Another wall thread 2 leaf

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

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: Greg

Gregwor wrote:

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:

Not preserved: 2-leaf-3-leaf-4-leaf-STC-diagram--classic-enh.gif

Not preserved: 2-leaf-vs-3-leaf-700pix.jpg

Not preserved: 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

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

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?

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".

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:

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

Gregwor wrote:

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:

Not preserved: Entries.png

Not preserved: 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

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

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. Greg

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

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

xSpace wrote:

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.

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.

xSpace wrote:

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.

This is the state of the building now.

TL of Leaf 1 TL of Leaf 2 F0 (empty cavity) F0 (insulated cavity) F1 35.71 36.45 14.04 10.06 58.52 Leaf 1 is 1" stucco , 11/16 mdf, 2x6 , insulated ( 2x General Gypsum for stucco) 26" gap Leaf 2 3x 5/8 General Gypsum I am planning to use green glue on this leaf. What can I do to fully decouple the walls , Neoprene under and decoupler like a RSIC-DC04? Thank you

11/16 mdf

Did they actually use MDF for sheathing? OSB or plywood is more likely. These all have different surface densities so I would confirm the material and then recalculate the isolation.

26" gap

That is eating into a LOT of space. Note, you will need the same surface density and gap for your ceiling as well.

Leaf 2 3x 5/8 General Gypsum I am planning to use green glue on this leaf.

You only need Green Glue between 2 of the layers, not between all 3.

What can I do to fully decouple the walls , Neoprene under and decoupler like a RSIC-DC04?

Well that opens up a few other issues. You COULD partially decouple the walls using a system like you mentioned. However, the slab is still connected to the outer leaf. Due to this, your isolation is limited to around what I believe is 60dB. You could split the slabs so that earth itself would be the only thing coupling the two rooms together. Otherwise, you have to get into the 6 figure price tag and actually float your inner room like Galaxy Studios has done. What I'm getting at with my entire post here is that you need to make sure you don't go overboard on some sections of the room (like the 26" gap maybe?) while being limited at other sections of the room (like the connected slab). Greg

100`s of people right here, over a decade and a half that I have witnessed...have achieved quality audio recording room status. Getting lost in the seduction of acoustics is common. If you have a mass/air/mass design then you can also achieve your goal. All the things Gregwor mentioned are pretty constant. I do not know what your isolation level goal is but it will be directly coupled to your budget.

Gregwor wrote:

11/16 mdf

Did they actually use MDF for sheathing? OSB or plywood is more likely. These all have different surface densities so I would confirm the material and then recalculate the isolation.

26" gap

That is eating into a LOT of space. Note, you will need the same surface density and gap for your ceiling as well.

Leaf 2 3x 5/8 General Gypsum I am planning to use green glue on this leaf.

You only need Green Glue between 2 of the layers, not between all 3.

What can I do to fully decouple the walls , Neoprene under and decoupler like a RSIC-DC04?

Well that opens up a few other issues. You COULD partially decouple the walls using a system like you mentioned. However, the slab is still connected to the outer leaf. Due to this, your isolation is limited to around what I believe is 60dB. You could split the slabs so that earth itself would be the only thing coupling the two rooms together. Otherwise, you have to get into the 6 figure price tag and actually float your inner room like Galaxy Studios has done. What I'm getting at with my entire post here is that you need to make sure you don't go overboard on some sections of the room (like the 26" gap maybe?) while being limited at other sections of the room (like the connected slab). Greg

Thank you for your reply. I think giving more information of my Surrounding area might give you more direction as to what I’m trying to achieve. Please see attached photo. I need to have as much isolation as possible, With in reason, I can see that a 26” gap eats in to my space a lot. How can I get isolation with out the 26” gap, And still be effective, What is the most effective, way to isolate the slab? It is a 6” slab with 2 ft deep stem wall. Is it cheaper to cut around the stem wall and lay s new separate slab on grade? What is the best way to decouple the walls from ceiling and floor. Thank you

The ceiling is a lot easier than the slab. You simply never make a hard connection to the joist framing. Hard connections in light weight framing are where "flanking" exist and it is acoustically troublesome as it can reduce your anticipated isolation goal number to "whatever the existing structures current fstc is, give or take" . Fstc being the field stc.

Thank you for the replies Does this not work for isolation of the slab?

I'm sure it would work alright. I'd just be scared about the insulation getting too compressed. That's why a spring system could be more controlled. Greg

Gregwor wrote:

I'm sure it would work alright. I'd just be scared about the insulation getting too compressed. That's why a spring system could be more controlled. Greg

Greg Thank again for all your info, that plan is from a pretty major design team that I’m sure you would know, guy has built and designed many great studios. I’m trying to read between the lines as in these studio plans there are several things that are questionable. RC all over this build, no real air gap between the buildings outside existing walls. I have been in this studio and it is super nice and seals up. What is my best design for my build At this point I have a slab on grade, I can decouple walls with neoprene, I could do a floor like was pictured in the drawing? How cost effective are spring jack type floors? Would I need to do both the live room and control room? My budget is more than $30k but not over $100k I’m sure I’m gonna run out of money before the end. Thank you for all your replies.

Here is another drawing from the same studio designer This shows the main existing wall on the base slab with the same iso slab I pictured in the last post. As you can see the interior walls is built right up against the existing wall. A triple leaf design.

Thank again for all your info, that plan is from a pretty major design team that I’m sure you would know, guy has built and designed many great studios.

The designer would have worked with whatever requirements the owner had. Maybe they didn't need much isolation?

What is my best design for my build

It looks like you're quite far from anyone or anything so you're only needing to stop outside sounds from getting in and to have isolation between your rooms.

At this point I have a slab on grade, I can decouple walls with neoprene, I could do a floor like was pictured in the drawing?

I honestly think you'd be fine building your room like most people on the forum do by not worrying about your floor. Just build on your slab and achieve (hopefully) around 60dB of isolation.

How cost effective are spring jack type floors? Would I need to do both the live room and control room?

You mean like this:

My budget is more than $30k but not over $100k I’m sure I’m gonna run out of money before the end.

Again, I think you should not worry about your floor. Spend your money on the other stuff. For example, I just got the quote to polish my control room and iso room floor (not my live room yet) and it's $9450 after GST. Budget gets eaten fast :(

Here is another drawing from the same studio designer This shows the main existing wall on the base slab with the same iso slab I pictured in the last post. As you can see the interior walls is built right up against the existing wall. A triple leaf design.

Without seeing more of the picture I can't really comment on it, but if what you're suggesting is true, it is bizarre. Crazy to float a floor and then use RC and not a true room in a room. Also, from what I see in the picture, it blows my mind to float the floor and ultimately chew up a bunch of height in the control room, leaving only 8'4" of height. Greg