1st Floor (Above Basement) Construction - Light Concrete?

Hi everyone, I've been lurking on this site for a couple years while preparing/saving/planning for a studio build out. The time has come and I've started on my project ... A bit of backstory ... I'm in Chicago and 2.5 years ago we bought an old funky bar that's 2 stories with an (unfinished concrete) basement. The 2nd floor has 2 apartments side-by-side.. we live in one and rent the other. The 'back bar' area is where we want to build the studio (and bought this building with that purpose). We bought it still dressed as a bar and have just begun demolishing the area, removing the bar fixtures, removing the filthy-cigarette-encrusted drop ceiling and carpet,etc etc (the place looks like it was probably pretty fancy in 1970 but has not been cleaned or maintained since 1980). The space is big enough for a comfortable control room, live room, vocal booth and drum booth. So the goal is 4 rooms. Oh, this space was originally an apartment when the building went up in 1926, then in the early 1970s the bar owners ripped out the apartment and made it a big open back-bar space with a dance floor, small stage, wood paneling, pool table, etc etc. OK, so above this back-bar space is where the rental apartment is. Luckily at the moment I rent to a child-hood friend who is fine with noise and doesn't care if i go until midnight drumming or mixing .. Of course in 3 years if he's married and moved out I'm going to have make sure the place is as soundproof as possible. Obviously the bulk of that responsibility will fall on the ceiling, but before I get there I wanted to know if anyone had any insight on pouring a layer of light concrete as the foundation on this floor. I do not have to worry about sound underneath (as it's just a basement laundry room) or the exterior walls really (we are in Chicago proper but are on a corner and the 3 walls of the studio face the side street, the garage, and my neighbors yard ... so we got somewhat lucky with that) ... Sp the real question is ... would adding the light concrete help with 1. isolation from room to room within the studio and/or 2. isolation to the floor above ? I know it's all about mass but i'm not sure how concrete applies from room to room in this sort of application ... Before any serious construction begins I do plan on having a structural engineer out to give me a run down (I can't do that until i get everything out of there though) however it looks like there were 3 support posts added to this back area (underneath) at the time it was redone in the early 1970s .. probably to meet Chicago code for letting 80+ people back there for dances, parties, etc. So I'm hoping we won't run into any issues there ... Thanks guys in advance! Hope this doesn't read too long! anthony

Hi. Please read the forum rules for posting (click here). You seem to be missing a couple of things! :) - Stuart -

Hi there! So sorry about that! I hope the attached image of the space is the last piece of the puzzle. I'm not looking for any answers involving a full build out yet ... As far as budget, I can go 20k max, but that's neither here nor there yet. I'm pretty sure that's every question on your list (i hope)! Hope this is what you are looking for! The exterior wall dimensions might lose some inches after they are framed and I guess the height may change if we pour concrete ... These dimensions are for the room in its rawest state .. Down to the sub-floor (hardwood floor ripped out) and down to the brick exterior wall. thanks! anthony

Does anyone have any thoughts on this? I'm curious for my own application but also in a theoretical sense. When the studio space is not on the 1st floor, does adding a light concrete layer first, then building a floating floor on top help at all ? Or would this just be a waste of time? I can actually acquire the concrete for free so it's not so much the expense with this step. Conversely, would putting the frame for the floor down first then adding a layer of concrete inbetween two layers of CDX board (for example) help at all? So for example, from the bottom up .. Floor Frame->CDX->light concrete->CDX (or other type of plywood for variation)->Hardwood thanks for any insight! i'm trying not to be a pest! anthony

Hi Anthony, and sorry about the delay! And also Welcome to the forum!

and doesn't care if i go until midnight drumming or mixing .. Of course in 3 years if he's married and moved out I'm going to have make sure the place is as soundproof as possible.

That would imply that in 3 years you'd have to rip out everything you do now, in order to be able to soundproof the place... :) You cannot soundproof after the acoustic treatment is done: the sound proofing has to go in first, then the treatment afterwards. In other words, if you think you might have to isolate ("soundproof") at some point in the future, then you should do it now instead, and save yourself a of of money and time!

Obviously the bulk of that responsibility will fall on the ceiling, but before I get there I wanted to know if anyone had any insight on pouring a layer of light concrete as the foundation on this floor.

What is the floor made of right now? If it is already concrete then you probably do not need to add more mass to it. But if it is wood, then you have the issue of structural integrity: is the existing structure able to safely support the huge added mass of a layer of concrete? Only a structural engineer can answer that question, so now would be a good time to hire one!

Sp the real question is ... would adding the light concrete help with 1. isolation from room to room within the studio and/or 2. isolation to the floor above ?

If you are going to go to all that trouble and expense, and you really want exceptional isolation, then you might as well float the to floors independently. That said, you should read this thread first, to understand all the implications: viewtopic.php?f=2&t=8173

Before any serious construction begins I do plan on having a structural engineer out to give me a run down

Yes! Very smart move!

When the studio space is not on the 1st floor, does adding a light concrete layer first, then building a floating floor on top help at all ?

Yes, it absolutely can make a big difference. The issue normally is cost, and also deciding if you even need to do it. I'd suggest that you buy yourself a sound level meter and do some tests to see how much isolation you are getting at present, and how much more you need. Based on that, you can decide if there is a concrete truck in your near future, or not.....

I can actually acquire the concrete for free so it's not so much the expense with this step.

Free concrete is good! But even tough the concrete itself might be free, the laying of the form work, the planning, design, structural calculations, acoustic calculations, floor jacks, labor, inspection fees, permits, and many other factors won't be. The cost of the actual "wet gray stuff" is only part of the equation.

Conversely, would putting the frame for the floor down first then adding a layer of concrete inbetween two layers of CDX board (for example) help at all? So for example, from the bottom up .. Floor Frame->CDX->light concrete->CDX (or other type of plywood for variation)->Hardwood thanks for any insight! i'm trying not to be a pest!

It sounds like you need to read something a bit more technical on floor isolation! Try this one: http://archive.nrc-cnrc.gc.ca/obj/irc/d ... /ir802.pdf :) - Stuart -