floor below studio a problem | John Sayers’ Recording Studio Design Forum archive

our studio's located above a restaurant. the problem is, the area where bands practice is directly above one of said restaurant's function rooms. It was only last night that i took a trip down to that function room to hear how loud it was, a little bit under conversation levels (maybe 50-60db?). I noticed that the function room had acoustic board at the ceiling. Outside the function room I noticed a vent that was hollow (with some air emanating from it. air conditioning, i suppose). The sound here was slightly more detailed than from within the function room. Our studio is raised from the second floor's concrete using wood (what sort i'm not sure, but it's raised) which is rather hollow, as evidenced by hearing people walk on it even though inside the room. The band room itself is only treated with acoustic board and a thick carpet over the wooden riser floor, and the door is a normal one. Since I have this problem already, I was thoroughly convinced that I'd have to invest in having the room sound proofed. My question would be: with a $500 budget, would it be possible to reduce the sound traveling to the function room below by raising the practice room's floor? I could have the carpet removed and a concrete slab placed over the wooden risers. Is that a good first step (since I am limited of budget) or would it be foolhardy to proceed in such a manner? thanks so much guys! this is a great board!