Design of two Rehearsal Rooms

Hello Folks, This project is not a recording studio: I'm helping a friend on building a couple of rehearsal rooms and I came up with this idea. I hope you share some thoughts about my design. About the building, this is going to be built in a second floor of a building (we rent the entire place) Walls are made of 15cm brickwalls. Both floor and ceilings are concrete, aprox 15 or 20 cm as well. (there is a 3rd floor) The whole idea here is to build 2 rehearsal rooms open for public, paid by the hour. So we have to work with this space. Room size is 9 mts x 6,75 mts. 2.5 mts high. The goal is to achieve a max of 45db noise to the outside, since we have neighbours in the north wall, and they could cancel our renting contract if they feel annoyed somehow by the noise. So its pretty critical that we isolate it properly. However, there's going to be 2 bands rehearsing at the same time, so isolation between rooms has to be decent also, or at least good enough to rehearse and not to be annoyed by the other band. Also there is 2 windows in the north (great!!) and west walls, but we will remove them and fill the space with brickwalls as well, so I think we have that problem solved Budget is pretty tight, I would say $6000 USD. We don't care about HVAC for now, they'll have to live with that. What other info could I tell you? Well, I dont care about rooms acoustics either, this has to work only! So don't mind almost cube shaped rooms, etc. (Some bands here in Chile are used to rehearse in some rat-holes so this is going to be pretty good actually) Good equipment, etc. Here are some pics about my design. Overall, its going to be steel studs framing ( I used wood for sketchup purposes) With 2 layers of 5/8" drywall on each side (2 on the outer framing, and 2 on the outer inner framing, so I can use the insulation as acoustic treatment, in other words: Rehearsal rooms are going to be built "inside out", and the second leaf is going to be built normally, that means, the drywall layers facing the corridor) The two rooms are going to have an inner ceiling (decoupled) as well (not shown), however the outer leaf is going to be directly attached to the existing ceiling and walls, like if it was an existing wall . Airgap between two rooms is 20 cm (not counting framing) and 10 cm from existing walls. Btw inner and outer leaf (corridor) is a 40 cm air gap There is also two structural metal beams that we have to live with, and i further used them to achieve a bigger air gap between leafs. hopefully that will increase isolation to that side I dont plan to float the floors since I dont know how (pads placement, density, etc), and its going to be expensive as well. I also consulted to a structural engineer and he told me the amount of mass we are adding shouldnt be a problem. What else? I also thought about building 2 drum-risers just for the drums, since the floors wont be floated, I'm worried about flanking noise to the first floor. However, that isnt a life-death thing because we are the people that will be using the house, and my partners wont feel annoyed if they hear some kickdrums going. If just a drum riser would help that, thats ok, if not, its ok as well. The only MAIN concerns are the neighbours (in the contract its says that if they feel annoyed by noise, we have to leave!!) So, thats pretty much it. Any suggestions?? I hope I was as detailed as possible and dont hesitate to ask me futher questions. I will really appreciate your time to help me out with this. Cheers Javier :shot:

Pic of the drywall design. Inside out for rooms, Normal for outer leaf towards the corridor. You think they will be too dead? can you alternate "inside out" designs? For example. Two walls of the room being "inside out" and two normal. Obviosly that will change airgap depending on the wall... Thoughts?

Framing modeling for between rooms

What is the name of the programm which you use for the last pic? looks like a very useful tool. cheers Mika

Its called INSUL and its pretty expensive... I used the demo version which shows random wall framings (after a few clicks you get the one you want :D )

Thanks :D WOW, cool software also Zobra ist nice. Tomorrow i will compare zobra with the porousabsorbercalculator.xls And you`re right, 990,- euro for Insul and 440,- Euro for Zobra is not cheap. cheers Mika

hi, Your design looks pretty good. A dead room can be ok for a rehearsal room. Go with inside out for now and if the bands feel like there in an Anechoic chamer, start adding some slats. What about the ceiling? Will it also be independant from the outer shell? As for the drum riser, it will either become a very expensive exercise in floating floors or a giant drum head! viewtopic.php?f=2&t=8173 Have you got a drum kit? Give the kick a go while some-one is down stairs.

lilith_envy wrote:

hi, Your design looks pretty good. A dead room can be ok for a rehearsal room. Go with inside out for now and if the bands feel like there in an Anechoic chamer, start adding some slats. What about the ceiling? Will it also be independant from the outer shell? As for the drum riser, it will either become a very expensive exercise in floating floors or a giant drum head! viewtopic.php?f=2&t=8173 Have you got a drum kit? Give the kick a go while some-one is down stairs.

Yes, the ceiling will be box in a box, just like the inner walls. I think Im going to alternate insideout walls, that means for instance, the walls towards the north will be normal as long with walls between rooms, and the rest will be inside out, or something like that. Because if I feel they sound too dead, puting slats or light wood layers in front would create a 3rd leaf. About the drum riser, Im thinking about puting 1 layer of high density rigid insulation on the floor, and then a couple of 25mm layers of masize wood and see how it helps flanking, and it wont be that expensive at all. Any more thoughts?

...puting slats or light wood layers in front would create a 3rd leaf.

Slats wont create much of a third leaf, as they work on the principle of a Helmholtz resonator, which is tuned to specific frequencies (or ranges of frequencies, if they are broadband). They are basically either transparent or reflective to all other frequencies, so it isn't really the same as a normal third leaf. The small 3-leaf effect you'd get is most likely going to be negligible. A panel trap would be a third leaf, certainly, but it only covers a small percentage of the total surface, and the peak sound level inside the panel trap is mostly around the tuned frequency of the trap itself, which is probably not the same as the resonant frequency of the MSM wall itself. So once again the third leaf effect is minimal. You'd only have a problem of the frequency of the trap was in the critical range around the frequency of the theoretical 3-leaf system. I wouldn't worry too much about acoustic treatment creating a drastic third leaf effect. It will have some effect, yes, but nothing to be concerned about (unless you make really large panel traps that are tuned to really low frequencies, that happen to be n the same range as that of the resonant frequency for the entire wall assembly). - Stuart -

Thanks Stuart. Also, I thought about it a lot, and its almost impossible to build the rooms with alternate inseout designs, since it will not be airtight (u have to think on how to put drywall for a sec and its pretty obvious) In that case I'd rather build it insideout Since you didnt talk about anything else I assume my design is good enough :) Now the plan is to make it happen in the construction stage, where everything needs to be built and sealed properly. PD: Cuando nos juntamos ? :D

Is my design either too good or boring that nobody shares some thoughts? :|