John Sayers' Recording Studio Design Forum Archive

Tried sending a couple since Feb, no responses so was just wonderin'...

I did reply back on March 14. Not sure if you saw that.

But basically, it doesn't seem like the plan you want to pursue is viable. I would do it differently, but it seems like you don't want to go that route.

- Stuart -

Soundman2020 wrote:I did reply back on March 14. Not sure if you saw that.

But basically, it doesn't seem like the plan you want to pursue is viable. I would do it differently, but it seems like you don't want to go that route.

- Stuart -

I sent you 2 PM's since then. I've copied and pasted the the last one below:

Hi Stuart!

Well, you were right all those months ago when you said planning and building this studio should, and will, take way longer than I'd like...

A quick reminder:

I bought 117m2 office space on the 7th and top floor and have been using the front space to record and mix in in a compromised way (no loud sound during business hours), while the rest of the space is being readied for the studio build.

Last I wrote I was contemplating either your's or John's services with a view to first deal with the isolation of the live area. Both of you suggest the whole 2 room studio (CR and LR) needs to be designed as a whole. My biggest concern is to not waste a lot of money on a design that still fails to isolate low frequencies heard by the several offices below. As far as the 2 offices on my level, I'm hoping some heavy walls will also be enough to not cause a disturbance. They are still vacant, so when they become tenanted I'm hoping to assert authority, being the existing tenant ...

So, the wall perimeter loads are supported by beams beneath and should support heavy walls (still not sure exactly how heavy). It's the floor that was always the issue, with 600 kg per m2 to handle both the LL and the ADL. You may recall my last idea to use concrete pavers resting on joists that are themselves resting on rubber blocks. The other idea was to float the walls separately, which may be necessary to limit the load on the floor. You weren't especially keen on with of these ideas IIRC...

Anyway, after much consideration, and owing to the fact that I'm at least breaking even with my current temporary set up, I've decided I don't need to rush things and perhaps do the build in stages. In this case, I should really worry about the outer shell first, then the inner floating walls and ceiling. Once I the box in a box is complete, I can then test how much difference the new walls make to the low frequencies escaping through the floor. This is without doing anything extra to the floor - yet... Yes, most unusual! But if the walls lead to an improvement, then I'll have a better idea about how to improve the floor, or if it's even worth attempting to do anything to it.

The walls will still allow me to mix and record moderate sound levels during the day without disturbing my 7th floor neighbours, nor the ones beneath me, so it's definitely worthwhile. But if it then appears that the floor will require a heavier floating slab than the building will allow to isolate loud rock drums, then it will best not to bother and continue to mix and record everything except drums during business hours.

If it seems that, say, an 80mm floating concrete slab might do the trick after all, then I will put down some rubber blocks, run some joists over the top and place 2 layers of concrete pavers on top. Maybe one layer first to see if that is even enough.

So yeah, I thinking to leave the floor until the end. I understand the disadvantage in not building the walls on top of a concrete floating slab floor, but I will eschew this in favour of the logistical advantages to be had doing things in the proposed manner.

I will require assistance in first completing the outer shell, then the floating inner walls, the ceiling (along with the HVAC) and the doors and windows. I don't want assistance with the internal treatment.

So, are you interested in helping me design the build in this manner?

Hi I'm not Stuart, but I've noticed something you need to rethink.

Your idea for starting with walls without doing the floor won't work as expected. Remember, your floor is shared with your neighbours on your level. The floor will transmit sound directly under the wall to them. Think of a railway track, if you tap the track with a rod, a person further down the track will clearly hear the tap.
Now concrete has high mass yes, but the sound will only need to travel the depth of your wall in the concrete below before transmitting to the air the other side of the walls. How much isolation do you need?

Your walls alone won't tell you whether the floor isolation will be effective. The whole room works as a system. The weakest surface transmission loss is the loss you will achieve across the whole system.

Thanks,
Dan

Waka wrote:Hi I'm not Stuart, but I've noticed something you need to rethink.

Your idea for starting with walls without doing the floor won't work as expected. Remember, your floor is shared with your neighbours on your level. The floor will transmit sound directly under the wall to them. Think of a railway track, if you tap the track with a rod, a person further down the track will clearly hear the tap.
Now concrete has high mass yes, but the sound will only need to travel the depth of your wall in the concrete below before transmitting to the air the other side of the walls. How much isolation do you need?

Your walls alone won't tell you whether the floor isolation will be effective. The whole room works as a system. The weakest surface transmission loss is the loss you will achieve across the whole system.

Thanks,
Dan

Sure, but with the walls separately floating, I can then "experiment" with the floor, whereas floating the floor first, then building walls atop it would mean I'd be stuck with either an over engineered floor, or an under engineered one...

If I create a raised concrete floor by using pavers /on joists / on rubber blocks, then if one layer of 40mm pavers does the trick I can stop there, if not I'll add another. I know it's not " the done thing", but I'm also considering having to remove said raised floor in around 10 years. Pavers are easier to install and remove I would think.

