Fully isolating a 3rd floor room in an older house?

I know this subject has probably been done over and over and I apologise but I wanted to ask for my particular building. If we were speaking hypothetically. How feasible would it be to completely soundproof a room on the upper floor of a house [circa 1900] ? When I say feasible I mean in terms of the materials needed, the weight of those materials in the floors of an older house, the cost of doing it and whether there can be any guarantees that it will actually work. I am happy to employ a structural engineer and make modifications to the existing structure with reason and if needs be but only if I know it can work. I’ve “soundproofed” rooms using the room within a room method before but I’ve never actually managed to fully isolate it, just greatly reduce any sound coming out. Here it would need to be fully isolated. As I said, I’m looking at the upper floor to use as my studio. If this were to end up happening, it would have the master bedroom for my house directly below it and my neighbours bedroom to the side of that. So the main concern is sound getting out and causing a disturbance to my girlfriend and my neighbours who also have a baby. I will primarily write, produce and mix in there, I often work late at night at high volumes 90-95db+ , I’m also installing a void acoustics rig in there which I haven’t had chance to test with a decibel meter yet but it’s essentially a small club rig and although it’s only an occasional reference, when I do use it, it will be loud. I will also record in there at times: Mainly vocals but I intend on using the space to record percussion occasionally too. Obviously that all means it would need to be extremely isolated in order to even be considered. I’m aware that if this could be done it would require a floating room within the existing room. The room I’d like to soundproof is currently 16ft x 15ft x 9ft and I’d like to keep it as big as possible. It also has a large window with a nice view and a smaller window to the side and I’d ideally like to keep those so the inner room would need to be in some part made of glass. My survey from when I bought the house says the walls are a combination of solid masonry and plasterboard lined timber framed internal walls. The floors are solid timber Obviously any studio needs acoustic treatment but I'm disregarding it at this stage until I know if the isolation can work. I’ve added some pictures and basic sketchup models to give an idea of how it looks. The first picture is the dimensions of the room. On the the second sketchup model picture, the green part is the room, orange are the parts of my property which should be silent and red is my neighbours. The last picture is a photograph of the property from the outside with the room in question highlighted in green. If I can give any more information to help, please ask. At the moment this is just a feasibility study but if it is a genuine possibility then I’d like to start to get together a realistic plan to build it. I'm based in the UK. ps. I am aware this is a potentially expensive job Thanks in advance

Hi there "woodfoot", and welcome to the forum! :) There's no simple answer to your questions, for many reasons. There are only complex answers, which I'll try to cover below, but first one of the reasons is an issue with terminology! :) Let me explain that one first, then we'll get into the details of what you can do to get where you want to go.

How feasible would it be to completely soundproof a room on the upper floor of a house

