Exterior wall piping and insulation

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by hans_idle, Jan 26, 2008.

  1. hans_idle

    hans_idle New Member

    Sep 16, 2007
    Sitting on my butt at a desk all day
    Princeton Junction, NJ
    When running ABS through an exterior wall for drain and vent, how does fiberglass insulation get put into place?

    The existing R-13 Fiberglass insulation was installed 2 different ways. In some stud cavities, the ABS was in front of the fiberglass and paper vapor barrier that comes with it. In these cavities, the fiberglass was squished between the ABS and the exterior wall. Does that reduce effectiveness?

    In other cavities, the vapor barrier had been peeled off of the fiberglass, and the ABS was between the fiberglass and paper barrier. In these cavities, the fiberglass was able to flow around the pipes. The paper barrier was stapled to the studs.

    I have to replace a good amount of the insulation, so I'll have to choose which way, or some other way to do it.

  2. fidodie

    fidodie New Member

    Jan 22, 2008
    new jersey
    keep the facing intact, slice up the back of the insulation, or separate along the side of it so te pipe is trapped inside the insulation - best to tuck some behind by peeling from the side, and sliding some behind the pipe.

    holes in the facing of insulation allow air infiltration, which is what they are trying to stop.

    you don't mention where you are, if it is a warm weather climate, slice along the back, cause it doesn't matter if the pipe gets cold...and unless you are in canada, the vent/drain won't freeze because of the nice warm gas emitted from below!
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  4. Redwood

    Redwood Master Plumber

    Dec 15, 2007
    Service Plumber
    A drain will not freeze because it drains dry after use. Drains only freeze when clogged, when the line has a belly in it, a faucet is dripping, or, toilet flapper is leaking. The low flow does not carry enough warmth with it and freezes in the pipe.
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