Floating Floor Question

Hi, I'm going to build my studio, which is going to be a room-in-a-room design. Both walls, outer and inner, are going to be brick walls. The question is, since the inner brick walls should be connected to the foundation structure below, is it neccesary to float the floor? Ari

If you want a room within a room - yes - you will need to float a separate floor, unless you float a separate slab on the existing slab and then build your inner brick wall on the floated slab. Why the double brick in the first place?? cheers john

Ok, so I have to make the room float entirely. Well, I'm not an expert in building construction, so the question is, how to float the floor then build the inner brick wall? Brick walls are far heavier than drywall system, and usually (what I know) should connected to the ground. I assume neoprene pads on timber floor won't handle brick walls on top of them, is it right? Or should I build floating concrete floor? If yes, how? Sorry for too many question.. Hope you can help me out. Thanks John, and thank you to all people who participated in the list. Ari

Ari - Joe Egan's studio has pics of floating a concrete floor at Studios Under Consrtruction site. http://johnlsayers.com/Studio/index.htm cheers john

Here's some other info on floating floors - http://www.kineticsnoise.com/architectu ... nstall.pdf these guys do everything from studio stuff to isolators for multi-ton punch presses and other heavy industrial isolation. If you're going to put a brick wall over the floated slab, you should make the slab at least 3-4" thick and add extra support http://www.kineticsnoise.com/architectural/kip.html wherever the brick walls go - and you're right, if this is going on a timber floor then forget it. And, to repeat John's question, why do you want inner brick walls? are bricks cheaper than wallboard where you live? Steve

Yes, Steve. Bricks ARE far cheaper here than wallboards. FYI, I live in Indonesia. And the price of wood had dramaticly increased over the past 5 years, but bricks are still cheap. Labours are cheap also here. The cost of 1 square meter stud wall is approximately 2-3 times the cost of a brick wall. Ok, I try to implement the floating floor design, but if I can't do it, do you think it's neccesary to float the floor only, so the floor structure is floated but not directly connected to the inner wall? Does it have any impact on soundproofing, since the vibration of the floor would not translated very easily to the walls? Ari

Ari, did you check out the kinetics link I posted? They have some very helpful literature, whether you use their products or someone else's similar ones. If concrete and masonry are cheaper there, I would check out the Kinetics information on concrete floating floors, download their installation PDF's just for the pictures on how it's done - Then, I would pour a 75-100mm thick floating slab and build the INNER brick walls on TOP of the slab, so that the entire inner room is floated. You would need extra pads under the slab around the edges, so that the slab would support the weight of the wall. You would also need to use steel rebar and mesh in the slab to keep it from cracking. The installation directions on the Kinetc site are almost a complete how-to manual on floating concrete floors. Check it out, download it, read and learn... If you haven't already downloaded the information, do yourself a favor and check out the links I already posted... Steve

Ok. I already download and read the information. Thanks Steve. I consult my builder here. FYI he has never built any recording facility before, just standard buildings. I explained to him about the springs, floating floor, and everything. Since specialized spring isolators like the Kinetics are rare here, (and if there is any, it would be imported gear, which would be very expensive) he suggested that the slab would be surrounded by loose sand. He said that loose sand has flexibility that might reduce vibration. Besides, it's cheap also. I'm not sure that it would be good advice, so I'm asking you all. Here's a rough drawing of what he suggested. As you can see, the inner brick wall is supported by a concrete slab, which is surrounded by loose sand (as a replacement of springs he said). Ok, any thoughts? Ari

Oops, the picture is not clear enough I think. This is better, you can see the loose sand surrounding the slab. (I make it darker in the picture) So the inner wall would be brick wall, but the floor is wood. Still thinking of better option to float the floor plus wall. I don't know if his suggestion will work. Any better ideas? Ari

Ari, what is the material directly UNDER the neoprene pads? Is this concrete, or wood? Also, I'm used to a concrete "slab" being a large, horizontal pour of concrete. Is what you're calling a "slab" under the inner wall, really a concrete "footing" resting on sand, with bricks on top? If so, I hope you can get some resilient "sway braces" like the ones on the Kinetics site, or your inner walls won't be very safe as near as I can tell... Steve

Are you sure you guys aren't overbuilding?? Why do you need to float a separate floor?? have you got trains passing under or near you?? - are you next to a freeway?? in Indonesia?? cheers john

Now that you mention it, Ari, you never did answer John's question and I didn't catch the fact either - Have you actually measured the Sound Pressure Levels outside the location you intend to build your studio ? If you only need 30 dB of isolation in order to get the inside as quiet as you want it, why spend the time and money to exceed what is required? Please don't skip over these questions, you will only be causing yourself extra work and cost... Steve

