Basement Support Columns & MSM work around question

[John Mor]

Hi there, thanks for maintaining this beautiful forum. This is my first post here, please excuse my MS paint skills and any possible lack of information.

This is a semi hypothetical situation, but it will help determine on what i should do next with this basement that i have access to. The dimensions of the rooms are irrelevant for now, since i haven't also figured them exactly yet as well.

The basement is under a 6 floor building (residential area) and it has support columns that could potentialy transmit sound easily throughout the entire building. The plan is to make 3 rooms, rehearsal, recording and control room. But let's focus on the 2 of the picture i attached.
These are not actual room ratios, it is mostly a theoretical question. Before i get to the Column question, here is some info:

1) Basement Floor is concrete, and i will isolate the rooms with 100mm concrete floating floor on 50mm rubber pads + porous material for damping.

2) The room walls will be MSM system, with double gypsum board 12.5mm, 150mm airgap, filled with insulation by 2/3. 1st leaf will be resting on the floated floor, 2nd leaf on the basement floor, except for adjacent A & B room walls.

3) Basement walls are also concrete, 400mm and then there's earth/soil outside on most sides. The rooms are placed minimum 1 meter away from these walls and based on the reading & info i've gathered so far, it won't be creating a 3 leaf system with such wall dimensions and space. But please correct me if i'm wrong.

4) Outer Ceiling is 170mm of concrete, inner ceiling will be gypsum board and i would prefer to not suspend it, but we will see about that.

My problem is that these columns are giving me a hard time in order to make functional rooms sizewise, so i kinda have to work around these limitations. Column size is 500 by 500 mm, so they do take up some space already. The picture shows a way i thought to at least minimize the real estate they take with the isolation walls, but i'm not sure if it is a good idea. They will be decoupled, yes, but they will be inside the airspace between the 2 rooms and i'm afraid that there's a chance of them resonating the frequencies that escape the gypsum board. Is that correct? What would you do differently in this regard?

Thank you.

John

[DanDan]

What type of sound are you hoping to isolate from where? I doubt if anything will get through the existing walls and earth, so let's focus on your new rooms. There is plenty of data and advice out there regarding plasterboard partitions. Note, the void in MAM systems needs to be fully filled with light fibre, but not compressed.
The elephant here is the ceiling. Plan?

[John Mor]

Hi DanDan, thank you for your reply and for you contribution here and in other forums. Noted your remark about fully filling the airgap.
I am mostly concerned about isolating the band rehearsals from the rest of the building. The floor directly above me is not an apartment, but the rest of the floors are, and I don't want any complaints by the neighbors whatsoever. Being able to record music as late as needed would be ideal.

I haven't quite understood if you responded to my question though, do you doubt that the columns will be excited if they are in between the M1 and M2 leafs?

I will share the updated floor plan as soon as i get it, for now i have one which isn't accurate.

[DanDan]

You are welcome. I do doubt that they would get excited. For safety or certainty this could be sort of tested. e.g. borrow a small PA and blast music at one of the pillars. Listen upstairs. I am concerned about isolation between your rooms and the first apartment above.

[John Mor]

You are welcome. I do doubt that they would get excited. For safety or certainty this could be sort of tested. e.g. borrow a small PA and blast music at one of the pillars. Listen upstairs.

That sounds promising, thank you. I could try that but i should also have the PA speaker decoupled somehow, like in my picture example, the pillar/column will only be exposed to airborne sound that leaks through the plasterboards.

I am concerned about isolation between your rooms and the first apartment above.

For the apartment above, as in airborn sound leaking through the ceiling, or both airborn and impact as well?

As for the rooms, they are all adjacent, starting from CR, Amp& Drum Room/ Rehearsal space. For the CR and recording room pair, i will use 3 layers of 12.5 plasterboard in each leaf.

My partner in this endeavor is also the owner of the place and a structural engineer, so i will ask him again tomorrow for the updated floor plan and share my rough ideas.

