best way to soundproof a ceiling?

Discussion in 'Archived Threads 2001-2004' started by chris larralde, Aug 8, 2001.

  1. chris larralde

    chris larralde Stunt Coordinator

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    My (soon-to-be) home theater resides directly under my son's bedroom, so I'd like to make the ceiling (his floor) as acoustically dead as possible. Right now I'm looking at a bunch of 2x6s -- no insulation or drywall. I've got an empty canvas to work with so bring on the suggestions! I think it goes without saying that I'll put up double drywall, but are there other techniques or materials to consider?
    regards,
    chris
     
  2. Ted White

    Ted White Agent

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    Chris,
    Yes there sure are better ways than simply installing drywall. Let me ask:
    What is the distance from the existing floor to the underside of the joists above?
    You mentioned you have open joists there now. What is there as far as wiring, plumbing, ductwork, etc?
    Lastly, What is the width of the room you have now?
    This will give a good indication as to what can be done to reduce the sound transmission.
    Ted
     
  3. Jens Raethel

    Jens Raethel Second Unit

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    Chris-
    Take a look at my theater cinemax.
    There is hope! [​IMG]
    ------------------
    Go see my new theater CINEMAX! updated 2001-08-01
    Then please sign my guestbook!!
    [​IMG]
    http://cine-max.tripod.com/cinemax/
     
  4. Howard_A

    Howard_A Stunt Coordinator

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    I used sound-deadening spray on all the vents and pipes in the ceiling and walls.
    I also had them install rolls of insulation in the ceiling and walls.
    I requested asphalt-impregnated sheathing as the first layer, and sheetrock on top of that.
    In the room above I installed rolls of WeatherWatch underneath the pad and carpet. It's basically a sheet of rubber that self-seals around nails and staples.
    You can also install sound channel or a suspended ceiling in you have the headroom.
     
  5. chris larralde

    chris larralde Stunt Coordinator

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    How about doubling up on the R11 insulation? Never hear of anyone doing that but it sounds like a good idea
    regards,
    chris
     
  6. chris larralde

    chris larralde Stunt Coordinator

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    Ted,
    My room is a bit narrow -- 9.5 X 13
    The ceiling is wired for a light fixture and has a heating duct running the length of the room ... that's it. Ceiling height is the typical 8 ft.
    Forgot to mention that I'll be using a projector with a screen covering the window at the far end of the room. This setup gives me a 110" 16X9 image [​IMG]
    I'm also on the ground level with a cement floor and cement foundation that comes up about 3 ft.
    chris
     
  7. Ted White

    Ted White Agent

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    Chris,
    The best approach is to "de-couple" the theater from the rest of the house. The theory employs a second inner wall and second ceiling. If the inner wall / ceiling envelope vibrates from bass, it will be difficult for the vibration to "jump" across the airspace between the inner wall / ceiling and the outer walls.
    This practice doesn't come without a price. It will reduce your width and length by 1 foot each way. You're fortunate because your ceiling joists above are open and generally unused. You'll be able to insert a floating ceiling into this existing ceiling, effectively losing only 2".
    As you mull this all over, please keep in mind that the sound will "flank" or go around whatever acoustic barrier you erect. That is, if you beef up your ceiling with double drywall, etc, but leave the walls as-is, the sound will simply penetrate the walls and travel up. This kind of isolation needs to be viewed as an entire system approach for a solution.
    When you say the room is narrow, can either wall be opened up or moved out?
    Final thought... Mass is the defense against bass. Insulation is needed, but doubling or tripling won't help you. Double layers of drywall give a significant mass to stop bass.
    Ted
     
  8. chris larralde

    chris larralde Stunt Coordinator

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    This may sound like a dumb question, but here goes:
    Doesn't added insulation = added mass? I keep hearing that it won't help, but I'm not sure I understand. I may be missing some very simple concept here [​IMG]
    Could you also expand on the floating ceiling. I understand the concept, but I'm trying to visualize how I would only lose 2" instead of 1' ... once again, I'm not quite getting it.
    Thanks so much for all of your input!
    Oh, I almost forgot -- I can't expand the width of the room unless I want to get into some remodeling that I'm not ready for.
    regards,
    chris
     
  9. Ted White

    Ted White Agent

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    Chris,
    These are not bad questions at all.
    First a couple points of clarification. The reduction in width is maybe 6" per side. Also, with respect to "mass", a better word would be "density". Fiberglass, even compressed somewhat, still isn't dense enough to stop bass waves.
    The Floating Ceiling requires that you insert new joists in between the old ones. They run paralell to the old ones. The ends of the new "floating joists" rest atop the interior theater walls. The new joists are set 2" lower than the old ones, so that whan you attach drywall to them, the drywall will never contact the old joists. No contact = no (little) vibration transmission.
    So the entire system isn't connected at all to the old. The inner theater walls are separated from the existing walls by 1 to 2". If these new inner walls get vibrated via bass, they can't easily pass this vibration along becaose there's no physical contact. The floating ceiling rests atop these interior walls, so at best the vibrating ceiling will vibrate the inner walls, and who cares?
    Does this make sense? The floating ceiling can be difficult to visualize.
    Ted
     
  10. chris larralde

    chris larralde Stunt Coordinator

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    I do get it now ... thanks a lot!
     

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