Concrete slabs / PVC / floor outlets | John Sayers’ Recording Studio Design Forum archive

Status: I've been lurking and reading while designing my studio. I was hoping to get my sketchup design 100% done before I posted, but I can't take it any longer. I need to start getting some feedback. One step at a time... I'm currently working with a structural engineer to approve removal of a block wall, as well as pouring slabs on top of the jumbo floor joists+subfloor. Drawing notes: *The light blue is concrete block, red is existing interior walls and light brown is my proposed studio walls. *Floor framing is 3 1/2" x 12 7/8" douglas fir @ 16" O.C. (except in the control room - engineered slab existing) *Sound lock next to the iso booth would NOT have a slab. This is where it would step down. I'd probably use a ramp to the live room. *2x4 walls going up - 12" minimum air gap for concrete block, 4" for back to back 2x4 walls Areas of concern: - Wiring - Joints - Underlayment What I'm thinking: I'm planning on running 2" PVC for power up the middle of the live room (new slab) with branches/tees to distribute floor outlets. I don't have a choice but to run wall outlets in the control room (existing slab). Audio/LV wiring - I'd like to run these along the concrete block wall in PVC. This would be between my 2 leafs (12" air gap minimum), probably mounted to the concrete wall about 1' off the ground. XLR floor panels in the live room and booth. After all of the PVC and wiring is in place, I'd use 1" rigid fiberglass with 3/4" fiberboard to build up to the height of the PVC. That would leave about 2 3/4" for the new slabs. I was planning on a 4" gap between each slab, and a 4" gap between each new slab and the exterior concrete block wall. Fill with rockwool (possible put 2" PVC with low voltage wiring first). It seems necessary, if I'm going to have PVC pipe exits at the joints of the slabs. Questions: Am I better off with a smaller joint at the slabs' perimeters and dumping the rockwool? I read up on Rod's method of using 1" gaps and caulking. Is that the best option, given my scenario? Isolation - What is better, running the slabs tight (1" joint) and wiring through walls or using a 4" joint with rockwool and having floor outlets? Instead, should I try to achieve a 1" joint and use 90 degree PVC elbows to bring the wiring up between the walls, and pour the slabs around the elbows? How does the "floor outlets / XLR panels" idea sound? Do I need to frame around them / seal with acoustic caulk, or is there a better method when pouring concrete around them? Is 1" rigid fiberglass plus 3/4" fiberboard my best option to build up the floor? Please let me know if you need more detail or would like my Sketchup file. Thank you in advance, Joel

File not preserved: Concrete slab.pdf