John Sayers' Recording Studio Design Forum Archive

Hello, my name is Inti and I’m from Montevideo, Uruguay. Nowadays I have a rehearsal room in my house, and I’m planning to build another one.
The main objective for the rehearsal room is to isolate as much as possible. We are talking about a rehearsal room that will often receive punk rock and heavy metal bands, so the average dB in the room will be about 115dB. The objective is the sound that is transmitted neighbor’s house is never over 60dB.
I’m on the second floor of a two floors building. On the first floor there is a doctor’s office (they work only a few hours from Wednesday to Friday.)
As you can see in the sketch up, the main idea is to build a room in a room.
Wall A is facing a neighbor room, here we have a 36cm solid brick wall covered in mortar.
Wall B is facing a medium traffic street, here we have a 36cm solid brick wall covered in mortar. This wall has a wood/glass door, I’m planning to change it for a double laminated glass window.
Wall C is an inner wall, it separates the rehearsal room from another room where I will have my desk.
Wall D is an inner wall; there will be a double door system.
Wall E is an inner 18cm solid brick wall covered in mortar. It separates the room from an inner corridor and the stairways of the house.

Walls- The system from inside will be:

Solid brick walls: 15cm air gap- 50mm rockwool (48k/ m3 density)- steel studs- 15mm wallboard- 12,5mm wallboard
Inner walls: 12,5mm wallboard- 15mm wallboard- steel studs- 50mm rockwool- 30cm air gap- steel studs- 15mm wallboard- 12,5mm wallboard
For the corners where the wallboards meet, I’m going to use Grabber (an acoustical sealant).

Ceiling: Over the ceiling is a mezzanine. For the ceiling I was planning to use a similar system from that for the walls: 12,5mm wallboard fixed to a 15mm wallboard, all this layer fixed to the wood studs from the mezzanine floor and 50mm Rockwool in the cavity.

Floor: The room has a pitch pine floor. This building is from 1938 and in this time local constructors use to do some kind of floating floor between levels. You could see in the sketch up the wood structure of this floor. Under the wood structure there is a 20cm cement slab.

Window: The window will have two laminated glass (12mm/10mm) and 40cm distance between glasses. I’m planning to build a solid wood frame and follow John's advice ( http://johnlsayers.com/Recmanual/Titles/Acoustics3.htm).

Doors For each door I’m going to use two 18mm MDF layer and a rigid fiber glass covered with fabric in the inner face. Between the doors and the wall rigid fiber glass covered with fabric too. All the system with rubber seals, surface mounted handle and automatic door closer.

Sound treatment: Firstly, corners will be treated with homemade bass traps.

I will be very grateful for any comments about this plan, I was reading a lot in the forum to achieve a decent idea to build it.
On the other hand, I have a big doubt about the floor, I had read that a floating floor is not a big idea cause to do it in perfect conditions needs a fortune. But the house already has the floating floor. So, what will you do with it?
My budget is around USD10.000.

Thanks a lot for your huge help with this forum.

Happy new year!!!

Hi Inti, welcome to the forum!

Since your attachment is a .rar, I'm not going to download it. But, I think I've grasped your idea enough from your description.

the average dB in the room will be about 115dB. The objective is the sound that is transmitted neighbor’s house is never over 60dB.

Okay, simple math means you need ~55dB of isolation. If you go to the design forum and use my transmission loss calculator, you'll be able to get a decent idea of how you need to construct your walls, floor and ceiling. Each one needs to be able to achieve that 55dB of isolation. That includes windows, doors and HVAC.

I’m on the second floor of a two floors building. On the first floor there is a doctor’s office (they work only a few hours from Wednesday to Friday.)
As you can see in the sketch up, the main idea is to build a room in a room.

Okay, as soon as you figure out how you need to build your walls and ceiling, contact a structural engineer and get their stamp approving the build. Since you're on the second floor, you NEED to make sure that the floor can deal with the weight you will be putting on it.

This wall has a wood/glass door, I’m planning to change it for a double laminated glass window.

If you're doing a room in a room, this existing outer leaf door would be replaced by a SINGLE laminated glass window. Note: SINGLE!

Solid brick walls: 15cm air gap- 50mm rockwool (48k/ m3 density)- steel studs- 15mm wallboard- 12,5mm wallboard
Inner walls: 12,5mm wallboard- 15mm wallboard- steel studs- 50mm rockwool- 30cm air gap- steel studs- 15mm wallboard- 12,5mm wallboard
For the corners where the wallboards meet, I’m going to use Grabber (an acoustical sealant).

Referencing what I said above, have you done the calculations (or used my calculator) to determine if this plan of attack will give you the required amount of isolation?

