new studio search for a concrete advice

Hi all, I am in the beginning of building my first recording studio and although I ‘ve spend lots of hours reading posts in this forum and reading books about the behaviour of sound there are some building details I cannot get a clear answer. My goal at this point is to gather as much information as I can get about treating the walls, ceiling and floors for best sound proofing results. The studio would be in the basement area of a three-storey building in the beautiful island of Crete. Everything in the building (and the basement of course) is made from well-build thick concrete including walls, ceiling and floors. My prime concern in this project is sound proofing the studio from inside and outside as it is situated in a residential area thus noise is a big problem. I am also concerned of disturbing the people from upstairs. It would be a general purpose studio, thus loud bands with heavy drums and bass amps would be part of the business. So, leaving air-con / ventilation aside for the moment, my questions are: a) Would a single partition wall (with air gap / insulation / double gypsum panels etc) like many I’ve seen posted around (eg.acoustics101) would be efficient to cover the inside concrete walls or do I need more insulation on the side of the concrete wall (eg. designs in Artifact Rec posts) or else? b) Would a similar STC construction (one layer of insulation / gypsum board and all usual precautions taken) be efficient for the ceiling? c) Would a double leaf partition (separate double stud etc) again like one featuring in the acoustics101 (STC 67) be efficient to divide the inner spaces (Control Room / Live Room) of the studio, taking into account that windows and doors meets the same STC? d) Would a floating floor (wooden frame on neoprene / MDF etc) gives me a significant isolation from sounds travel to the upper floors? If yes, would it be fine if first build the walls (floating), then floors & ceiling separately? e) The basement has one completely open space window attached to the outside world that I would like to cover it completely as this is part of the control room area. What’s the best way to do that for maximum sound proofing? This Control Room wall is the only one in the studio exposed to the outside. How should I treat it from the inside for max sound proof? Any help would very much be appreciated. dB

Following my previous post, I thought to give some more information (and questions) about my project and hopefully to get some responses. I am in the process of building the studio in a basement – all walls, ceiling and floor made of concrete. The studio should have a Control room, Live room, a Vocal booth and a drum booth - total area of these spaces of 60 square meters. Main problem: sound travelling mainly to the upper floors. I've attached a drawing with my soundproofing ideas about the inner walls, ceiling and floor. From the information I collected from the forum I now think that a floating floor is necessary in order to avoid the vertical sound wave transmission to the upper floors. However, I don’t know if a floor like the one you can see in my drawing would be adequate. Does the insulation (mineral wool) have to fill all the space between the concrete floor and the plywood board in order to avoid ‘booming’? I also haven’t made my mind yet about the ceiling contraction. Is the one featuring in the drawing enough to stop any sound leakage to the upstairs floors? Do I need more mass on the concrete side of the wall instead of insulation? The concrete ceiling has a diameter of 15cm. I have tried to make some measurements with a hand-held SPL meter but I cannot be certain about the results as a large area of the basement (the entrance) is still completely open. The work sequence would be: Treating the concrete perimeter of the walls. Raise the inner walls to separate the rooms (Control, Live ect). Then do the ceiling and the floor. There are also some window openings I have to cover, one of which is attached to one of the Control room walls (Haven’t figure out yet if I use gypsum boards with insulation or some other construction material – these very large windows are exposed to the outside). Details about the materials can be found in the drawing. Notice that I am using some materials not found anywhere else in this forum. That’s because it is difficult to get some of the materials pointed out in this forum here in my island, therefore I am trying to find some alternatives - hopefully doing the work right.

This is the floor plan of the studio. Notice the drum booth. As you can see is isolated from the rest of the studio areas. I know this is not the best place to have it, but due to basement’s limited space and ‘strange’ shape, plus a major necessity for a drum booth, I prefer to build a drum booth – even with no visual connection but just a video connection with the rest of the areas – than not having it at all. Placing the drum booth near the other studio areas, it will take valuable space from either the Live or the Control room areas. Any comments welcome.

I don’t want to be impolite, but could someone of the moderators in this forum please explain me what I have done wrong in my posts to deserve not replies? Have I made stupid questions, not provided enough information or my post just ‘passed through unnoticed’? Wish I had Rod’s book, everyone says it's great, but last time I’ve ordered something from Amazon never arrived (I am living in a remote place in Greece and things moving very slowly here – if ever). Replies or not, so far I’ve already learned many valuable things from this forum and I think it’s a great place on the Internet for someone starting a recording studio. However, because this is my first time building a studio, with a limited budget, I wish I had some help from the forum 'cos I can't afford many costly mistakes. Probably some of my questions have already been answered in other posts, but personally I couldn’t get any concrete answers. Maybe because English is not my native language. Anyway.. Once again, I will really appreciate any of the help you can offer.

and one more drawing...