As I said, and as Dan said, and as John said, and as other designers that you have contact also said: your plan to do it your way is not viable. I'm not sure why you want to insist on that, when you have so many knowledgeable people telling you the same thing.

As I also said, I would do it differently, but you don't seem to want that: you seem to want somebody to validate your non-viable plan, so you can go ahead with it. To my way of thinking, that doesn't make a lot of sense.

I was contemplating either your's or John's services with a view to first deal with the isolation of the live area. Both of you suggest the whole 2 room studio (CR and LR) needs to be designed as a whole.

Exactly. I did not discuss your project with John, and he did not discuss it with me, yet we are both telling you the same thing: it MUST be designed as a whole, together, all parts included. Trying to design bits and pieces on the fly, and experiment along the way, then add some more bits and pieces... well frankly, that's doomed to fail. Here you have two experienced studio designers (John MUCH more experience than I am, of course) both telling you that the correct way to approach studio design is to do the whole thing as a single integrated unit. I'm not sure why you don't want to accept the word of two experienced designers about this.

My biggest concern is to not waste a lot of money on a design that still fails to isolate low frequencies heard by the several offices below.

Which is precisely WHY it must be designed as a unit! All parts together! If you try to do it in random parts, you might well get to the situation where you build one room that isolates reasonably well, but when you add the other room, that trashes the isolation of the first room! That's a very real, very valid possibility, because adding the second acoustically isolated space WILL interfere with the isolation system for the first space. Simple physics. Which is why they must both be designed together.

As far as the 2 offices on my level, I'm hoping some heavy walls will also be enough to not cause a disturbance.

"hoping" is never a good way to design a studio, and no, just putting up heavy walls by themselves will NOT "be enough". Besides, you don't have the luxury of being able to put up heavy walls, since you have a rather limited load capacity on your existing floor: you cannot put up very heavy walls, because you would overload the building's floor. Walls are linear loads, with all of the weight concentrated along a single thin line, not spread out over a large area. One again, your studio isolation is a SYSTEM, not a bunch of parts. The whole is greater than the sum of the parts. The parts interact to create an effect that is much greater (and much different) then simply adding up the individual effects of the separate parts.

Let me put it in terms of a musical instrument: Your approach is like saying "I want to build a guitar, so I'm going to start by getting one string and hang it in mid air, to see how that works when I pluck it, and if it doesn't sound good then I'll forget using strings, because I will have proved that they don't work". A guitar strong only woks as such when you add the body, neck, frets, and all the rest of the guitar. You CANNOT test how the string will sound, unless you build the entire guitar. The rest of the materials completely change the way the string sounds. Not one of the components of a guitar will sound anything at all like the finished product, if you just test it by itself, hanging in mid air: you MUST put them together, so that they can all interact in the correct way to produce a true "guitar sound". Yet what you are proposing is to hang a string, test how it sounds, take it down, hang a fret board, test how it sounds, take it down. Hang a pieces of flat wood with a hole in it, test how it sounds, take it down. Hang a piece of curved wood, test how it sounds, take it down. Then based on all of that, you want to say that you now know how the guitar will sound...

So, the wall perimeter loads are supported by beams beneath and should support heavy walls

"Hope" and "should" are not good ways of designing a studio...

It's the floor that was always the issue, with 600 kg per m2 to handle both the LL and the ADL.

No, the floor by itself is NOT the issue: it is PART of the issue. It puts a limit on how much total weight you can have, but that's not the ONLY issue. Just one of many.

You may recall my last idea to use concrete pavers resting on joists that are themselves resting on rubber blocks.

Yes I do recall that, and at the time I gave yo a series of reasons why I would not go with that approach. So did another studio designer. But you still want to do it...

The other idea was to float the walls separately, which may be necessary to limit the load on the floor. You weren't especially keen on with of these ideas IIRC...

Exactly. And neither were the other studio designers that you approached, and then told me about.

I've decided I don't need to rush things and perhaps do the build in stages.

And that's fine! You can certainly BUILD in stages, but you cannot DESIGN in stages. That seems to be a distinction that you are not grasping. The entire studio MUST be designed as one single unit, to do the job that you want it to do, but it can then be BUILT in stages, if your cash flow budget is limited. For example, you could build just the control room, then save up money until you have enough, then build the live room. That's not a problem. Provided that they were both designed together, initially. Building in stages is entirely possible, and sensible. Designing in stages is not.

In this case, I should really worry about the outer shell first, then the inner floating walls and ceiling

No you should not. You should worry about the complete design, considering all the parts, and how they will interact. Going back to my analogy above, you are saying that you should first worry about the neck of the guitar, then the bridge, then the flat back piece, each separately, and hope that somehow that should tell you how the finished guitar will sound...

Once I the box in a box is complete, I can then test how much difference the new walls make to the low frequencies escaping through the floor.

Analogy: "Once I have the neck and bridge and back piece complete, I can test how much difference the tuning screws will make to the low frequencies, ... even though I don't yet have a resonant body for the guitar, nor have I put strings on it"....

This is without doing anything extra to the floor - yet... Yes, most unusual!

