Conceptualising in Sketchup - Average Thickness for walls...

Hey hey, I am in the process of sketching things up in googles sketchup and need to figure out what wall thickness to use for outer walls and specific inner ones on average for my drawings including mostly isolation but possibly HVAC ducts and whatever else (considering avoiding running electrics or anything unnecessary inside the walls). Now I've tried searching, reading stickies and a big "depends" is what is holding me back as I cannot determine any of the main variables at this stage and the main point of sketching is to balance between possible inside dimensions. For instance, do I want use a "smaller" ratio for the live room (still having 6m floor-ceiling) to make space for an extra iso room? I have 101 of these questions so I need to have average ballpark figures since the usual variables are different for each of the 101 conceptual variations of the whole build. The reason for sketching vaguely is that I am not the main money person behind a possible new build so I have to liase with people who do not understand either acoustics or my own arena which lies within generally the creation of music and by corollary in production/sound engineering. I have nothing specific to help me out apart from budget (expressed in square meters the way you would when budgeting a flat in a bigger complex - don't ask, it has already been driving me nuts) and the limitations of the dimensions of the plot of land. What I need is to figure out: How on average the outer wall of a main live room would have to be thick to achieve good sound isolation against outside noise? Lets assume that we are using economical techniques, the simpler the better since labour and design costs often trump material costs, probably some version of typical large building blocks(ceramic?)/insulation/air/insulation/again these largerish blocks that the english name of, escapes me. The building will be separated from other buildings in a residential area by at least 8m's given the local laws (where you have to build at least 4m's from the edge of the plot) so I am less worried about isolating the other way around, especially given that the plot is located in Poland where residential buildings tend to have thick walls and at least some basic insulation as standard. Only on one side will there be a residential building closer than 8m's since that building is on the same plot of land. I assume that good isolation one way should provide at least the necessary isolation the other way around - I want what everybody wants, the best point on the diminishing returns graph for value for money in terms of isolation. The building needs to be able to operate 24/h, I'd rather have no windows in the sound part of it, only in the lounge/office for simplicity. What I am aiming at is having a large live room with 6 meter ceilings at about 9.6mx13.98m and then attached to that on one side a control room with 3.4 m ceilings and two isolation booths also with 3.4m ceilings, behind that stairs to a second floor above CR/IB for office/rec room. How on average the internal wall between live room/control room and control room/iso booth and live room/iso booth would have to be thick to achieve very good sound isolation both ways? I would prefer to record only grand pianos in the space but the reality is that it has to be good for anything. Rather than building specialised rooms for amps of all kinds I'd rather be able to throw some rockers stack into one of the iso rooms as a very good isolation will not be wasted on the occasional cranked amp given that I want these big enough to fit a drumkit. The building will most likely have 3 isolated walls in full (since there is no point economically to skimp on isolation on the second floor given that it could always be transformer in the future into a mastering suite) while the back wall, where the stairs/bathroom/entrance/storage will be connecting will probably be less isolated to save money. I have originally thought about surrounding the main live room with all the other facilities so that the live room achieves the best isolation against outside noise however I just don't have that much square footage to use up. Anyway at this stage I mainly need to know how thick to sketch the walls and how thick to sketch the ceiling and the lounge/office floor (one above the CR/IB). I have no idea if 70dB of isolation from the outside is enough in the live room. If 100dB is enough or an overkill between live room and iso booth. Is there any point in having 70dB between live and corridor to stairs and so on and so forth and how that translates to a fantasy average thickness. I'm writing this after a whole night of coffee, learning how to use sketchup, running numbers for everything outside of my area of expertise so my mind is completely toasted at the moment so apologies for the rambling. I need to make all of these sketches soon in between moving house and being very stressed to mostly convince the other parties involved that whatever was already put together planning wise is insane and wrong and to push for more square footage and to drop inefficient building techniques so I will have specific questions later on and sketches to share and will apply all the good stuff there is on the forum and in other webby reservoirs but at the moment I'm just stuck on putting together some average values to conceptualise from. I do have history in design so I'd rather do everything myself with the kind help of impartial minds and choose technologies before I hand it over to someone with studio design experience, especially since I am doing iconoclastic things like not including a huge neve or ssl desk into the whole of it for instance or gasp fabricating my own boom stands instead of paying 1.2k pounds per one. All of this will be located in central-eastern europe so I am aiming for simplicity and common sense so that I can have skilled labourers under smart direction pull it all off and avoid spending money on needless aesthetics. Where I am located now in the UK for instance there are these old school round metal pipes for distributing electrical cables which in my opinion look excellent in a large space, save for some weird RF interference I'd rather have that than complicate the wall and the isolation just to hide everything. First class of design many years ago we where shown the NYC fire escape stairs and how if you can't hide something you should display it - which I plan to execute as much as possible. Where was I. Ah yeah, the thickness... Big Thank You, P to the H to the B