There's the issue: "Completely soundproofing" something is actually impossible, since the term itself is impossible. Any sufficiently loud sound will always penetrate any barrier that Man could conceivably build. The loudest sound that ever occurred in recorded history was heard around the other side of the world, and cracked concrete slabs hundreds of kilometers away. (It also killed everyone within a very large radius). So acousticians seldom use the term "soundproof", since it it physically impossible to "proof" something against "sound". Worse still, "soundproofing" means different things to different people: for some people, the term doesn't mean stopping sound from getting through, but rather just means making the room sound good. So acousticians prefer to use the terms "acoustic isolation" to describe the science of reducing the amount of sound that gets through a barrier, and "acoustic treatment" to describe the science/art of making a room sound good. This distinction in terminology might not seem relevant at all, more like nit-picking, but it's actually very important. You've no idea how many times we've seen major misunderstandings here on the forum, when people misuse terms and things don't work out the way they thought they would, simply because they were using the wrong word... So no, you cannot "soundproof" your room. But you sure can "isolate" it. It is indeed possible to design and build an isolation system that will make the typical studio sounds you play inside, inaudible to those outside. It can be done. There's no question about that, since it is possible to measure how loud your loudest sound is, and also to define or measure how quite you need to have things outside the room to meet your definition of "inaudible". Doing that simple process will give you a number, which tells you how many decibels of isolation you need, and there are many publications that show how many decibels of isolation you can expect from different methods of constructing your floor, walls, ceiling, doors, windows, HVAC system, and electrical system. So the basic answer is that you certainly can isolate your room sufficiently. The question then becomes "How much are you prepared to spend to achieve this?". That's also not an easy question to answer, though. It works like this: Each time you want an additional 10 decibels of isolation, you need to block ten times more energy than the previous step. That's a bigger issue than it seems at first glance. A typical house wall will give you around 30 decibels of isolation, so if you want 40 dB then you need to block ten times more energy than a typical house wall. But if you wanted to block 50 dB, then you need to block 10 x 10 = 100 times more energy than the house wall. If you wanted 60 dB, then you need to block 10x10x10 = 1000 times more energy than a house wall. If you want 70 dB, then its ten thousand times the energy block. 80 dB is a hundred thousand times more. Etc. This is because the decibel scale is logarithmic. The very best isolated studio on the planet is probably Galaxy Studios, in Belgium, and they get just a tad over 100 dB of isolation, meaning that nobody would hear you scream if you were murdered inside there... but the gunshot that killed you would still be faintly audible outside. (Sorry about the macabre illustration, but it's a good way of pointing out that "soundproofing" isn't possible). However, 100 dB of isolation does mean that even the wildest drummer alive, with the biggest, baddest, loudest drum kit ever conceived, playing the most ear-destroying thrashing death-metal drum solo ever written, would not be audible in the slightest in the next room. So the degree of isolation they achieved at Galaxy serves their purpose perfectly... but it did cost them several million dollars to get there, and I'm assuming that you don't want to blow several million dollars on your upstairs bedroom! :) OK, all of that long, ranting, preamble is meant to just lay out the reality of what you are trying to achieve, so you can get a better idea of the concepts and costs, in order to determine if this is something you want to do, or not. Now to get down to brass tacks:

When I say feasible I mean in terms of the materials needed, the weight of those materials in the floors of an older house, the cost of doing it and whether there can be any guarantees that it will actually work.

