Long Post but...
This is what I did to my room. I was about 1/2 done with my first theater and we went out of town in the spring of 2008. The electricity went out during a heavy storm and when we came back to town on sunday I went down stairs. The sump pump had backed up and flooded the whole basement. Wicked throughout the carpet, up the drywall and it was trashed.
I had plans of a back up sump, drainage set up but did not get to it. I figured I had time.
I gutted the basement down to the foundation blocks and have been working on it ever since.
It was the only room in the house that the wife gave me
so I started over.
Here is what I did:
1. My room was 19' x 21' open floor plan with Heating, Sump Pump, and water softner againt one wall.
2. I built a wall with a door to separate all of this from the final room leaving an 19' x 16' space to work with. The HVAC room is 5' x 19' for my HT.
3. From Floor to Ceiling I had 8' 4" so I could sacrifice a few inches.
4. The stairs comes down and the HVAC room is to the right and the Theater Room is to the left.
5. I made a small hallway as you come down the stairs that was 4 wide between the HVAC room and the HT.
6. Then I basically built a framed a regular 2"x 4" 16" On Center studded wall and laid it on the floor with treated lumber and pink gasket for the entire 19 x 14 space leaving 1" away from the foundation blocks.
7. I still strapped down the wall to the concrete with Tapcons so it would not move.
8. I completely sealed around the perimeter on both sides of the platform and drilled some 2" holes every 24" in the studs in the middle of the internal studs for airflow (Explained later)
9. put down 2 layers of foam gasket (pink)(helped with squeaks) on each stud and screwed down 3/4" plywood and caulked all the seams with 50 year caulk.
10. Then another layer of 3/4 Plywood with 3 tubes of Green Glue per 4 x 8 sheet.
11. Then built walls on top of that staying 1" away from foundation and rubber under the bottom plate and these for the top plate and the joists.
12. resilience and clips for ceiling
13. Backer boxes on all lights, switches, outlets.
13. 2 layers of 5/8" double drywall with green glue walls and ceiling.
14. Insulation in walls and ceiling.
15. layer of Mass Load Vinyl on floor under Carpet.
16. Ran HVAC from other room through some soffits I built inside the Double Drywalled room.
17. In the HVAC room I have a high out put dehumidier that circulates air around the outside of the room and is split and piped in and out of the subfloor to circulate dehumidfied air.
18. The hallway is Tiled like a bathroom with a 3 inch tile trim that runs the whole length of the subfloor.
I was not looking for 100% soundproof room and so far nothing vibrates upstairs which is good.
The door is my next project to keep the sound in the room.
There is a small stage that is filled with sand on top of this and the sub is isolated with a 4 inch Auralex SubDude-Like board on the stage.
I have a riser as well for a couch and 2 recliners for front.
I believe final demensions for ceiling height is:
Riser area 7'
Main Floor 7' 8" (Still Taller then my parents unfinished basement)
I know I lost some ceiling Height but in a test, I took a hose and ran water to test and it worked great.
We'll see when I get the door in an run some sound tests to see if the floor causes some booming but without the door so far so good.