Well, it has been several months and things are starting move somewhat. Since the walls and ceiling don't meet Massachusetts building code, the homebuilder is preparing to correct the situation. They recently did a test on the unit to the left of ours which is current unsold. They used RSIC-1 over the existing ceiling, new insulation, and new 5/8 drywall. I told them it was a mistake to build over the existing ceiling, but they did it anyway. Turns out that this structure does meet the STC=45 and IIC=45 so they're going with it regardless that it could be done better. Here's the structure in our unit as it stands now:
Wood trusses 24" OC with wood strapping running perpendicular at 16" OC. The strapping is nailed where the walls meets the ceiling so it explains how sound is getting through to walls. The air cavity between my ceiling and the floor above is pretty deep at 24" and does have insulation already. My plan is to remove the existing drywall and cut the strapping along the joists as close to the edges of the rooms as possible so in essence they aren't connected to the ceiling in the middle of the room. I also plan to add an additional layer of 5/8 with GG to what they plan already. The demolition and additional 5/8 with GG would be done at my own expense. I plan to do the demolition no matter what, but not sure what it'll cost per square foot do put up another layer of 5/8 and how much more benefit I would experience.
Does it sound like I'm moving in the right direction? Thanks!