For your insulation, you need to completely fill the cavity. So if your gap is 15 cm, you need three batts of 50mm rockwool. Also, maybe try to find rockwool that has a lower density than 48kg/m3. If you can, try to get it between 30 and 45.

Is there a reason you're using 15mm, then 12.5mm drywall? The thicker the drywall, the heavier it is. The heavier it is, the better your transmission loss! Again, maybe you've done the math and you only need 15mm + 12.5mm.

Ceiling: Over the ceiling is a mezzanine. For the ceiling I was planning to use a similar system from that for the walls: 12,5mm wallboard fixed to a 15mm wallboard, all this layer fixed to the wood studs from the mezzanine floor and 50mm Rockwool in the cavity.

Here is your first biggest design flaw. Your ceiling cannot be attached to the existing structure. It needs to sit on top of the inner leaf walls. If you build it your way, there's no way you'll achieve 55dB of isolation.

Floor: The room has a pitch pine floor. This building is from 1938 and in this time local constructors use to do some kind of floating floor between levels. You could see in the sketch up the wood structure of this floor. Under the wood structure there is a 20cm cement slab.

My guess is that you'd be best to remove the pine floor and build your inner leaf on the concrete slab.

Window: The window will have two laminated glass (12mm/10mm) and 40cm distance between glasses. I’m planning to build a solid wood frame and follow John's advice ( http://johnlsayers.com/Recmanual/Titles/Acoustics3.htm).

The thickness of your laminated glass will depend on your wall construction. Just make sure it is equal to or greater than the surface densities of your walls.

Sound treatment: Firstly, corners will be treated with homemade bass traps.

Building your walls and ceiling using John's inside out method will open up a ton of treatment possibilities.

I will be very grateful for any comments about this plan, I was reading a lot in the forum to achieve a decent idea to build it.
On the other hand, I have a big doubt about the floor, I had read that a floating floor is not a big idea cause to do it in perfect conditions needs a fortune. But the house already has the floating floor. So, what will you do with it?

See my comment about it love.

My budget is around USD10.000.

Since you didn't give us dimensions and I didn't open your .rar file, I can comment on whether this is a reasonable amount or not.

You also didn't mention HVAC. Typically HVAC eats up a large portion of a budget. Also, laminated glass is very expensive. To save money, you could look into fluffy fibreglass insulation between your leaves.

Thanks a lot for your huge help with this forum.

Happy new year!!!

Happy new year to you as well! I'm stuck in a hotel room with a super sick wife and kids right now hahaha. 45 minutes until 2019! Yay!!!

Greg

Hola, Inti, y muy bienvenido al foro! Y feliz año nuevo también!

OK, adding to what Greg already said...

average dB in the room will be about 115dB. The objective is the sound that is transmitted neighbor’s house is never over 60dB.

Excellent estimation! Most new members don't bother measuring that or defining it. Good job! So in other words, you are aiming for around 55 dB o isolation. Certainly attainable, if you design right.

I’m on the second floor of a two floors building.

That's a problem! Isolating a room that is not on the ground floor, is much harder.

Solid brick walls: 15cm air gap- 50mm rockwool (48k/ m3 density)- steel studs- 15mm wallboard- 12,5mm wallboard

There is no need to mix two different thicknesses of drywall. The slight advantage you gain from the mismatch is offset by the reduced mass. It is pretty much always better to go with two layers of the most dense material.

Inner walls: 12,5mm wallboard- 15mm wallboard- steel studs- 50mm rockwool- 30cm air gap- steel studs- 15mm wallboard- 12,5mm wallboard

How thick are the studs? How much gap is there between the frames?

For the corners where the wallboards meet, I’m going to use Grabber (an acoustical sealant).

You will need acoustic caulk EVERYWHERE! Not just in the corners. Getting excellent air-tight mass-consistent seals is fundamental to getting good isolation.

Ceiling: Over the ceiling is a mezzanine.

Built how? Materials? Thickness? What is above that?

For the ceiling I was planning to use a similar system from that for the walls: 12,5mm wallboard fixed to a 15mm wallboard, all this layer fixed to the wood studs from the mezzanine floor and 50mm Rockwool in the cavity.

As Greg mentioned, you will not get good isolation like that. Your inner-leaf ceiling must not even touch the outer-leaf at any point. It can only rest on top of the inner-leaf walls.

Floor: The room has a pitch pine floor. This building is from 1938 and in this time local constructors use to do some kind of floating floor between levels. You could see in the sketch up the wood structure of this floor. Under the wood structure there is a 20cm cement slab.

