Modular booth inside a room.. suitable isolation?

I am building a small post production studio in NYC. The building is not necesarilly quiet, and there is definitely a lot of street noise coming from 10 floors below. The floors are poured concrete so It is a pretty solid base. I am having a contractor build the walls to an STC 50 rating (with an isolation line between the studs, two layers of sheetrock, etc.), there will be two control rooms sharing a approx 6x8 iso booth/live room. My question is, If I float the floors and have about an STC 50 rating on the walls, will I be able to get away with a prefab booth, like soundsuckers or whisper room? The situation will be one of these booths placed in a room between the two control rooms that are floated. I will install windows in the control rooms to line up with the prefab booth. I will be doing voiceover and some foley in the booth, and I am most concerned by noise getting in from the control rooms, or vibrations in the building, street etc. Seeing If anyone out there has had success with this scenario? My other option is ordering something from IAC or Acoustic Systems.. which takes a few months, and costs alot more. thanks for any help.

Exro, sorry for the delay in getting to your post - I'm in the midst of a fairly complex video project, being asked to work extra 12-hour shifts at work, and feeling a bit less "chipper" than I'd like so I've gotten pretty far behind (er)... Until you mentioned the word, "foley", I'd have thought that one of the double leafed whisperrooms might have been enough but serious foley needs DEAD quiet AFAIK - Have you or your contractor got specific load ratings for your floors from city planning, or whoever handles that sort of thing in your city? If there's enough support, you'd probably be better off building in place by floating a 2" or thicker concrete floor over something like the Kineticsnoise.com RIM system, then building inner walls on that floated slab, outers on the original floor. Pretty much all "in the box" vox booths are meant to be dis-assembled and moved, and as such it's more difficult to obtain good iso with low cost - IIRC, the larger whisperrooms go for around $10k or so. One of the advantages of build-in-place is that you'll have wider air gaps between inner and outer mass, and it's no big deal to double the mass in each leaf while you're at it. Those, and tight caulking, will give you several extra dB of isolation - ALL of which will get you much quieter foley... Steve

Knightfly.. thanks for the advice. It is not in the budget to got all out on a foley room. Perhaps in the future...

If you can find out what your floors are rated at for additional load and give us a ballpark figure for budget, we should still be able to get you your money's worth or better - let us know more about your construction abilities, willingness to DIY or not, etc, and check with your building's engineer for loading, and maybe we can get you what you need... Steve