HI there HoboRec, and Welcome to the forum!
Congratulations on your plans for your studio! The basic concept looks pretty good. So I'm just adding a few comments here, in general.
As you mentioned, what you have there is sometimes called a "corner control room", since the rear wall is a corner, not a wall. When done like that, the room is sort of set up on the room diagonal, from one point of view. And that's a good thing! There are benefits to doing it like that. Also some downside, of course /everything in studio design is a trade-off!) I've done a couple of corner control rooms, and they can work well. The acoustic treatment is a bit different from a more conventional rectangular room, but the same rules apply.
The total space is 8x10 meters.
That's pretty decent! That's a good-sized space. That allows you to have around 20m2 for the control room, which several rechnical guidelines say is the smallest size for good acoustic response (you can go smaller, but it gets harder to treat effectively). The remaining 60m2 can be split between the other rooms. Maybe 40 or so for the live room. I'm guessing that the area to the right of the control room is an isolation booth?
On your plans, you are showing everything as only a single "leaf" walls, but in reality you'll probably want to do it all as "two leaf" walls, in order to get good isolation between rooms, and good isolation to the outside world. That takes up more space, of course, but it's necessary if isolation is important /and it usually is!)
You also show a set of double doors between the booth and the live room, but double doors isn't a good idea in a studio: it's hard to get them to seal properly when they are closed, and good seals is really important for isolation. In the final build, you will have two sets of double-doors there, back-to-back, which complicates things even more. I'd suggest doing that with sliding glass doors, rather than hinged doors. You can get pretty big sliders if you need to have large access opening between rooms, and the sight lines are fantastic. You can still get good isolation with sliders. The other big advantage of sliders is that they don't take up any floor space! Hinged doors have to swing out into the rooms on either side of the wall, so that "door sweep" area is basically not usable: you cant set up mics, instruments, gear, furniture, or anything in the "sweep" area, so you lose a lot of usable floor space like that. Sliding doors don't take up any space in the room, so you can use all of the floor area.
The ceiling hight on the left side of the building will be 4m and 3m to the far right
That's also a good height! For acoustics, room height is paramount, and especially for live rooms: instruments and mics like to have high ceilings. For that reason, I'd suggest flipping your plan around a little, with the iso booth on the left, under the higher ceiling, and the "utility" rooms (kitchen/bathroom) on the right, where the ceiling is lower. Having a lower ceiling for the kitchen and bathroom is not a problem. They don't need height, but the iso booth does.
"This means the ceiling in the control room will slant diagonally, so probably have to make a false ceiling and fill it up with rock wool?" Right! You do, indeed, need to get a level ceiling for the control room. It can slope from front to back of the control room (lower at the front, higher at the back), but it should not slope from left to right. The reason for this is symmetry: the left half of the room needs to be a "mirror image" of the right half, as much as possible, so that the acoustic response on both sides is the same. That way, your left ear and right ear hear the same "signature" in the room. If there's a difference in acoustics on the left and right side, the sound stage you hear will be "skewed" on way or the other, and you'll subconsciously try to compensate for that in your mixes. So your mixes won't translate well: they will seem a bit "offset" to left or right when you play them back in other places, or they just won't sound good, overall. So symmetry is important, and your ceiling needs to be about the same on the left and right. It CAN slope in this direction if you need to do that for structural reasons, but it still has to be symmetrical. For example, it can be higher in the center of the room, and lower out to the side walls.
Also, you'll need to have a "false ceiling" in any case! Even if your outer roof was already flat, you'd still need the inner-ceiling, because that's the only way you can get good isolation between rooms, and to the outside world. Here's some information on this issue, that you might find useful:
Deciding on isolation for your studioHow much isolation does your studio need? How can you figure that out? Is it even important?Speaker setup, and the equilateral triangleAngled walls: What are they for? Do you need them?What is "room-in-a-room" construction?What is MSM? How does it work?"Total budget hopefully around $30.000. The only contractor we will hire is for the concrete foundation." 30k for 80m2 seems a little on the low side. That's around USD 375 per square meter. For a typical home studio with existing structure, the average range is around US$ 500 per square meter. I'm not sure about building materials costs in Sweden: maybe it is less expensive to build there... but I'd suggest revising your budget upwards.
Of course, the above is just the cost of building the studio itself, without considering audio equipment. Depending on what you want to do, and what gear you already have, that could add up to many more dollars.
A big part of studio design is the control room speakers: You should put some thought into that before you budget for the gear, and before you get into the details of the control room design. When I'm designing a control room, I usually start out with the speakers before considering anything else. Based on the basic room shape, I narrow the list down to speakers that are suitable for that specific size and shape, then consider the purpose of the studio, and narrow the list down again. If the studio is a high-end professional studio for commercial music production, the list will be a bit different than if it is a home hobby studio. Mastering studio is different again. Once you decide on the speakers, you can plan the room shape and layout in more detail, and that in turn will lead to the basic concept for the needed acoustic treatment.
So I'd suggest you do that too: look at the rough angles and shape of the room as you have it right now, look at all the speakers that are currently available in your area, and eliminate the ones that would not work well with your size and shape of room. Then consider what you plan to do in that room, and eliminate speakers that aren't good for that.
And of course, another major issue when choosing speakers (and designing the control room!) is whether or not you are going to "flush mount" your speakers (also called "soffit mounting"). I highly recommend doing that, since the benefits are really worth the effort. This choice (soffit mount, or not) greatly affects the overall room design, and the overall acoustic treatment as well. Most speakers can be soffit mounted, but some can't, so you need to take that into account as well. The dimensions of the speaker you decide on are really important for the soffit design: The soffits have to be big enough that the speakers can physically fit inside them, for example, and the size of the front baffle of the soffit depends to a large extent on the size of the speaker.
So there's a few more things that you might want to consider in your room design.
Probably your first step before doing any of the above, is deciding on how much isolation you need for your studio. You should determine that in decibels: More technically, this is "transmission loss". In other words, if you have a rock band in there, playing at 115 dBC, then how quiet must that be outside the room? Is it ok (and legal!) for the level to be 70 dBC outside the bulding, or must it be 40 dBC? But it also goes the other way: how loud are typical ambient noises outside your place? Wind, rain, thunder, hail, aircraft fling over, traffic on nearby roads, railways in the area, neighbors mowing lawns, dogs barking, cows, birds, etc., Compare that with how quiet do you need that to be inside the studio, so those sounds won't get captured by an instrument mic or vocal mic, and won't annoy you and the musicians when you are trying to track and mix?
You should put a lot of effort into determining this number (isolation for your studio), because that dictates the overall design and construction of the walls and ceiling. It’s one thing to isolate a studio for 35 dB, and a very different thing to isolate it for 60 dB. Completely different techniques and materials.
Once you have that determined, and your isolation system designed, you'll know how much of your 80m2 floor area is actually left over, within the isolated part of the building, so you can figure out where to put the internal walls between the rooms, to maximize usable space and acoustics. Once things you should consider: your kitchen and bathroom don't need to be isolated from the outside world! Only the studio itself needs to be isolated from the world (and also isolated from the kitchen and bathroom, of course.... you don't want the sound of a flushing toilet to get into your vocal mics!)
Anyway, that should give you some additional things to consider in your design. But you do have a good-sized space, so you certainly can have a successful studio there, if you design it well and build it properly.
- Stuart -
and i'd try to go with a full 4.2m on the outside wall with a truss roof frame. and 3.8m ceiling on the inside of the studio rooms. definitely if pouring slabs - separate ones for each rooms + one for the bath + kitchen.