John Sayers' Recording Studio Design Forum Archive

Hello Everyone, Greetings from India. I have been following this forum and am glad to have come across such resourceful information.

I am in process of building up my recording studio, It is in a commercial building on the second floor.
Present Height is 12'2".

Attached is a basic dimensional layout, Structural walls are plastered brick wall 16inches thick with 4inch rockwool 96kg/m3 installed in between. These walls have already been constructed. H.V.A.C: Split Ac's 2Tonnes to be installed in each room, Piping already done in the structured walls.

I know there are a lot of discrepancies in the design considering the room sizes and windows orientation, but this is something I cant change and have to make do with.

Floor Construction

Considering it is a Commercial Building, I thought of going with a basic floating floor design using U-boats. 3 inch air gap is kept from the main walls to the subfloor construction on which the inner walls will rest.

Wood Baton framework 4x1.5 inch with U boats installed at 1feet gap at the periphery(Load Bearing) and 2 feet gap at the rest of the framework. U boats to be stapled to the batons. 2 layers of 2inch thick rockwool 96 density to be filled inside the cavity.
Now should i go for Rockwool or Sand inside the cavity?


Then followed is fixing of 2x12.5mm thick plyboards and a reflective hard veneer tile for finish.
Is this apt for floor Isolation?

Walls Construction

Walls to be resting upon the floating floor with 3inch gap from the main walls.

Walls to be made 4inch thick Steel studs with 2 layers of 5/8" dryboard on the back wall facing the structural walls.
Rockwool Inside the cavity. M.L.V 3mm thick 4.9kg/m2 to be stapled to the inner frame wall, then followed by clips and resilient channels spread 2.5 ft apart decoupling the inner 2 layers of 5/8" boards from the main framework.
Acoustic caulk and tape over the boards connections and crossovers.

Is this system apt for Wall Isolation?

I read somewhere for a 2leaf M.S.M system to work the weight of both of the walls have to somewhat similar.
Also any literature link to calculate weight of the walls will be really helpful.

Ceiling Construction

Drop Ceiling, 2layers of 5/8" boards decoupled using the resilient channels.

Now, I was planning to go for a flat ceiling design in all the rooms except control room A and B, where an elevated ceiling with a 1 feet rise from the studio table wall to the back wall.

Doors and Windows Construction

Double doors to be made and installed in each room with a sealed air gap.
Can anyone please guide me what materials should i use for the build?

Also any links for installation for the same will be really helpful.

Windows

I have though of installing a 8mm toughened window followed by a 12mm soundproof double pane windows, followed by a 8mm window. Both the 8mm windows to be splined at an angle of 12-15 degrees.
Soundproof double pane windows pre made with an inch air gap, argon sealed to be installed with proper caulking.

Would this be apt to achieve proper isolation through windows?

Also in my control rooms, my critical first reflections fall on these windows, which i know is really bad. Any ways of making that better?

Please pardon my technical knowledge of these things.

This is the design so far, Only structured walls have been made yet, rest all the inner structure is yet to be installed.
I am losing on the rent by day and plan to order the material within this week.

The main purpose of the build is "Isolation" from different rooms, in order to fully utilise all the rooms for their specific purposes.

Thanks and Regards

Hi Tushar, and Welcome!

Structural walls are plastered brick wall 16inches thick with 4inch rockwool 96kg/m3 installed in between.

When you say you have insulation "in between", do you mean that there are two walls of 16" each, with insulation between them, for a total of 16" + 4" + 16" = 40"? Or do you mean 6" + 4" +6" = 16"?

These walls have already been constructed.

Are those the hashed walls on the diagram?

H.V.A.C: Split Ac's 2Tonnes to be installed in each room, Piping already done in the structured walls.

Did you decouple the piping where it passes through the walls, so that it does not create flanking paths?

Considering it is a Commercial Building, I thought of going with a basic floating floor design using U-boats.

That would be a mistake. Here's why: http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173

Wood Baton framework 4x1.5 inch with U boats installed at 1feet gap at the periphery(Load Bearing) and 2 feet gap at the rest of the framework.

I'm not sure I understand what you mean by that. Please make a drawing, so we can see what you mean.

