Flooring Alternative for New Studio

I am building a recording studio in New Mexico. The studio is being constructed in a warehouse shell that is approx 1500 Sqft. I am using a double framed walls as specified in the "Home Recording Studio", and these walls are to be built on an existing concrete slab that forms the bottom floor. I am very grateful to this site for all the recommended tips. Here's my problem- In the warehouse there is an existing deck (12ft) with staircase. This deck is approximately 11x18ft. For numerous reasons I am forced to try and locate my control booth in a floating room I am going to build on this deck. Underneath the deck is an existing office that belongs to me, and I'm not worried about isolation in/out of this room. Most of the sound generated in this room will be from monitoring/mixing at reasonable spl's. I know the deck can handle a reasonable amount of weight (as we just demo'd about a ton of material from up there)... But I'm not sure what to do for the flooring in this room. Currently the deck is basically a 1/2 layer of tounge and groove plywood ontop of vertical 2x4's. There are some spots where it has a hollow sound and it is not quite firm enough. The finished floors will be ultimately be manufactured wood. Any suggestions? I'm trying to stay away from concrete or sand... A friend recommended building a 2x4 frame, filling it with fiberglass insulation and covering the whole floor with another layer of plywood... but I'm not really sold on that idea... Any help would be greatly appreciated. If this question has already been answered please point me in the right direction. I've searched around the site for quite some time and haven't found an answer.

jesse_zen wrote:

Here's my problem- Currently the deck is basically a 1/2 layer of tongue and groove plywood on top of vertical 2x4's.

A ton is pretty much wimpy weight when it comes to studio construction, and 2x4's are wall stud material... not floor joist material. If the platform were made of 2x8's or 2x10's, I'd say go for it. Otherwise, you really gotta loose the 2x4's. I seriously doubt that any inspector would let you get away with even reversing your design by putting the office above the control room either. 2x4's just can't handle the weight when used as a floor joist. Think about it... (even though I doubt there's too many basements around you) look at buildings with basements and two story homes... They use at a minimum 2x8's and more often than not, 2x10's are the MINIMUM allowed. Are you absolutely sure the floor joists of the deck are 2x4? Since this is a commercial building, I'm pretty sure you'll have inspector's pretty much on you to follow an even stricter commercial code. Which is somewhat confusing, as I can't believe the inspectors let them build an office below that platform if the ceiling of it would be used for storage. To stop that "hollow" sound, you'll need to have some major stiffness and mass in that floor... and a 2x4 deck just ain't gonna cut it. Just curious, why are you forced to keep this deck? Is it because of the office below? Got any detail pix of the existing ceiling/floor structure that you can post?

Yep, MadMax said it all. Ain't no way that 2x4s are going to support anything worthwhile. about all you could put on there safely is a layer of drywall for a ceiling, but not much beyond that. If you had a ton of stuff stored up there, then you got lucky, I think, in that it didn't come down on your head! Hire a structural engineer to take a look at what you have, what you need to do (many, MANY tons of mass, not just one), and tell you what size joists you need there. But like Madmas said, they will probably be 2x10 at least. - Stuart -