new freestanding studio building - noise considerations

[jacko]

I'm making draft plans and ideas for my possible future recording studio.
I want to build a 160sq meter building out of which 80sqm will be the live room. The walls will be 3-4 meters high and there will be a gable roof.
The live room will serve for very loud rock bands so not only drums will be an issue but also cranked up JCM800 or Ampeg SVT.

Most importantly I would like to make the building soundproof as much as possible. There will be at least 10 meters on each side of the building to my neighbours land and at least 20 meters to the closest building. If possible, I'd like my neighbours comfortably rest outside in their gardens without hearing noise from my studio.

Before I meet an acoustic designer and an architect I'd like to find out from the practical point of view what building structure will I need to use to make my neighbours happy.

Please correct or confirm my assumptions and answer my questions, thank you!

1. For a freestanding building with concrete slab on grade I won't probably need a floating floor in the live room.

2. There will be outer walls and inner walls spaced apart.

3. Inner walls would support inner ceiling, spaced apart from the roofing structure.

4. Can inner walls be made of wood frame and gypsium board or should I rather think of denser material?

I will probably have more questions which I will be posting here as I progress with plans and ideas.

[Soundman2020]

Hi there "jacekmilaszewski", adn welcome to the forum!

Please read the forum rules for posting (click here). You seem to be missing a couple of things!

First, a general comment:

I want to build a 160sq meter building out of which 80sqm will be the live room. The walls will be 3-4 meters high and there will be a gable roof.

That's a really nice sized building for a studio. Excellent prospects for success!

Most importantly I would like to make the building soundproof as much as possible. There will be at least 10 meters on each side of the building to my neighbours land and at least 20 meters to the closest building. If possible, I'd like my neighbours comfortably rest outside in their gardens without hearing noise from my studio.

OK, so high level of isolation is necessary. It would be good if you could put numbers to that (in terms of how many decibels of isolation you need).

OK, about your questions...

1. For a freestanding building with concrete slab on grade I won't probably need a floating floor in the live room.

Correct. There should be no problem at all with getting good isolation, based on your general outline.

2. There will be outer walls and inner walls spaced apart.

Correct: The materials used to build each "leaf" of that double-wall, and the gap between the two leaves, are calculated using simple equations, to get the level of isolation you need.

3. Inner walls would support inner ceiling, spaced apart from the roofing structure.

correct. Once again, the building materials and the size of the gap are calculated.

4. Can inner walls be made of wood frame and gypsium board or should I rather think of denser material?

Yes, no problem with that. Here too the spacing of the wood frame away from the outer leaf, and the surface density of the drywall (gypsum board) are calculated in order to give you the amount of isolation you need. What are you planning to use for the outer leaf? Brick or concrete block would be excellent choices, as you need high isolation.

I will probably have more questions which I will be posting here as I progress with plans and ideas

Excellent! That's what the forum is here for, and I'm really looking forward to seeing your project move ahead!


- Stuart -

[jacko]

5. The outer shell of the building will be concrete 24cm thick, around 450kg/sq.m. density (close to 2000kg/cubic meter). The inner shell is not decided yet and I would like to ask for some advice.
I found on this website some interesting graphs: http://www.bobgolds.com/WallCharts/

If my walls looked like this:


The STC/frequency chart would look like this:


There is still significant amount of low end passing through the walls.

Should I take some extra measures and build even thicker walls to make sure that loud bass guitars and drums are not heard by my neighbours?
How about making the inner partition with 12cm thick concrete block instead of drywall?

[jacko]

I just went to a studio which is built on grade. It doesn't have inner shell, just one layer of 30cm concrete wall with styrofoam thermal insulation on the outside (under plaster layer). Concrete floor. No resiliency at any place in the building. It has insufficient transmission loss.
Measured by the outside wall with Radioshack meter this studio gets around 38dBC or 48dBA isolation. What I hear from drums the most is the area between 100Hz and 250Hz, but higher frequencies are also audible. Frequencies lower than 100Hz don't seem to be much of a problem (don't appear to be annoying).

If I build a sealed inner shell and if I create double leaf wall: [concrete block - 5cm mineral wool - 20cm air space - 5cm mineral wool - double gypsum board on studs], am I going to see significant drop in transmission in this 100-250Hz area? I feel that 20dB more isolation would be needed to make the sounds out of the studio acceptable for neighbours. Thanks!