EDIT: Made the rooms layout a bit more understandable hopefully!

[Paulus87]

I'm not seeing much of an issue with what you're trying to do here...

You effectively need to build two fully decoupled bunkers within the basement, in the space either side of the pillars. 4 walls and a ceiling, heavy drywall, 3-4 layers.

Floated floor is unnecessary in your case and will likely make things worse unless you are prepared to spend a lot of money. It's especially useless if one wall of each bunker is going to be connected to the same floating floor.

What are the pillars built from?

[John Mor]

Floated floor is unnecessary in your case and will likely make things worse unless you are prepared to spend a lot of money. It's especially useless if one wall of each bunker is going to be connected to the same floating floor.

Hi Paul, thank you for your response. I am located in Greece, and buildings like this are entirely made from Concrete pillars & ceilings reinforced with metal. Brickwork on the walls. Sound transmission is a real issue in these buildings. I live in a same type building right now and i can hear every single impact noise there is, no matter how far it takes place, disturbingly loud. These buildings are a real mess acoustically. And i will be having lots of extra loud & low tuned heavy metal bands rehearsing there, so..Also there's always the case that 2 bands will be rehearsing at the same time.

It's especially useless if one wall of each bunker is going to be connected to the same floating floor.

There will be 2 floated floors, one for each live room, decoupled.

What are the pillars built from?

The pillars are 50x50 cm concrete & metal and they are 6 floors tall and are also connected with same type support beams everywhere.

[Paulus87]

Floated floor is unnecessary in your case and will likely make things worse unless you are prepared to spend a lot of money. It's especially useless if one wall of each bunker is going to be connected to the same floating floor.

Hi Paul, thank you for your response. I am located in Greece, and buildings like this are entirely made from Concrete pillars & ceilings reinforced with metal. Brickwork on the walls. Sound transmission is a real issue in these buildings. I live in a same type building right now and i can hear every single impact noise there is, no matter how far it takes place, disturbingly loud. These buildings are a real mess acoustically. And i will be having lots of extra loud & low tuned heavy metal bands rehearsing there, so..Also there's always the case that 2 bands will be rehearsing at the same time.

It's especially useless if one wall of each bunker is going to be connected to the same floating floor.

There will be 2 floated floors, one for each live room, decoupled.

What are the pillars built from?

The pillars are 50x50 cm concrete & metal and they are 6 floors tall and are also connected with same type support beams everywhere.

I see - sorry, it sounded like from your post that you were going to build all the walls except the two opposing walls between each room on the existing slab, and then the two rooms were going to be built on the same floating slab, but, if you're going down the route of two fully decoupled and floating concrete slabs on top of the existing slab, I would get a structural engineer involved as well as a company that specialises in noise & vibration control, such as Kinetics. They sell springy pads that work very well and will be able to advise you on which product you need. As an alternative you could also use a couple layers of the semi rigid rock wool insulation designed for this purpose, off the top of my head the density is around 120kg/m3. The best option by far would be springs that are correctly calculated to not only support the load of the rooms, but also have just the right amount of compression to isolate down to your lowest target frequency. They would be very expensive though.

Regarding the pillars resonating from the airborne noise inside the cavity, I think it's not going to be as bad as you think. Impact noise yes, but airborne noise not so much - The sound will first be attenuated by the drywall layers, then the cavity itself will be full of insulation, which will dampen the cavity resonance. The mass of the concrete pillars should be more than sufficient to stop any residual airborne noise, most of it will reflect back. Impact noise carries very well in dense concrete, and although airborne noise can make concrete (or any mass) "sing" it is not anywhere near to the same extent, except at that mass's resonant frequency

To be safe, I would put a bitumen damping layer between each layer of drywall, as well as wrap the pillars in some kind of damping layer as well. This is effectively like putting a towel on a drum. The decoupling of the frames, floor, walls, and ceiling along with the damping of the cavity insulation and damping layers should be extremely effective. Keep the air gap between the two rooms as big as you can (within reason) so that you have maximum possible LF isolation under the constraints that you have.