Now should i go for Rockwool or Sand inside the cavity?

If you are talking about a stud framed wall with drywall, plywood, MDF or something similar on it, then do NOT EVER use sand in the cavity. The weight would destroy the wall. Use only mineral wool or fiberglass insulation, with the correct density. If that is a floor you are talking about, then the entire approach is not correct (see link above): you will need to do the math to correctly float the floor, and you need a lot more mass than you are thinking of right now. What is the load rating for the existing floor in the building? You will be adding several tons of load on top of that, so you need to be certain that it is able to safely support that.

Then followed is fixing of 2x12.5mm thick plyboards and a reflective hard veneer tile for finish.

If we are still talking about the floor, then that's nowhere near enough mass.

Is this apt for floor Isolation?

Floor isolation from what? How much isolation do you need (in decibels), and what frequencies do you need it at?

Walls to be resting upon the floating floor with 3inch gap from the main walls.

So you are talking about floating your entire room, not just the floor? That's a very, very different issue. Have you hired a structural engineer who is experienced in doing the calculations for vibration isolated structures?

Walls to be made 4inch thick Steel studs with 2 layers of 5/8" dryboard on the back wall facing the structural walls.
Rockwool Inside the cavity. M.L.V 3mm thick 4.9kg/m2 to be stapled to the inner frame wall, then followed by clips and resilient channels spread 2.5 ft apart decoupling the inner 2 layers of 5/8" boards from the main framework.

That would be a FIVE LEAF wall? That would give you terrible isolation in low frequencies.

I think you should spend some time researching the concept of fully-decoupled two-leaf MSM isolation. You are way over-designing this wall, and it will not do what you are hoping it will do. An isolation wall should only EVER have a single air cavity, with only two massive leaves (one on each side of the cavity). Anything more than that REDUCES low frequency isolation. It makes it worse, not better.

Is this system apt for Wall Isolation?

No.

I read somewhere for a 2leaf M.S.M system to work the weight of both of the walls have to somewhat similar.

Yes, but you are not building a two-leaf MSM system: what you describe is a five-leaf MSMSMSMSM system...

Also any literature link to calculate weight of the walls will be really helpful.

The best I know of is the Wyle report. It is old, but still very valid, and very useful. : https://app.box.com/shared/jcaoavdc8g

Drop Ceiling, 2layers of 5/8" boards decoupled using the resilient channels.

Attached to what?

Now, I was planning to go for a flat ceiling design in all the rooms except control room A and B, where an elevated ceiling with a 1 feet rise from the studio table wall to the back wall.

You could do that, yes, but why did you choose a 1 foot rise? Did you ray-trace the room interior to make sure that such a rise will create an RFZ at the mi position in the vertical plane?

Doors and Windows Construction

Double doors to be made and installed in each room with a sealed air gap.
Can anyone please guide me what materials should i use for the build?

Each of the two doors should be made from solid wood. Do not use a standard hollow-core door, or an insulation filled door.

I have though of installing a 8mm toughened window followed by a 12mm soundproof double pane windows, followed by a 8mm window. Both the 8mm windows to be splined at an angle of 12-15 degrees.

That would be a FOUR LEAF window, and the angled glass would reduce isolation even further. The correct way is to use two panes of thick laminated glass, one in the outer leaf, one in the inner leaf. Nothing else. Not angled.

Also in my control rooms, my critical first reflections fall on these windows, which i know is really bad. Any ways of making that better?

Don't put the windows in that location! That's the only real solution.

Only structured walls have been made yet, rest all the inner structure is yet to be installed.

I'm confused about which of the walls you consider "structural walls", which ones already exist, and which ones you plan to build. Please mark those on your diagram, in different colors.

The main purpose of the build is "Isolation" from different rooms, in order to fully utilise all the rooms for their specific purposes.

How much isolation? You need to define that in real-world numbers. You need to decide how many decibels of isolation you need, and what frequency range you need it at.

I'd also suggest that you buy two books: "Master Handbook of Acoustics" by F. Alton Everest , and "Home Recording Studio: Build it Like the Pros", by Rod Gervais. Those will clarify a lot of things about why you are approaching this incorrectly, and how to do it correctly.


