Sound proofing floor

WHat about that soundproofing vinyl that is meant for walls? You could put that on your floor first before building a new floating floor above it.

Check out the following site for advice:

http://www.soundproofing.org/index.html

Your walls will also carry vibration to the structure below, so soundproofing could be a pretty big project.
Good luck.

Emailist,
I had that in mind- using the mass loaded vinyl on the floor.
Larryi,
I plan on using that vinyl on the walls as well.
My challenge is this: I will build the floor out of plywood and it will be supported at both ends. The span is about 11'(that's the width of the room), so I'll have a joint some where in the middle which will be staggered, and will be forced to use some lumber 2x4 or other. If I stand the 2x4 on edge to keep the floor from springing to low in the middle my floor gets thicker, something I don't want. So I was thinking towards the middle of the span installing srings of a sort? Foam? Rubber? Sorbothane?
But what will it feel like to walk on? And if I am sitting in the middle of the floor and the raised floor sinks to the spring material then it defeats the purpose of the raised floor which is suppose to be decoupled. Any suggestions. How much air do I need between the raised and existing floors to stop the sound from passing through?
In the end I think I will be installing the raised floor joists on edge.

If you have a layout of your equipment and furniture that you will be using it would be a big help in determining placement of minimal support for your added floor.
Don't forget to use T&G ply & glue the joints with something like PL400.
Instead of mass loaded vinyl try to find the heaviest cheapest vinyl flooring on sale(sized to fit room as one piece) and pick up the heaviest "used" foam u/l from a flooring contractor(it normally just goes in the garbage).
Glue the foam to the floor and lay the vinyl over it-gluing the vinyl only to the walls all around to prevent leakage. Relaxed vinyl is vastly more effective.
A layer of vinyl directly on the floor beneath the u/l would be an excellent economical improvement as well.
I will be very interested to follow your endeavour.(I would not recommend lifting your original floor, not worth it, but highly recommend you eliminate any squeaks before you start-and if I were doing it I would rescrew the original floor as a first step using 1&3/4 inch deck screws. Rattles would be very annoying. If the result is not quite adaquate the next step would be to work on the ceiling below. Cheers. Pete

Psacanli,
Thank you!
One other concern of mines(I know, it never ends) is the outgassing from the foam. I am not a health nut, actually a quite balanced health oriented individual. The outgassing is an important concern though, and in the winter when the stack effect forces air and vapors to move upwards it'll just end up saturating my living space. So I am hesitant with not just the foam but most materials that are being considered. I think the vinyl will not present as big an issue as foam would. The outgassing concern is what has kept me from going forward with this project as it has been on my mind for a while. Any suggestions Psacanli?