Seeking advice on separation wall

[Soulshaker]

Hi guys,

I'm having difficulty figuring out how to build control room front wall with existing wall. In my pics you'll see I have a wall partially separating my live room and control room area. If I build as in the drawing, connecting my outer shell around control room to existing outer shell and inner walls of control room not connected to any other walls this appears to work but sound wouldn't be stopped from coming into outer area around control room from top of existing wall.Do I need to make outer control room walls cover ceiling as well?

As always thanks for your time & expertise,

-Jason-

[John Steel]

Hello & howdo' Jason?
If I understand your question correctly, you are asking if the CR design in the sketch creates a flanking path to the outer leaf? If so, it doesn't look to me as if it does. If I may ask a further question, why not push back your CR inner leaf walls to where the red lines I've added are and utilize the extra space? BTW, I am not claiming any level of "expertise" here! Best wishes, John.

file2.jpg

[Paulus87]

Hi,

I'm having a little difficulty seeing exactly how your current room is constructed, it seems like that partial wall is actually a double wall with a small gap between them? Can you draw out exactly how your walls are constructed so we can advise you better? Nevertheless, if it is just a single wall then you can do as follows...

First, are you able to remove that partial wall altogether? I am guessing not as it looks like a supporting wall. If not, can you remove the panels from it to leave the exposed studs? If not then it's still not really a problem since it has massive holes in it. But would be better if you remove the panels giving you extra cavity space for your insulation between the control room and tracking room.

Just build your inner control room and tracking room shells either side of that partial wall, not touching it. With the panels removed it is no longer a wall and is simply a supporting structure for your roof.

Lastly, why is your control room shaped like that in your design? It is not a good shape for a control room and by the looks of it you could utilise all that space a lot better.

Paul

[Soulshaker]

Thanks guys,
That wall did have a garage door before I added the addition and it is load bearing. (Image-Early Garage Wall) is before I removed door. (Image-Garage Wall) is after treating wall. The entire live room is a 2 leaf system on 3 sides but the garage door wall is different. Here's what consists in the walls starting from the live room side. 1st wall (Inner Leaf) is- 5/8" Drywall/Green Glue/5/8" Drywall.Studs/Insulation. 2nd Wall is-
5/8' Drywall/Green Glue/5/8' OSB/Studs/Insulation/ on the existing garage side that same wall is 5/8" Drywall/Green Glue/5/8" Drywall.

The area in (image Existing Garage) was already insulated & drywalled. I added another layer of 5/8" drywall with green glue the whole existing garage. I had planned to build out control room like the drawing in (image-Drawing) inside it. I probably screwed this whole thing up.

[Paulus87]

So, if I understand correctly that wall between the control room and live room is a triple leaf wall like the STC 50 assembly in this image?

Paul

[Soulshaker]

Where the control room inner leaf would face the inner leaf of live room would be 2 leaf but where the rest of that entire wall faces would be a triple leaf which I know is not ideal. If I'm correct basically this would mean my transfer of sound would be fine between the 2 rooms but the bleed from the live room into the surrounding area around the control room would suffer. Is that correct? Thanks again guys for all the advice. I really do appreciate it.

-Jason_

[Paulus87]

Where the control room inner leaf would face the inner leaf of live room would be 2 leaf but where the rest of that entire wall faces would be a triple leaf which I know is not ideal. If I'm correct basically this would mean my transfer of sound would be fine between the 2 rooms but the bleed from the live room into the surrounding area around the control room would suffer. Is that correct? Thanks again guys for all the advice. I really do appreciate it.

-Jason_

How big is the cavity (drywall to drywall) between the live room and control room?

If you take the panels off of the ancillary areas wall then it will no longer be triple leaf. Even if you just make some large holes in the drywall panels then that would be fine.

Something that would be super helpful is if you could draw out EXACTLY where your current framing and drywall layers are, it’s too confusing to follow otherwise.