And most impractical, and most doomed to failure, and most doomed to spending several times what it would cost to do it once only, designed correctly.

But if the walls lead to an improvement, then I'll have a better idea about how to improve the floor, or if it's even worth attempting to do anything to it.

Analogy: "But if the glue on the bridge leads to improvement, then I'll have a better idea about where to place the frets, which I will make from either carved Styrofoam or silly putty, if the Styrofoam doesn't work well..."

The walls will still allow me to mix and record moderate sound levels during the day without disturbing my 7th floor neighbours,

No they wont. Sorry. Not going to happen like that. A control room is a SYSTEM, designed from the start to be one. Not a bunch of random experiments in an uncontrolled environment, with no proper test equipment.

But if it then appears that the floor will require a heavier floating slab than the building will allow to isolate loud rock drums, then it will best not to bother and continue to mix and record everything except drums during business hours.

On the other hand, it might just be better to design it properly from the start so that it WILL provide the correct level of isolation.

If it seems that, say, an 80mm floating concrete slab might do the trick after all, then I will put down some rubber blocks,

I wouldn't. Since you want the best possible low frequency isolation, I would use steel springs plus neoprene pads for that. Not rubber. Steel is more linear and gives you better low frequency isolation. Neoprene is better for the mids and highs. The combination covers all bases.... provided that you calculate it correctly.

run some joists over the top and place 2 layers of concrete pavers on top. Maybe one layer first to see if that is even enough

"Maybe" and "to see if" are not a good way of designing a studio...

So yeah, I thinking to leave the floor until the end.

Analogy: "So yeah, I'm thinking to leave the guitar body and sound hole to the end, since I think that maybe I should see if possibly what I hope perhaps might could ..."

I understand the disadvantage in not building the walls on top of a concrete floating slab floor,

I'm not convinced that you do understand that. Analogy: "I understand the disadvantages of not having any strings on the guitar, but I'm sure I can experiment and learn to play it without strings..."

but I will eschew this in favour of the logistical advantages to be had doing things in the proposed manner.

I don't see any advantages at all: not logistical, not acoustical, not financial, not any other way either.

I will require assistance in first completing the outer shell, then the floating inner walls, the ceiling (along with the HVAC) and the doors and windows. I don't want assistance with the internal treatment.

Analogy: "I will need assistance in first completing the neck and tuning screws, which I plan to make from candy floss, then making the rear panel from concrete, along with the bridge and the frets from depleted uranium. I don't need assistance with the strings, body, or tuning of the guitar, because I won't need those anyway, in my case..."

Sorry to be a little sarcastic with my guitar analogy, but I'm trying to draw your attention to the fact that your approach is not viable. There's not point in designing a studio unless the design is complete, including the geometry, layout, and treatment. They all go together, and are inseparable, to a large extent.

So, are you interested in helping me design the build in this manner?

To my knowledge, you have approached at least three studio designers, plus an acoustic isolation engineering company, and they have all told you the same thing: your propose methodology is not viable. The studio needs to be designed as a whole, all together, including the isolation as one part of that. Getting basically the same answer from all of us, as well as from Dan (who doesn't know the full background like the rest of us do, but was still easily able to immediately spot a major shortcoming of what you propose...), should tell you something.

Let me give you another analogy: If you approach Elon Musk, and asked him if he would design a car specially for you, but you insisted that the wheels must go on the roof, and you'd like to experiment with a bright green plastic windshield that must be in the floor, but you don't want an interior design for the seats, steering wheel, pedals, control panels, dashboard, or any other part, since you can do that yourself... do you think he would be interested in designing your car for you? I rather think you'd get the same answer from him that I'll give you: I'd be happy to design your studio for you if you allow me to do it the way I think it will work best, as an entire complete system, not restricted by nonviable limitations imposed on the outcome before I even start. I'm sure the reason you even asked me, or John, or the other guy, is because you have seen other studios that each of us has designed, and you were impressed with the way they worked out. You liked what you saw when other customers hired each of us to do our best, not hindered by unrealistic, ill-advised, unnecessary restraints. If there are no restraints, other than real physical limitations (load bearing capacity, building dimensions, budget, etc), then probably any of the three of us that you have approached already would be happy to take on the job, and produce a good design that would do the job, or at least get as close as the physical limitations allow.

So if you are asking if I'd like to take on your studio design project, then the answer is yes, I'd love to! But not with restrictions that I know in advance will prevent me from producing a design that works.

Your idea for starting with walls without doing the floor won't work as expected.

Correct!

How much isolation do you need?

Good question....

The whole room works as a system.

Exactly! Spot on! And you know this personally, Dan, because you have worked through the process, and and understand it.

The weakest surface transmission loss is the loss you will achieve across the whole system.

Right!

Sure, but with the walls separately floating, I can then "experiment" with the floor,

Why? How? What would be your test methodology for determining if it would be better to float of not float? Would you build the entire room first, not floated, test it, then tear it down and re-build it floated, to test again? If not, then how would you determine how each complete SYSTEM was performing?

whereas floating the floor first, then building walls atop it would mean I'd be stuck with either an over engineered floor, or an under engineered one...

