I'll try to draw with text and then explain. _________ [S [I] S] [S [I] S] [S [I] S] [S [I] S] [S [I] S] ========= For S and I: use 'normal' woo

I'll try to draw with text and then explain. _________ [S [I] S] [S [I] S] [S [I] S] [S [I] S] [S [I] S] ========= For S and I: use 'normal' wood, or if using metal mandate expanding spray-foam insulation (to dampen vibrations). I MUST be insulated (should be fire code, as well as noise and common sense code). The brackets are 'dry wall' but mandate the higher quality stuff that won't support mold growth. Yes, there's an inner gap between the outer walls, and the floor/ceiling have a bit of extra padding of some structured engineering product that dampens vibrations. The outer walls have studding to allow for cords and in-wall plumbing. Do NOT run plumbing or put any shelving/fixtures on walls adjacent to another unit. I haven't seen, or figured out my self, how to make the vertical noise isolation equally effective. I suspect a dedicated between floor crawlspace would be effective (but raise costs notably). The core-wall approach CAN lower costs since it allows for a structural core with studs as dense as desired and no cut-outs.