Concrete Walls

Discussion in 'Home Theater Projects' started by Steven McCaa, Sep 11, 2005.

  1. Steven McCaa

    Steven McCaa Auditioning

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    I am in the process of designing my new home (and therefore home theatre). My house will be built with Insulated Concrete Forms (2.5" of EPS foam on both sides of a 6" concrete core). Sound isolation is very important to my wife; so I am considering having all 4 walls for the home theater made of concrete. In addition the roof could also be made of concrete & EPS. ICF homes in general do a fantastic job of isolating outside noise, but not so sure with low frequency bass notes. I know concrete is a good transmission source, but I figure the 5" of EPS should tone it down a bit. The theater will be in a basement, right under the main living room.

    Cosidering that it will add ~$10K to the cost of the house I dont want to do this and then have to still deal with more isolation.

    Thanks!

    Steve
     
  2. Jeremy.H

    Jeremy.H Auditioning

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    If you look at the designs sprinkled around the net one thing you'll find is that none of them use just concrete walls. If your wife is asking that you cut down on the noise then your best bet is to build a room with in a room.

    Leave a 2" space bewteen the exterior and interior walls & ceiling. Use a floating floor and insulated doors. Look at insulating materials like resilent channels, MLV, mineral insulation, acoustic foam, etc.

    There are some many things that you can, it just depends on how much money and how quiet you want it to be.

    Good luck!
     
  3. chris_everett

    chris_everett Second Unit

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    Well, 6" of concrete has plenty of mass, taking care of one of the three keys of soundproofing. The other two are to make a room airtight, and to build in some seperation, neither of which would be very difficult in this sort of space.

    Seperation could be accomplished with Resilent Channel, as Jeremy mentioned. The EPS foam may also help provide that (how are the walls finished?) On the other hand, you may be able to save $10K and put some of that money into traditional soundproofing and have good results, for less $$$

    The real question is how quiet you need it to be.
     
  4. Steven McCaa

    Steven McCaa Auditioning

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    Perhpas I should be more clear. The core of the walls is concrete, then EPS foam provides the form of the walls (and thermal insulation). On any interior wall it must then be covered with a 30 minute fire barrier (Usually 5/8 wall board.). My line of thinking is that the superior mass of the wall vs. 2x6 studs should help significanlty (80lbs/Sq.Ft). I can still do all the other things that are done with a normal wall. These walls are very air tight. In doing more research I am thinking of the following wall construciton:

    (starting from the HT room going out):

    5/8" QuietRock or Wall board
    Smear of Green Glue or Resiliant Channel?
    5/8" Wall board (Only if Green glue eats EPS)
    2.5" EPS foam
    6" Concrete
    2.5" EPS foam
    Smear of Green Glue (Only if Green glue does not eat EPS)
    5/8" Normal wall board

    Celing could be:
    5/8" Quietrock or Wall board
    Green Glue
    5/8" Wall board
    2"+ EPS
    Concrete
    Subfloor
    Sound isolation padding
    Carpet/Floating hardwood

    I am planing or a fully insluated door (perhaps dual door opeining in opisite directions), and running dedicated AC ducting to the room as well.

    Steve
     
  5. chris_everett

    chris_everett Second Unit

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    I don't know much about the "green glue" so I would be inclined to use Resiliant channel, but other than that I think that that would be a very quiet room.
     
  6. Steven McCaa

    Steven McCaa Auditioning

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    I emailed the Green Glue folks and got some interesting info back.

    First of all it will not attack EPS; but EPS is not dense enough to be a good substrate. It really must go between wallboard.

    They do not reccomend resilient channel as the air gap will have its own resonance.

    By the way the STC of most ICF walls in ~50 vs 34 for standard 2x construction.

    I am leaning now to:
    5/8" Wall board
    Smear of Green Glue
    5/8" Wall board
    2.5" EPS foam
    6" Concrete
    2.5" EPS foam
    5/8" Normal wall board

    Hoping to get to an STC of around 70.

    Steve
     
  7. David Noll

    David Noll Stunt Coordinator

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    Steven,

    Just to understand from a builders perspective...Are ICF, insulated concrete forms, being used for interior walls? Are you doing this just for uniformity in the theater only or all throughout your basement?

    David
     
  8. chris_everett

    chris_everett Second Unit

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    Well, I wouldn't expect the green glue folks to recommend RC, it is effectivly a competing product.....

    Aside from that, you may want to switch one layer of the 5/8" wall board to 1/2". You'll save a couple of $$ and you won't have two layers that resonate at the same frequency.

    Also, an STC of 50 as a starting point isn't bad _at all_ I doubt that my room is any better than that. (Mine is a "garage" HT. Only in the immeditaly adjacent spaces can you tell a movie is playing, even at very high volume levels.)

    One other question. What are you planning to do with the floor? If it's on concrete, you may want to build a subfloor for the subs to sit on, and "float" the subfloor.
     

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