So you would rather build the room several times over, wasting huge amounts of time and money, to get it "just right", rather then designing it to be the best it can be within the physical limitations imposed by the building?

I know it's not " the done thing",

Right. There are very good reasons why it is not done, and why three experienced studio designers were not interested in taking on the project your way...

but I'm also considering having to remove said raised floor in around 10 years. Pavers are easier to install and remove I would think.

I gave you a very realistic, very viable, very solid, sound, tried, tested, workable alternative for doing the floor, but you rejected it outright, in favor of your unrealistic, non-viable, untested, untried, unknown system that three studio designers pointed out serious flaws with....

Consider this: If I am sick, and I think I have stomach ulcers, and I then go to three different doctors and tell them that I have stomach ulcers and I need to have my toe amputated to fix that, and they all tell me that my diagnosis is actually wrong, it is appendicitis, not stomach ulcers, and that amputating my toe would not work in either case, but then I insist that the only solution is to amputate my toe, what conclusion would you draw about my medical skills?

Sorry to be harsh again, but I don't know any other way to draw your attention to the obvious here: your plan won't work, three studio designers have told you this. All three would take on your project in a heart-beat if you would just let them do what they do best. But none of them are interested if you will only hire them to do it in a way that they have already told you is not going to work...

I can't speak for John, but I suspect he told you the same thing, or something similar. So did the third guy, I presume.

So I don't know what else to say here! You have a god sized space, there are limits on structural loads, limits on access for bringing in materials and tools, but even so it could very probably be turned into a good studio that isolates well and has good acoustic response as well. It has good possibilities, if designed right and built according to the design. There's not much more I can add to that!


- Stuart -

The walls can't sit on a floated floor floated (too heavy), however, I can (according to SE) have heavy walls since they are supported by stuctural steel beams directly beneath the entire perimeter of the 2 rooms.

So the walls have to be separately floated. End of story. If that was the job description you would design around that requirement. What is so strange about leaving the separate floating floor til last? Is it because you thing it simply MUST be a poured concrete slab? Couldn't it be cement sheets on joists and isolators (spring or rubber)? Concrete pavers is an alternate (albeit untried) idea. If pavers fails, it is easy to take them out and build the cement sheet floor on the same joists (similar weight to pavers).

I have had 2 other studios since 1992 on upper floors. The second one I paid to have built and co designed it. I'm not a total newbie that risks losing his life savings. I can live with the slight risk of the pavers not working.

If I can't get any professional assistance with this build I will need to go it alone, but I'd be disappointed that I couldn't get the best advice on how to do what I'd like to the best way it can. Even if it's considered unviable to some.

It seems with designers it's "my way or the highway" - so inflexible!

princeplanet wrote:The walls can't sit on a floated floor floated (too heavy), however, I can (according to SE) have heavy walls since they are supported by stuctural steel beams directly beneath the entire perimeter of the 2 rooms.

So the walls have to be separately floated. End of story. If that was the job description you would design around that requirement. What is so strange about leaving the separate floating floor til last? Is it because you thing it simply MUST be a poured concrete slab? Couldn't it be cement sheets on joists and isolators (spring or rubber)? Concrete pavers is an alternate (albeit untried) idea. If pavers fails, it is easy to take them out and build the cement sheet floor on the same joists (similar weight to pavers).

I have had 2 other studios since 1992 on upper floors. The second one I paid to have built and co designed it. I'm not a total newbie that risks losing his life savings. I can live with the slight risk of the pavers not working.

If I can't get any professional assistance with this build I will need to go it alone, but I'd be disappointed that I couldn't get the best advice on how to do what I'd like to the best way it can. Even if it's considered unviable to some.

It seems with designers it's "my way or the highway" - so inflexible!

Hi again,

As Stuart said there is no problem with building the rooms in stages, but the design must be complete.
Just as a side point, if placing steel beams around the perimeter will support your walls, why cant the floor supports also rest on these beams and walls on top of the floor thereby transferring the load onto the steel beams? I'm sure if the structure truly cannot support the walls on a floor (can't see why not, when the walls are the same mass either way) then one of the designers will work around that; but you need them to design the whole system in one go. Give the numbers to them: max live/dead load per m2, immovable structural support locations and dimensions, budget, can you build it yourself, etc. If anything comes from your contact with the designers, please take away this: it will be cheaper and take less time to design the floor and the walls together. You've come to the conclusion that you need a floating floor. This means you need reasonably high isolation at least. You can calculate whether 40mm floating will be enough in the design, you don't need to build it first. If you build 40mm you cannot just add an extra 40mm. You'd need to change the whole spring support system then rebuild with 80mm. If a designer calculates it for you then they can provide estimated TL for both cases and you pick the one you want. The worst that can happen doing it this way is that you've paid for a design that you need to save up for before building/build 1 room at a time. The worst that can happen your way is the room doesn't isolate well and you need to rip it out and start again/pay twice as much fixing it.

