Studio on 6th floor of building: Bad Idea?

Greetings forum members! I've been reading about studio construction and reviewing photo diaries and discussions of studio builds for about 2 years now. Its been a little tricky finding the answers to some of my queries, but maybe that's because I'm asking the wrong questions. I know if I'm asking advice it should be short and full of details, so here goes: Simple recording/rehearsal space: 800 sq ft. 6th floor of a brick building approximately 50' wide x 116' long. 15" thick concrete floors. Ceiling height is 11'. Isolation from the first floor is my only concern right now. The 6th floor is only storage space, so I asked some friends to haul their gear up and play loud heavy rock so I could gauge the sound transmission to the first floor. Cars driving by were louder than the band, but I could feel vibrations in the concrete columns. Sound seems to travel through the stairwell and elevator shaft more than anywhere else. I hope to build walls between columns as shown as red in the attached drawing. Is this a bad idea? Is there any value in a double leaf wall in this situation? Any advice on reducing vibrations through 6 concrete floors? Thanks for taking the time to read this. I appreciate any help you guys can offer! -Trip

Hi Trip, and welcome! It's late, and I need some sleep, so real short answers:

15" thick concrete floors.

Good!

Ceiling height is 11'.

Nice!

but I could feel vibrations in the concrete columns. Sound seems to travel through the stairwell and elevator shaft more than anywhere else.

You have two problems, then: #1 flanking into structure. #2 airborne sound. Solution: You need to decouple and isolate! What instruments were your friends playing? My guess: Drums, bass, electric guitars, keyboards. What where you hearing/feeling most? My guess: drums, bass. Solution: Put the drums and bass amp on well isolated risers.

I hope to build walls between columns as shown as red in the attached drawing. Is this a bad idea?

If that is going to be your outer leaf, then that looks fine to me! But not if it is your inner leaf...

Is there any value in a double leaf wall in this situation?

Yep! :) (If you do it right...). Leave a large air gap (6" or so) all around that room, and build your second leaf there, fully decoupled.

Any advice on reducing vibrations through 6 concrete floors?

Yup! Don't let the sound get into the building structure in the first place! In other words, isolate the room interior from the building. - Stuart -

Stuart, Thanks for the advice! I will look into isolation risers! Instruments used were: Bass, Guitar, and Drums.