Need help with isolation - studio rebuild

Hi All, I am from São Paulo, Brazil, and I am starting to adapt a video/photo studio into a musical rehearsal studio. Apart from the room acoustic treatment, which I will deal with later, my first concern is about isolation. Problems/description: 1- Part of the wall on the right of the picture is shared with a neighbor. About 1/3 of it. That wall, however, must be around 30 cm thick, as there is my studio wall, the outer wall and his wall. They are all one wall, however. I did a test plugging an electric guitar and producing 105 dbA in the room. The measurement on his side of the wall was 42 dbA. 2- The wall on the left is shared with a neighbor's laundry and deposit. Again, it is probably 30 cm thick. 3- The ceiling is probably my weakest link. It is a kind of very think concrete and we measured around 65 dbA coming from it. 4 - The front brickwall is 18 cm thick. 5 - The floor is concrete, directly on earth. 6- The doors are made of metal, but they are hollow. 7- I want to keep the light coming through the window, thought about using glass blocks 8- The air conditioner works fine, but makes an audible low frequency noise. The repairman said it's impossible to get rid of the noise. All the contractors said I should get rid of that and use the split system. Anyway, I had three different contractors (specialists) come to my studio to give me an estimate and a project for the isolation I need in order to be able to have a band rehearsing in my studio - in the future, I intend to build a control room inside and work basically in a recording situation. Now, however, I want to open as a rehearsal studio. First contractor's opinion: Build a drywall/rockwool ceiling, build a drywall/rockwool wall on the right side only. Fill the doors with sand. Second contractor's opinion: Build a drywall/rockwool ceiling, build drywall/rockwool (density 60 kg/m3) walls all over. Leave the floor alone. Buy 2 acoustic doors. Third contractor's opinion: Build a triple drywall/rockwool ceiling, build triple drywall/rockwool walls all over. Build a floating floor (neoprene and wood). Build a sound lock at the entrance, buy 2 acoustic doors. The thing is, as you might have noticed, I am all confused about how I can achieve enough isolation without breaking the bank. So, I am attaching some pictures of the place, as well as the floor plan, and I would like to hear opinions about what is really necessary and what is overkill. Thank you very much!

Please help! Thanks!

Hi Tux, and Welcome to the forum! :) Sorry about the delay in replying, but there's a lot going on here right now, and I don't have a lot of spare time lately!

That wall, however, must be around 30 cm thick, as there is my studio wall, the outer wall and his wall.

30 cm is a good, but you are also describing a three-leaf wall, which is potentially not so good. How are each of those walls built? Are all three of them typical Sao Paolo concrete and brick construction, or something else? How big are the gaps between those walls?

5 - The floor is concrete, directly on earth.

Excellent!

6- The doors are made of metal, but they are hollow.

Not so excellent... They will probably have to be replaced or modified.

8- The air conditioner works fine, but makes an audible low frequency noise. The repairman said it's impossible to get rid of the noise. All the contractors said I should get rid of that and use the split system.

The contractors are right! Get rid of that, and get a suitably dimensioned split system. They aren't expensive, and you sure will need one for Sao Paolo climate! But in addition to the air conditioner, you will also need ducts to bring in fresh air, and exhaust stale air.

First contractor's opinion: Build a drywall/rockwool ceiling, build a drywall/rockwool wall on the right side only. Fill the doors with sand.

Not such a good idea.

Second contractor's opinion: Build a drywall/rockwool ceiling, build drywall/rockwool (density 60 kg/m3) walls all over. Leave the floor alone. Buy 2 acoustic doors.

Yes! This makes sense. Except that you can probably build good doors much cheaper than buying them.

Third contractor's opinion: Build a triple drywall/rockwool ceiling, build triple drywall/rockwool walls all over. Build a floating floor (neoprene and wood). Build a sound lock at the entrance, buy 2 acoustic doors.

Forget this guy: he doesn't have a clue! Why would you need a flimsy floating floor when you already have a perfectly good concrete slab on grade?

The thing is, as you might have noticed, I am all confused about how I can achieve enough isolation without breaking the bank.

First, we need to know what you are trying to do here! what are your goals? Do you want to have Pink Floyd rehearsing their entire repertoire at 3 AM? Or do you just want to play your acoustic guitar at midday for a few minutes? Very different requirements. Also, do you want to record, or just rehearse? And is this a commercial studio or just a hobby studio? How many rooms do you need in there? Is it just going to be one room, or do you need a control room plus a live room? And a vocal booth too? What about storage? Bathroom? Etc. You also need to tell us about your isolation needs from the outside world: I have only been to Sao Paolo a dozen or so times, but what I do remember is that some parts of the city are very noisy, with heavy traffic, the aircraft, people, music, etc. And if you are close to Congonhas, then you have SERIOUS isolation needs! So the more you can tell us about what you want to do, the easier it is for us to make suggestions on what you can do. - Stuart -

Thanks for the reply Stuart! Let me try and give you more details. - the walls on the sides are party walls, that's why they are thick, but there's not space between the layers, so they are actually one wall. They're brick and concrete. - Regarding the 3rd contractor's idea, he arguments that if I don't build a floating floor the vibration from the floor will spread through the existing walls and low frequency will be heard. I had a 4th contractor come see the build and he shares this opinion too... - this will be a commercial rehearsal studio, one room only, to begin. But I intend to build a control room inside the same space in a year or 2 and start recording. - As it is going to be a commercial studio, I do need enough isolation so I don't disturb my neighbors late at night, although I do not want to go past midnight - I already have bathrooms, storage and other facilities in the house (not shown on the floor plan) - the area where the studio is located is a commercial/residential area. No heavy traffic, no airplanes or anything unusually noisy. Thanks a lot for the help!