Hi there "Bhop", and welcome to the forum! :) The main reason you can't find an answer is because you are asking the wrong question! But don't worry: You are starting from a very common misconception, and it takes a while to get your head around the basic concepts of isolation. The misconception is that you have to build two walls around your studio, one to keep the sound out from everything, and the other to make the individual rooms. As a result of this, people think that the first wall must be thicker and made especially to isolate, and the "other" walls don't have to be so thick. Or vice-versa. Or that one wall blocks some of the sound and the other wall blocks the rest. Or something. That's not actually the way it works. The basic concept with isolation is that there are not two walls: just a single "isolation system". This is non-intuitive at first, but starts making sense once you grasp the physics. ALL the parts of a wall interact to provide the isolation, and no one part of the wall is responsible for the isolation, by itself. The parts act together. The whole is greater than the sum of its parts. The reason for this is that the isolation wall is actually a tuned resonant system, that has to be tuned correctly. All parts of the wall affect the tuning. Whatever you change in the all, inside or outside, will affect the tuning, which in turn affects the isolation. So there is no "outside that soundproofs" or "inside that separates". Both sides of the wall work together. So, for maximum isolation at minimum cost, you need what is called "fully-decoupled two-leaf MSM wall" for ALL of your rooms. "Two-leaf" means that the wall has two sides to it, an "outer" side and and "inner" side. Each of those is made up of one or more layers of mass, such as drywall, OSB, MDF, plywood, brick, concrete, etc., and ALL those layers are together, touching each other. One common way of building a "leaf" like this is with a simple 2x4 stud frame that has 2 layers 16mm drywall (= "plasterboard", = "gypsum board", = "sheetrock") on just ONE side of the frame: the other side is open. That makes a very good "leaf". So "two leaf" means that you have two such structures close to each other AND NOTHING ELSE! No other walls within several meters. Nothing. Just the two leaves. "Fully decoupled" means that these two leaves do not touch each other ANYWHERE. They are totally separate. Not even a single nail or screw can join them together. The reason for this is very simple: sound will make one side vibrate, and if there is anything that joins that side to the other side, then that "thing" will transmit the vibration directly, causing the other side to vibrate, and hence there is no isolation. "MSM" means "Mass-Spring-Mass", which is the principle of physics that makes this whole thing work. It is principle of a weight bouncing up and down on a spring. It is the same principle as a pendulum swinging back and forth inside a clock, or a child swinging on a swing, or the suspension in your car. It is a tuned system that will ONLY resonate naturally at one specific fundamental frequency: It will not resonate at any other frequency, and in fact RESISTS all other frequencies. That's why it works to isolate sound. If you tune the resonant frequency low enough, well below the lowest frequency that you want to isolate, then the wall will resist all other frequencies: that's what we call "isolation". So MSM, or Mass Spring Mass, the two "leaves" are the two "masses", and the "spring" is the air trapped between them. It is that simple. Both leaves and the air between them all work together as a tuned system, to give you the isolation you need. The only other thing that is needed is some way of damping the resonance inside the wall, and that is done with simple fiberglass or miner-wool insulation, filling the air gap. So you cannot say that the outer wall must be thicker or thinner to increase or decrease isolation: the thickness of a leaf, by itself, has zero effect on the MSM resonance. What matters is the MASS of that leaf: Or more accurately, it is the "surface density". How many kilograms does each square meter of the wall weigh. That's the key to tuning the wall. Increase the mass, means that the resonant frequency goes down, which is good, so you want as much mass as you can get on each leaf. So very dense materials are good for this: extremely dense things things like steel plate, aluminium plate, lead sheeting, etc. are wonderful, but expensive. More common materials are brick, concrete, drywall, OSB, MDF and plywood. They are not so dense, but you can layer several sheets together to build up the mass if you need to. And they are relatively inexpensive, easily available, easy to work with, etc. So typically, ALL leaves in your structure will be the same thickness: a bit more than 4 inches or so, or roughly 10 to 12cm. That is made up by the 3.5" (5cm) of the studs themselves, plus a couple of layers of drywall on one side. But that is the thickness of the LEAF, and a wall actually consists of two leaves with a gap between them. The size of the air gap is the other factor that governs the resonant frequency: more air gap means a lower frequency, which is good. So the size of that gap depends on YOUR needs, in YOUR studio for YOUR situation. You have to tune your walls as needed for your isolation. The general MINIMUM gap that you need between leaves is about 10cm, but more commonly it will be 20 to 40 cm, or even more. Note that "gap" here refers to the gap between the LEAVES, ie, between the surfaces of the mass inside the wall. So if you have two normal stud frames each with drywall on the outside, and the frames are just 2cm apart, then the air gap is already 20cm deep. The rest comes from the studs themselves. So, the ENTIRE wall for a studio will be about 25cm to 30cm thick, give or take, for typical applications. That would be a -leaf MSM wall made from two separate 2x4 stud frames, 2cm apart, and each frame will have two layers of 16mm drywall on only ONE side of the studs. If built with standard 2x4 lumber, that wall would be 26.2 mm thick. HOWEVER! That might or might not be what you need! It all depends on how man decibels of isolation you need, and what is the lowest frequency that you need to isolate, and how well you need to isolate that frequency. There are MANY ways of building an MSM wall, with different materials and techniques. The one that you will choose is the one that best fits your needs and your budget. For example, instead of being drywall on a frame, a "leaf" could also be brick or concrete if you wanted, which is great as you get much greater mass and much higher density. Etc.