Well, the situation is just opposite. It's not the sound from the outside that I'm worry about. It's the inside noise, such as drums and bass, (especially that low frequency rumbles) that I'm afraid going to leak out to my neighbour. The space that would be my studio is sharing the same wall with the neighbour. I live in a quiet residential area, and most people live here are elder people. Since I really have no experience, and money for experiment, and it's cheap here for a brick wall construction, (not concrete walls anyway) that's why I'm thinking of brick walls and that stuff. Ari P.S. FYI, the total estimated cost for all the construction work, without any acoustic treatment, is approximately $600. I apologize for any question that might seems like a very beginner question, cause, really, I'm a beginner here. And there are not enough source of information here for building a recording studio. In fact, most studio here aren't provide good isolation, and the builder have no knowledge in studio building, except that they are using 'acoustic product' which are acoustic tiles, acoustic wallpapers, and they said they have experience in studio building. And when I mentioned them that air gap between walls would provide isolation, you know what, they laughed at me!

Under the neoprene pads are the existing cement floor. And the most left and right walls are the existing space's walls. And what I mean by slab is actually concrete footing. Sorry. So if I follow that plan, I will dig the existing floor down to the soil for concrete footing, but instead of filling it again with soil and compacted it, I fill it with loose sand. And if sway braces are needed, I'm going to use them. Am I overbuilding it? Ari

"they laughed at me!" - Ari, we have a saying here, "He who laughs last, laughs BEST"... Meaning, let them laugh - when they see how well it works, YOU'll be the one laughing... Now we're clear on WHY you want good soundproofing, I have to agree - a lot of older people I've met have better (or at least more sensitive) hearing than I do, and are usually the first to complain about noise. "the total estimated cost for all the construction work, without any acoustic treatment, is approximately $600." - This means very little to me, because I have no idea what labor or materials cost in Indonesia - I was just recently amazed that some materials cost over 5 TIMES as much in England as they do here, so now it wouldn't surprise me to find that bricks and labor cost anywhere from 1/8 to 10 TIMES what they do where I live. If you can do what needs to be done and stay within your budget, that's the main thing. I've never seen double masonry walls used, so I have no experience as to how well they work - it does make me nervous to think of putting that much weight on a bed of sand, even with the use of sway braces for the tops of the walls, especially since I'm not sure how effective the sand would be for isolation. I've seen gravel after it was compacted with a vibrator, and when you walk on it you feel like you're walking on concrete. There is no "give" whatever. I can't help but think that it would be the same with sand, since sand is really just "little tiny gravel". After thinking about it (I'm typing this part about 20 minutes later than the preceding part) here's my conclusions - I don't think it's a good idea at all to bed walls in sand - all I can see happening is fallen walls. If the existing floor is already a concrete slab and you're going to have to cut rhrough it, then you should do that with a concrete saw about 4" inside the outer (existing) wall, and COMPLETELY SEVER the slab all around the perimeter. Then, cut out the part of the slab where the new inner walls will go, dig down far enough for a good footing, then using a masonry drill you would drill holes sideways into the center of the inner slab and insert steel Re-Bar (reinforcing bar, used to strengthen concrete, I hope this is common in your area) - the idea here is that you want to "key" the inner slab into the new footing you're going to pour for the new inner brick walls. Once the rebar is inserted in the holes drilled into the inner slab, you would pour a new footing for the new inner wall, being careful to NEVER BRIDGE the air gap between inner and outer footings or walls. Placing boards and plastic sheeting over the old part will help, but you need to carefully inspect after forms are out to make sure there is NO HARD CONTACT between inner and outer footings or walls. If you can afford it, the old wall should be cleaned and "rendered" - you put about a 1/2" coat of mortar over the bricks, it improves isolation by several dB. If you're planning to insulate the gap between walls (and you should, it will improve isolation by several dB), you should then install "impaling clips" (these are the little "spikes" you mount on a wall, then "impale" the semi-rigid insulation on the spikes - this insulation can be either mineral wool or semi-rigid fiberglas, (or there may be other types available in your area, you need to let us know on this) I'm not sure what materials are available or their cost, but you need to match this wall/floor construction with equally good ceiling construction or there is no point in doing ANY of it. Sound is like water, only without the disadvantage of GRAVITY - in other words, ANY weak place will seriously damage the isolation. My point here is, what materials do you have/can afford that can be used for ceiling construction? I need to know about framing (wood or steel) roof support (if it will be a suspended ceiling) and what type of cladding (gypsum wallboard, cement board, particle board, anything with good mass) If you do the floor and new walls as I suggested, you will get good isolation in those areas - if you can do the ceiling as well, it should be a very quiet construction. The overall goal is to make a complete inner room whose walls/ceiling/floor have NO HARD CONTACT with ANY of the outer structure, and with as wide a gap (air) between the two shells as possible. If you can't continue that plan for ceiling construction, we need to re-think what you CAN do, and what would work the best. Your comment about a budget of 600 dollars needs to be clarified - is this in US dollars? I get an exchange rate of 8550 Rupiahs per US dollar, which would mean a budget of 5,130,000 Rupiahs. Since I'm not familiar with your economy, I don't know whether that's a lot of money or just a "wheelbarrow full of nothing" - What is the typical labor cost per hour there, in rupiahs? Are you planning to do the labor yourself, or hire others? I'm trying to get a feel for costs here, so anything you can tell me will help figure out whether this is a do-able project. "I apologize for any question that might seems like a very beginner question, cause, really, I'm a beginner here." - Ari, please don't EVER apologise for curiosity - NOBODY ever learns ANYTHING if they are not curious - if I have to be around a NON-curious person for very long, my thoughts turn to either ESCAPE, or to VIOLENCE... We will keep at this until your questions are answered, your building is finished, and your neighbors are still asleep in their hammocks... Steve