Hi there newtones, You don't "deserve" to be ignored. :-) The experts on this forum are busy, and sometimes threads fall through the cracks. I'm sure that's what has happened here. Be patient, and I'm sure some of the experts will respond. I'm not an expert, but I think I may be able to predict some of what the experts will say. ;-) First of all, I don't think you are going to need to float your floor, given that you have a concrete basement floor. There are a couple threads currently very active about this.... the consensus seems to be that it's too difficult and expensive to build a floating floor correctly, and unless you are willing to do the math and spend the money to do it right, it could actually make things worse. A concrete basement floor is itself very massive, and has the added benefit of being dampened by a piece of dirt that is thousands of miles thick. ;-) If you build it correctly (airtight, etc), you should have little or no flanking problems through a basement concrete floor. Instead of floating, you can build your framing up from the concrete floor, just use room-within-a-room construction (see the stickys if you can't get a copy of Rod's book) to make your studio rooms. Each room of your studio should have its own ceiling that is attached to the wall frames, so that you don't attach them to the concrete ceiling of the basement, which would provide a path for sound/vibrations to travel upstairs. As an aside, I can't really see any detail in the floor plan you've posted. Rules about image sizes are strict in this forum, so is there any chance you could link to a larger version of that file off-site, so that it doesn't mess up the forum page width? I can't really see much of anything in that version. Good luck, be patient, and keep asking good questions.....

thanks a lot for your quick response. I will try to be patient as you say and make a link for a bigger studio plan picture soon. cheers!

It looks to me like you're getting 'way more complicated than necessary - check out the threads in the REFERENCE section, then look through other long thread such as Sharward's, Aaron's, Guitardad's, and see how others are building. In the REFERENCE section under Drywall and Caulk there are comments about using different thickness of materials and why it isn't necessary, or even desirable. There's a new section there on why floated floors are usually NOT a good idea - this is even more so with limited headroom to begin with. Your concrete outer shell is one leaf of mass - all you need inside that is one MORE leaf of mass, something like 2 layers of 15mm drywall/gypsum is fine. Total air gap is measured from mass to mass, not to frames or insulation - up to 12" (300mm) you get a worthwhile help in low frequency isolation, beyond that only if you are building new and can make the outside shell large enough to not limit your inside space. A ceiling is just a wall that's horizontal, so the same physics apply - 2 layers of 15mm gyp on your resilient hangers with fluffy fiberglass insulation resting on the gyp is the way to go. If you're gonna be deafening in there, green glue costs about the same as a third layer of drywall but doesn't lower your headroom or add much weight. Please re-read the "stickies", and try another sketch - if you make it EXACTLY 700 pixels wide nobody will yell at you, and it lets you give more detail. JWL is right, we're usually leading a VERY full life - please don't think anyone is purposely ignoring you... Steve

After cheking the Floating Floor Sticky and taking into consideration that the studio would be in a concrete floor basement (plus I am not able neither anyone else I know in this town is able to make a really good floating floor with a resonance frequency below human hearing), I am posting a new wall / ceiling graph without the floating floor this time. My question now is, would that be ok first to raise the wall (concrete floor to existing concrete ceiling) (as all my previous graphs shows) and then make a separate ceiling for each of the rooms (Control / Live etc)? Would a construction like the following graph (or similar idea) is also valid? or none of them.. any help...

Hi Steve, Unfortunately I missed your reply so I've post another graph on the same dimensions. I will check the Drywall and Caulk section and try to keep things simple. I already had in mind that the air gap should be from one mass to another not counting insulation and studs - it was just a mistake in the graph. What you think about my last question? ' would that be ok first to raise the wall (concrete floor to existing concrete ceiling) (as all my previous graphs shows) and then make a separate ceiling for each of the rooms (Control / Live etc)? ' thanks dB

This http://www.johnlsayers.com/phpBB2/download.php?id=6586 Is what you want, and you're right - separate ceilings will help room-to-room isolation. (Ignore the upper floor, this one's wood. Same principle applies though... Steve

I understand now that this is a right way to do it. But do I defeat the 'room within a room' scenario if I make the walls from concrete floor to concrete ceiling (or at list just the metal frames) with some short of damping up & down - then build the new ceiling within the walls (like in any of my previous graph files)? Is this an option or is it completely wrong? and just stick with the design on the link you 've send me in which the top side of the walls meets the new ceiling? thanks dB