Paul

[Soulshaker]

Where the control room inner leaf would face the inner leaf of live room would be 2 leaf but where the rest of that entire wall faces would be a triple leaf which I know is not ideal. If I'm correct basically this would mean my transfer of sound would be fine between the 2 rooms but the bleed from the live room into the surrounding area around the control room would suffer. Is that correct? Thanks again guys for all the advice. I really do appreciate it.

-Jason_

How big is the cavity (drywall to drywall) between the live room and control room?

If you take the panels off of the ancillary areas wall then it will no longer be triple leaf. Even if you just make some large holes in the drywall panels then that would be fine.

Something that would be super helpful is if you could draw out EXACTLY where your current framing and drywall layers are, it’s too confusing to follow otherwise.

Paul

Here is a side image of the cavity layers. My live room is to the left and its a typical 2 leaf room within a room assembly. the room to the right is my old existing garage which has insulation and 2 layers of drywall with green glue on all the walls.

From left to right in the image of entry is as follows-

Live room
Drywall-Green Glue-Drywall-Studs-Insulation

Air Gap

Drywall-Green Glue-OSB Plywood-Studs-Insulation-Drywall-Green Glue-Drywall

Hopefully this helps

[Paulus87]

Where the control room inner leaf would face the inner leaf of live room would be 2 leaf but where the rest of that entire wall faces would be a triple leaf which I know is not ideal. If I'm correct basically this would mean my transfer of sound would be fine between the 2 rooms but the bleed from the live room into the surrounding area around the control room would suffer. Is that correct? Thanks again guys for all the advice. I really do appreciate it.

-Jason_

How big is the cavity (drywall to drywall) between the live room and control room?

If you take the panels off of the ancillary areas wall then it will no longer be triple leaf. Even if you just make some large holes in the drywall panels then that would be fine.

Something that would be super helpful is if you could draw out EXACTLY where your current framing and drywall layers are, it’s too confusing to follow otherwise.

Paul

Here is a side image of the cavity layers. My live room is to the left and its a typical 2 leaf room within a room assembly. the room to the right is my old existing garage which has insulation and 2 layers of drywall with green glue on all the walls.

From left to right in the image of entry is as follows-

Live room
Drywall-Green Glue-Drywall-Studs-Insulation

Air Gap

Drywall-Green Glue-OSB Plywood-Studs-Insulation-Drywall-Green Glue-Drywall

Hopefully this helps

Hi,

Yes that helps, it’s now clear.

All those layers you have there combined make a triple leaf assembly. You now have 2 options:

What you really should do is remove the middle layer of drywall (the layer which is inside the cavity attached to the control room studs) obviously you would have to remove the inner face first in order to get to it.

You can apply it to the inner face of the control room wall so that you’ll have:

Live room:
2x layer is drywall - studs

- insulated air gap -

Control room:
Studs - 2x layer of drywall

That will give you the highest level of isolation.

However, the alternative is just remove the drywall layers on the inner face of the control room, then re-apply it by cutting it to fit in between the studs, pressed up against the outer layer of drywall (the layer I told you to previously remove).

That would give you an inside out wall, where you can insulate between the studs and cover with fabric, so in other words the exposed studs become your acoustic treatment framing.

However, your air gap between the control room and live room would now be diminished compared to the first option. If you let me know what the size of the air gap would be in both cases then I can tell you the potential isolation you can expect with each option. Remember the air gap is measured between drywall panels and not just the gap between the framing, and that whole cavity should be filled with insulation. The insulation is your air gap.

Btw, if you decide to do option 2 then let us know before you start so we can advise you how best to do it.
Paul

[Soulshaker]

Where the control room inner leaf would face the inner leaf of live room would be 2 leaf but where the rest of that entire wall faces would be a triple leaf which I know is not ideal. If I'm correct basically this would mean my transfer of sound would be fine between the 2 rooms but the bleed from the live room into the surrounding area around the control room would suffer. Is that correct? Thanks again guys for all the advice. I really do appreciate it.