The walls can't sit on a floated floor floated (too heavy),

Wrong. Yes they CAN. And that's the CORRECT way to build a floated room. It places maximum mass on the isolation mounts, which is what you NEED to get maximum isolation, and it also spreads the total load more evenly across the existing floor, avoiding the line-loads that would otherwise be the case. Do the math. You will see that building the walls on top of the floor is indeed the best way to do this. If you don't agree, you better call Galaxy Studios in Belgium to start with (among many others), and warn them that they built their studio wrong. Even though they hired the two best acoustic engineers in the world, along with the best structural engineers.... And have the best-isolated studio on the planet, achieving slightly over 100 dB of isolation.

But I already know that you don't agree, and won't do the math either, because I already know that when you spoke to the engineers at the company that manufacturers the isolation mounts that you would need, as I recommended you should do, you rejected their advice as well as everybody else's, and thought your plan was better than theirs... even though they design and build floating structures and systems every single day, all around the world, with great success, and have been doing so for decades...

Is it because you thing it simply MUST be a poured concrete slab?

No. I already told you, privately, how I wold do it, and you absolutely rejected it outright, without even checking into it. You looked up one number, and decided that my carefully consider solution was therefor no good for you, without even asking how I planned to do it. The alternative I suggested did not involve concrete, nor "pavers", but would have provided the necessary mass and isolation in a manner that could then have been removed, easily, at any time in the future.

It seems with designers it's "my way or the highway" - so inflexible!

That's extremely unfair, considering the thousands of dollars worth of free advice I already gave you, both on your original thread ( http://www.johnlsayers.com/phpBB2/viewtopic.php?t=20980 ) and also in private, and the numerous ways I attempted to be highly flexible and adapt the proposed design, amny times over, to YOUR absolutely rigid, totally inflexible, totally silly restrictions and limitations. I told you many times that I would do the design, even though two other top designers had already declined to take on the project (for the same reasons I gave), on the condition that you would relax your intransigent obdurate adamant insistence on refusing to listen to reason, or follow established, proven, tested theory and practice, instead trying to re-invent the entire science of acoustics, all by yourself, based on nothing but whims, imagination, hopes, feelings, "should" and "maybe". One year ago, in a post that you never even bothered acknowledging, least of all reply to, I told you exactly how I would go about planning your studio, in public, and ended up with this comment: "I would not try to invent untested combinations of esoteric materials that nobody every thought of before, in the hope that they would bypass the laws of physics." You are still ignoring that advice, and the advice of two other leading studio designers, and the advice of the engineers that design floated isolation systems. And you still think you can do better....

I have had 2 other studios since 1992 on upper floors. The second one I paid to have built and co designed it. I'm not a total newbie

And yet... http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20860 .

So the walls have to be separately floated. End of story.

Well, good luck with your build! Please do keep us informed of how it works out. Let us know if amputating your toe does, in fact, cure appendicitis...

I would still take on your project (which would probably be a very stupid move, on my part), but only if you abandon this untenable slap-hazard plan that you have, and agree to let designers do what designers know how to do. But apparently, that's not going to happen. So as you say, you are on your own. End of story.


- Stuart -

Waka wrote:

princeplanet wrote:The walls can't sit on a floated floor floated (too heavy), however, I can (according to SE) have heavy walls since they are supported by stuctural steel beams directly beneath the entire perimeter of the 2 rooms.

So the walls have to be separately floated. End of story. If that was the job description you would design around that requirement. What is so strange about leaving the separate floating floor til last? Is it because you thing it simply MUST be a poured concrete slab? Couldn't it be cement sheets on joists and isolators (spring or rubber)? Concrete pavers is an alternate (albeit untried) idea. If pavers fails, it is easy to take them out and build the cement sheet floor on the same joists (similar weight to pavers).

I have had 2 other studios since 1992 on upper floors. The second one I paid to have built and co designed it. I'm not a total newbie that risks losing his life savings. I can live with the slight risk of the pavers not working.

If I can't get any professional assistance with this build I will need to go it alone, but I'd be disappointed that I couldn't get the best advice on how to do what I'd like to the best way it can. Even if it's considered unviable to some.

It seems with designers it's "my way or the highway" - so inflexible!

Hi again,

As Stuart said there is no problem with building the rooms in stages, but the design must be complete.
Just as a side point, if placing steel beams around the perimeter will support your walls, why cant the floor supports also rest on these beams and walls on top of the floor thereby transferring the load onto the steel beams? I'm sure if the structure truly cannot support the walls on a floor (can't see why not, when the walls are the same mass either way) then one of the designers will work around that; but you need them to design the whole system in one go. Give the numbers to them: max live/dead load per m2, immovable structural support locations and dimensions, budget, can you build it yourself, etc. If anything comes from your contact with the designers, please take away this: it will be cheaper and take less time to design the floor and the walls together. You've come to the conclusion that you need a floating floor. This means you need reasonably high isolation at least. You can calculate whether 40mm floating will be enough in the design, you don't need to build it first. If you build 40mm you cannot just add an extra 40mm. You'd need to change the whole spring support system then rebuild with 80mm. If a designer calculates it for you then they can provide estimated TL for both cases and you pick the one you want. The worst that can happen doing it this way is that you've paid for a design that you need to save up for before building/build 1 room at a time. The worst that can happen your way is the room doesn't isolate well and you need to rip it out and start again/pay twice as much fixing it.