Is building the two rooms out of concrete blocks instead of drywall an option? You could use block and beam for the ceilings. You would need to check everything out with a structural engineer to make sure the existing slab can support the extra load (I expect it can since it is under a 6 storey building) but then you would have about the best isolation you could ever wish to have.

[John Mor]

I see - sorry, it sounded like from your post that you were going to build all the walls except the two opposing walls between each room on the existing slab, and then the two rooms were going to be built on the same floating slab, but, if you're going down the route of two fully decoupled and floating concrete slabs on top of the existing slab, I would get a structural engineer involved as well as a company that specialises in noise & vibration control, such as Kinetics. They sell springy pads that work very well and will be able to advise you on which product you need. As an alternative you could also use a couple layers of the semi rigid rock wool insulation designed for this purpose, off the top of my head the density is around 120kg/m3. The best option by far would be springs that are correctly calculated to not only support the load of the rooms, but also have just the right amount of compression to isolate down to your lowest target frequency. They would be very expensive though.

Regarding the pillars resonating from the airborne noise inside the cavity, I think it's not going to be as bad as you think. Impact noise yes, but airborne noise not so much - The sound will first be attenuated by the drywall layers, then the cavity itself will be full of insulation, which will dampen the cavity resonance. The mass of the concrete pillars should be more than sufficient to stop any residual airborne noise, most of it will reflect back. Impact noise carries very well in dense concrete, and although airborne noise can make concrete (or any mass) "sing" it is not anywhere near to the same extent, except at that mass's resonant frequency

To be safe, I would put a bitumen damping layer between each layer of drywall, as well as wrap the pillars in some kind of damping layer as well. This is effectively like putting a towel on a drum. The decoupling of the frames, floor, walls, and ceiling along with the damping of the cavity insulation and damping layers should be extremely effective. Keep the air gap between the two rooms as big as you can (within reason) so that you have maximum possible LF isolation under the constraints that you have.

Is building the two rooms out of concrete blocks instead of drywall an option? You could use block and beam for the ceilings. You would need to check everything out with a structural engineer to make sure the existing slab can support the extra load (I expect it can since it is under a 6 storey building) but then you would have about the best isolation you could ever wish to have.

Ah, yes, sorry i might have overcomplicated the writting part and made it confusing. Only the outer layer will be resting on the basement floor. The inner layers will be on the floated floors.

About filling the entire cavity between plasterboards, i have 150mm room to play. So i was thinking of using slightly denser material at the plasterboard sides and less dense in the middle. For example. 50 mm rockwool 40kg - 50 mm mineral wool 17kg - 50mm rockwool 40kg. Instead of going for a full fill of the same material. Rockwool might be too dense to decouple and mineral wool too fluffy to dampen. Does that make any sense to you?

On the bitumen, i cannot find the equivalent product available in Greece, but there are several damping rolls available, so which properties of this product are important here? I ask so that i could find one with similar properties.

We could use concrete blocks filled, but that will take more space, and probably cost more too? And the problem with using the block and beam technique, is that there are several support beams (30cm) in the ceiling already which with plasterboard are so much easier to build around. But yeah i could ask my engineer on that too.

Thank you.

[Paulus87]

I see - sorry, it sounded like from your post that you were going to build all the walls except the two opposing walls between each room on the existing slab, and then the two rooms were going to be built on the same floating slab, but, if you're going down the route of two fully decoupled and floating concrete slabs on top of the existing slab, I would get a structural engineer involved as well as a company that specialises in noise & vibration control, such as Kinetics. They sell springy pads that work very well and will be able to advise you on which product you need. As an alternative you could also use a couple layers of the semi rigid rock wool insulation designed for this purpose, off the top of my head the density is around 120kg/m3. The best option by far would be springs that are correctly calculated to not only support the load of the rooms, but also have just the right amount of compression to isolate down to your lowest target frequency. They would be very expensive though.

