Insulate drip sound in vent pipe?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by mikeandrosalyn, Sep 12, 2007.

  1. mikeandrosalyn

    mikeandrosalyn New Member

    Messages:
    2
    Location:
    Atoka, TN
    We have a 3" PVC pipe in our bathroom that runs up to the attic. The water heater, AC unit and other items are all attached to this vent pipe "system".

    It runs about 10' straight down a wall and then has a 45 degree angle. This is where the "drip" sound occurs.

    How do I insulate it so that it isn't so loud? It is heard from both sides of the wall (bathroom and a bedroom) and is driving me crazy.
  2. patrick88

    patrick88 Plumber

    Messages:
    836
    Location:
    Webster Ma.
    insulate it and the board it up. Make sure you dont cover any clean outs that are in the pipe.
  3. talkingdog

    talkingdog New Member

    Messages:
    33
    Location:
    Kyoto Japan
    What sort of insulation products are there on the market for sound problems in pipes like this?
  4. mikeandrosalyn

    mikeandrosalyn New Member

    Messages:
    2
    Location:
    Atoka, TN
    We tried using "Great Stuff" (you know, that great expanding foam in a can insulation), but that didn't help. Any help you could offer in insulation that will attenuate the noise would be great.

    Right now, it's just a PVC pipe in a hollow wall with the drywall over the top. It's a veritable echo chamber in there.
  5. patrick88

    patrick88 Plumber

    Messages:
    836
    Location:
    Webster Ma.
    i have seen just regular pink or yellow the same stuff you stick in a wall.
  6. insulation in wikipedia will tell you that there are no magic solutions in sound insulation.

    Varying your materials is a good tactic. Some materials block some types of sounds, other materials block others. Do not double up two layers of the same product, that creates a reverberation point so some sounds get amplified instead of reduced.

    Density is one good starting point. That is a part of the reason why cast iron drains make little noise.

    Trapped air in certain configurations is another good starting point. Open-cell foam blocks sound transfer, but closed-cell foam carries sound through its cells and transfers the sound along to the next cell. Some intrawall insulation batts are sold for both heat/cold as well as sound insulation. E.g. Roxul batts.

    I guess you have to open one wall. Use 5/8" fire rated drywall to rebuild it. That stuff is several times denser than regular sheetrock.

    Seal the pipe everywhere. Any gap will carry a lot of sound. Think of it like a gap in an exterior wall when you want to prevent air from leaking into the house during a storm. There has to be at least one layer of something airtight, so you cannot rely on just the fluffy kind of insulation.

    Summary: plan for a multi layered approach, extremely well executed. Include at least one airtight layer, one dense material, and one airfluff layer.

    david
  7. Livin4Real

    Livin4Real New Member

    Messages:
    192
    Location:
    Indianapolis, IN
    Just hit a local car/home audio/video store and pick up some dynamat or other sound-deadening material, cover it up with that. If possible wrap the pipe in it. I do a/v installs on the side and it's great for in-wall/ceiling speakers and anywhere else you need to stop soundwaves or rattles.
    Last edited: Sep 12, 2007
  8. talkingdog

    talkingdog New Member

    Messages:
    33
    Location:
    Kyoto Japan
    The reason why I ask is that we have specific, dedicated sound insulation products on the market here, made for plastic waste lines. It looks like there is a jacket outside with some sort of foamy layer inside, and there are covers for elbows, etc. I am curious as to how effective these are. The makers claim they knock off 10 decibels or something, but I am dubious.
  9. jjamison

    jjamison New Member

    Messages:
    9
    If you have access to the pipe, I'd be tempted to take a saw and put in bend about halfway before the water builds up too much velocity. JJ


  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,270
    Location:
    Cave Creek, Arizona
    drip

    One problem is the drip sound. The other one is that those items are directly connected to the vent in the first place. Doing so, can introduce all kinds of "I smell sewer gas in my house. What is the problem" type of questions.
  11. jjamison

    jjamison New Member

    Messages:
    9
    I don' think a 45 degree jink out and then a 45 degree jink back in line would interfere with the functioning of a 3" vent. jj

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