So how about Cosmetic Floating Floors ?....

Hello I realize I'm opening a can of worms with the phrase "floating floor", and please believe that I have used the search bar, and have read Stuart's and Brien's threads, and John's definitive thread as well. And I apologize if I should have been able to figure out this question from my reading, but I feel like its been left a little ambiguous in regards to a cosmetic floating floor. It could just be me and my ignorance, but hopefully I'm not the only one and answering my question won't be a complete waste of time/redundancy. :) I completely heed the warnings about the lack of soundproofing ability for a poorly done floating floor, and how in most cases it is detrimental and best to leave the slab alone for soundproofing. Also, I understand that the amount of mass needed to float a floor successfully and be soundproof would require serious calculations, which let's be honest, many of us are unable/unwilling to do (myself included). BUT John mentions option 2, as laying a floated floor for cosmetic reasons, both for look and being able to chase cables under the floor (to under the mixing desk). And then went on to say that it did work in a few studios. So is this possible without boat loads of math and all the problems that arise with a new resonating cavity? I'd like to put 2x2" batons on my slab (which is in a detached garage, ergo good enough) and some hardwood on top using the 50mm gap to make a few conduits for cable, and filling the rest of the air gaps. My walls would be anchored into the slab, so the floor would not need to support any weight besides my gear and myself. It would just touch the edges of the new walls. 1) Can I add rigid insulation between the slab and wood flooring to make it one continuous mass, eliminating its desire to resonate? (so obviously its not adding to any isolation, but I don't need it to). 2) Or would something like sand work, as I don't have to worry about its weight falling through to some other room beneath? My slab is a bit utilitarian and wouldn't polish well, as its not a fine grain concrete like some screed floors. Sadly, as I actually really like the look of polished concrete. And I'd like to obviously like to run the aforementioned cables instead of gluing wood directly on the slab and having cables exposed on top of the floor. But I am willing to listen to your answers and go a different way, so please stop me from going down this dark road if there is no way around it, even cosmetically. Thank you in advance!!

I wouldn't attache anything hard to the concrete and then build on it, especially if it were filled of insulation. Now if you laid sleepers (furring) on the slab and used sand...this sand has mass and you can route conduit, cables, etc. A damped floor can be constructed using 703 (owens corning) rigid insulation panels laid flat on the slab and then cover with 2 layers of 3/4 inch plywood, running one layer and then the next layer perpendicular to the first layer.

Thank you Brien. Please excuse my ignorance, but my understanding from looking at diagrams on the web, is that sleepers are 2x4's laid down but not attached? If that's the case, then does the top layer (hardwood planks, or ply) get nailed to the tops of the sleepers? And lastly, some diagrams have sleepers resting on beds of insulation, that also fill in the spaces between the 2x4s. Is this correct that the sleepers should ideally be resting on insulation/rubber/sand or is direct contact with the slab ok? cheers!

"Is this correct that the sleepers should ideally be resting on insulation/rubber/sand" No A sleeper is attached to the main substrate. It is a hard connection between foundation and a systematic path to attach the flooring. Used extensively for solid hard wood flooring and creates the "echo" or hollow sound most noted with this type of application. What you are trying to avoid is this hollow sound AND the possibility of creating a diaphragm which will work in the same way a drum head does. Still the sleepers are hard connected to the substrate (A substance or layer that underlies something, or on which some process occurs, e.g. hardwood flooring installation.) and the sand goes into the cavities created by this material installation process.

Is there any reason why you can't just use leveling cement, followed by laminate flooring? If you want to have conduit in your floor, then maybe you could just chase the concrete, install the conduit, pour your leveling cement, and put down laminate flooring? It seems to me that would be more cost effective, quicker, less complicated, and avoid all the pitfalls that Brien is mentioning about resonant cavities under your floor. Just a though. - Stuart -

Thanks for dropping by Stuart! Hmm, I guess one reason being that I'm not sure if I'm capable of making a level concrete floor on my own, but I suppose that's what self-leveler is for with instructional youtube videos. But also its for aesthetic reasons mainly, as I don't really care for the look of laminate and there is something welcoming about a proper wooden floor. I think if laminate were a serious option I would go with a bare concrete floor as that's more appealing to me. Another possibility for me would be to just glue some ply down (with some padding underneath for leveling) and then glue a T&G manufactured wood floor on to that and possibly give up on chasing cables. Its a tough one, as laminate looks kind of cheap and bare concrete is great but doesn't allow for floor panels as easily. I've read your views on carpet and rubber tiling, so have already discounted those. cheers

Self leveling cement in a DIY environment is more expensive than you may imagine. 50 pounds runs right at 30 US dollars and does not cover that much square footage...will break if you nail into it and by design is not supposed to be used in this type of application. It will fail. By design, the manufacturer is thinking you will install tile on it and that is about as far as the warranty will go.

I'm not sure why you would want to nail laminate floor into the underlying concrete... :) But point taken on the cost issue: leveling cement ain't cheap. And if the OP doesn't like laminate, then it's a moot point, I guess. Which leads back to the original question... You CAN build a raised floor like you proposed originall, yes, but as Brien already pointed out, there is the possibility of resonance if you don't either damp the cavity properly or fill it. As with any surface next to an air gap, it will resonate at a certain frequency. So either you need to tune that to a useful frequency for the room (hard to do), or tune it so low that it is out of the range of interest, or damp it heavily, or fill the cavity with something solid. - Stuart -

Anyone that is "learning" will conclude that to simply get a material with a name that reveals both what it does and is also a marketing device will assume that this material will in fact self level. Not only does it not self level it can create more irregularities in a substrate than may have existed. Assuming we have an unbuilt project, which is the case here, and we throw in "self leveling" high strength concrete onto the existing floor the next phase will be to construct walls and that leads to a hard fastener in the rat sill of the wall assemblies.