Regarding the pillars resonating from the airborne noise inside the cavity, I think it's not going to be as bad as you think. Impact noise yes, but airborne noise not so much - The sound will first be attenuated by the drywall layers, then the cavity itself will be full of insulation, which will dampen the cavity resonance. The mass of the concrete pillars should be more than sufficient to stop any residual airborne noise, most of it will reflect back. Impact noise carries very well in dense concrete, and although airborne noise can make concrete (or any mass) "sing" it is not anywhere near to the same extent, except at that mass's resonant frequency

To be safe, I would put a bitumen damping layer between each layer of drywall, as well as wrap the pillars in some kind of damping layer as well. This is effectively like putting a towel on a drum. The decoupling of the frames, floor, walls, and ceiling along with the damping of the cavity insulation and damping layers should be extremely effective. Keep the air gap between the two rooms as big as you can (within reason) so that you have maximum possible LF isolation under the constraints that you have.

Is building the two rooms out of concrete blocks instead of drywall an option? You could use block and beam for the ceilings. You would need to check everything out with a structural engineer to make sure the existing slab can support the extra load (I expect it can since it is under a 6 storey building) but then you would have about the best isolation you could ever wish to have.

Ah, yes, sorry i might have overcomplicated the writting part and made it confusing. Only the outer layer will be resting on the basement floor. The inner layers will be on the floated floors.

About filling the entire cavity between plasterboards, i have 150mm room to play. So i was thinking of using slightly denser material at the plasterboard sides and less dense in the middle. For example. 50 mm rockwool 40kg - 50 mm mineral wool 17kg - 50mm rockwool 40kg. Instead of going for a full fill of the same material. Rockwool might be too dense to decouple and mineral wool too fluffy to dampen. Does that make any sense to you?

On the bitumen, i cannot find the equivalent product available in Greece, but there are several damping rolls available, so which properties of this product are important here? I ask so that i could find one with similar properties.

We could use concrete blocks filled, but that will take more space, and probably cost more too? And the problem with using the block and beam technique, is that there are several support beams (30cm) in the ceiling already which with plasterboard are so much easier to build around. But yeah i could ask my engineer on that too.

Thank you.

Danosa make a good product, they do one which is a asphalt roofing product, but has no texture. So it's just a black roll that you staple on to between the plasterboard layers. About 3.5kg/m2. Anything similar to this will help. Ice and Water shield is another one.

Taking a second look at your plan - I assumed mass layer 1 was your existing concrete shell. Looks like you're planning to build something like this:

outside - Concrete - gap - plasterboard layers on frame - gap - plasterboard layers on frame - inside

Is there a reason for this? You really only need:

outside - Concrete - gap - plasterboard layers on frame - inside

[John Mor]

Danosa make a good product, they do one which is a asphalt roofing product, but has no texture. So it's just a black roll that you staple on to between the plasterboard layers. About 3.5kg/m2. Anything similar to this will help. Ice and Water shield is another one.

Taking a second look at your plan - I assumed mass layer 1 was your existing concrete shell. Looks like you're planning to build something like this:

outside - Concrete - gap - plasterboard layers on frame - gap - plasterboard layers on frame - inside

Is there a reason for this? You really only need:

outside - Concrete - gap - plasterboard layers on frame - inside

Hi Paul, thank you, i will look it up.
Yes, there is reason why we have chose to do this like that,
the pillars don't allow for a different plan sadly, and there will be a 1000mm corridor around the live rooms and a hall/lounge . Isn't it big enough to avoid triple leaf?

[Paulus87]

Danosa make a good product, they do one which is a asphalt roofing product, but has no texture. So it's just a black roll that you staple on to between the plasterboard layers. About 3.5kg/m2. Anything similar to this will help. Ice and Water shield is another one.