Just a thought, Looks as a nice construction. Why not building the inner walls on the floating floor? Make the floating floor in concrete as well. With the right material (Kinetics thing that Steve often menten, E.A.R. foam, CDM materials or SYLOMER) this can perfectly be done. Weight is no problem. I do not think it becomes more expensive (in Western terms). Eric. PS: I once worked for ca 1.5 year in Indonesia (Bandung in 1976)

"I do not think it becomes more expensive (in Western terms). " - Exactly my concern, Eric - Ari posted early on in this thread that a floated concrete floor was too expensive - now I'm trying to get him to clue me in as to what is expensive and what is cheap in Indonesia - it seems to me that having the existing floor slab-sawn to isolate from outer walls would be about as costly as doing a real floated concrete floor, but then I'm still reeling from the discovery that London charges over 5 TIMES as much for gypsum wallboard as I pay for it here, so, as the wife said to her drunk husband, "What a WINO..." (What do I know?) Hopefully, with enough input from Ari, we can get him set up with all the isolation his old and crotchety neighbors need... Steve

I must say I find it interesting that timber is more expensive than brick in Indonesia. Isn't timber one of your biggest exports?? cheers john

Maybe that's the problem John - they exported it all... Seriously, lumber seems to be going up here as well, gotta be at least partly because we (not me, I know better) have been selling all the GOOD logs to the Japanese, they go out of the ports here by the million board feet. Pretty soon, all you'll be able to buy are fiberglas or steel "2x4's"... Here's a list of Indonesia's exports, BTW - oil and gas, electrical appliances, plywood, textiles, rubber from this site http://www.odci.gov/cia/publications/fa ... os/id.html Now we know everything about Indonesia except which part Ari's from, and how expensive materials really are... Steve

Thanks for the answers, everyone. You guys even checked the list of Indonesia's exports. Wow! Steve, about the answers you gave me about the re-bar, inner and outer footing etc, is it something like this? (See picture below) I think the inner footing is still having hard contact with the outer footing through the cement floor. Is it okay? Or did I misintepret your explanation? As for ceiling construction, the inner ceiling would be built over the inner wall, so no contact with the existing structure, it would be gypsum board on a frame, with rockwool insulation. About budget, yes, US$600. Actually for Indonesians nowadays, it's quite expensive, since Indonesia suffers from economy crisis. Rupiah lost its value from Rp.2500/US$ to Rp.8500/US$. At the peak of the crisis few years ago, it even reach Rp.15000/US$. I don't really know about economy, but maybe because the timber price has to follow the current world market price, because they are export goods, and bricks are made for local market, so the price pretty much unchanged. A brick is Rp.200, the price is the same now and ten years ago. 18mm plywood soared from Rp.30000/item to Rp.120000/item. What confuses me is that the price of gypsum board has never really go up, the 12mm gypsum board costs Rp. 30000/item. The price of concrete and timber had extremely soared, but the brick isn't. So I hope that my studio would be more bricks than woods or concrete. :) Eric, can you give details on building inner wall on a floated slab, maybe in drawings? Sorry, lack of construction skill. :) Ari P.S. Eric, I live in Bandung! Where did you work? I'm not even born at that time.