Soundman2020 wrote:

Hi Tux, and Welcome to the forum! :) Sorry about the delay in replying, but there's a lot going on here right now, and I don't have a lot of spare time lately!

That wall, however, must be around 30 cm thick, as there is my studio wall, the outer wall and his wall.

30 cm is a good, but you are also describing a three-leaf wall, which is potentially not so good. How are each of those walls built? Are all three of them typical Sao Paolo concrete and brick construction, or something else? How big are the gaps between those walls?

5 - The floor is concrete, directly on earth.

Excellent!

6- The doors are made of metal, but they are hollow.

Not so excellent... They will probably have to be replaced or modified.

8- The air conditioner works fine, but makes an audible low frequency noise. The repairman said it's impossible to get rid of the noise. All the contractors said I should get rid of that and use the split system.

The contractors are right! Get rid of that, and get a suitably dimensioned split system. They aren't expensive, and you sure will need one for Sao Paolo climate! But in addition to the air conditioner, you will also need ducts to bring in fresh air, and exhaust stale air.

First contractor's opinion: Build a drywall/rockwool ceiling, build a drywall/rockwool wall on the right side only. Fill the doors with sand.

Not such a good idea.

Second contractor's opinion: Build a drywall/rockwool ceiling, build drywall/rockwool (density 60 kg/m3) walls all over. Leave the floor alone. Buy 2 acoustic doors.

Yes! This makes sense. Except that you can probably build good doors much cheaper than buying them.

Third contractor's opinion: Build a triple drywall/rockwool ceiling, build triple drywall/rockwool walls all over. Build a floating floor (neoprene and wood). Build a sound lock at the entrance, buy 2 acoustic doors.

Forget this guy: he doesn't have a clue! Why would you need a flimsy floating floor when you already have a perfectly good concrete slab on grade?

The thing is, as you might have noticed, I am all confused about how I can achieve enough isolation without breaking the bank.

First, we need to know what you are trying to do here! what are your goals? Do you want to have Pink Floyd rehearsing their entire repertoire at 3 AM? Or do you just want to play your acoustic guitar at midday for a few minutes? Very different requirements. Also, do you want to record, or just rehearse? And is this a commercial studio or just a hobby studio? How many rooms do you need in there? Is it just going to be one room, or do you need a control room plus a live room? And a vocal booth too? What about storage? Bathroom? Etc. You also need to tell us about your isolation needs from the outside world: I have only been to Sao Paolo a dozen or so times, but what I do remember is that some parts of the city are very noisy, with heavy traffic, the aircraft, people, music, etc. And if you are close to Congonhas, then you have SERIOUS isolation needs! So the more you can tell us about what you want to do, the easier it is for us to make suggestions on what you can do. - Stuart -

- the walls on the sides are party walls, that's why they are thick, but there's not space between the layers, so they are actually one wall. They're brick and concrete.

OK, great. So you already have a good, solid outer-leaf then.

- Regarding the 3rd contractor's idea, he arguments that if I don't build a floating floor the vibration from the floor will spread through the existing walls and low frequency will be heard. I had a 4th contractor come see the build and he shares this opinion too...

Well, you MIGHT need a floating floor, but it is VERY unlikely, and even if you do, the method that #3 suggested is way wrong for a studio! You said that he has suggested "build a floating floor (neoprene and wood)": Sorry, but that won't work. There is nowhere near enough mass in a wood deck to be able to get the frequency low enough. The correct way to build a floating floor in a studio is by pouring a new concrete slab on top of a wood deck, and supported by proper floor isolation springs. That's why I said that this guy does not have a clue, and should not be involved in your build. The vast majority of studios do not need floated floors, especially if the existing floor is a good concrete slab on the ground. Floating a floor properly is not as simple as throwing down some 2x4s on neoprene pucks, then nailing a sheet of plywood on top. That is a recipe for disaster, and will most likely do the exact opposite of what you want. In order to understand the issues, I'd suggest that you read these threads: viewtopic.php?f=2&t=8173 viewtopic.php?f=2&t=8134 viewtopic.php?t=8135) And to understand the theory and laboratory tests behind floated floors, try this: http://www.nrc-cnrc.gc.ca/obj/irc/doc/p ... /ir802.pdf

- this will be a commercial rehearsal studio, one room only, to begin. But I intend to build a control room inside the same space in a year or 2 and start recording.

Then you should plan the control room now! Even if you don't build it yet, it will still become part of the isolation system of the live room, so it needs to be designed correctly now. The entire facility must be designed as one unit, right from the start, even if only some parts of it are built initially. Where is that control room going to be? Will it be inside the same area as shown on the plan, or in a different place?

- As it is going to be a commercial studio, I do need enough isolation so I don't disturb my neighbors late at night, although I do not want to go past midnight

It seems that the ceiling is your weak point, not the floor, so you should probably be concentrating your efforts on isolating the complete ceiling now.