I assume that good isolation one way should provide at least the necessary isolation the other way around

Right!

How on average the internal wall between live room/control room and control room/iso booth and live room/iso booth would have to be thick to achieve very good sound isolation both ways?

This is where your question was leading you wrong: There is no such thing as an "internal wall between live room/control room". There is just a two-leaf system. The control room is built as one single leaf, and the live room is built as one single leaf, and the iso booth is built as one single leaf. As a group, they are also surrounded by one single leaf that separates them all from the outside world. So, wherever you are standing in the studio, there are exactly two leaves between you and the next room. If that "room" is part of the studio or not, there are still two leaves between you and it. If you are in the control room, then there are two leaves between you and the live room, as well as tow leaves between you and the iso booth. There are also two leaves between you and the parking lot outside the building, and also two leaves between you and the bathroom. No matter which way you look, there can ONLY be two leaves between you and the next room. And this is where it gets weird: Most people think: "OK; if two leaves is good, then three leaves must be better, so I'll build three-leaf walls!". Bad, bad. bad idea. If you build three leaves, then the isolation will be WORSE, not better, for the low frequencies. And since the low frequencies are the hardest isolate anyway (drums, bass guitar, keyboards, piano, etc.), 3 leaf walls are a really bad idea for a studio. The reason for this strange result is like I said at the beginning: a wall is a tuned system. If you change anything about it, you re-tune it to a different frequency. It turns out that putting a third leaf inside a wall re-tunes it to a much higher frequency, all other factors being equal. so three-leaf systems must be avoided, if possible. Sometimes you have no choice, and in that case you have to compensate for the third leaf by increasing the air gaps and adding more mass, but that increases costs and wastes space, so it is better to avoid 3-leaf construction as much as possible.