-Jason_

How big is the cavity (drywall to drywall) between the live room and control room?

If you take the panels off of the ancillary areas wall then it will no longer be triple leaf. Even if you just make some large holes in the drywall panels then that would be fine.

Something that would be super helpful is if you could draw out EXACTLY where your current framing and drywall layers are, it’s too confusing to follow otherwise.

Thank you so much Paul. I understand what your saying. I did a good job on the whole addition (live room) of having everything correct but I really screwed up the transition. Anyway I'm willing to do either of the options you presented because its certainly is worth it. I included a pic of the layers with a tape measure on it. It looks like if I remove everything and did a true 2 leaf that my air gap would be 10 3/4". If I did the 2nd option of an inside out the air gap would be 2 1/8". Please let me know your thoughts, once again I'm very grateful for yours and others expertise,

-Jason-
Paul

Here is a side image of the cavity layers. My live room is to the left and its a typical 2 leaf room within a room assembly. the room to the right is my old existing garage which has insulation and 2 layers of drywall with green glue on all the walls.

From left to right in the image of entry is as follows-

Live room
Drywall-Green Glue-Drywall-Studs-Insulation

Air Gap

Drywall-Green Glue-OSB Plywood-Studs-Insulation-Drywall-Green Glue-Drywall

Hopefully this helps

Hi,

Yes that helps, it’s now clear.

All those layers you have there combined make a triple leaf assembly. You now have 2 options:

What you really should do is remove the middle layer of drywall (the layer which is inside the cavity attached to the control room studs) obviously you would have to remove the inner face first in order to get to it.

You can apply it to the inner face of the control room wall so that you’ll have:

Live room:
2x layer is drywall - studs

- insulated air gap -

Control room:
Studs - 2x layer of drywall

That will give you the highest level of isolation.

However, the alternative is just remove the drywall layers on the inner face of the control room, then re-apply it by cutting it to fit in between the studs, pressed up against the outer layer of drywall (the layer I told you to previously remove).

That would give you an inside out wall, where you can insulate between the studs and cover with fabric, so in other words the exposed studs become your acoustic treatment framing.

However, your air gap between the control room and live room would now be diminished compared to the first option. If you let me know what the size of the air gap would be in both cases then I can tell you the potential isolation you can expect with each option. Remember the air gap is measured between drywall panels and not just the gap between the framing, and that whole cavity should be filled with insulation. The insulation is your air gap.

Btw, if you decide to do option 2 then let us know before you start so we can advise you how best to do it.
Paul

Thank you so much Paul.

I understand what your saying. I did a good job on the whole addition (live room) of having everything correct but I really screwed up the transition. Anyway I'm willing to do either of the options you presented because its certainly is worth it. I included a pic of the layers with a tape measure on it. It looks like if I remove everything and did a true 2 leaf that my air gap would be 10 3/4". If I did the 2nd option of an inside out the air gap would be 2 1/8". Please let me know your thoughts, once again I'm very grateful for yours and others expertise,

-Jason-

[Paulus87]

1st Option.jpg

Thank you so much Paul.

I understand what your saying. I did a good job on the whole addition (live room) of having everything correct but I really screwed up the transition. Anyway I'm willing to do either of the options you presented because its certainly is worth it. I included a pic of the layers with a tape measure on it. It looks like if I remove everything and did a true 2 leaf that my air gap would be 10 3/4". If I did the 2nd option of an inside out the air gap would be 2 1/8". Please let me know your thoughts, once again I'm very grateful for yours and others expertise,

-Jason-

Hi Jason,

Cool, so actually your air gap for the 2nd option would be about 6.25" as you need to include the depth of the 2x4 - remember you always measure the air gap panel to panel, not from the edge of the stud. That's actually fairly decent.

