Another wall thread 2 leaf

[1970428scj]

Hi everyone, starting planning for a new studio build.
The building I am starting with is 2x8 stud construction with outside walls being stucco.
My plan was to remove the drywall on the inside , place a bat of insulation then an air gap of an 1” or 2 then 2x6 , bat of insulation, then 2 layers of drywall. This would then make the existing structure 2 leaf
30’x40’.


So my question is, is it a good idea to then double leaf again for my rooms n room.

Thank you all so much

[Gregwor]

So my question is, is it a good idea to then double leaf again for my rooms n room.

It is not. 3+ leaves offer great high frequency isolation but, in the same space required to make 3+ leaves using the same amount of sheathing, if you were to build a 2 leaf system, you're going to get way better isolation at low frequencies. Low frequencies are the ones we really care about in the studio world.

Here are some reference pictures to solidify the concept:

2-leaf-3-leaf-4-leaf-STC-diagram--classic-enh.gif

2-leaf-vs-3-leaf-700pix.jpg

MSM-two-leaf-WallChunk-conventional-NOT-inside-out--three-room--with-corridor--S04.png

Greg

[1970428scj]

So my question is, is it a good idea to then double leaf again for my rooms n room.

It is not. 3+ leaves offer great high frequency isolation but, in the same space required to make 3+ leaves using the same amount of sheathing, if you were to build a 2 leaf system, you're going to get way better isolation at low frequencies. Low frequencies are the ones we really care about in the studio world.

Here are some reference pictures to solidify the concept:

2-leaf-3-leaf-4-leaf-STC-diagram--classic-enh.gif

2-leaf-vs-3-leaf-700pix.jpg

MSM-two-leaf-WallChunk-conventional-NOT-inside-out--three-room--with-corridor--S04.png

Greg

Thanks for the reply,
I have stucco, insulation, 2x6 stud, air gap, 2x6 stud ,insulation, 2 sheets of drywall.
I can easily add mass to the drywall side, I can also increase the air gap, I could also use 2x 8 on the drywall side .
Any advise is welcome
Thank you

[Gregwor]

Are you able to post a SketchUp drawing of your idea similar to the one I posted above so we can confidently comment on your situation?

Thanks!

Greg

[1970428scj]

Hi Thank you for your reply.
It’s not done yet but this may give a better idea.
Grey wall is 2x6 with stucco, this is the outside wall.
There is insulation , 6” air gap , then insulation , 2x6 , 2x 5/8 sheets of drywall.
Green glue in middle.
Is RC a help here, what else can I do to get more isolation?

[1970428scj]

Please have a look at this for a live room, the outside wall is stucco, not sure how to calculate this mass, so I used 2x 5/8 drywall in its place.
The air gap seems to make the biggest difference, From what I have read RC will hurt the low end performance?
Does stone wool have an advantage over regular insulation,
Green glue?
2"x6" stud construction on the inside leaf, enough to carry the weight of 3 drywall 5/8".

[Gregwor]

Grey wall is 2x6 with stucco, this is the outside wall.
There is insulation , 6” air gap , then insulation , 2x6 , 2x 5/8 sheets of drywall.

Chances are, there is something like 7/16" OSB sheathing between the stucco and framing. I did a quick Google search and it appears that a generic stucco can have a density as low as 1830 kg/m³. The real problem with this is that there may be spots of it that are only like 1mm thick. Using the quick conversion calculator on my transmission loss calculator, 1mm thick at that density says it's surface density will be 1.83 kg/m².

There is no need to use a 2x6 unless your walls are 10+ feet tall. Save your money and use 2x4. Note, the calculator gap is calculated between the framing material and it also adds in the depth of the framing material.

Example: 2x6 outer leaf framing, then a 2 inch gap, then a 2x4 inner leaf framing. That means the calculator would use (5.5 + 2 + 3.5 = 11 inches) in it's formulas.

So, if you change your framing to 2x4 in the calculator, add 2 inches to your gap to achieve the same isolation figures.

Right now, if we assume 7/16" OSB with 1mm of stucco (remember, we have to use the smallest surface density values of your system) on 2x6 for your outer leaf, an 8" gap (added 2" to account for the 2x6 to 2x4 swap), then a 2x4 holding 2 layers of 5/8" drywall, our calculator will look like this:

Entries.png

Chart.png

Is RC a help here, what else can I do to get more isolation?

Not if your leaves are fully decoupled.

From what I have read RC will hurt the low end performance?

Not on a regular wall. It performs worse at low frequencies compared to a fully decoupled MSM build.

Does stone wool have an advantage over regular insulation,

For your wall cavities, use whatever is cheaper or easier to work with.

Green glue?

I highly recommend it even though it's wicked expensive. At least it's really easy to work with.

2"x6" stud construction on the inside leaf, enough to carry the weight of 3 drywall 5/8".

2x4 is what you should use if your walls are shorter than 10 feet tall.

If I were you, I would maybe drill a small hole through the wall to see just how thick your exterior sheathing is. If it is as thin as I suggested, you might have to beef it up.

Greg

[1970428scj]

Grey wall is 2x6 with stucco, this is the outside wall.
There is insulation , 6” air gap , then insulation , 2x6 , 2x 5/8 sheets of drywall.