You hit the nail on the head with that! That's a very good set of the five key points. I think I've answered one of your points there: "Can there be any guarantee that it will work?" Yes, there can. If you do what Galaxy did, the you'd get the same isolation. So from that point of view it is feasible: you really can get isolation that makes even the loudest studio to be totally inaudible outside. So that one is covered: it is feasible, and can work. That leaves materials, weight, structure, and cost. But before we can go into that, the first things we need is a realistic number to work with. Once again, I'm going to assume that the two extremes I have mentioned are both out of the question for you: At the high end you do not need the extreme 100+ dB of isolation that Galaxy gets, and at the low end you also need way more than the typical 30 dB that a house wall gives. I'll go further, and say that you need more than 40 dB and less than 90 dB. That's still a huge range, covering five orders of magnitude of sound intensity, so we need to narrow it down more. You mentioned "percussion" and also "95 dB". So your peak is at least 95, and perhaps as much as "percussion". Assuming that "percussion" can also included an acoustic drum kit, your highest level could be around 115 dB, but from what you said, it sounds like that won't be the norm. Let's say 105 dB, for argument's sake. (You can define this more accurately by actually setting up a tracking session that you think would be the loudest you are ever likely to do, and measuring that.) So I'll assume that your peak is 105 dB. That answers "How loud are you?", so now you need to define "How quiet do you need to be?". That's another grey area with no simple answer. For a sound to be truly inaudible, it needs to be at least 10 dB quieter than the ambient level, so one possibility is for you to measure the ambient level at several locations around your room, subtract 10 dB, and call that your goal. But like most things in acoustics, it isn't that simple. Human hearing is not linear, and not flat, meaning that sounds at the same level relative to each other will be perceived differently depending on the frequency of the sound, and also the absolute level. For very loud sounds, we perceive all frequencies at roughly the same level, subjectively, but for very quiet sounds we perceive the mid range to be louder than the lows or the highs. This works in your favor, actually, so it is reasonable to assume that as long as "your" sound outside the room is not more than about 10 dB louder than ambient, it won't be audible to most people, provided that it is bass-heavy music. In other words, an electric bass that gets through your wall and measures 10 dB louder than ambient would be inaudible to most people, but a sax or violin that gets through your wall and measures 10 dB louder than ambient would be very audible to most people. Once again, there's no easy answers, unfortunately, but a reasonable rule of thumb is to aim to get your entire spectrum down to ambient level or a bit more, but certainly no more than 10 dB above ambient. So, assuming that your ambient level where you live is typical of most residential areas, to be truly "inaudible" you'd need to produce no more than about 35 dB outside your walls when you are producing your peak 105 dB within. Bingo! We got a number! 105 - 35 = 70. So you'd need about 70 dB of isolation. But do take that with a major grain of salt! I based on that on a whole series of assumptions that may or may not be valid for YOU. The only way to know what your actual number has to be, is for you to do some measurements. But for now, we'll work with 70 dB isolation as your goal. That's about the limit that you can reasonably attain for a typical home studio build, if it is very well designed, carefully built, and has a good budget behind it. You did imply that "money is no object" here, so I'm assuming that you have that "good budget" from now on, meaning that this is going to cost you some place in the five-digit range (as measured in dollars, euros, or pounds). So that answers another of your questions: "Is it feasible from the monetary point of view?" The answer is "Yes, assuming that you are prepared to splurge somewhere between 10k pounds and 99k pounds". It will most likely be in the lower half of that range. If you don't want to invest that much, then no, it is not feasible. This is just not going to happen for less than 10k, and will likely cost a few times that. That leaves two more questions: weight, and structure. They go together. To understand this part, it's good to first answer yet another question: "So how exactly do you go about stopping sound getting from point 'A' to point 'B'?" It turns out that there are only a handful of possible methods. The first thing you can do is to make a barrier so rigid and stiff that the sound waves cannot make it vibrate in the first place. Unfortunately, there are no such materials available on planet earth: Even solid bedrock isn't rigid enough to do that. That's why earthquakes can be felt hundreds of km away: the rock is flexible enough to transmit the vibrations. The second thing you can do, is to make a barrier so massive (heavy) that the sound waves cannot make it vibrate. Once again, there are no such materials. Earthquakes are the perfect example here too: even the entire planet isn't massive enough to stop their waves traveling thousands of miles! The third thing you