Using Greg's incredibly handy MSM TL Calculator (which he so generously provided for us all to use here, thanks Greg!) I've run the two simulations to give you an estimate of your potential transmission loss with each assembly. Keep in mind this is just an estimation and I haven't included the green glue in the data as there's no option to include it in the calculator and it's difficult to predict since it has a damping effect, but it just means your actual transmission loss should be even higher than predicted here:

Here's option 1:

1st Option.jpg

Here's option 2 (with the inside out wall):

2nd Option.jpg

The insulated cavity resonance is really important. Ideally you need it to be half of the lowest frequency of your monitors, so if your monitors go down to 40hz then the cavity resonance should be 20hz or more, this will ensure excellent isolation. That's one of the reasons why a larger cavity is much more effective than a smaller cavity. But nothing is ever normally ideal when building a studio, so you have to compromise.

So, obviously option 1 will provide the best isolation, but since this is a wall between live room and control room the isolation doesn't actually need to be incredibly high due to the fact that you'll generally be monitoring what's coming out of the live room anyway.

If you went with option 1 you'd also have the tedious process of trying to neatly cut out the drywall AND the OSB and remove it, while trying not to damage it in order to reuse... that would be a bit of a nightmare.

If it were me I would just compromise and make that wall an inside out wall (option 2) - so you remove the most inner layer of drywall and then re-apply it between the studs, inside the stud bays, leaving the studs revealed.

You would do this by cutting the drywall to fit in the stud bays, then fasten it by using wooden cleats or battens around the perimeter pressed up against the drywall and fastening the timber cleats or battens through the sides into the studs. This is what people round here call "beef up". Once you have it fastened you can caulk around the perimeter to seal the edges to the studs so there are no air gaps. You want this beef up drywall layer to be pressed up tight against the existing drywall layer, you could use green glue here if you wish but not vital.

Where the inside out wall transitions into your non-inside out walls, you need to make sure that the studs are connected and that there are no gaps on the corners, obviously the drywall layers won't meet, but as long as the studs meet (put more studs there if you need to fill a gap) and it's all sealed completely air tight then you're good. All of your inner and outer shells need to be completely air tight, don't forget about the ceilings/roof.

Once you've done that you'll have a nice load of framing into which you can put your insulation as part of your acoustic treatment for your control room.

3 other points:

1. I noticed in your air gap between the two walls there is a literal air gap. The insulation you have in the framing is good, it's also the right type, but it should also fill the entire cavity. I'm not sure if you'll be able to put any more insulation in there the whole way across the wall now since you can't access it, but if you can find a way to do it such as push it in with a pole or something?! that would be good.

2. You mentioned that your live room walls are constructed like a proper double leaf assembly. Does the outer leaf of that assembly extend all the way round the perimeter of your control room/other areas as well? If so, does the wall that you're going to modify connect to that same wall in anyway? If it does, you need to break the connection. Hope that makes sense?

3. That wall that you're going to modify between the control room and live room - right now it extends the entire width of your space, if your control room is only going to be a portion of that width and you're going to have other rooms around the control room, then you need to break the wall so that there is separation between the control room and the other areas outside of the control room. Here's an example of what I mean:

Screenshot 2020-03-30 at 11.20.07.jpg

You see how there is a cavity all the way round and in between the rooms? There is no hard connection between any of the inner and outer walls of the actual studio. That is what you need through out your studio.

Hope this all helps,
Paul

[Soulshaker]

1st Option.jpg

Thank you so much Paul.

I understand what your saying. I did a good job on the whole addition (live room) of having everything correct but I really screwed up the transition. Anyway I'm willing to do either of the options you presented because its certainly is worth it. I included a pic of the layers with a tape measure on it. It looks like if I remove everything and did a true 2 leaf that my air gap would be 10 3/4". If I did the 2nd option of an inside out the air gap would be 2 1/8". Please let me know your thoughts, once again I'm very grateful for yours and others expertise,

-Jason-

Hi Jason,

Cool, so actually your air gap for the 2nd option would be about 6.25" as you need to include the depth of the 2x4 - remember you always measure the air gap panel to panel, not from the edge of the stud. That's actually fairly decent.

