There is a pipe in my house that has endured extensive corrosion. I have talked with inspectors and plumbers and everyone agrees that something should be done about it. I have had trouble getting a clear answer on a solution I feel confident about.

The pipe is cast iron and around 6" in diameter. It comes out of a concrete wall and into the floor. I believe that it attaches through the concrete wall into my garage where there is a similar diameter pipe that runs from the floor to the ceiling and possibly connects to a bathroom.

The pipe is very difficult to access. It is in a small room and right next to the furnace. There is just enough space for a single person to be able to walk up to the pipe.

I recently had a plumber come and do some other work for me and asked if he could give me a quote for the pipe. After looking at it he said he had no idea how they would replace it but that it would probably require digging into the concrete and potentially having to jack it up.

He also said that it might be possible to repair the pipe. He said that since it was only for drainage and not under pressure that I might be able to clean it up with a wire brush, cover the corrosion in J-B weld, and then cover the whole thing with flex tape.

I know very little about plumbing but I feel I would be able to perform the repair job the plumber described. I'm concerned though that I would only be obscuring the problem or making it worse.

Can anyone shed some light on this issue and help me to understand if the stated repair approach is acceptable? If it is questionable, how should I go about getting it taken care of?

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  • Can you get to the pipe before it comes through the wall, from the outside?
    – JACK
    Apr 29, 2022 at 19:31
  • Sort of. It appears to run through the concrete for 1 or 2 feet and then has an exposed ~8ft vertical run through my garage. Apr 29, 2022 at 19:58
  • I'm thinking you might be able to replace the 90 degree bend and section through the wall and attach to existing pipe with two Fernco couplings.
    – JACK
    Apr 29, 2022 at 20:08
  • Fernco couplings may not be allowed where you live, and if they are allowed there may be some specific restrictions on how they can be used. Before you start down that path, it would be a good idea to check with your local building inspector. Also keep in mind that rubber couplings are only going to fix what is visible. The corrosion that is most definitely happening under the floor will still need to be dealt with sooner or later.
    – Z4-tier
    Apr 29, 2022 at 21:58
  • Where does it go downward? Out to your sewer/septic drain? This looks like a good option for a blown in pipe liner, but you need to get to both ends.
    – Tim B
    May 3, 2022 at 19:02

1 Answer 1


That looks like it is part of your drain-waste system. It's a little odd the way it comes up and then disappears right into the wall, but it almost certainly is connected to the sewer.

A lot of folks living in houses built during the post-WW2 boom are in the same spot. These cast iron pipes are only made to last 50 to maybe 100 years at most (exactly how long can vary a lot). Once they start to rust, they begin to fall apart need to be replaced. Think about it this way: if that section of the pipe is rusting, do you think the parts that you can't see under the floor are going to be in better shape? The only proper fix is what that plumber suggested, which is to jackhammer into the floor to gain access to the pipes, and replace them.

If you go looking for a deal, you will find plumbers that will happily offer you one. They will offer to patch or repair the rusted out pipe without the digging and for much less money than the guy with the jackhammer. Just know that such repairs invariably fail and leave you in a worse position than before. If you're planning to sell the house very soon and you don't care what you dump on the next guy, go ahead and kick that can down the road. If you want it fixed right, you're not going to like the bill, but at least you'll know it won't be an issue again for a very long time.


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