The building will most likely have 3 isolated walls in full (since there is no point economically to skimp on isolation on the second floor given that it could always be transformer in the future into a mastering suite) while the back wall, where the stairs/bathroom/entrance/storage will be connecting will probably be less isolated to save money.

Sorry, but you can't do that! Isolating a room is like building a fish tank: You cannot keep water in the aquarium if you put glass on all sides but cardboard on the back! Even though the glass does a good job of stopping water, the cardboard does not, so the water leaks out anyway. Same with your studio: all six sides must be done to the same level, or the sound will leak out through the weakest side. So your floor, ceiling and four walls must ALL be isolated to the same level. Actually, the floor is usually the exception: If you have a good concrete slab sitting on the ground, that is generally fine for the common floor for all the rooms, so you only need to build decoupled 2-leaf MSM structures for the ceiling and the walls.

I have originally thought about surrounding the main live room with all the other facilities so that the live room achieves the best isolation against outside

You don't need to do that, and it most likely would not work anyway, unless you build all the walls as MSM systems. But if you do that, then you don't need to surround the live room with other rooms.... :)

I have no idea if 70dB of isolation from the outside is enough in the live room. If 100dB is enough or an overkill between live room and iso booth.

There is a huge, major, enormous difference between 70 dB of isolation and 100 dB of isolation. In fact, there is a difference of a factor of one thousand! Isolating to 100 dB means that you have to block one thousand times as much energy as for 70 dB. Each time you go up be 10 dB, that makes it ten times more energy that you have to block. In fact, the very best isolated studio in the planet gets about 100 dB, and it cost them millions of dollars to do that. That is a major undertaking. Each of their rooms weighs hundreds of tons, and is totally floated on huge springs plus polymer pads: You can do that if you want, but you'll need a really big budget! Even 70 dB is a tough goal to meet: Most good studios get around 60-something db of isolation, and most home studio builders are happy to get 50-something. However, only YOU can say what yo NEED for your build: you have to measure actual levels with a sound level meter. First measure how loud a typical recording session is, then measure how quite you have to be. The difference between the two is how much isolation you need. Measure with "C" weighting and slow response.

Is there any point in having 70dB between live and corridor to stairs and so on and so forth and how that translates to a fantasy average thickness.

You can't think of this in terms of "I need 70 to the stairs, 50 to the bathroom, 90 to the office, 40 to the parking lot". Isolation does not work like that. Rather, you need to calculate how much TOTAL isolation you need, and that's the number you use to design all of your walls. Just like the fish tank example above, your total isolation is only as good as the weakest link. And your weakest link is normally not the walls, floor or ceiling. Usually, the weakest link is the doors, windows, electrical system, and HVAC system.

Where I am located now in the UK for instance there are these old school round metal pipes for distributing electrical cables which in my opinion look excellent in a large space, save for some weird RF interference I'd rather have that than complicate the wall and the isolation just to hide everything.

Actually, you can't do either of those! :) Or you can, but only if done carefully. The reason is that your leaves MUST be sealed, totally air-tight. Each leaf is a fully hermetic "envelope" around the room, and you cannot poke holes in it for running dozens of your electrical conduits through! You can have ONE SINGLE penetration where power comes into each room, and from that point it must be distributed solely with surface-mount systems. So your power feed normally comes into a distribution panel or junction box, and from there several conduits or surface-mount ducts or cable trays run to each of the surface-mount plugs, surface-mount switches, surface-mount light fittings, etc. You CANNOT just punch holes through your isolation walls: even a tiny crack can seriously compromise the isolation that you worked so hard to get. All you can afford in each room is only one carefully managed penetration for power, and another two carefully silenced penetrations for your HVAC (one fresh air supply, one stale air return). And those penetrations have to be done very carefully, properly sealed, silenced, an with the mass duly replaced. Fortunately, most of that surface-mount stuff can easily be hidden behind the final acoustic treatment that will line each room in the end, so it won't be seen (unless you want it to be seen, as part of the aesthetic design). The electrical work is done on the surface of the inner leaf, and since most of that will be covered with the acoustic devices, if you plan carefully you can hide all of the electrics, as well as the lighting: just have concealed lighting, which can give a really nice effect, with a few point spots on specific locations. - Stuart -