Using Greg's incredibly handy MSM TL Calculator (which he so generously provided for us all to use here, thanks Greg!) I've run the two simulations to give you an estimate of your potential transmission loss with each assembly. Keep in mind this is just an estimation and I haven't included the green glue in the data as there's no option to include it in the calculator and it's difficult to predict since it has a damping effect, but it just means your actual transmission loss should be even higher than predicted here:

Here's option 1:

1st Option.jpg

Here's option 2 (with the inside out wall):

2nd Option.jpg

The insulated cavity resonance is really important. Ideally you need it to be half of the lowest frequency of your monitors, so if your monitors go down to 40hz then the cavity resonance should be 20hz or more, this will ensure excellent isolation. That's one of the reasons why a larger cavity is much more effective than a smaller cavity. But nothing is ever normally ideal when building a studio, so you have to compromise.

So, obviously option 1 will provide the best isolation, but since this is a wall between live room and control room the isolation doesn't actually need to be incredibly high due to the fact that you'll generally be monitoring what's coming out of the live room anyway.

If you went with option 1 you'd also have the tedious process of trying to neatly cut out the drywall AND the OSB and remove it, while trying not to damage it in order to reuse... that would be a bit of a nightmare.

If it were me I would just compromise and make that wall an inside out wall (option 2) - so you remove the most inner layer of drywall and then re-apply it between the studs, inside the stud bays, leaving the studs revealed.

You would do this by cutting the drywall to fit in the stud bays, then fasten it by using wooden cleats or battens around the perimeter pressed up against the drywall and fastening the timber cleats or battens through the sides into the studs. This is what people round here call "beef up". Once you have it fastened you can caulk around the perimeter to seal the edges to the studs so there are no air gaps. You want this beef up drywall layer to be pressed up tight against the existing drywall layer, you could use green glue here if you wish but not vital.

Where the inside out wall transitions into your non-inside out walls, you need to make sure that the studs are connected and that there are no gaps on the corners, obviously the drywall layers won't meet, but as long as the studs meet (put more studs there if you need to fill a gap) and it's all sealed completely air tight then you're good. All of your inner and outer shells need to be completely air tight, don't forget about the ceilings/roof.

Once you've done that you'll have a nice load of framing into which you can put your insulation as part of your acoustic treatment for your control room.

3 other points:

1. I noticed in your air gap between the two walls there is a literal air gap. The insulation you have in the framing is good, it's also the right type, but it should also fill the entire cavity. I'm not sure if you'll be able to put any more insulation in there the whole way across the wall now since you can't access it, but if you can find a way to do it such as push it in with a pole or something?! that would be good.

2. You mentioned that your live room walls are constructed like a proper double leaf assembly. Does the outer leaf of that assembly extend all the way round the perimeter of your control room/other areas as well? If so, does the wall that you're going to modify connect to that same wall in anyway? If it does, you need to break the connection. Hope that makes sense?

3. That wall that you're going to modify between the control room and live room - right now it extends the entire width of your space, if your control room is only going to be a portion of that width and you're going to have other rooms around the control room, then you need to break the wall so that there is separation between the control room and the other areas outside of the control room. Here's an example of what I mean:

Screenshot 2020-03-30 at 11.20.07.jpg

You see how there is a cavity all the way round and in between the rooms? There is no hard connection between any of the inner and outer walls of the actual studio. That is what you need through out your studio.

