Originally Posted by JapanDave
What are you using for seals around the doors? That is one place that sound will escape. Remember you are only as strong as your weakest link.
There are only three weak spots in the design, the doors, the airflow in the attic, and the air condition system.
As for the enterance:
Just weather stripping; one for the external door and another for the internal room, seperated by 4 feet of air and decoupled (room-in-room design), both are actually metal external doors.
So for the enterance-walls, the sound will have to go through two layers of 5/8's with GreenGlue, a layer of soundboard, a hat channel, a layer of roxul, another hat channel, another two layers of 5/8's with GreenGlue, a layer of soundboard, 4 feet of air space, and then another two layers of 5/8's with GreenGlue, a layer of soundboard, a hat channel, a layer of roxul, a layer of R20 and then 3/4" OSB.
OR... it could just going through one door, 4ft of air, and then the other door
So definately the weaker spot.
If it doesn't work, I'll have to beef them up even further.
note: The neighbors are on all sides, between 60-100ft away.
As for the attic flow:
Not many options there, more layers of Roxul and OSB I guess, you need some level of airflow.
I haven't come up with an air condition system-design yet, more research is needed, but I do have "some" ideas for it to make it as sound-proof as possible.