"I think the inner footing is still having hard contact with the outer footing through the cement floor. Is it okay? Or did I misintepret your explanation?" - You're not too far off what I was referring to Ari - only you would need to cut completely through the existing slab just inside the outer wall , then again about 400 mm inside, then dig out the concrete between those two cuts, drill the horizontal holes into the inner, remaining slab, and finally pour a new footing around the added re-bar. Doing this, you would need to insert something soft, like sound board or possibly foam insulation board, against the outer, remaining part of the floor slab so that you don't bridge the inner remaining slab to the outer. If your existing slab is thick, for example 200mm or more, then depending on how expensive it is in your area to have concrete slabs cut (they do this with a diamond grit blade and a special, water-cooled saw - it's pretty costly here in the US) - you might be better off just doing a 75-100 mm floated slab and then building your brick walls on top of that. Here is Kinetics version of floated concrete floor using their rolls of pads separated by soft fiberglas - I'm linking to it mainly for illustration purposes. Note that they show a perimeter isolation board - this can be just soft "sound board", such as Homosote or Celotex, the main thing is that the floated slab NOT touch the wall (in your case, the existing wall) - please check out ALL the material they show on floated floors, so you can get an idea of what's involved. http://www.kineticsnoise.com/architectu ... nstall.pdf In order to build a new brick wall on top of a floated slab, you would need to increase the number of pads under the portion of the slab where the wall will go. The floated slab itself should have extra re-inforcing steel around its perimeter where the brick wall will sit. Depending on the cost to cut through the existing slab floor and its thickness, it may be cheaper to just add a floated slab. If cutting through the existing slab in just one place would be cheaper, and if the slab is thick enough NOT to need an additional footing under it where the brick wall would go, you may be able to cut along the existing wall, clear through the concrete floor, then fill that cut with caulking, and build your new inner brick wall just inside the caulked floor cut-through. That method wouldn't give quite as good isolation as a true floated floor, but would be pretty good provided the slab is COMPLETELY severed by the perimeter cut, and you don't accidentally bridge the cut when building the inner wall. If none of this made sense, post back and I'll draw a picture or two... Steve

Today I just inspecting the space with the builder, and here's what I found, the floor is just a cement floor, maybe only 5cm thick. Below that is just soil. Here's the picture. If this is the condition, what should I do? Ari

Ari, in that case here is what I would do - I've edited your drawing (on one side only, you would do this all around the perimeter) Note that in many parts of the world you can't just build a wall on top of a straight, same thickness footing - that's why I drew the footing as I did. Your local codes should cover this, there's nothing magical about this part. Only the NON-rigid separation from outer walls and INNER floor. BTW, your inner brick wall, if your bricks are about 100mm thick, will weigh about 350 pounds (160 kg) per lineal foot, so your footing needs to be able to support that weight without settling. Codes usually call for the footing to be resting on "undisturbed earth", meaning you dig down, remove all loose material, set your forms, pour the concrete, pull the forms, cure the concrete, insulate with foam (see drawing) then build the wall, render the inside (bricks are porous enough that this is necessary for good isolation) then add whatever wall covering you intend. Don't forget to render the outer wall, dry it, glue the insulation on BEFORE you build the inner wall... Doing JUST THIS should improve isolation tremendously - if it were me, I'd do JUST THIS MUCH and not float the inner floor right away. Once you finish the new wall and do your ceilings as you mentioned, with NOTHING in the inner part solidly attached to the outer part, I would put a drum kit and drummer, bass player and huge amplifier in the room, close the doors (You ARE planning a sound lock (double door with a few feet between, absorption on all surfaces), right? Have the drummer and bass player play as loud as they know how, and check the level while standing next to the wall inside your neighhbor's building (be sure and ask permission, and explain that you're trying to NOT disturb them EVER, even a little bit) - If you (or more importantly, your NEIGHBOR) can't hear ANYTHING, just move the rest of your stuff into your new studio (after whatever acoustic treatment you need to do) and enjoy. If your neighbors are not quite happy, THEN you can invest in a floated floor. Whatever acoustic treatment you do inside the inner walls will have almost ZERO effect on sound proofing, especially with double brick walls, so you won't have to tear anything out in order to find out if this treatment is enough. Yes, the room will sound crappy for this test, but that's to be expected with no acoustic treatment inside. It wouldn't hurt at this point if you were to provide more details of your intended ceiling construction - remember, the weakest link will define the performance of the entire structure... Steve