Yes, all true and appreciated. But if I were to change my mind and go 80mm instead of 40mm, I simply remove one layer of pavers (easy) and slip twice as many isolators under the joists to hold the double weight. It's not "starting all over again" and it's not costing twice as much in time and money.

As for the floated floor being too heavy if the walls are built on top, that is the advice from the SE. The steel beams are beneath the existing floor slab. The floating floor's perimeter will be too far on the inside of it, apparently.

Thanks for trying to be helpful.

"But if I were to change my mind and go 80mm instead of 40mm, I simply remove one layer of pavers (easy) and slip twice as many isolators under the joists to hold the double weight." That doesn't make sense at all. You might want to check your math on how isolators work...

As for the floated floor being too heavy if the walls are built on top, that is the advice from the SE.

Either you didn't understand what he said, or he didn't understand what you were trying to explain!

This is very simple: You have a load limit for your floor. It can only support a certain maximum load. That is expressed as average weight/area. In your case, IIRC the SE told you that your live limit was something like 700 kg/m2. That means that you could draw a 1 square meter grid on your floor, place a 700 kg block of lead in the center of each of those grid squares, and that would load your floor to the limit. Assuming you have 100 m2 floor, the total load would be 700 x 100 = 70,000 kg.

Now, if your SE told you that there is better support around the perimeter of the floor, due to some type of joist under your slab, or just due to normal edge support, then you could MOVE some of those lead blocks around: take some away from the middle, and put them closer to the edge. Or cut some in half and move one half towards the edge while leaving the other half where it was. But you HAVE NOT CHANGED THE TOTAL LOAD!!! You seem unable to grasp this. The TOTAL load is still the same. You STILL have 70,000 kg of mass on that floor: all that you changed, is that you distributed it differently, but the TOTAL has not changed. If does not matter if you distribute it evenly, or concentrate it all at the edges, as long as you do not exceed the total, or the average load. This is what it means when the SE states that the live load capacity of your floor is 700 kg/m2. If he is also saying that there is better underlying support around the edges then he should have told you how much, and where. For example, he should have specified that you can increase the load within 1 m of the perimeter to 1400 kg/m2 if you want to (or whatever the number was), but then you would have to DECREASE the load on the rest of the floor (away from the perimeter) by the SAME amount. Such that the TOTAL load remains at 70,000 kg or less.

This is not hard to understand.

The SE MUST have given you all of this information in the report he gave you, and signed. It's just a matter of looking it up, to find out what the MAXIMUM load is around the perimeter, and how far out that can be spread, away from the perimeter. It must be in his report. If not, then the report is incomplete, so you should ask him to supply that info.

So. now that we have established how this all works in real life, consider how this loading issue would work for two situations: 1) a floating floor alone with separately floated walls, and 2) the correct way of doing it: floating the floor and slab together, as a single unit. The difference is NOTHING AT ALL! There is no difference. Zero. Zilch It is exactly the same. If you think there is a difference, then you don't yet understand how structures are floated.

If your walls weigh (for example) 50,000 kg, and your floor weighs (for example) 20,000 kg, then the total weight is still 70,000 kg. Period. End of story. As long as you distribute that load evenly across the floor, you are NOT overloading it. And if your SE prefers that you place most of the load near the perimeter, and less in the middle, then what the hell is the problem with doing that? Why on earth do you not understand that it is dead easy to distribute the load that way too, even with a floated room? There is NO difference at all from the structural point of view. If the SE wants a higher load at the edges and less in the middle, then just do it that way!!!! Spread the load unevenly on the isolation mounts (not rubber pads, though... ), instead of spreading it evenly! It's a no-brainer, and not hard to understand at all. Move the load to the perimeter, away from the center. Piece of cake!

And while it makes no difference STRUCTURALLY; it makes a HUGE difference ACOUSTICALLY. You can achieve a MUCH higher load on each isolation mount like this, thus LOWERING your resonant frequency and greatly IMPROVING the low frequency isolation, which is what you keep on saying you want to do. Yet you keep on rejecting the best, lowest cost, simplest, fastest way to do it!!!!!!! It also improves isolation in many other ways, but since you haven't yet grasped this simple basis, I don't see any point in going into the more advanced aspects of how it would help you.

Bottom line: do it your way, with separately floated walls and floor (that would be extremely hard to seal together, apart from anything else, since they would have to move independently...) and throw away major mountains of low frequency isolation. Or do it the right way, and get all of that back again, for lower cost, greater stability, greater simplicity, faster build, etc.

I can't put it in simpler words than that.

The floating floor's perimeter will be too far on the inside of it

Huh? Say what? The edges of the floor would be in the exact same location as the walls! That comment makes no sense at all. No logic. Since the FLOOR would support the WALLS, then the edges of the FLOOR in the "built correctly" scenario would be in exactly the same place as the WALLS alone would have been in the "build it randomly and hope for the best" scenario. This is not hard to understand or visualize.