I would suggest that you take a close look at that, and remove that wood flooring completely. It is not doing you any favors, and it will not be able to handle the huge amount of mass that you will need to have in your room's walls and ceiling.

Doors For each door I’m going to use two 18mm MDF layer and a rigid fiber glass covered with fabric in the inner face. Between the doors and the wall rigid fiber glass covered with fabric too. All the system with rubber seals, surface mounted handle and automatic door closer.

Sound treatment: Firstly, corners will be treated with homemade bass traps.

Is this going to be a control room / mixing room too? Or just a rehearsal room? You probably do not need bass traps in all corners for a rehearsal room. Some corners, yes, but not all.

But the house already has the floating floor.

It is not a floating floor! It might look like it, but floating floors had not even been invented in 1938! Even if it is a later attempt at a floating floor, it still is NOT a floating floor, because it is impossible to get enough mass using only wood to do that. Remove it, and just keep the original concrete slab as your floor, then lay thick laminate flooring over a good acoustic underlay, or perhaps use the Rod Gervais method of partially decoupling your inner-leaf floor (after you build the inner-leaf walls!), if you can spare the height.

Since your attachment is a .rar, I'm not going to download it

ditto.

contact a structural engineer and get their stamp approving the build. Since you're on the second floor, you NEED to make sure that the floor can deal with the weight you will be putting on it.

In Spanish, that's usually a "calculista" in some LA countries, but could also be "ingeniero estructural" in others.

You also didn't mention HVAC. Typically HVAC eats up a large portion of a budget.

Montevideo is not terribly hot, but the humidity is pretty high, averaging something like 70%. if I recall correctly. So you will need a good HVAC system to deal with that: very high latent heat load, in addition to the sensible heat load. Also, if you have a storage room of some type for instruments, mics, equipment, that room needs to be part of the HVAC system as well. Many instruments and some mics change their tone with changes in temperature and humidity, so moving them form a warm humid environment to a cool dry one means that the tuning will change over time, as they acclimatize: you'll be re-tuning your instruments and repeating takes as the mics adapt, all the time. Keep the entire interior at about 21° and around 40% RH, all the time (not just when you are inside!).

- Stuart -

Greg, Stuart, thanks a lot for your responses! I'm working on a new SketchUp, not so much heavy so I can attach it without compressing and everyone could see more clearly the rehearsal room plan. I'm going to consider all your advices for it. Besides, I have ordered Rod's book, and I'm going to contact a structural engineer to be sure about the floor.

Once again, thanks for your great help.

I'll come back soon!

I'm working on a new SketchUp, not so much heavy so I can attach it without compressing

It will probably still be too big to post directly, so just upload it to somewhere like Dropbox, and post a link here.

Looking forward to seeing that!


- Stuart -

Hello everybody, I'm still working on the new design. I've been looking for almost two weeks and couldn't find any metal frame inside-out ceiling example. Do you know if anybody had done something like that? Could it be worthwile?

I can't think of a way metal would work for an inside out ceiling in that in order to properly seal it, you'd need it to be rectangular type tubing at which point those areas would create a three leaf system AND they would resonate like a drum. What is stopping you from using engineered stud for your inner leaf joists like everyone else does?

Greg

Gregwor wrote:I can't think of a way metal would work for an inside out ceiling in that in order to properly seal it, you'd need it to be rectangular type tubing at which point those areas would create a three leaf system AND they would resonate like a drum. What is stopping you from using engineered stud for your inner leaf joists like everyone else does?

Greg

Greg, when you said engineered stud is referring to wood stud, isn't it? If so, here in Uruguay wood studs are considerably more expensive than metal framing, that's the issue. But if wood studs are the only way to go with inside out ceiling I'm considering to go in that way.

I suppose there MIGHT be some way to do that, but I don't work much with metal framing, and I've never seen an inside-out metal ceiling done, anywhere. I agree with Greg: It's easier to go with wood framing. We know it works, and we know how to do it...

- Stuart -

Hello again, I’m back with the rehearsal room project. I had been adjusting the plan considering Rod Gervais’s book guide and Gregwor and Stuart advices.

So, refreshing and reconsidering:

The main objective for the rehearsal room is to isolate as much as possible. We are talking about a rehearsal room that will often receive punk rock and heavy metal bands, so the average dB in the room will be about 115dB. The objective is the sound that is transmitted neighbor’s house is never over 60dB.

I’m on the second floor of a two floors building. On the first floor there is a doctor’s office (they work only a few hours from Wednesday to Friday.)
As you can see in the sketch up, the main idea is to build a room in a room.