If your inner wall frames touch the floor, they get damped somewhat by the fact that the concrete has earth below it - if they touch the CEILING, then any sound that vibrates the inner wall will get transmitted into the concrete CEILING, and from there into the above room and the sidewalls, etc, with the definite probability that the sound will then re-radiate from upper walls - the end result will be more sound getting into ALL the rest of the house. The most effective way around this is to build your entire new room (except for floor contact) so it does NOT touch the rest of the building with any HARD contact. To keep the inner walls from moving, and depending on how close they are to your outer walls, you use some sort of resilient SWAY braces between inner and outer walls. In some cases (walls too far away) a similar, resilient coupling can be used to the existing concrete ceiling to keep the walls from swaying. Then, if there is enough headroom, NEW ceiling frames are put across the new walls and the ceiling gypsum hung from those new ceiling joists. This takes more headroom, but does NOT require resilient mounts for the ceiling to hang from. With lower headroom, you would use expanding anchor bolts into the concrete ceiling to support individual resilient mounts, then support metal hat channel from those, then stuff fiberglass insulation into the framework and screw your two layers of 15mm drywall to those channels. The second layer should be cut differently than the first, so each seam in the second layer is offset from that of the first layer by one channel, typically either 400 or 600mm. What you want to avoid is any HARD contact between either the ceiling, or the inner walls, with anything on the OUTER shell. Even a single bolt between these two areas is BAD. If you think you understand what I mean by the above, try a new sketch and post it - if not, I'll try to find time to draw one for you but it may take a while... Steve

Think I've got most of it. Definetely the part that the walls should not touch the concrete ceiling and use resilient SWAY braces for wall stability. The part about lower headroom (which is my case) I have to think about it seriously tomorrow. It's too late here in Greece, I have already spend more than 10 hours in my pc. thanks a lot for your help.

Do I get closer with this graph? -------------------------------------------------------------------------------- If I stick to the three layer gypsum wall - just to be on the safe side - would the three different gypsum layers be an option for a single leaf? or is it better to make it like two 15mm gypsum layers fasten togeher in a way to form one big mass and then a third of different thickness (eg. 9mm) to add even more mass but avoid resonance? If going with this last option (if valid), how do I attach the third layer (9mm) without forming one single mass with the other two 15mm layers? Is the answer here?: 'Fastening a second layer when there is NOT RC under, the most practical way is to mount the first layer using half as many screws as normal, same with any following layers EXCEPT the outer layer – this one should have full fastening schedule used, and with long enough screws to penetrate all layers and solidly fasten to the studs. ' or this applies only for wooden frames?

Why would not not simply build a new room that is completely disconnected from the existing one? That's what I'm doing: new wall and ceiling framing has no connection at all with the existing structure. --Keith :mrgreen:

Keith, if the ceiling is already low the least reduction would be direct connection of resilient mounts into existing concrete ceiling, channel supported by the mounts, double 15mm drywall. If ceiling height is already low, it's doubtful there would be enough height to use large enough NEW ceiling joists to support the new inner ceiling correctly. As to the multiple thickness of drywall, if you read through the sticky's you'll see that neither Rod nor I recommend that - it's a pain in the butt to stack 2, much less 3, different thicknesses of drywall - it's confusing and leads to mistakes as to which thickness you're using next, and the main reason - the "coincidence frequency" this is supposed to "fix", is typically around 2-3 kHz - it's much harder to stop BASS than this frequency, and if you have enough mass to handle the bass you won't even NOTICE a slight dip in upper midrange Transmission Loss. Other than that, sounds like you're getting a pretty good grasp... Steve

Ceiling height is a problem here. I wish I was able to build a completely separate room within. Maximum height in the basement is 2.80m only. The way I see it, please correct me if I am wrong, it's enough to build a new metal frame around it (walls & ceiling but not floating the floor) and leave something like 50mm air gap on top and sides to act as a 'spring'. Counting the metal studs / insulation plus two 15mm gyspum boards I end up with something like 2.65m of available height. Probably I will also need some short of acoustic room treatment that would also take some height away, but my main consideration at the moment is sound proofing. If this goes wrong I would have a serious problem in the future. Going back to the layers questions, if I go with the 15mm gypsum layers plan, am I correct to assume that the two gypsum layers should form one mass? and does the outer 15mm layer has to be solidly fasten to the metal studs also? Would all the above be enough for sound proofing the drum booth or do I have to take any further precautions just for that room (eg. leave a larger air gap on top & sides)? A product similar to Sheetblok between the gyspum layers will it help further for sound proofing the drum booth or adding mass is the proper way to go? I know, to many questions...Thanks for everything so far. Dimitri