There must be some other issue here that you are not mentioning: There is no logical, structural, or acoustic reason for you to go down the path you have stubbornly set your heart on, without actually understand the details at all, and DESPITE being told that it is wrong by three studio designers AND the engineers that make the mounts you would need. Sorry, I don't get it. This whole thing makes no sense at all. Zero. None. There's a "hidden agenda" here that you are not talking about, and I have no idea what it is. No sane person can be this stubborn in light of multiple experts telling you not to do it your way, unless there's something else at play....

- Stuart -

OK. I'll go back to the SE and find out why he gave the impression he did. He was paid, but did not provide a written report and conveyed all information through someone acting on my behalf as my Project Manager....

The advice, I thought, was that the total weight of the walls and ceiling on top of the floor would be too much, but that floating them separately would be OK. However, I'm not sure whether the SE was considering load distribution and various ways to redistribute the load so that the perimeter and floor can share the load in order to allow the desired respective masses.

So perhaps you may be correct in that either myself or the SE are misunderstanding something, and I'll report back when I get more info. As for the idea that John is in agreement with yourself regarding floating walls, choice of isolators, cavity resonances, density consistency across all surfaces etc, I think you'll find he expresses very different views. You have inferred in the past that John's experience outranks your own, and that anything an SE suggests is not to be argued with. If I seem "intractable" it may be due to placing import on theses sources, even above your own, at your own behest. It is not out of disrespect for your own generous advice, nor out of being unappreciative, believe me!

It would be great if the SE will reconsider the load distributions in favour of enabling walls/ceiling atop a heavy floating floor, but I would be surprised, and also pissed off if he failed to provide creative distribution solutions as I explicitly asked for them!

Let me try him again....

He was paid, but did not provide a written report and conveyed all information through someone acting on my behalf as my Project Manager....

Ummmm... don't look now, but it sounds very much like you were scammed! You hired a professional engineer to answer specific engineering questions, and he gave you nothing in hard copy? No report? No e-mails? Not even a text message? It sounds like you were had! I would suggest that you ask for either delivery of the full written report, signed by him, or your money back.

The thing is, he told you a lot of things, including what the floor loading can supposedly be (I think it was 700 kg/m2?), but you have nothing to support that! So if you did build your studio, taking care to only load it to 600 kg/m2 to be safe, but the sub-floor failed anyway, then YOU would be liable for the damage (and any injuries, / deaths). If you have nothing in writing to back up your loading, then it is legally your fault, no matter what he told you. Your word against his. Not likely to stand up in court! They would throw the book at you, even though you acted in good faith, based on what he told you. You really do need to get this in writing, urgently. I've never heard of a structural engineer being hired to do a structural analysis, but then not present a signed, written report. This is very strange. That would be akin to hiring an architect to do the plans for your house, but then he never presents any plans, and only describing verbally what the house would look like...

The advice, I thought, was that the total weight of the walls and ceiling on top of the floor would be too much, but that floating them separately would be OK.

It might well be that this really is what he told you, but once again, if something goes wrong it's your word against his, if there is nothing in writing. He can claim he told you nothing of the sort, and even claim that he told you NOT to do ANYTHING.. and you would have no way of proving him wrong.

But either way, that's clearly not even logical. The weight of the "floor-plus-walls" is exactly the same as the floor and the walls taken separately. If I have a coin that weighs 5 grams and a matchbox that weighs 1 gram, then the total weight of both together is 6 grams, regardless of if I put the coin in the box, or on the box, or under the box, or next to the box without touching it. 5 + 1 is always 6. The same with your room: the total weight of both together is the same as the weights taken separately.

I'm not sure whether the SE was considering load distribution and various ways to redistribute the load so that the perimeter and floor can share the load in order to allow the desired respective masses.

Apparently not. He doesn't seem to have much idea of how floating systems work, nor how the load distribution can be changed as needed. For example, if there happened to be one huge steel girder running under the middle of the floor, then it would be smart to increase the loading right above that girder, and reduce it in the areas where there is no underlying support. And if there happened to be two girders, it would make sense to put most of the weight over those, divided evenly between them. That can be done. In the design of the floor system, it is possible to distribute the load any way you want it (within reason! There are limits, depending on several factors) .

You have inferred in the past that John's experience outranks your own,

Absolutely. No question about that. Which is why I always suggest that anyone who wants to pay someone else to design their studio, should turn to John Sayers as their very first option. He's the best there is, and a large chunk of what I know about acoustics, I learned from studying his designs, and analyzing how they work.

and that anything an SE suggests is not to be argued with.

If it is in writing, and signed, then yes, I'd agree with that for sure! But if it was just heard secondhand through an intermediary, and there's no evidence at all that that's what he actually said, then I'd pass on trusting that... especially when it flies in the face of common sense, and basic structural principles.

If I seem "intractable" it may be due to placing import on theses sources, even above your own, at your own behest.