can do is to "decouple": take away all possible paths for the vibration to follow between "A" and "B". That also includes taking away the air, since sound travels pretty well through air. This does work, since earthquakes cannot be felt nor heard on the moon, so if you can persuade NASA to let you build your studio on the moon, you'll be fine! :) Otherwise, no luck. There's a final option: "damping". You can make the sound waves move through molasses so thick and "gooey" that it "bogs them down", until they sort of "run out of steam" before getting to the other side. You do that by putting fibrous things in the path pf the sound waves, such as fluffy insulation, but it isn't very efficient. Once again, there's no material on planet enough sufficiently "gooey" to completely stop sound. And that's about it. There are no more options: Mass, stiffness, decoupling, damping. There are no other ways to stop sound. And none of these four are very good.... by themselves... ! But it turns out there's another option: by combining all of the above in certain ways, you can really have a huge effect. For example, if you set up two "leaves" of massive, rigid surfaces, such that they are not connected to each other ("decoupled"), then put some damping between them, you have an excellent barrier that really does a great job at stopping sound from getting out of your room. One common example is to have two sheets of drywall attached separate stud frames, with only an air gap between them, and insulation in the air gap. Very effective, and not too expensive. That's a "fully decoupled two-leaf MSM" wall, in technical jargon, or a "room-within-a-room" in simpler terms, and it isolates very well. Done right, it can isolate to levels of 50, 60, 70, 80 even 100 dB: It stops a lot of sound from getting out. That's how Galaxy is built, so it certainly does work. This works because it is a resonant system, a tuned filter, sort of like a parametric equalizer on your console or DAW: it is a bandpass filter, tuned to one frequency, which it allows to pass really well, but it actively resists all other frequencies. So if you tune it right, such that the "band" that it "passes" is subsonic, then it does a darn good job of isolating all sonic sounds. But there's also a drawback: it has to be tuned to at least one octave below the lowest frequency that you need to isolate, and that takes a lot of mass and a big air gap if you want to isolate the entire spectrum. Which takes us back to your situation, and your question regarding weight and structural integrity. The solution to get you where you want to go, is indeed, what you already suspected: you need to build a "room in a room" studio. You already have the "outer room", which is your house itself (provided that it is only one single leaf), so all you need to now is to build the inner-room, on top of a firm, solid, massive base. If this were a room on the ground floor, then your job would be an awful lot easier, since the ground itself gives you a major helping-hand. Trying to do it on an upper floor is still feasible, just harder. The reason why building on the ground makes it easier, is because the ground provides that massive, rigid, well-damped base that you need. You don't have that on your third floor, so you'll have to provide a massive, rigid, decoupled floor on top of which you can then build your studio. The best bet for getting 70 dB of isolation, is to have a concrete slab as the base for your studio, and to have it decoupled from the rest of the house. Obviously, you can't just run upstairs with a few bags of cement, and pour a concrete slab up on the existing floor of your house ( :shock: ). This will need some form of structural reinforcing under it, to take the weight of the concrete. Likely this will need some hefty joists to support the concrete (either wood or metal joists could be used), and columns going down to the ground to support those joists. It sounds scary, but it's probably not as bad as you think. That can all be done with minimal "invasion" of the rest of the house, if planned carefully. However, you'll need to hire a structural engineer to design that support system: it's not something that you can do yourself, and nor can some guys on an Internet forum tell you how to do it: it needs a qualified professional to go in to your place, inspect it all over, inspect your plans, do the math, produce a plan, and present it to the relevant authorities for authorization, stamps, signatures, etc. OK, so assuming you do that, the rest is simple: Beef up and seal the existing outer leaf, put up stud framing for the inner-leaf walls and ceiling, put some drywall ("plasterboard" in the UK) on the framing, put in the doors and windows, put in the HVAC and electrical, put in the treatment, and you are done! That would be the plan to get you 70 dB. But what happens if you don't have that kind of money, or don't want to go that far in terms of complexity? Firstly, you wont get 70 dB! But you can still get pretty good isolation. You could get at least 40 dB without too much hassle, and you could probably also get 50 dB, without needing to go to an isolated concrete slab. 50 dB is probably about the limit of what you could expect, realistically. The only question there would be: "Is 50 dB enough?". Only you can answer that. It would be a lot cheaper, and is also very feasible, but might not meet your goals of being able to play/track/mix loud music late at night.