Hi Stuart, Thank you for your time and reply. Those are some excellent points. I did mean surface mount electrical wiring, sorry din't describe it properly. I normally see those in these plastic pipes (cross section is an oblong) but in the old building I am located in they used what looks like these thin hot water type of copper/iron pipes without the heat insulation on the outside and I thought that It looks really good when painted, plus it does not need to touch the wall all the time so can somewhat float with few points of contact with the wall. I was thinking about distributing power along the wall/floor edges while distributing my starquad underneath the ceiling as I am not a big fan of those big interfaces (not sure how to call it properly) people put on walls - just another element in the signal chain to worry about in my opinion. I am also trying to avoid patch-bays of any kind. The walls on the outside of the building need to be made from these hollow concrete/ceramic blocks so the inner leaf should be made from the exact same stuff correct? I am dedicated to having the live room with at least 6m ceilings but toying around with dimensions and thus ratios. Original plan was about 130m2 but now it looks that it might need to be scaled down to about 80m2. Good news is that it would be a complete new build and the planning permission allows for a big, relatively flat roofed building. How do you deal with moisture in case of these type of blocks (which are thick, they are used to build houses in that part of the world and the walls are between 20-30cm at least) collecting in between the leafs where the insulation (miner wool = mineral wool = rockwool, pink fluffy one right, not the one used to traps?) is located? In houses build badly with these type of blocks the moisture is sometimes a problem so with two leafs the moisture would pass at best through the first inner leaf and then get stuck in the insulation. I am very painfully (sniff) aware that a decent HVAC system is very important. The studio needs to have great acoustic spaces and an excellent working environment above any sort of nostalgia gear or a sexy hammond so that is where the money will go first and foremost. I don't have a budget to furnish the place with wordclass gear plus in Poland it would be hard to beat the studios attached to classical venues so at least commercially I am aiming at a wonderful place to be at first and foremost. The studio depending on how things go business wise might be the central part of a small, upstart label so renting it per session is not the main scope. That is why I am struggling to build a large place rather than a small place with loads of treatment and esoteric gear - always a time in the future to maximise the space once more money rolls in. Would underfloor heating be a problem? Was thinking of having fresh air inlets just above floor level coming from a hvac system (main pipe could be distributed along the wall/floor edges and enter the live room as you say only in one place), with the hvac unit responsible for transporting fresh air but also cooling the air during summer and dehumidifying the air all year long but not heating it. Having the air ascend as it warms up from the under floor heating and then be sucked in to another pipe system beneath the ceiling and then exit the room in one place. This way whatever is sucking the air out could be just some sort of isolated fan system running on low rpm given that hot air travels upward. I want to avoid moisture collecting in the room. I am planning a small moisture controlled storage for my own personal use as guitar storage but if I could make the live room amazing for a grand piano to live in, that would be definitely something... once there is money for a decent grand. There will definitely be a proper concrete slab and foundations, again that part of the world = big, deep, heavy foundations. Possible issues I would expect with foundations designed by an architect that would put empty space beneath the main slab and between the foundation instead of filling it with earth, making it resonated at higher frequencies but that is something I will deal with at a later date. Foundations are very expensive in my experience and given how houses are built there it will be a battle yet to fight regarding this for me. The whole building unfortunately might need to be connected somewhat with a residential building given the planning permission, noise is not an issue with that residential building (whew) just changing the tuning that you mentioned by unbalancing the outer leaf with what would effectively be a third leaf on part of the wall. Another thing that bothers me is that I wanted to make sure there are wide doors to enter into the studio itself with an overhang outside them so that one could back up a van, open the large doors and transport gear in any weather. These would not be the main doors, just loading doors and otherwise that overhang area would serve as two/three car parking for essential staff (including me :D 8)) so I will be searching for a solution that screws with the isolation the least at the cost of ease/speed of operation It might be that the connection of the residential will be handled by connecting the two buildings with that overhang and a wall on one side (I will provide sketches to show what I mean). I will do some thought experiments with the system you mentioned with different types of leafs and dimensions. Meanwhile if anybody would like to address the other points It would be much appreciated. Right now I am at the stage where I can still pull out of the whole thing if I judge it to be impossible given the budget. The budget is a decent given the standards of the country the place will be located in it's just that it is based on a modern house build and there is a regular square architect, involved with all that will be built on that plot of land which makes it more difficult. If it does move further than just pure concept then I will share my findings and what I can of the build process. Since I have to choose two out of either fast, good or cheap I definitely am going for good and cheap as in my opinion being economical is the only way forward right now and I will jump ship with the project if it won't be good. As it is forming up right now there will be no or minimal debt involved with the place and given the relatively low property tax it should be possible to let the place go from zero to operational and optimised in a number of years. :blah: Baby steps, P Edit: Btw. noticed you're from Santiago where one of my best friends is from as well, so I raise you a mime drink to Chile!

