He accepted.
I hope he's willing to sign that in writing this time! That would be a reasonable deal all around.
I cant do wood framing, he will ask me for more money and its also much more expensive than the metal framing. It is also easier and faster with metal framing.
Fair enough. Then let's stay with metal framing on isolation hangers. So what's important here is to make sure that the ceiling is PROPERLY isolated from the concrete.
The gap from the frame according to the other construction i showed you (the one in greek) is 10cm.
Just to make sure we are talking about the same thing: You are saying that the distance from the bottom surface of the concrete, to the top surface of the drywall, is 10cm? If so, that should be fine. More would be better, of course, but 10 cm is the minimum recommended gap. If the gap gets much smaller than that, then you start losing isolation very quickly. And yes, you do need to put insulation in that gap: either mineral wool of around 50 kg/m3, or fiberglass of around 30 kg/m3. Fill the entire gap if you can, but do not force the insulation in there! If you force it in, then it could create flanking paths. Put in just enough so that it fits nicely, and no more. In other words, if you can buy insulation that is exactly 10cm thick, that would be perfect, but not insulation that is 11 cm thick. And if you can only get 5 or 6 cm in, well, that would be OK, but not optimum.
Space-wise i cant afford loosing more than 15cm from the existing walls.
You mean 15cm on each side, I hope, and not 15 cm total? So once again, just to make sure we are talking about the same things, you are talking about having a distance of about 12cm from the surface of the concrete wall up to the inside surface of the drywall, then two layers of 15mm drywall, for a total thickness of 15 cm? Then the same on the other side of the room. Is that correct? If so, then yes, that is fine. And once again, fill that entire gap with insulation, if you can, or at least fill half of it. When I say "fill half of it", I'm talking about thickness, not height! So you'd have insulation all the way form the floor to the ceiling, but only 5 or 6 cm thick. And "fill completely" would be all the way from floor to ceiling and 12cm thick.
I prefer to explain things like this in very simple terms, just to make sure that there are no problems with the language barrier, since I don't speak any Greek at all!
1) Insulation on concrete walls not more than 50kg/m3 dense.
Correct. 50 kg/m3 is for mineral wool (rockwool), but if you use fiberglass insulation then it should only be about 30 kg/m3.
2) Begin framing from ceiling with the decoupling suspensions like this, something between these (i dont know what to choose i wait for my friends proposals,
It would be better to call the manufacturer and ask! They will tell you what the CORRECT product is for you. tell them that you will be hanging roughly 30 to 40 kg/m2, with an air gap of 10cm filled with insulation, and you need to have a resonant frequency as low as possible for that structure, preferably below 20 Hz. They will tell you which model of hanger you need, how many you need, and how to space them. This is very important!!!! You are building an MSM resonant structure up there, and it MUST be tuned correctly! If you put in too many, or not enough hangers, or if you space them too close, or too far apart, or if you use the wrong ones, then you will have tow potential problems: #1 is that the structure will not isolate correctly, and #2 is safety: you might be loading it incorrectly, and end up with 300 kg of drywall falling on your head... So call them, or even better send them an e-mail, carefully explaining what you want to do, and asking for their recommendation in which device to use, how many, and where to put them.
The manufacturer is the person best qualified to tell you about this.
3) Wall framing on decoupling rubbers,
Forget those: you don't need them. They will not do anything useful, acoustically. Your concrete floor is on the GROUND, and that means that the entire planet is acting as a damper on your floor, so little tiny things like that will not help any. A waste of money.
4) Floor...you told me i dont need and i understand but i have the materials and money spent so why not to make
I'd say one excellent reason for not making one, is ceiling height! You don't have much, drums need height to sound good, and trying to float your floor will just waste height. If you have the materials, use them to make a drum riser. Much more useful.
100kg/m3 rockwool 5cm,
Too dense, and too thin. That will NOT decouple, and also is so dense that it does not have good low-frequency absorption.
