In my case I had to remove previous insulation, find where the I-jousts met the concrete, and try to seal up the outer cavity so sound doesn't travel up above the concrete walls and into the 1st floor ones. To accomplish this, I added some blocking BEHIND my existing 2x4 wall because the I joist placement wouldn't allow me to get on the other side. I then sealed the crap out of every possible gap. Now, I'm even thinking about adding a layer of drywall to the side of the I-joust tomorrow because that will now be my weakest link in the outerleaf because there is barely any mass compared to the rest of the concrete outer leaf! Point being, I can see how these types of things are very easy to over look when you are in the "planning and design" phase and can easily contribute to a decrease in isolation

outerleafgap.jpg

blockedouterleaf.jpg

Anyway, moving forward... the bottom and left wall have not changed and remain a standard double 2x4 wall with 1" air gap and 2 layers of 5/8" drywall with GG. on each side. The latest design below shows the double 2x4 walls with the concrete on the top and right walls in the drawing. The wall towards the top will now be using John's inside out wall method which I'm assuming needs to be rigid OC703 like insulation instead of standard fluffy pink stuff to get the proper absorption. I plan to use some black burlap over the insulation and hopefully some wood slats. Which brings me to my two open questions I have:

1. Should I design the wood slats over the inside out wall now or wait to do a REW analysis once the room is completed? I've seen number designs ranging from the 534 pattern, to using 468 slats with the same slot, to Rod's recommendation of using 1x6 with a 0.75" slot. In the end, this room is primarily used for drums so any feedback here is appreciate.

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. There are three options really:

a. include the airlock as part of the overall MSM system and have only one leaf on either side as pictured below.

airlock_option1.jpg

b. Continue the double leaf wall as its own system and just add standard walls on the other side not by the sound proof rooms because the distance is large enough where the triple leaf affect doesn't apply?

airlock_option2.jpg

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

Thanks in advance for your thoughts!

[nmk85roll]

HVAC Update

I also forgot to mention that i'm officially going with mini splits now in each room. I really want full isolation and decoupling from the rest of the house so it just made sense. I'll be adding a SHR150 HRV for fresh air for each room as well. Silencer boxes have not changed and will remain one on the intake and one on the outtake ducts for the HRV.

[Soundman2020]

It seems that we are all obsessed with the inner leafs and sealing them properly, yet I see maybe 10% of design threads even mention sealing the outer leaf properly!

BOTH leaves must be sealed very well. This is a basic requirement for good isolation. I try to emphasize that as much as possible. Even a tiny crack or gap can have drastic consequences. The basic rule: if air can get through, then so can sound.

but I can't imagine everyone already had a nice sealed up outer leaf.

Sealing up the outer-leaf is critical. I push that concept on every thread where isolation is an issue. Sometimes I get tired of typing the same thing over and over....

I then sealed the crap out of every possible gap.

Now, I'm even thinking about adding a layer of drywall to the side of the I-joust tomorrow because that will now be my weakest link in the outerleaf because there is barely any mass compared to the rest of the concrete outer leaf!

That would be good, yes, but instead of guessing how much mass you need on that part of the wall, you should do the math to make sure. As you say, it's the weakest link, so that's where you need to concentrate your efforts the most. So it's worth spending the time to work through the math, and double.check that that the amount you are putting on there, combined with the depth of the air gap, and the insulation fill, will produce the MSM frequency and isolation characteristics that you are aiming for.

The wall towards the top will now be using John's inside out wall method which I'm assuming needs to be rigid OC703 like insulation instead of standard fluffy pink stuff to get the proper absorption.

Either type of insinuation will work, provided that it is the correct density for the task. OC703 is easier to work with, and performs very well, but it's also a bit more expensive.

I plan to use some black burlap over the insulation and hopefully some wood slats.

Why? Not meant to be a trick question, but rather a question to get you thinking about WHY you might want slats on there. Not just because you saw it in a few other rooms that you liked, but because you NEED them there.... Did you check what acoustic conditions you will have on that wall, at that location, and figure out that the best way to deal with that was using slats? Is that going to be a tuned or un-tuned device? If tuned, what frequency range will you tune it to? If untuned what size slats will you use, and why? What size gaps will you leave between them, and why? With studio design, everything matters. Nothing can be done by guesswork, or just because "I saw that in Franks' thread, and thought it looked cool, so I'll do it too...."!

1. Should I design the wood slats over the inside out wall now or wait to do a REW analysis once the room is completed?

I'll repeat the same question as above: Why do you think you need slats on that wall anyway? If you can't answer that question honestly, with a valid acoustic reason for putting them there, then you need to do some more research.