I normally see those in these plastic pipes (cross section is an oblong)

OK, those are probably structured-cabling ducts. Very good stuff for studios.

but in the old building I am located in they used what looks like these thin hot water type of copper/iron pipes

Metal electrical conduit. Some countries only allow metal, some allow metal and PVC, others only PVC, and in some countries you don't need conduit at all. But even so, it is still god to use it. Metal conduit is more expensive than PVC, and not as easy to install, but it is an option.

plus it does not need to touch the wall all the time so can somewhat float with few points of contact with the wall.

It still needs to be anchored. Code usually specifies what type of brackets and what the spacing between them should be. There's no need to try to isolate it form the wall. The only place where you do need isolation is on the single conduit that brings the electrical feed into the room: that needs to have a section cut out the middle, between the two leaves, and then have that replaced with a suitable rubber sleeve.

I was thinking about distributing power along the wall/floor edges while distributing my starquad underneath the ceiling

Normal practice in studios is to run the electrical installation up high, at the top of the wall, and the signal cabling down low, either in the floor or at the bottom of the wall. That keeps them far apart. So you just drop down vertical feeds to each power outlet or switch. Also, electrical and signal cables should only ever cross at right-angles, never running parallel close to each other.

The walls on the outside of the building need to be made from these hollow concrete/ceramic blocks so the inner leaf should be made from the exact same stuff correct?

If possible, yes, but it is not absolutely necessary. You could also do the inner-leaf walls with normal stud-and-drywall construction, provided that it is done correctly as a single leaf and with sufficient mass.

I am dedicated to having the live room with at least 6m ceilings but toying around with dimensions and thus ratios. Original plan was about 130m2 but now it looks that it might need to be scaled down to about 80m2.

6m ceiling is great for a live room! And even 80m2 floor space is still pretty good. But if you can get more floor space, that would be great too. Bigger rooms usually sound better, and have fewer modal problems in the low end, since there are many more modes, closer together.

How do you deal with moisture in case of these type of blocks (which are thick, they are used to build houses in that part of the world and the walls are between 20-30cm at least) collecting in between the leafs where the insulation (miner wool = mineral wool = rockwool, pink fluffy one right, not the one used to traps?) is located?

If it is built properly, then there should be no water in there! Why do you think there would be water? That simply should not happen. The foundations should be suitably sealed and protected, with whatever drainage systems are necessary built around them, and the walls should be built correctly to, with proper DPC and sealing, then the surface should be sealed correctly too. Your architect and building contractor will know how to do this correctly: That's their job!

In houses build badly with these type of blocks the moisture is sometimes a problem so with two leafs the moisture would pass at best through the first inner leaf and then get stuck in the insulation.