- Stuart -

Soundman2020 wrote:When you say you have insulation "in between", do you mean that there are two walls of 16" each, with insulation between them, for a total of 16" + 4" + 16" = 40"? Or do you mean 6" + 4" +6" = 16"?

Two Walls 6" each with 4" insulation. total 16".

These walls have already been constructed.

Are those the hashed walls on the diagram?

Yes.

Did you decouple the piping where it passes through the walls, so that it does not create flanking paths?

Not Really. Pipes were wrapped around with a 1" thick rubber insulation and grouted with plaster. no decoupling from the wall.

Considering it is a Commercial Building, I thought of going with a basic floating floor design using U-boats.

That would be a mistake. Here's why: http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173

Thanks for the link.

Then followed is fixing of 2x12.5mm thick plyboards and a reflective hard veneer tile for finish.

If we are still talking about the floor, then that's nowhere near enough mass.

Walls to be resting upon the floating floor with 3inch gap from the main walls.

So you are talking about floating your entire room, not just the floor? That's a very, very different issue. Have you hired a structural engineer who is experienced in doing the calculations for vibration isolated structures?

After reading your link, I have got the answer for this. There is a gym located on top of my floor, considering the amount of equipment load it can handle, I am sure it can take up the floating room design, though again it is just a mere guess.

Also, I am not much concerned about noise transferring from my floor to beneath as i tested my drumkit in this untreated space and nothing reached the below floor. My only concern, is to not let the noise travel through the adjacent recording rooms through the floor.


So for this I think floating room is not essential? Also how should i plan my floor construction in this case?

Walls to be made 4inch thick Steel studs with 2 layers of 5/8" dryboard on the back wall facing the structural walls.
Rockwool Inside the cavity. M.L.V 3mm thick 4.9kg/m2 to be stapled to the inner frame wall, then followed by clips and resilient channels spread 2.5 ft apart decoupling the inner 2 layers of 5/8" boards from the main framework.

That would be a FIVE LEAF wall? That would give you terrible isolation in low frequencies.

Thank you so much for this, So considering I have a MSM system aready in place with my plastered brickwalls, Just adding boards to both the leaves to increase the mass will do? Or how else should i look at construction of these walls?

So, I am looking at somewhat 40db Isolation at 50Hz, and 60db Isolation at 250-16KHz.

Surface Density of both of my walls are around 182Kg/m2, giving me a resonant frequency that is high. Of the order 205 Hz?

So by adding 1 layer of plyboard 12mm thick and 2 layers of 5/8" plasterboard/soundblock on each of the leaf be enough for achieving such isolation?

Now, I was planning to go for a flat ceiling design in all the rooms except control room A and B, where an elevated ceiling with a 1 feet rise from the studio table wall to the back wall.

You could do that, yes, but why did you choose a 1 foot rise? Did you ray-trace the room interior to make sure that such a rise will create an RFZ at the mi position in the vertical plane?

Not really, i just though of creating an unparallel surface between the ceiling and floor. Any free software/sheet to use this ray tracing method?

Doors and Windows Construction

Double doors to be made and installed in each room with a sealed air gap.
Can anyone please guide me what materials should i use for the build?

Each of the two doors should be made from solid wood. Do not use a standard hollow-core door, or an insulation filled door.

So, a solid core flush door attached with 2 layers of 18mm MDF each side, be good enough?

I have though of installing a 8mm toughened window followed by a 12mm soundproof double pane windows, followed by a 8mm window. Both the 8mm windows to be splined at an angle of 12-15 degrees.

That would be a FOUR LEAF window, and the angled glass would reduce isolation even further. The correct way is to use two panes of thick laminated glass, one in the outer leaf, one in the inner leaf. Nothing else. Not angled.

So, Two 12mm laminated glass properly sealed be good enough?

I'd also suggest that you buy two books: "Master Handbook of Acoustics" by F. Alton Everest , and "Home Recording Studio: Build it Like the Pros", by Rod Gervais. Those will clarify a lot of things about why you are approaching this incorrectly, and how to do it correctly.

Thanks, making the order now.