Taking a second look at your plan - I assumed mass layer 1 was your existing concrete shell. Looks like you're planning to build something like this:

outside - Concrete - gap - plasterboard layers on frame - gap - plasterboard layers on frame - inside

Is there a reason for this? You really only need:

outside - Concrete - gap - plasterboard layers on frame - inside

Hi Paul, thank you, i will look it up.
Yes, there is reason why we have chose to do this like that,
the pillars don't allow for a different plan sadly, and there will be a 1000mm corridor around the live rooms and a hall/lounge . Isn't it big enough to avoid triple leaf?

If there's going to be a corridor then yes that's fine, maybe you could upload a floor plan of the entire facility?

[John Mor]

If there's going to be a corridor then yes that's fine, maybe you could upload a floor plan of the entire facility?

Ok great!
We were just working on that with my partner who is also a structural engineer. A first basic floor plan with the rooms layed out is almost ready. There are a few points we sure need to double check with you and anyone in the forum. Hopefully tomorrow it's going to be ready. Thanks again!

[John Mor]

The elephant here is the ceiling. Plan?

...maybe you could upload a floor plan of the entire facility?

Hey Dan and Paul, hope you are doing great. Here is a first basic 2D layout finally. I need to make this in sketchup somehow so that you can see the leafs clearly, but this will take some time as i have difficulties importing the file in a 1 to 1 ratio and the lines get blurry. In order to keep this thread going, i am posting this, till i figure it out.


Link for high res : https://drive.google.com/file/d/1OMaBH4 ... sp=sharing

There are many things to figure out yet, for example : There is no 2nd leaf for the flush mount wall side yet, the inner leaf of the CR terminates on that wall as of now. We could extend the room till the stairs and seal it with plaster board and an extra door on the side but it will be very claustrophobic and akward to navigate. Right now the stairs don't have anything on the side. The ideal would be to have glass on the side of the stairs so it doesn't feel claustrophobic, but that will be expensive. What about thick plexiglass?

The flush mount walls are also not fined tuned at all, just a 30 degree angle for now. I wanted them to be as big as possible, i will figure the exact position later with sketchup. Paul, i read some great info about flush mounting on your thread, cheers for that!

A few words on the rooms.

So, as you can tell, i am going for a NE control room design. I'm a fan of Newell and Northward designed rooms. I'm going for my own aesthetic that is more on the brutalism side of architecture, but that's for another time.
For the speakers, i lean towards getting a pair of Focal trio 11 be, or the Neumann kh420. The Focals extend very close to the room's longest mode, so there will be support. The KH420 go even lower. I try to avoid subs, and since there's a boost with the hard flush, i think it's cleaner that way. I will be also using nearfields, my Amphion one18s. I plan on either filling the entire back wall with 1 meter deep mineral wool (unless there's a point of diminishing returns), or trying out hangers and membrane absorbers combo. This room will not have concrete floated floor, i still want to see if i will use the type of floor that Rod Gervais mentions in his book, or just go with the basement concrete. Ceiling treatment and side treatment, as deep as i can get too, with some slats for self noise cues.

Next to the CR, the recording room. I imagine this room being treated with lot's of diffusion and reflective surfaces. Also absorption behind these. It will be a drum and amp room. I will have movable absorptive panels too, and a dry, absorptive wall maybe. We will see. I might do a small booth in there for vocals, in case a band wants to record a live performance. I want to put 2 windows in this room, so that there's line of sight for both live rooms.

And finally, the rehearsal room which is a bit bigger. It will also be working as a recording room for live band recordings, isolating the instruments by spreading them in the 2 rooms. Or if a project suits the sound of this room better, i could always use that instead. I plan on having a bit more absorptive treatment there, and maintain some of the liveness too, so that the bands can rehearse easily.

This is the main concept, and of course i could expand a lot more, and i will once i figure out every little aspect.

Looking forward for your beedback and thank you for your time!

[DanDan]

There is no difference between densities used to fill the void. However it is necessary to create a full fill, touching, damping, the sides. But not compressed.

Void Density.png