Condo sound proofing ...

Discussion in 'Insulation and Radiant Barriers' started by condo, Oct 23, 2011.

  1. Oct 23, 2011 #1

    condo

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    I have a two story condo that shares a common wall with a single story (vaulted ceiling) unit. I am going to be attempting some soundproofing on the common wall which is a staggered double stud wall. My plan at this time for the wall is to use Green Glue and 5/8" drywall.

    My question is regarding the floor joist cavity area that abuts the common wall. The joist run perpendicular or 90 degrees to the common wall. I would like some opinions on what might be a good way to reduce the noise transmission in the area between the 12"-joists where the floor meets the wall, not sure of the spacing yet.

    If I have to I can access that area buy cutting an opening in the drywall ceiling from below. I was think about caulking and batt insulation a foot or two of that area next to the common wall but after reading the "Sound Proofing with blown in insulation" thread it sounds like that might not be too effective.

    Thank ...
     
    Last edited: Oct 23, 2011
  2. Oct 24, 2011 #2

    isola96

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    I think you answered your own question on how to do this, the good thing about Batt is you can cut it to any shape u want.
     
  3. Oct 24, 2011 #3

    condo

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    What type of insulation material would be most effective for that application?
     
  4. Oct 24, 2011 #4

    isola96

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    You dont want blown in insulation that's if your doing a hole floor or entire house
    The batt is what u want put the spray foam in a can in any cracks you see.
     
  5. Oct 24, 2011 #5

    condo

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    Fiberglass?

    With or without foil or paper backing?
     
  6. Oct 24, 2011 #6

    condo

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    I guess I'll seal then a layer of fiberglass insulation and top that with cotton batt or Roxul maybe ...

    Thanks ...
     
  7. Oct 24, 2011 #7

    isola96

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  8. Oct 24, 2011 #8

    condo

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    Thanks but way over budget, the green glue and drywall for one small room are less than one 5"x8' batt.
     
  9. Oct 24, 2011 #9

    isola96

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    Oh ok sorry about that.
     
  10. Oct 24, 2011 #10

    nealtw

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    If you have staggared 2x4 studs in a 2x6 wall you will have limited success because the the 2x6 top and bottom plates are common and they transfer sound to your joists.
     
  11. Oct 25, 2011 #11

    condo

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    Thought that might be the case but I still want to address the things I can do something about and I won't know how much of a problem that will actually be till I do the GG and drywall.

    I'm going to evaluate room by room as I go though. Starting with the masterbath which is affected the most, on the upstairs floor anyway.

    I'm more worried about one drywall layer not being enough on the walls but before I do two layers upstairs it probably makes sense to do the first layer on the bottom floor first ???
     
  12. Oct 25, 2011 #12

    isola96

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    We're are you doubling up on drywall?... Not on ceiling I hope.

    Sent from my iPhone iOS5
     
  13. Oct 25, 2011 #13

    condo

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    Not planning on doing anything to the ceilings at this point, just the walls ...
     
  14. Oct 25, 2011 #14

    Ted White

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    Here's a general rule about insulation in an acoustical wall or ceiling application: Nothing works better than cheap fiberglass. You could spend big money on exotic insulation, but performance will not improve.

    You could build a formidible wall between you and your neighbor, but the ceiling, floor, and two side walls could allow sound to pass AROUND your new wall. This is flanking: FlankingSoundproofing Company

    The primary path betwen you and your neighbor is through that common wall, so treating it alone will bring some relief, but there will likely be a flanking issue that will ultimately define the results.
     
  15. Oct 25, 2011 #15

    condo

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    Great thanks ...


    One other area I am not sure what if anything I do about is in the second bathroom the tub/shower combo is located on the common wall.
     
  16. Oct 25, 2011 #16

    Ted White

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    That shower usually replaces drywall in that general area. So any little tapping (water) on the fiberglass shower will transmit effectively into the wall cavity. There it can travel up, down, sideways and of course straight into the neighbor's area. Any remediation at this point would be a major remodel.

    Having said that, I would assume a fire rated wall is in place, meaning both your side and their side likely has a single layer of 5/8" drywall. Still, remediation at this point would be a major remodel.
     
  17. Oct 25, 2011 #17

    condo

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    Would blown in insulation or spray foam help for that location?

    Also I have warped stud in the wall (creating a hump) that I am wondering if that would create a contact point with the drywall. Should I precoat that area with Green Glue and allow it to set up a bit?

    Is it ok to apply the Green Glue to the wall instead of the drywall?
    The reason I ask is it might be easier working in the limited space Masterbath to do that.
     
  18. Oct 25, 2011 #18

    Ted White

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    Blown in is tempting, but there's a great risk of compaction. If the insulation becomes overly compressed / compacted, it will conduct a vibration. This is the problem with foam. It's too dense and conducts a vibration readily. Doesn't matter if it is open or closed cell.

    Pre-coating a stud with Green Glue will not help at all. Too much vibration at that contact point means conduction will continue.

    You can apply the GG to the existing wall, or the back of the new drywall. Either way will work
     
  19. Oct 25, 2011 #19

    condo

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    Was thinking of pre-coating (running a bead) on the hump in the drywall between the second layer of drywall to help maintain the required gap. I would think if the GG set up a bit ( just a bead or so) that it might prevent contact at that point.

    Will the GG sag much in vertical application?
     
  20. Oct 25, 2011 #20

    Ted White

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    Regarding point #1, GG on the framing is not helping. You need to avoid contact. Consider a block plane and shaving that piece.

    GG will not sag because it is only used sandwiched between two sheets of building material that are thoroughly screwed together. There is nothing to sag
     

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