Again, if the source didn't provide a written report that you can refer to, then it's a moot point, and I would not trust that source! Maybe you misunderstood him, or maybe he actually said every word you think he did, but if it isn't in writing then it just "isn't". There's no "there" there. Even if you remember it perfectly, word for word, but it's not in writing, I would not trust it at all. That's what a structural engineer is supposed to do: check, analyze, advise, and document. That's what you hired him for! Not to say a few words (through a third party!), but to put those same words down on paper, next to his signature, so you can take them to your relevant authorities when the time comes, and get the permits you will need to get. Without the signed report from a certified SE, you likely won't be able to get your permits.

As my son-in-law (who is a lawyer) likes to say: If it ain't in writing, it ain't there.

It would be great if the SE will reconsider the load distributions in favour of enabling walls/ceiling atop a heavy floating floor, but I would be surprised, and also pissed off if he failed to provide creative distribution solutions as I explicitly asked for them!

It might be that he just doesn't understand how studio floor isolation works! He might be assuming that the load can only every be distributed evenly, homogeneously, across the entire floor. He SHOULD know better, or at least have taken the time to check with the manufacturers of those systems to see what the capabilities are....

Let me try him again....

Insist on that written report! You paid for it, so you are entitled to it. If he refuses or baulks, then you have a big problem... nothing he said has any meaning at all, and it can't be trusted. Hopefully, it was merely an oversight, and he just forgot to give you the report! It might not be very long: perhaps just a handful of pages, with a cover letter. So don't expect that it will be reams and reams. But there has to be something in writing that backs up what he told you verbally, with all the numbers, some diagrams, and specific recommendations.

Fingers crossed that it was just an honest mistake, and he had forgotten to mail it to you!


- Stuart -

Well, the months fly by don't they... Last thing I said I'd do was to get more info from the SE, and I did ask him once again, but he keeps re sending a copy of an email where he states the structure will hold 650 kg's per m2 and that this should allow for for 500 kg per m2 for the Live Load (but that we may be able to "borrow" from the LL and redistribute to the ADL...).

So no new info regarding the lineal load limits for the walls, or any possible ways to redistribute the load toward the edges of the space where there is structural support. I was about to engage another SE when the adjoining 2 offices came up for sale. I calculated it would be more affordable in the end to buy these offices than it would to isolate against them. Months later, after much negotiation and persuasion ( i had to find a small syndicate to invest in these offices along with myself), it looks likely this deal will go through. This puts me in control of who gets to move into these adjoining offices, and hopefully we can find tenants that are tolerant of a little sound here and there. If not, then we lose money on the deal as we have to pay annual Outgoings, which are quite expensive.

The reason I was able to find willing co purchasers is that the entire building has been in talks with a developer who is offering pay each owner triple what their lots are worth, if everyone agrees to sell. This complicates things further for my part - do I risk borrowing funds (now that I am broke again) in order to build the studio properly? Or do I do it less properly (i.e., cheaply) given that we all may triple our investment in 5 years (maturation of tenancies)? If my business is doing well, I don't have to agree to sell, and because 100% of owners must agree (law), I can remain if I wish....

Anyway, it now seems I will be able to get away with less isolation than first thought because my neighbours on the same level will be manageable. The neighbours beneath me don't worry me so much now that we've done more tests from my my test booth with a professional acoustician who measured 110dB pink noise from the booth and could not detect any audible frequency from downstairs over the 40 dB ambient noise (HVAC). We did a kick and snare drum test also and audibility was so slight as to be negligible. This latest series of tests surprised me as previous tests were more audible, however, the booth is now raised 120 mm off the ground (previously only 80mm) and the gap has been filled with tontine (previously none). Perhaps these 2 things have made the difference?

The acoustician seems confident that a similar construction for a larger drum room (10 times larger) will perform equally as well, so If I have a concrete or CFC suspended floor for the drum room only, as well as 2 amp booths, then the rest of the area (as well as the control room) can be built upon a "damped deck" of sorts given that the loudest things (drums and amps) with be isolated in their respective booths.

Now given that I have to do this cheaply, I no longer have a budget for professional design (sorry Stuart!). Is it OK if I re engage with this forum as a DIYer and seek advice and comments about the ideas I'm about to try to put into practice? I'd like to start with a few different layout designs for your feedback, but only if anyone out there has time to check them out. I feel like I've used up my quota of advice already around here ...

Welcome back!

Interesting situation you're in there.
I think there's some more advice here for you .
DIY takes quite a lot of effort to design on your part though.
The format tends to be this:
I'm thinking of using <Insert building material/acoustic device here> because my research suggests that it might solve a prob I have. What are your thoughts?

If people aren't too busy you so should get some help in a day or so.

If you want to go DIY then first thing you should do is, start a new thread in the design section and put your initial plans and drawings / models.
Now buy Rod Gervais' book, Home Recording Studio: Build it like the pros.
Now read this cover to cover (seriously it's that important) it might take you a week or so to get through it.
As you read you will probably want to make some changes to your design, so add to your design thread and read the comments.

Dan