Originally Posted by wingm8
I'm not too concerned about sound reaching the bedrooms since the theater is on the opposite site of the house. Sound going directly upstairs and outside is more of a concern as well as sound coming in (not too worried about that though, very quiet neighborhood).
Do your neighbors use lawnmowers, have dogs, occasional parties outside, drive a motorcycle, etc.??? They may not be as quiet as you think.
If some sound goes upstairs, I'm not too worried, since I'll be in the theater anyway. The theater is partially subterranean, which might help some with the sound reaching the neighbors. The wall facing the neighbors two walls (one 2x4 wall and then a wall that is 2x6 on top of a block wall). That should help cut down sound transmission I hope.
Those concrete block walls will be good for your neighbors but bad for you; they will reflect sound back into the room. Furthermore, sound will behave differently along the portion where the concrete block is not present (on same walls).
I was thinking originally of doing DD+GG on the ceiling, but many experts here have stated a half-way solution is no solution at all. I'm not sure that going all-in on the soundproofing will even be worth it with the window and large french door anyway. Can someone let me know their thoughts on my situation?
I would do clips and channel on the ceiling at a minimum. You can deal with the french door and window most efficiently by sealing them off when you soundproof the room (if that is an option), or using a plug in the case of the window. Your best bet would be to build an inner stud wall in front of them to give you plenty of space for isolation. Another (perhaps more efficient) option would be clips & channel.
Everyone's situation is unique, and their tolerance for extra effort and budget is unique, and their desired outcome. That said, I would definitely do clips and channel on the ceiling as a minimum. Any basement theater really needs that or you're going to have sound transmission in both directions (from whatever is going on above into the theater room and from inside the HT room out). The flooring and framing above your room will conduct sound all over, not just up and down. Sound travels remarkably well across wood studs.
Now, in my case I have a 2nd floor HT room above my garage and with an attic above the room. For my ceiling, I chose to do OSB+DD in the middle and a DD soffit around the perimeter. I chose not to use clips and channel and secure my room-within-a-room double stud walls to the ceiling joists. It was a calculated decision based on cost, effort, and perceived gain of using clips versus not using them. Time will tell if it was a wise choice or not, but in my case the potential downside is limited by my future use of the HT room and the home environment. The attic above is pretty big, so there's lots of air to help dampen the HT room noise (plus the mass on the ceiling, plus tons of insulation above the room). Even though that's the case, I am aware of joists in the ceiling that are horizontal toward the one room (a bedroom) that shares a wall with the HT room (the other walls face either the attic or outside).
Seperate concern: The wall between the theater at the adjacent room is a 2x6 shear wall with an extra 2x4 wall next to it (not touching, was added for sound-reduction, perhaps naïvely). I'm concern that I've created a "triple-leaf". Given my thoughts above, can someone let me know if this is something to worry about? Can I do anything about it? I can't remove the plywood because it's shear wall (structural requirement).
Back to your situation.... Again looking at your walls.... Even though you have double stud walls, as
pointed out, the wall in between those studs is a no-no and will create a triple-leaf effect when you cover either side of the double wall with drywall.
How is that inner wall attached and what is it attached to?
Quite frankly, in your case I would suggest you go with clips & channel for your entire room. You have a number of noise issues that would be significantly mitigated via use of C&C: windows, concrete block, triple leaf wall, floor above ceiling.