basement music room

been reading more threads and trying to figure out how to finish the floor. A few questions: I osb the best choice for the floating floor? How does it compare to mdf or some other choice(formaldehyde free)? Will 2 layers on a 2x2 frame with 1/2" EPDM pucks work or is the air space too small( head room issues)? Seems like a vapor barrier is not a good idea in the basement: Is it safer not to use to prevent possible mold problems even if the basement is extremely dry? Have read different threads suggesting various choices for floor insulation. Is 703 a waste to use in the floor as opposed to cheaper stuff? How essential is it to have some kind of spacer material between floor and walls? Inner walls will sit on top of floor with sill seal. eric

I osb the best choice for the floating floor? How does it compare to mdf or some other choice(formaldehyde free)? Will 2 layers on a 2x2 frame with 1/2" EPDM pucks work or is the air space too small( head room issues)? MDF has a bit higher mass, which would help lower resonant frequency - however, MDF isn't as strong as OSB for spanning across a given distance - one way to do this is use OSB as the first layer, then 1-2 layers of MDF for the increased, and DIFFERENT, mass. YOu can get a decent sounding room using that light a floor, but you will NOT get complete isolation to lower frequencies without a higher mass, deeper air gap floor; to get the floor resonance BELOW the lowest frequency you can hear so all audio frequencies are on the same side of the resonance peak, you need at least 3-1/2" of concrete over 3/4 OSB over 2x6 joists on EPDM pucks; If that heavy duty a floor isn't possible for whatever reason, you at least need to make sure the floor you build doesn't resonate (has good damping) - a complete fill of insulation with light compression of the insulation will handle this part. Be aware that the floor you described will NOT isolate the bottom 2-4 octaves as well, and will have one specific frequency (at resonance) - this resonance will be a lot less objectionable with the proper insulation fill to maintain damping. Seems like a vapor barrier is not a good idea in the basement: Is it safer not to use to prevent possible mold problems even if the basement is extremely dry? Depends; we talking floor, walls, inner, outer...? Generally, though, you're safer NOT using a vapor barrier if not sure. You need to clarify this one more. Have read different threads suggesting various choices for floor insulation. Is 703 a waste to use in the floor as opposed to cheaper stuff? In most cases 703 is overpriced and harder to get than rock wool, and 2.5 PCF rockwool is fine for wall, floor, ceilng, basically almost anywhere you need insulation. How essential is it to have some kind of spacer material between floor and walls? Inner walls will sit on top of floor with sill seal. For wood frames, it doesn't matter much at all; actual sealing will be by caulk around each layer of the wall; the frame is only there to hold up the wallboard. For steel framing, there should be a Thermal Break (sill seal or 30# building felt) under the steel channel, especially if the steel is on concrete; even on wood, it's not a bad practice... Steve