Hi Stuart and thank you so much!
And I thought I was going in the right direction here! hahahahaha
OK, so you need a LOT of isolation! that's for sure.... This is not going to be easy!...
Well yes, but on the other hand I probably won't be playing late at night. It's just going to be until say, 9pm, and my roommates are cool enough to tolerate some of it. And the neighbors can't really complain if it's it's not absurdly loud and doesn't go after 10pm.
Excellent! That's very good news. So you only need to do the other two sides, and the ceiling, the door, the HVAC, and the electrical.
Ok, so no need for any additional structures, (wood frames, insulation, plasterboards, etc) there, right!?
Or should I also build the frame, plasterboard? Maybe no need for mineral wool.. What should work best...?
And if I build the drywall there, could it touch the brick wall at all?
TOP BARE LEFT WALL - Baixa.jpg
OR
TOP WITH DRYWALL - Baixa.jpg
Also excellent!
That would get you about 30 dB of isolation, which is not very much. In order to get the very high levels of isolation that you want, you'll need to do a proper 2-leaf "room-in-a-room" studio. That means building the other two sides of the outer-leaf, but with a lot more mass than you show, then building a completely separate room inside that shell, also massive.
More like this...?
wall frame ROOCKWOOL B - Baixa.jpg
It'd be almost 19cm thick. Two layers of 12,5mm plasterboard, 5cm rock wool, 5 cm space, 5cm rock wool, one layer of plasterboard.
Would it need insulation on both leaves? If I got it right, in the MSM system, the mineral wool is considered "spring", not mass, right..?
Not really. It would look nice, but it wouldn't serve any useful acoustic purpose: And it would be hard to build that.
Yeah, I figured that it wouldn't make any diference indeed. So no angled walls!
For the floor, I'd just leave it as it is, and put the drums over a drum riser, to isolate the impact from the floor.
Yep!
Yeah!! I got something right!!
For drums, make it as high as you can, within reason. Drums love airy spacious rooms, and if you want to track your drums, then you need a lot of space above the overhead mics to prevent artifacts from ceiling reflections.
Up we go! No need to worry about room ratios then!?
For Sao Paolo? In summer? With several musicians in there? Hmmmm.... I would suggest going to a 12.000 BTU unit. Maybe even more than that, if you plan to have a lot of amps and other gear in there, and a lot of lights, and a lot of people... There are equations for figuring out how much cooling and dehumidifying capacity you need. Don't guess. But knowing how the climate is in Sao Paolo, I would suggest something bigger than 9.000 BTU.
Since the garage sits on the ground it stays pretty cool even on hot summer days, but maybe a 12.000 BTU wouldn't be a lot more money than the 9.000.
OK, so that's the cooling, but what about the rest of the HVAC system? I don't see any ventilation on your drawing: no ducts, no vents, no fans, no silencer boxes... You need to do that as well.
Hmmm... right... So, I've checked some threads here on ventilations and silencer boxes. How about this? I'd put one intake and one exhaust, one on each end of the studio.
SILENCER BOX - Baixa.jpg
ventokit.jpg
The room will have 26 cubic meters, so that times 5 (cicles of air per hour) is 130. There is a model that has a capacity of 150m3/h.
One of those for the intake and one for the exhaust should do it I suppose.
Not really: You need a high level of isolation, and your plan is not going to do that. You need to do a proper "fully-decoupled two-leaf MSM isolation" system. That's the best way to get high isolation at low cost.
A few more drawings to illustrate.
decupled wall - Baixa.jpg
decupled wall B - Baixa.jpg
decupled wall C - Baixa.jpg
Your plan would give you about 30 dB of isolation. A typical home studio gets 40 to 50 dB. Professional studios might get 60 to 70 dB, but that's not so common. It is hard to do,m and expensive.
Ok so, to be realistic, I'm aiming for 50dB here.
Each time you go up by ten decibels, you need to block ten times more energy, and it gets ten times harder. So going from 30 to 40 dB means you need to block 10 times more. Going from 30 to 50 means you need to block 10x10=100 times more. Going from 30 to 60 means you need to block 10 x 10 x 10 = one thousand times more. And going from 30 to 60 means you need to block ten thousand times more energy than your current plan. Decibels is a logarithmic scale, so things get very big, very fast as you move up. This is why it is very difficult and very expensive to get 70 dB. You could probably get to 60 dB, if your isolation plan is very very carefully designed, and you build it very, very carefully, and you have a good sized budget. It would be a lot easier to go for 50 dB.
How about now, do you think it should do it? Is 50dB (maybe 60) doable?
The budget I have is around USD 2.000. Not much I know, but for the basic I think it's enough...
Actually, no it isn't. That's about the cost of the HVAC system, all by itself. 2k would not even be enough to by the materials that you will need for your current plan, and certainly not enough to get 60 dB. Or 50. Or even 40.
Ok, maybe I could go up 1k or 2... But for the previous concept 2k was enough here in São Paulo. I have a good spreadsheet with all the materials needed. I got all the initial prices from Leroy Merlin online store, which is about the priciest you could get for construction materials here. I'm pretty sure I can get way better prices once I have the concept and the material list right and start quoting.
Your framing is incorrect. That would not pass inspection, and would not work for isolation walls. It is not even safe: the ceiling would probably collapse. I would suggest that you do some research on-line on how to frame a structural load-bearing wall, and also look into how ceilings are built safely, taking into account spans, dead loads, live loads, deflections, etc.
I'm an architect, but here in Brasil we don't work with wood frames at all, so I don;t have much experience with it. But I'm sure the walls and the celling will work, as far as safety goes. In any case, I'll check with some friends and see what they think.
And that kind of structure, indoors, doesn't need to go through inspection here in São Paulo, so no problem there.
But the biggest point is that you cannot get the type of isolation you want from the plan that you have. You need to move up to a proper two-leaf "room-in-a-room" build, with lots of mass on each leaf, a large air gap, and perfect seals.
Maybe I'm right this time! But then again... maybe not...
Thanks a lot Stuart!