I’ve never actually managed to fully isolate it, just greatly reduce any sound coming out. Here it would need to be fully isolated.

:) See above! It all depends on what you define as "fully isolated". I suspect 70 dB would meet your definition, but I might be wrong...

I often work late at night at high volumes 90-95db+ ,

If you could get 50 dB of isolation 8with the low cost option I outlined briefly above), then your levels outside would be around 40 to 45 dB, which might or might not be acceptable. I'd suggest that you do some tests, to make sure. Play music at around 50 dB, and see if you find it objectionable. On the other hand, if you get 70 dB of isolation (with the full plan outlined above), then your levels would be 20 to 25 dB outside the room, which is almost certainly inaudible, even late at night, even for sleeping babies. That would be around 10 dB below the ambient level of a typical quiet bedroom, so pretty much guaranteed to be imperceptible.

I’m also installing a void acoustics rig in there

I'm not familiar with that. What is a "void acoustics rig"? Do you have a link to that?

when I do use it, it will be loud.

How loud is "loud"? That's the key. You need to put a number on that. I've been estimated everything above assuming a peak level of around 105 dB, but your REAL level might be different. When you get a chance, measure it with a good sound level meter, "C" weighting, "Slow" response.

but I intend on using the space to record percussion occasionally too.

Measure a typical session of the types of percussion and percussionists you think you'll be tracking, once again so you have a real world objective number, not just a guess from some guy on a forum around the other side of the world ... (me! :) ).

The room I’d like to soundproof is currently 16ft x 15ft x 9ft and I’d like to keep it as big as possible.

Keeping the interior space as big as possible means that you'll need to use higher density materials. The tuning of the MSM walls and ceiling is accomplished by setting the mass (surface density) and the air gap to whatever is needed to get the level you want at the frequencies you need it. You can reduce the air gap, provided that you compensate by increasing the mass. You can further reduce the thickness of the walls by putting more mass in a thinner volume, meaning that the materials themselves need to be more dense. A typical material used in studio construction is drywall (plasterboard), which is reasonably dense, and reasonably inexpensive. The density of drywall is around 650 kg/m3. Using fiber-cement board allows you to get the same mass in about half the thickness, since fiber-cement board has a density of around 1300 kg/m3. It's a bit more expensive, but saves you space. Moving up from there, brick weighs in at around 2000 kg/m3, concrete is around 2300 kg/m3, and glass is around 2500 kg/m3. All are good for studio construction, albeit more expensive than drywall or fiber-cement board. But you can still go higher, if money is not a problem. Aluminium sheeting is even more dense, at around 2800 kg/m3, and steel plate is way up, at around 8000 kg/m3. That's about as far as you'd want to go, reasonably, but with lots of money, you can go even better: lead is about 12,000 kg/m3, gold is 19,000 kg/m3, and platinum is 21,500 kg/m3. So if you want to get the maximum possible space inside while still having maximum possible isolation, then build your walls from gold or platinum! :shock: :ahh: :) Imagine that: You could have gold sheeting walls just a couple of mm thick, instead of 4 inch thick bricks! :) In other words, it's a trade-off between how much you want to spend and how much you want to save space in the room. Pretty much everything in studio design is a trade-off, in one way or another. It's a matter of finding the right balance. For many studio builders, the most cost effective materials for building walls are brick at the high end, and plywood at the low end, with drywall falling somewhere in between.

It also has a large window with a nice view and a smaller window to the side and I’d ideally like to keep those so the inner room would need to be in some part made of glass.

Not a problem. Glass has very good density, and many studios are built with good isolation windows, both internally (between rooms) and also to the outside world. So you can keep your windows.

My survey from when I bought the house says the walls are a combination of solid masonry and plasterboard lined timber framed internal walls. The floors are solid timber

Are all of the walls around the proposed room masonry? If so, that's a rally good start. However, if one of the walls around that room is just drywall, then that will need to be beefed up considerably. What about the party wall, that separate you from the neighbors: is that masonry, or is that drywall? But there's one important item that you didn't mention, and that's the sixth side of the room: the roof. What is that made of, and is it ventilated? Is the attic space up there open to your neighbour's attic space, or does the dividing wall go all the way up to the roof deck? Is your roof tied directly to the neighbour's roof, or are they separate structures? Sorry for waffling on for half an encyclopaedia, but since this is going to be a rather expensive job I thought it would be better if you understand the issues a bit better, to help you take your decision.

I am happy to employ a structural engineer and make modifications to the existing structure with reason and if needs be but only if I know it can work.

As I mentioned above, it is both feasible to do this, and also very necessary to hire the structural guy, and if you do want to get maximum isolation, then modifications will be needed, and can probably done without messing up the rest of the house too much.

ps. I am aware this is a potentially expensive job

Yup! For sure! :thu: Having said all that, is there any other place where you could maybe build something more easily? For example, out in your back yard? It would likely be simpler and cheaper to build something from the ground up, if that's an option for you. - Stuart -

I am thinking about 500K USD would start the project....so lets do it!!!