Dripping main sewer stack- from upper floor rehab

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Jeff Jot, Apr 5, 2021.

  1. Jeff Jot

    Jeff Jot New Member

    Apr 5, 2021
    This is a real puzzle, and I'm hoping it isn't something bad :/
    Just purchased a house 'as-is'..... already closed on it and the deal is done. Its a small house that was divided into a duplex.
    The second floor residence is reached by outside deck stairs.
    What they did was, they closed off the original stairs as a closet inside the house. And on the landing of the stairs, inside the closet--- they put the water heater for the upstairs apartment. So the water is split into two meters, and two water heaters.
    Now, the sink, toilet and shower upstairs, as well as the kitchen faucet have been run all at once, for a long period, flushing, etc. And there apparently is no blockage at all- the drains are working fine.
    Except for one thing.

    Obviously they added these drain pipes for the upstairs and connected it to the main stack. They look to have rusted through and been patched. After running the water for a long time, everything drains as I said, but there is some slight dripping coming from the drain stack here for awhile, every time.

    What I'm worried about, and the only possible thing I can think of..... is that water is backed up and sitting always in the drain stack, sort of like a giant sink trap. And maybe it moves, when the faucets/toilets are used upstairs?
    Maybe by an ill-thought-out drain stack assembly?
    Or am I overthinking this.
    How could the main stack be dripping, and apparently..... rusting through like this?

    Attached Files:

  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    That looks pretty wonky. You might consider cutting some of that out and replacing it.
    Fittings into a horizontal should be wye or combo fittings.
    The do make shielded couplings that are sized to go from old cast to plastic. And also old cast to no-hub cast.
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  4. Jeff Jot

    Jeff Jot New Member

    Apr 5, 2021
    It looks like they used a bunch of old pipe they had on hand to Dr Seuss the thing, but it can't be that old because the house was just converted into a duplex in the last 3 years or so.
    It seems a lot more work than its worth for a drain pipe to cut all that cast iron out, I am inclined to just seal the spots where it leaks real good with pipe sealant.
    I just wondered about the part that appeared rusted through, and if it was an indication that water was backed up/sitting in the pipe.
    Maybe it was.... perhaps there was a clog, and the place sat vacant a long time, then later it was cleared.
  5. Tughillrzr

    Tughillrzr In the Trades

    Jan 29, 2020
    New York
    X2 w terry!!
    It Looks like they used bondo to repair the cast!
    Hey if you plan on using sealant you’ll be like the last guy. No quick fix for that mess. That will just lead to a callback. Just because they converted it recently doesn’t mean it’s new. it’s old. Looks like it was rotted through in spots and someone did a heck of a job. no body wants to thread galvanized drain piping nowadays for the ease of it.
    Last edited: Apr 6, 2021
  6. Tuttles Revenge

    Tuttles Revenge In the Trades

    Oct 15, 2014
    Is it dripping on that horizontal or is the drip coming from above the floor down the PVC? Is it me, an optical illusion or is that PVC cut right above the cast iron?

    The bondo patch on the cast iron is doomed to fail further as the cast gives way and bondo onto rust/wet is never going to hold long term. That section looks like its 2" .. I would at least replace that portion from the last good hub to each of the steel drains/vents.. whatever they are.
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