Chances are, there is something like 7/16" OSB sheathing between the stucco and framing. I did a quick Google search and it appears that a generic stucco can have a density as low as 1830 kg/m³. The real problem with this is that there may be spots of it that are only like 1mm thick. Using the quick conversion calculator on my transmission loss calculator, 1mm thick at that density says it's surface density will be 1.83 kg/m².

There is no need to use a 2x6 unless your walls are 10+ feet tall. Save your money and use 2x4. Note, the calculator gap is calculated between the framing material and it also adds in the depth of the framing material.

Example: 2x6 outer leaf framing, then a 2 inch gap, then a 2x4 inner leaf framing. That means the calculator would use (5.5 + 2 + 3.5 = 11 inches) in it's formulas.

So, if you change your framing to 2x4 in the calculator, add 2 inches to your gap to achieve the same isolation figures.

Right now, if we assume 7/16" OSB with 1mm of stucco (remember, we have to use the smallest surface density values of your system) on 2x6 for your outer leaf, an 8" gap (added 2" to account for the 2x6 to 2x4 swap), then a 2x4 holding 2 layers of 5/8" drywall, our calculator will look like this:

Entries.png

Chart.png

Is RC a help here, what else can I do to get more isolation?

Not if your leaves are fully decoupled.

From what I have read RC will hurt the low end performance?

Not on a regular wall. It performs worse at low frequencies compared to a fully decoupled MSM build.

Does stone wool have an advantage over regular insulation,

For your wall cavities, use whatever is cheaper or easier to work with.

Green glue?

I highly recommend it even though it's wicked expensive. At least it's really easy to work with.

2"x6" stud construction on the inside leaf, enough to carry the weight of 3 drywall 5/8".

2x4 is what you should use if your walls are shorter than 10 feet tall.

If I were you, I would maybe drill a small hole through the wall to see just how thick your exterior sheathing is. If it is as thin as I suggested, you might have to beef it up.

Greg

Thank you for the reply,
The walls are 10’ tall now , but the ceiling is being opened to 12’ they are 10’ now.
What is the idea air gap for a tracking room , drums etc vs the air gap for a control room?
The stucco material is really pretty thick it is 1” .
The floor is one slab, is it smart to isolate the control slab from the live room?
I deleted the iso booth. In the current studio (old one) we have 4 gobos and have had great success with just those.

This is a stand alone building, with one neighbor about 750 feet away,I need to make sure I have excellent isolation. And TL
I understand the calculator, but donot understand the f0 f1 etc can you please help me understand what I’m looking at, for the best results
What would you suggest ? To improve this.

Thank you

[Gregwor]

The stucco material is really pretty thick it is 1” .

That's great then!

The floor is one slab, is it smart to isolate the control slab from the live room?

Smart, yes. But, I'd say only when you are pouring a fresh slab. Right now, I doubt you could just cut the existing slab, put a whole bunch of weight around it's perimeter and not experience cracking or sagging due to lack of support under the slab.

I understand the calculator, but donot understand the f0 f1 etc can you please help me understand what I’m looking at

F0 and F1.png

You can see that they are calculated frequencies. The calculator uses these to determine the amount of isolation below, between, and above these frequencies.

for the best results What would you suggest ? To improve this.

The only way to get more isolation is to increase your sheathing mass or the gap.

Here are two images that show the difference between increasing one or the other.

Increasing Panel Mass.png

Increasing Panel Spacing.png

Greg

[xSpace]

What type of seismic hangers are you considering using on your interior walls?
Or is that something you haven't thought of yet?

[1970428scj]

Thank you for the replies,
I wanted to post a few photos of the build.
30’x40’ walls are 10 ft.
Going to look at cost to raise the ceiling,
This is current condition as of today.
Completing more demo, I was able to have a better look at the stucco
The Exterior walls are stucco with 1” stucco and half-inch chip board/ plywood.
It seems like a nice mass.
Thank you for your replies

[1970428scj]

What type of seismic hangers are you considering using on your interior walls?
Or is that something you haven't thought of yet?

I have not made it that far, the picture above is us demo ing , to see what is under the drywall,
I did not look for hangers but I’m sure there is existing straps of some sort, as this build was permitted and built in 2010.
This is the wall achor system.
Thank you for your reply.

[xSpace]

Yes sir. What I refer to is this. How do you intend to keep the new interior walls vertical, what is going to keep them up, versus collapse?

Especially where you are, these things cannot be over looked, insurance, local building code...everyone is going to be asking.

[1970428scj]

Yes sir. What I refer to is this. How do you intend to keep the new interior walls vertical, what is going to keep them up, versus collapse?

Especially where you are, these things cannot be over looked, insurance, local building code...everyone is going to be asking.

Thanks for your reply, I have looked at Acoustical Surfaces products a bit, but between working and demo I have not had a great deal of time to research.
This building was framed and drywalled for a 3 bedroom 2 bath. It was a foreclosure. I bought the property 3 months ago. It needs some of the doors moved around and windows taking out, and the exterior walls repaired. I am trying to stay ahead of the construction process as much as possible so I am not doing things wrong. I simply do not have the $$ to hire a proper designer.
Do you have product that you have used in the past that you could suggest?
I am here to learn more and get correct advise. Thank you for the help.

[1970428scj]

This is the state of the building now.