A friend of mine told me to get 100kg/m3 rebonded foam 5cm,
Whoooaaaa!!!! Foam? What TYPE of foam? You need to know: Closed-cell foam is no use, acosutically. Open cell foam is OK, but even then that 100 kg/m3 sounds way too dense. Can you provide a link to the web site of the manufacturer, and specifically to the section on their web site that has the acoustic properties? You need to know what the gas flow resistivity is for that foam, in order to find out if it is any use, acoustically.
I hate to say this, but listening to your friends was what got you into this problem in the first place, so maybe it would be better to actually found out for sure that what your friends are telling you is good advice! There are a LOT if myths about acoustics, all over the internet, so it is wise to check what other people tell you, and read the actual science and the acoustic numbers for anything that you plan to do in your studio from now on. Your friend might be giving you good advice, but you'll never know unless you check the actual facts and figures.
1 layer of water proof plywood, 2 layers of gypsum board and i layer of plywood again
Still not enough mass for a proper floating floor: That's only about 40 to 50 kg/m2 there. You need something like 200 kg/m2, (depending on the spring, cavity, and fill). That's why proper floating floors are done with concrete. And you don't even have a spring in that system you describe, so it isn't floating anyway!
These things have to be calculated! You can't guess and say "I think I'll use this foam because my friend said it was good", or "I think I'll put a few layers of drywall and some plywood there". You need to do the mathematics! First, you need to decide how many decibels of isolation you need, and what is the lowest frequency range that you need to isolate. With those two numbers you can calculate the amount of mass and the spring resilience that you will need to accomplish the goal. Or if you already know what the spring resilience is (for example, if you already have the springs) then you can just use that to calculate the mass and air gap. If you don't do the math, then the chance are really good that you will NOT get a good outcome! You can't guess: you need to sit down with pencil, paper and a calculator, and figure these things out.
If you don't figure it correctly, then there are only two possibilities: 1) You will have too much mass for the spring, it will over-compress and "bottom out", and therefore you will have no isolation. or 2) You will not have enough mass for the spring, it will be under-compressed and "top out", and therefore you will have no isolation. There are no other possibilities. That spring has to be compressed just the right amount for the mass that you have on top of it. Too much and it won't work. Too little and it won't work. You MUST do the calculations!
That's why we could look at your photos, and see that the contractor didn't have a clue: clearly, he did not do ANY calculations for your floor, since it will never work like that. If you don't do the calculations, then you'll end up with a DIFFERENT floor, but it still won't work. Acoustics is a science, with equations an calculations. It isn't about listening to friends and guessing.
5) The doors when i say triplex i mean the laminated. The ones with membrane inside. I dont know if we talk about the same thing.
Ahhhh! OK, that's fine then. I misunderstood. I thought you meant it had three separate pieces of glass in it. Laminated glass is excellent. How thick is the glass? (total thickness, both panes plus the membrane).
So what do you think? Do i really need air gap? Can i fill the entire cavities with rockwool? You said that before...But we need MSM right? with no air gap we dont have spring. Is it right?
It's the same thing: Insulation is mostly air anyway, so when we say "air gap" we are talking about the entire space in the cavity, regardless of whether it has any insulation in it.
Yes, the air is the spring, and the insulation is the damper. It is just like the example of car suspension that you used earlier: You have a spring to give you the "bounce", and you have a shock absorber to damp the oscillations by absorbing some of the energy. That's what the insulation does in a wall cavity: it absorbs the resonant energy. In acoustic, that is sometimes called "damping".
So yes, you can (and should!) fill the entire cavity, if your building code allows it. BUT! As Rod has mentioned here, there are sometimes fire regulations on how insulation can be installed in walls, so check with your building inspector to see if you are allowed to fill the entire cavity. If you can, then that's great. If not, then fill as much as you are allowed to. Just so you get an idea: you can get an improvement of about 10 decibels in isolation by putting insulation in, and maybe as much as 16 db, under some circumstance. That's a LOT of extra isolation! But even if you can only fill it half way, you can still get maybe 6 dB of improvement, as compared to no isolation.
I wish i had posted i day before...but anyway, better late than never..
At least you didn't post one week later! It would have been much sadder, and very much more infuriating to find out afterwards, when it was all finished and didn't work! So at least you only found out one day late. Things would have been worse...
- Stuart -