Sound Proof the Ceiling or the floor above?

EDIT: New questions and updated design start in post 17: http://www.avsforum.com/t/1454177/sound-proof-the-ceiling-or-the-floor-above#post_23161020

I am currently working with an architect to design a custom home including a basement home theater. I'm trying to decide on the most cost effective method of controlling noise transmission between the theater and the rest of the house. The house will be built using ICF (Insulated Concrete Forms). For the basement this basically means 2.5" of foam insulation on either side of an 8" concrete core.

In the photo below the hashed walls are the ICF walls basically surrounding the theater on most of three sides with concrete and earth. The other walls will most likely be staggered stud walls.

My biggest concern is sound transmission from the hardwood floors above and to a lesser extent the sound escaping the theater through the ceiling.

I've done my research read about sound proofing ceilings using all kinds of crazy techniques and about using under-laments like Serenity Mat under the floor above.

I can do either or both but which option is the most cost effective? Treat the floor or treat the ceiling?

• Will a floor treatment (like Serenity Mat) help with sound escaping from the theater or just help deaden the foot-falls from above?
• How would using a floor solution by itself compare with the various ceiling sound proofing options found here:
  http://www.soundproofingcompany.com/soundproofing-solutions/soundproof-a-ceiling/
• On a side note to avoid flanking through the side walls I wonder if any decoupling would be provided when attaching drywall to the furring strips in foam insulation of the concrete walls?
• ohhh... I wonder if I could use green glue between the forms and the first layer of drywall? Wonder what green glue would do to the polystyrene of the forms?

The more I type the more questions I think of... I better stop for the night.
(This is one of 2 designs I am considering)



Here is a pic of an ICF Form to show the furring strips embedded in the foam. Typically drywall would screw directly to the furring strips in the form.



Edit: Changed the ICF form pic to more clearly show the construction and furring strips.
Edited by jroyv - 4/3/13 at 2:27pm

Thanks Guys for all the comments.

I was hoping to avoid studding out the side walls. I want this room to have an open feel and keep my walkways close to 3' wide. The "furring strips" are actually extensions of the reinforced plastic ribs that hold the two sides of the form together. They end 1/2 an inch below the surface of the foam and have sections rated for 400 lb pullout (similar to a 2x4). I shouldn't have any issues attaching traditional double drywall and green glue combo to the forms (no green glue against the forms).

If I was going to give up width for stud walls on both sides I guess I could do the whole room within a room thing, I have the ceiling height. I'm not sure I would take it that far though if I could solve my primary concern by using something like Serenity Mat under the floors above.


Sorry about the rough sketch the "loveseats" are just representations, visio has limited furniture options First two rows will be theater seats with about 6' 10" to contain the reclining second row. The back seats will not be recliners just comfy gaming seats and at most "overflow" theater seating. I'm ok with them being out of the optimal sound envelope. as long as I can get 7-8 "good seats" in the fist two rows. I do as much xbox and PC gaming in there as I do movie watching.

As for the riser most of the section of the theater that is surrounded by the ICF walls will be one form (16") deeper than the rest of the basement. So i'll end up putting a wood riser to support the entire second row while getting over 10.5' feet of height at the front. There will actually be a second wood riser under the 3rd row of seats. I will most likely at least stud out the front wall so I can get a good quality in-wall center channel behind the screen.

I think you are correct? If you decouple your studded walls next to your foundation walls and use clips or some other method of decoupling on the ceiling I wouldn't think any additional decoupling would be necessary on the walls.

I was asking about applying the drywall directly to my ICF walls, in which case (as Dennis pointed out) the foam would be a rigid surface not allowing for any decoupling.

I'll have to play with my design and see how much space I am willing to give up. I have to decide if I am willing to give up the space required to properly do the decoupling or if I can live with adding mass and dampening elements.

I know, I know... my current theater is only 11' wide at the front. But with this one I wanted to be able to do 4 theater seats across AND keep 3' isles on each side. Going for an open feel and clean look.

Crude sketchup of Design 1

The furring strips are High-density, Molded Plastic Webs spaced every 6" horizontally. Once the wall is done the center of those webs are embedded in an 8" core of concrete and rebar and they extend through foam insulation on each side providing the furring strips and attachment points 1/2" below the surface of the foam on both the exterior wall and the interior.

Additionally there are "Heavy-duty Attachment Points (450lbs.+). Located every 8" vertically and every 6" horizontally, allowing for secure attachment of bracing or heavy cabinetry."

I've seen almost every type of siding attached to these on the exterior and cabinets, stud walls and drywall on the interior.

I think the clips would work if I go that route.

Thats a good point Big. Every thing else I have seen attached to the forms had the load on the foam spread over a wider area where by design the clips would be concentrating that load somewhat. There are a couple other places I might use that technique too... Thanks!

I'll go ahead and post the other design I am considering since my thread in the General Home Theater forum isn't getting much love.

Design 4: The front of the theater will be the same as Design 1 but it gives up the double entry and splits the gaming area into two separate sections. Allows for more creative "game station" setups and potentially more overflow seating. Gives up the cool double entry though.

OK I have an other question.

If you are doing a true Room in a Room design. IE - none of the interior walls or ceiling are coupled to any of the exterior walls & ceiling, why would there be any reason to also use clips?
You have already decoupled everything by doing the room in a room. Haven't you?

I picked up this pic from an other thread and marked it up for an example.




This is from a great build thread by the way.
http://www.avsforum.com/t/1437336/fall-frenzy-bigmouthindc-hits-the-road-again-destination-columbus-indiana

Thanks for the clarification Big.

Just thinking out loud. How far off the back wall would the back row need to be to be in the sound field of the rear speakers in a 7.1 config?

I've seen a couple different recommendations and they vary from 1 ft, 1.5 ft to 2 ft and more.

Edit: Moving this over to my Design Thread to keep everything in one place:

VTHT 2.o - Planning a Theater & Whole House Build

OK I may be over thinking this but here we go. Dimensions have changed slightly from initial posts so I am considering a room-within-a-room design.

The current sound containment plan would include

• Stud walls all the way around the theater placed 1/2" - 1" away from all surrounding walls and ending 2" below the level of the floor joists above.
• Ceiling Joists interleaved with the floor joists above resting on the decoupled stud walls about 2" below the level of the floor joists
• OSB > Green Glue > Drywall on all interior surfaces giving me my "shell". All soffits and columns will be built inside this shell.
• All lighting, outlet boxes, in-wall speakers and low voltage penetrations will be in the soffit or columns inside of the shell.
• Penetrations through the shell will include, HVAC Supply, HVAC Return, Main Door and low voltage/electrical wiring.

I will include the EQ room as part of the sound containment envelope.

Rough Plan


SketchUp Top


SketchUp Top Anfled


ICF


Floor Ledger


In the last 2 pics I am trying to detail the floor ledger attachment methods and over all ICF construction because the details are different than traditional construction. The basement and both levels above are ICF construction. 8" of concrete on the basement level and 6" on the 1st and 2nd floors surrounded by 2.5" of foam on each side. The flanking paths are different that traditional construction.

Decoupling the ceiling makes sense.
Decoupling the rear wall and the part of the side walls not adjacent to the foundation makes since.
Am I really getting any benefit from placing decoupled walls in front of my foundation walls?
What I am trying to figure out is am I wasting 8" of room width for very little gain?

What do you think of the current plan overall? Any suggestions?
Edited by jroyv - 4/5/13 at 8:26pm