[jacko]

here is my first floor plan idea

[Soundman2020]

I just went to a studio which is built on grade. It doesn't have inner shell, just one layer of 30cm concrete wall with styrofoam thermal insulation on the outside (under plaster layer). Concrete floor. No resiliency at any place in the building. It has insufficient transmission loss.

Yup! That's what single-leaf construction will get you: Mass Law is not very heartening.

Measured by the outside wall with Radioshack meter this studio gets around 38dBC or 48dBA isolation.

For 30cm thick concrete walls, that's about right. 45 dB isolation would be the rough prediction for that.

What I hear from drums the most is the area between 100Hz and 250Hz, but higher frequencies are also audible.

So mostly snare and toms? Or is the kick smaller and tuned high?

Frequencies lower than 100Hz don't seem to be much of a problem (don't appear to be annoying).

There might not be a lot of energy below 100 Hz for a drum kit that is tuned high. It would be better to test the low end using a six-string bass and a nasty amp...

If I build a sealed inner shell and if I create double leaf wall: [concrete block - 5cm mineral wool - 20cm air space - 5cm mineral wool - double gypsum board on studs], am I going to see significant drop in transmission in this 100-250Hz area? I feel that 20dB more isolation would be needed to make the sounds out of the studio acceptable for neighbours. Thanks!

Theoretically, that would give you roughly 55 dB of isolation, but it would go a lot lower down the spectrum than what you saw. If you built it right, it would isolate down to about 30 Hz., and isolate very well from about 48 Hz. upwards. The isolation dip at 150 Hz would be gone. Or rather, it would be pushed down way lower, to a point where it doesn't really matter (unless you want to record earthquakes, canon, and alien spaceships blowing up Planet Earth...).

In other words: Yes, with that plan you'd get pretty good isolation down to low frequencies.

Of course, this assumes that you design and build the doors, windows and HVAC system to high levels of isolation too. Especially HVAC: that's usual the part that people forget about, until it is too late to get it right...


- Stuart -

[jacko]

The materials used to build each "leaf" of that double-wall, and the gap between the two leaves, are calculated using simple equations, to get the level of isolation you need.

Are these equations available?
I failed in finding them.

[Soundman2020]

Are these equations available?

In many places, and many forms. The best resource I know of for understanding 2-leaf MSM construction is the Wyle report. It's old, but very good:

https://app.box.com/shared/jcaoavdc8g

Also, for further understanding and more equations I'd suggest two books: "Master Handbook of Acoustics" by F. Alton Everest (that's sort of the Bible for acoustics), and "Home Recording Studio: Build it Like the Pros", by Rod Gervais.

There's also a great paper called "Accuracy of Prediction Methods for Sound Transmission Loss" from the the 33rd International Congress and Exposition on Noise Control Engineering in 2004, but I don't have a link for downloading it.

- Stuart -

[jacko]

Coming back to the building's foundation I would like to ask if I understand this correctly: There is one huge concrete plate / slab that supports the whole building, including the outer walls and the inner walls? The soil that supports the building reduces flanking through the foundation slab?



I've also seen constructions where there are foundation footings separated from inner concrete slab isolated from outer structure. Is it going to make significant difference in terms of transmission loss?

So mostly snare and toms? Or is the kick smaller and tuned high?

The kick was maple 22"*16". Tuned lower than 100Hz, I'd say closer to 70-80Hz. In the room it sounded deep with hefty low end. Outside the studio it seemed that mostly 100Hz and above was heard from the kick.

[jacko]

Question regarding the inner wall of the liveroom:

If instead of wood studs and gypsum board I would use concrete blocks to build the inner wall, what is the thinnest structure that is strong enough to support, let's say 5 tonnes of ceiling (wood beams, mineral wool and gypsum board)? I need a rough estimate, eventually I will of course make a design with all construction details properly calculated by specialists.

[stevev]

If instead of wood studs and gypsum board I would use concrete blocks to build the inner wall, what is the thinnest structure that is strong enough to support, let's say 5 tonnes of ceiling (wood beams, mineral wool and gypsum board)? I need a rough estimate, eventually I will of course make a design with all construction details properly calculated by specialists.

You'll need to run that past a structural engineer even to get a rough figure Jacko. But for arguments sake, and me not being qualified in any engineering capacity, a 190 x 190 x 390 besser (breeze) block wall, properly core filled with concrete and with F12 reinforcing bar in to the slab and through every second (if not every) hollow, would probably get you there.......but that may be over or under done depending on the strength and load bearing capcity and design of the slab as well as the roof spans etc etc....which is why you need an engineer to asses such an idea.

all the best,

Steve