New Studio Started - Checking In...

I have just started construction on a new studio which I am building in a garage. I did some research on room ratios and shape using some books from Phil Newell, and taking a page or two from Hidley rooms I have worked in. Anyway, here are the particulars: I am in a residential area, my closest neighbors house is about 200’ feet away. The raw garage structure is a sand-filled block structure built in the early ‘70s. It is 28’x21’ w a 9-1/2’ ceiling height. The garage does have attic space of about 5.5’ at the center, making it I think a nice place for the HVAC blower unit and some storage. My main goal when planning was making a good control room. I sacrificed a lot of live room space to make the control room effectively, 14’wide by 17’ deep. I will be doing more mixing of others’ projects than tracking. The “live” room will be about 12’x17’ finished. As you can see from the photos, I framed a room with 5/8 sheetrock on the outside. (I have not sealed the corners yet) and framed a ceiling, all of which does not touch any of the block wall, or existing ceiling. The studs however, are sitting directly on the slab. You can also see that I have already insulated and rocked the existing garage ceiling with no holes/breaks in it. The live room side has not been done yet. As far as equipment, I have a SSL 4048G console, and about 4 racks worth of outboard gear. The SSL rack will be in a closet between the live room and the control room. I also plan on using my Sony APR24 2” machine, which I am forced to put in the corner of the control room. Let me know where/if I go wrong: I am planning on: 1. Using Roxul SAFB throughout the construction. 2. Applying 5/8 sheetrock directly to the “new” ceiling (one Layer) 3. Applying RC to the walls with 1 layer of 5/8 and one layer of 1/2” rock. 4. Treating the lower back control room wall with a 8” bass trap made from 703, framing and fabric, with a diffuser above. 5. Creating a raised floor from the equipment racks forward with PVC 4” conduits for cabling. Do you think that cement board attached to the studs first, then the RC and then 5/8 rock would be better? I thought a slot wall on the left and right of the console would also help, any thoughts on this? I would appreciate any thoughts, as I am not too far, and can still make changes. I do have a budget of about 11K to complete this project. Thanks

since you're already on the path (with the 5/8 already on the outside), why not make the walls "inside-out" and make the interior walls slats to gain the benefit of treatments built in?

Not sure I understand what you mean?