I've seen number designs ranging from the 534 pattern, to using 468 slats with the same slot, to Rod's recommendation of using 1x6 with a 0.75" slot.

Once again, Why? Just because you saw it in a book, and Rod did it that way in some of his rooms? Or because you did the acoustic analysis of your room yourself, and it showed that you would need a binary array diffuser done with slats at that location?

I'm not trying to be denigrating here: just pointing out that rooms should be DESIGNED for their purpose, with the right treatment in the right location for the right reasons. The reason "I saw it in a book", is not valid, unless your room is identical to the one in the book, and is going to be used for the exact same purpose. If Rod was using that devices in a control room or vocal booth, and you have a drum room, then likely it is the wrong treatment. Even if Rod's room was also a drum room, it it still possibly the wrong treatment, unless your room is the same shape and size as his.

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?

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.

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?

Just pointing out things that you might have missed.

Silencer boxes have not changed and will remain one on the intake and one on the outtake ducts for the HRV.

Well, that's not going to accomplish much, is it? For a studio, you need one silencer box on EACH leaf penetration for EACH duct. So for one room, you need four silencer boxes. For two rooms it would be eight silencer boxes, although you could bring that down to six if you design carefully.

Did you do the math to determine how big the silencer boxes must be? What flow rate are you considering for each room? And what flow velocity? Did you calculate the static pressure of the system for each room, and is your HRV able to handle that static pressure by itself, or will it need booster fans? What is the latent heat load and sensible heat load that each mini-split must deal with, for both maximum and minimum occupancy, and on climate extreme days (hottest day in summer with full occupancy / coldest day in winter with minimum occupancy)?

There's a LOT of math that goes into designing an HVAC system. When I'm designing a full studio, I usually spend about as much time just on the HVAC system as I do on all of the rest of the studio put together, including structure, isolation, layout, geometry, acoustics, etc. It's a huge subject and often overlooked by first time studio builders. Which is why I'm drawing your attention to it.

- Stuart -

[Soundman2020]

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 -

[nmk85roll]

Now, I'm even thinking about adding a layer of drywall to the side of the I-joust tomorrow because that will now be my weakest link in the outerleaf because there is barely any mass compared to the rest of the concrete outer leaf!That would be good, yes, but instead of guessing how much mass you need on that part of the wall, you should do the math to make sure. As you say, it's the weakest link, so that's where you need to concentrate your efforts the most. So it's worth spending the time to work through the math, and double.check that that the amount you are putting on there, combined with the depth of the air gap, and the insulation fill, will produce the MSM frequency and isolation characteristics that you are aiming for.

Already did the math which is why I'm going with a single layer, probably add green glue inbetween as well to stay consistent with everything else. The 12" I Joists weight ~3 lb per linear foot which comes out to be ~14.5 kg/m2 which is about 40$ more mass than a single layer of drywall so adding one layer should be good.

I plan to use some black burlap over the insulation and hopefully some wood slats. Why? Not meant to be a trick question, but rather a question to get you thinking about WHY you might want slats on there. Not just because you saw it in a few other rooms that you liked, but because you NEED them there.... Did you check what acoustic conditions you will have on that wall, at that location, and figure out that the best way to deal with that was using slats? Is that going to be a tuned or un-tuned device? If tuned, what frequency range will you tune it to? If untuned what size slats will you use, and why? What size gaps will you leave between them, and why? With studio design, everything matters. Nothing can be done by guesswork, or just because "I saw that in Franks' thread, and thought it looked cool, so I'll do it too...."!

I mentioned it earlier that I want to take advantage of the absorption of an inside out wall, but I'm also concerned with a drummer, including myself, going through it! My goal is not to have it target a specific frequency but use it untuned for broadband absorption, which is where I go th te idea of the 534 pattern and the other recommendations. I know targeting a specific frequency can be difficult and even minor errors in construction can alter the resonation so you may end up making your situation even worse by taking out frequencies that you need and not the targeted one in the first place.

1. Should I design the wood slats over the inside out wall now or wait to do a REW analysis once the room is completed?

[/quote]I'll repeat the same question as above: Why do you think you need slats on that wall anyway? If you can't answer that question honestly, with a valid acoustic reason for putting them there, then you need to do some more research.

See my answer above, but this is also why I mentioned that it might be smarter to do a REW analysis first so I know which size slats and slots to use. Either way, I feel like I need SOMETHING there to protect the wall, and a broadband absorber is usually useful.