Wall A (inner length: 400cm) is facing a neighbor room, here we have a 36cm solid brick wall covered in mortar.
Wall B (inner length 384cm) is facing a medium traffic street, here we have a 36 cm solid brick wall covered in mortar. This wall has a wood/glass door, I’m planning to change it for a double laminated glass window.
Wall C (length 227cm) is an inner wall, it separates the rehearsal room from another room where I will have my desk.
Wall D (length 242cm) is an inner wall; there will be a double door system.
Wall E (length 217cm) is an inner 18cm solid brick wall covered in mortar. It separates the room from an inner corridor and the stairways of the house.

All walls height is 240cm.

Walls- The system from inside will be:

Solid brick walls- 10cm air gap- 2x 50mm Rockwool batts(40k/ m3 density)- 2x4” wood studs- 15mm wallboard- 15mm wallboard

Inner walls- 15mm wallboard- 15mm wallboard-2X4” wood studs- 20cm air gap- 4x 50mm Rockwool batts-2x4” wood studs- 15mm wallboard- 15mm wallboard
I’m going to use Grabber (an acoustical sealant) to seal between wallboards.

Ceiling: For the ceiling now I’m planning to use an inside out ceiling, 2x6” frame, an inner 50mm Rockwool batt, 15mm gypsum board, over the gypsum board another 50mm Rockwool batt.
Over the ceiling is a mezzanine: it has structural steel beams, rigid fiber glass, MDF 15mm floor.

Floor: A structural engineer confirmed me that I could take out the pitch pine floor. I’m going to do it and and place a vynil floor. The system will be similar to Rod Gervais’s page 270 example: 12mm rigid fiber glass, 18mm plywood, 15mm vynil floor.

Window: The window will have two laminated glass (12mm/ 10mm) and 40cm distance between glasses. I’m planning to build a solid wood frame like the one attached (the idea and the image are from another post from this forum)

Gregwor mentioned: “If you're doing a room in a room, this existing outer leaf door would be replaced by a SINGLE laminated glass window. Note: SINGLE!”
I´m sorry but I don’t get this point. I need to isolate the rehearsal room from the street noise, won’t it be better to construct a double laminated glass window?

Doors: For each door I’m going to use two 18mm MDF layer and a rigid fiber glass covered with fabric in the inner face. Between the doors and the wall rigid fiber glass covered with fabric too. All the system with rubber seals. A surface mounted handle and automatic door closer.

HVAC: Mini split ductless system 12000BTU (I have been using one like that in another rehearsal room with similar dimensions for more than 2 years and it is still working perfect).

My budget is around USD10.000

Link to sketchup model: https://www.dropbox.com/s/r85jgs6pwgkbl ... l.skp?dl=0


Thanks for all your help.

Gregwor mentioned: “If you're doing a room in a room, this existing outer leaf door would be replaced by a SINGLE laminated glass window. Note: SINGLE!”
I´m sorry but I don’t get this point. I need to isolate the rehearsal room from the street noise, won’t it be better to construct a double laminated glass window?

The outer leaf needs a SINGLE laminated glass window. Then the inner leaf needs a SINGLE laminated glass window. That would create a proper two leaf system, mimicking your walls.

Doors: For each door I’m going to use two 18mm MDF layer and a rigid fiber glass covered with fabric in the inner face. Between the doors and the wall rigid fiber glass covered with fabric too. All the system with rubber seals. A surface mounted handle and automatic door closer.

Screwing into MDF does not provide very strong connections. Solid core door slabs are built with a real wood frame around dense material such as particle board. This allows a person to screw hinges into real fibrous wood. I would highly suggest buying a manufactured solid core slab (with no holes in it) and then add a layer or two of MDF to it. Also, in your Sketchup, you show some very crappy looking hinges for your door. Furthermore, you only put one hinge at the top and one at the bottom. You need to make sure that you use very heavy duty commercial grade hinges and use 4 of them.

My budget is around USD10.000

You said materials are cheap there. I can't comment on your budget as I'm not sure just how cheap materials are. But where I live, that wouldn't be enough.

Link to sketchup model: https://www.dropbox.com/s/r85jgs6pwgkbl ... l.skp?dl=0

I took a quick look through your model. You didn't use any components or layers so it makes it very very difficult to navigate. Thankfully you made scenes. If I were you, I would go through and make components and assign them to layers.

I'm not sure what the standard building practices are where you live, but I've never seen walls constructed in that manner. You have everything on edge which in my mind would not provide enough stability.

Also, there is no drawings of your silencer boxes.

I would suggest adjusting your SketchUp and repost it so that we can review it in more detail. Also, make sure you're drawing everything in such a way that it is constructed to code. The forum's biggest priority is that people build things so that they are SAFE!

Greg