Hope this all helps,
Paul

Hi Paul,
I'm leaning towards option 1 because it is better and I don't really have to reuse any of the Drywall & OSB. Couldn't I just tear out Drywall and throw away. Then take a saw zaw and cut out OSB/Drywall leaving what little that would still be attached on backside of studs> Then fill cavity with more insulation and put 2 new layers of Drywall? I almost feel like its not really much more work than option 2. I beefed up walls in my live room putting drywall between studs and that takes some time as well. So unless I'm missing something option 1 doesn't seem that much harder. To be clear we are just talking about this one wall? Take another look at my drawing, my outer wall of live room doesn't connect to inner shell at all. The existing garage perimeter wall is a normal wall that I just added a layer of Drywall & Green Glue to. If I redo this wall as you proposed could I do the control room walls as in the picture? a 2 leaf with the inner control room walls not attaching? Would this still technically be a 3 leaf because the outer perimiter of existing garage is drywalled?

[Paulus87]

Okay cool, yes of course you don’t need to reuse, I just thought it would be a waste not to use all that mass. But yes, just cut it out and replace like you said.

I’m having a hard time to follow your drawing because I can’t see the layers of the walls, I just see lines and I don’t know if the lines are outlines of solid walls or if the lines themselves are separate walls???

If the lines themselves are walls then yes that will work. You really just have to keep in mind that with timber frames walls, you only ever want mass layers - studs - cavity - studs - mass layers, and the insulation goes all the way between the two lots of mass layers. Just follow that pattern for all your studio rooms (including ceiling and roof) and you’ll be fine.

Your iso booth in the live room should really also follow that pattern, but if you only need a little separation then you can just make the walls of the booth beefy on both sides, it won’t be perfect but might be enough... if you have the option of also making your booth with decoupled double leaf assemblies then do it.

Paul

[Paulus87]

I just want to add... is there a reason your control room needs to be that shape? If that’s the only option then that’s fine but if you can just use a rectangular shape that would be much much much better acoustically, as well as easier to construct. By building it the shape in your drawing you’re going to have all sorts of unknowns and reflections to deal with, which can easily be avoided by constructing it using an easy predictable shape such as a rectangle.

Paul

[Soulshaker]

Okay cool, yes of course you don’t need to reuse, I just thought it would be a waste not to use all that mass. But yes, just cut it out and replace like you said.

I’m having a hard time to follow your drawing because I can’t see the layers of the walls, I just see lines and I don’t know if the lines are outlines of solid walls or if the lines themselves are separate walls???

If the lines themselves are walls then yes that will work. You really just have to keep in mind that with timber frames walls, you only ever want mass layers - studs - cavity - studs - mass layers, and the insulation goes all the way between the two lots of mass layers. Just follow that pattern for all your studio rooms (including ceiling and roof) and you’ll be fine.

Your iso booth in the live room should really also follow that pattern, but if you only need a little separation then you can just make the walls of the booth beefy on both sides, it won’t be perfect but might be enough... if you have the option of also making your booth with decoupled double leaf assemblies then do it.

Paul

Hi Paul,
I color coded all the walls so I could define better. On the live room side the outer (Red) wall is from outside to inside,
Siding-OSB-Studs Beefed Up with Drywall inside-Insulation-Air Gap-

Inside (Yellow) Wall is completley freestanding.
Studs-Insulation-Drywall-Green Glue-Drywall

My existing Garage Outer Perimeter (Pink) Wall is
Siding-OSB-Insulation-Drywall-Green Glue-Drywall

The (Orange) Wall is the wall I'm going to change to your specifications where the 2 rooms meet. I haven't framed up control room walls but I planned to make (Orange) from outside
Drywall-Green Glue-Drywall-Studs-Insulation
ands (Green) Wall same thing in reverse. The control Room shape was a plan made by someone who I'm not taking advice from now so I will go with a rectangle and I'm looking for plans that would fit my space. The Iso I was going to go with single Leaf-2 Layers of Drywall with Green Glue on each side. I believe that I'll et enough isolation for an Amp or scratch vocals etc. The area to left of control room on bathroom side will be another Iso room with more Isolation.

I do believe I could push up more insulation between the 2 rooms. Do you think it would be easier if I used rigid 703 so Could push up & position or should I try regular?

Thanks again,'

-Jason-