A 50mm air gap won't help you much on isolation, but if it's all you can get then that's what you do - for the ceiling, I would first find out what weight each (of whatever resilient isolators are available to you) can support in your particular ceiling (a local engineer's input would be very valuable here) - then I would space those resilient mounts across the ceiling, close enough together so they can support THREE layers of 15mm gypsum - this, because without wider air gap the MASS is your only friend. Walls - since you will only be putting wallboard on ONE side of the steel studs, you want STRUCTURAL grade studs (they are heavier gauge than the NON load-bearing ones) - otherwise, the studs may twist (or worse) with no wallboard on their second side. (Yes, BOTH layers of gypsum wallboard need to be snug against each other on the SAME side of the stud frame) - since there will be no wallboard on the second side of your wall frame, you can use full schedule fasteners (screws every 8", or 200mm) for BOTH layers - just be sure to make marks so you know where your screws are in the first layer, so you can OFFSET them for the second layer. Be sure the screws you use are for METAL - they have a finer thread and are self-drilling. You will need two or three different lengths to ensure that you have enough penetration to hold each layer of wallboard - each screw should be at least 1/2" longer than the layers of wallboard it has to penetrate, and 3/4" longer will be even better. For walls, leaving a wider air gap means you can do with only two layers of 15mm wallboard - of course, in walls AND ceiling you want fiberglass insulation - not sure what's available to you there, but in this country there is a "standard" fluffy type of fiberglass insulation, density about 12-14 kH/m^3, that works nearly as well as the 40-48 kG stuff we use for acoustic treatment. If possible, for the drum room ceiling, I would use wider channels (or extend the isolators) to increase your air gap - this will help low frequency isolation. I would still use 3 layers of 15mm if your engineer knows that your existing concrete ceilings will support that much weight safely. This engineer part is REALLY important unless you don't mind dying for your art :cry: To re-cap - from outside to inside you want a space, then steel frame, then insulation between framing pieces (with some sort of strapping material horizontally across the studs to keep the insulation in place - either lightweight lath screwed to studs, or heavy twine wrapped around screws in the studs, or?) then 2 layers of gypsum wallboard (3 for drum room) and you're DONE. Anything else is just for looks or acoustic treatment. For more on this, read the stickies on drywall/caulking. Bottom line - between noise and the rest of the world, you want only TWO masses, separated by air/insulation. More mass, better isolation. Wider air/insulation gap, better isolation. Insulation density for best low frequency isolation should be 40 kG (2.5 PSF) or LESS. And don't forget to find an engineer to ask about your ceiling strength... Steve

Great help Steve! To re-cap from my part: In the DRUM booth I have the luxury to leave 10cm of air gap for the walls but not for the ceiling. So, if I've got it correct, two 15mm gypsum layers would be fine for the walls here, although for the ceiling I would still need three layers of the same thickness - if of course the engineer allows it. For the REST of the studio, ceiling same as above (three 15mm layers if the engineer...) and two 15mm layers for the walls (not 100% sure here if you are saying I can still get away with just two layers, taking into consideration my 50mm air-gap wall limit here). Of course I will use insulation for every new leaf. I can find here mineral wool of 40kg / 50mm. Now...a last BIG IF: If the building can't handle the three 15mm of gypsum layers, is there another workable solution without compromising sound proofing? best, Dimitri

newtones wrote:

Ceiling height is a problem here. I wish I was able to build a completely separate room within. Maximum height in the basement is 2.80m only.

OK... Not having a scale drawing of your side view is what threw me.

"If the building can't handle the three 15mm of gypsum layers, is there another workable solution without compromising sound proofing? " Only thing I know of would be using either Green Glue between two layers, or someone on your side of the ocean had another similar CLD coating, don't remember now who it was. Keith - me too. I've developed an "in head" alarm whenever I see a metric dimension less than 3 meters :wink:

Another graph with some of the edits. I'll check an engineer and let you know guys how each going. Best Dimitri

Thanks... That's helpful. 8) --Keith :mrgreen:

Do you guys have any ideas about the studio floor? At the moment is bare concrete. As I have dumped the floating floor idea, I am searching for a new non-floating floor solution based on the facts that I want to keep all studio cables hide and not compromising studio acoustics. Second part of the question probably goes to the Acoustic forum, but what about the first part? Is there a floor solution to allow me pass the cables conduits underneath and be a non-floating one (so to avoid any possible floor resonances)? I am completely ignorant here, but would a simple raised wood floor completely filled with sand or other flexible material be a solution? I was also thinking to run cables conduits following the perimeter of floor but not sure if this is a good idea, thinking that this would possibly compromise audio quality, increase audio latency and waste of money. Dimitri