I noticed in my basement by one of my drains the pipe that goes up to vent is disconnected. It looks like the connection must have rusted and broke free at some point. I believe this means the sewer gases are currently venting into my basement.

I'm wondering what my options are for fixing this. My thoughts so far would be cutting off part of both pipes that create the L connection and attaching PVC (or other plastic) pipe to each end and connecting the PVC in an L shape.

Is this the right away to approach this?

Open to any suggestions as well as answers to the following:

What to use to cut the existing metal pipes? How to properly attach the PVC to the existing pipes? What's the appropriate type of replacement pipe to use?


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  • If you don't smell 'em, then the sewer gasses probably aren't there, so don't panic.
    – FreeMan
    Nov 13, 2023 at 21:29
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    – isherwood
    Nov 13, 2023 at 21:50

2 Answers 2


Cutting - either rent an iron pipe cutter, or use a hacksaw with some care. The pipe cutter will do it clean and quick, the hacksaw is messy.

Joining - "Ferncos" (the "Band-aid" of the flexible rubber coupling market) Which means you can use any brand you like, but some people will know them better as Ferncos even if that's not the brand they are pointing at.

Pipe: PVC (white, usually, plastic) or ABS (black, usually, plastic) rated for (interior) DWV (drain, waste, vent) use.

Strategy: suspect the rest of the joints and replace as much as possible with plastic now, or you might be coming back to do it again later. Up to you.

  • Right. Do the accessible stuff.
    – Ecnerwal
    Nov 13, 2023 at 21:53

I am not a plumber. However, I have a similar problem. Based on my experience, I offer these observations:

  1. Cast iron pipe (CI) OD is smaller than PVC. In my case, the CI is ~4.25", vs 4.5" for PVC. This makes 'normal' couplings (eg, Fernco 1056-44) very sloppy on the CI.
  2. One end of the Fernco 3000-44 "shielded" coupling is a proper fit on the CI. The coupling's full-width metal band will also give a stronger joint.
  3. ... However, that coupling's larger end ID (4.44") is too small for PVC. To match IDs, I'm using a Charlotte #119 adapter coupling.

All of that seems to be much harder than it ought to be. So, I could be daft. Make of it what you will.

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