I have been working on the design for my HT and have started to think about sound proofing and isolation. The space is above my (2) garage and the exterior is stucco on 3 walls. The back wall backs up to my (2) built in racks and a craft room wall. The room is 21 x 13.5 x 9. There are (6) can lights and (2) hvac supplies in the ceiling, no returns. It is open attic above the ceiling.
Keeping sound from reaching other parts of the house is not a big concern. We don't have kids and if we are using the space everyone in the house will be in the HT. From my reading I can see the advantages of keeping noise out of the room and keeping the noise floor down.
So from my attachments you can see that the room has already been sheet rocked with normal 1/2" material. The builder was not supposed to drywall this room but the crew did it anyway. I was hoping to not have to do a bunch of demo to get started. So my questions are:
1) Would it be a huge mistake to proceed from where the construction is now?
2) Will I see some benefit by placing GG and 5/8 drywall over my existing drywall. Would this be a suitable compromise?
3) If I need to pull it down and do staggered studs or clips I can but will it make a HUGE difference? I am really tight on space at 13-6" so the loss of width worries me as well.
Here is a generic listing of downloadable documents available from the NRC on Isolation methods. The NRC is an excellent source of tested construction methods. Pay particular attention to the doc regarding flanking paths.
Be aware, EVERY part is required. You cannot fix part of the system and scrimp on another part and assume it is 'good enough'. It does NOT function that way. The system is Only as effective as the least effective component.
You must first determine exactly how much isolation you require: (max internal level in db SPL - maximum external level in dB SPL) = minimum amount of isolation required.