Tehn make sure it is not built badly! :) Check the architect's design carefully, to make sure that proper drainage, sealing and construction techniques are indicated, and then supervise your contractor's workers very carefully during the actual build, to male sure they are doing it right.

Would underfloor heating be a problem?

It should be fine, as long as the entire HVAC system is designed properly, taking that into account. That is what the "H" part stands for in "HVAC" ! :)

Was thinking of having fresh air inlets just above floor level coming from a hvac system (main pipe could be distributed along the wall/floor edges and enter the live room as you say only in one place), with the hvac unit responsible for transporting fresh air but also cooling the air during summer and dehumidifying the air all year long but not heating it.

HVAC is normally done more in the ceiling, for both inlets and outlets, but whatever your HVAC contractor suggest is the way you should do it, in terms of where to put the registers and what the total flow volume should be. But do make sure you get an HVAC contractor who has done high-end studios before! HVAC for studios is not the same as HVAC for offices, shops of homes. There are a LOT of things that need to be taken into account: very low air speeds and high air volumes, not the other way. Silencer boxes on every wall penetration. Properly line ducts. Straight, long runs. Low noise grills/registers (not the normal cheap type you buy on Home Depot!). Vibration mounts and isolated sleeves on the air handler. Etc. Those are all things that he never even has to think about for a non-studio installation, but all of them are critical for studios.

Having the air ascend as it warms up from the under floor heating and then be sucked in to another pipe system beneath the ceiling and then exit the room in one place. This way whatever is sucking the air out could be just some sort of isolated fan system running on low rpm given that hot air travels upward.

It's actually quite a bit more complicated than that! :)

I want to avoid moisture collecting in the room. I am planning a small moisture controlled storage

That's the job of the HVAC system: It must be dimensioned correctly to provide the correct level of de-humidification for all the rooms, based on occupancy, volume, heat generation rates, relative humidity, etc. The equations for calculating this are rather complex, and you cannot just guess! :shock: So make sure that when you choose your HVAC contractor, you get one that knows what he is doing, and will give you a full technical report on all of the above. Proper HVAC is not a luxury for a studio: it is a basic requirement. Many instruments and some types of mic are sensitive to changes in temperature and humidity, so you MUST have this under control: if not, the sound of the instruments and singers will change throughout a session, as the mics and instruments adapt to the changing temperature and humidity. The last song you record in the evening will just not sound the same as the first song you record in the morning, and there is no way to correct that in the mix,... Proper HVAC is an abolute necessity.

Possible issues I would expect with foundations designed by an architect that would put empty space beneath the main slab and between the foundation instead of filling it with earth, making it resonated at higher frequencies

That would be a really bad idea! The slab MUST be "on grade", meaning that it rests on the ground (obviously, with the suitable barriers in between, as needed to prevent gas and water infiltration, etc.). It is a bad idea to have an air gap under your slab.

Another thing that bothers me is that I wanted to make sure there are wide doors to enter into the studio itself with an overhang outside them so that one could back up a van, open the large doors and transport gear in any weather. These would not be the main doors, just loading doors and otherwise that overhang area would serve as two/three car parking

There's no problem doing that. It could easily be a separate combination loading dock / storage room with a roller-door, and the actual isolation doors into the live room on the other side. Not a problem.

Right now I am at the stage where I can still pull out of the whole thing if I judge it to be impossible given the budget.

Perhaps you could build it in stages? For example, build the outer-leaf shell, bathrooms and control room initially, leaving an empty space where the other room(s) will go later. Then at least you could make money mixing and mastering, while you save up to build the rest. Or go the other way: build just a live room, leaving the rest empty, and rent it out as rehearsal space, until you make enough to build the control room. That's what I would do.

Edit: Btw. noticed you're from Santiago where one of my best friends is from as well, so I raise you a mime drink to Chile!

Salud! (As long as you are drinking with a good Chilean wine, or even a nice chilled Pisco Sour! :) :yahoo: :!: ) - Stuart -