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My house's sewer system is encased in the basement floor, and there are sections of the old cast iron system that need to be replaced, including two old floor drains and a rusty section of the kitchen sink drain where it meets the concrete floor.

I understand that replacing these parts of my sewer will mean cutting into the concrete floor. But is there a way to install the new drains such that they can be serviced without concrete work? I know that it's common to install shower rough-ins in a pit of sand, then cover it with a tile. Can that also be done for other parts of a basement sewer system, like a floor drain? If that's not a good idea, why not?

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  • Floor drains might not go into the sewer system...
    – keshlam
    Jan 28, 2023 at 9:38
  • What territory are you in? Are you certain it's a main sewer & not just a spur?
    – Tetsujin
    Jan 28, 2023 at 13:11
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    Use schedule-40 PVC (not thinwall SDR) and provide sufficient clean-out access so it does not need to be dug up again, and it will outlast you. If you can manage to fuss with "foamcrete" on a small scale you can use that as a fill that's a bit easier to break up should you ever need to break it up again, but if you do the pipes right, you won't need to.
    – Ecnerwal
    Jan 28, 2023 at 13:25
  • @keshlam in my house, the floor drains connect to the main sewer.
    – adamj537
    Jan 28, 2023 at 15:02
  • "sections of the old cast iron system that need (?) to be replaced" - how many thousands of years old is your house? need or 'Going to do work and add stuff, so I have to'? I mean, I've seen stubs go bad like what your sink connection must look like (pictures?), but never underground.... That's why Chicago code requires cast iron below grade; it'll last the life of the house and then some.
    – Mazura
    Jan 28, 2023 at 17:58

2 Answers 2

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Added cost, obviously, for a rarely needed access. I'm guessing there might be increased risk of water or radon infiltration if this isn't done well. Tripping hazard if done particularly badly.

In general, I approve of the impulse to allow for future access if you have to open it up at all. But given that drain pipes have an MTBF measured in decades, and when they do fail usually just need to be snaked or flushed (with the exception of tree root problems), I'm not sure of the economics in this case.

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  • Actually a very good time to run a radon test. If you're cutting through the floor anyway, it's easy to put in some radon remediation pipes, should they be needed, before you patch it up again.
    – Ecnerwal
    Jan 28, 2023 at 13:50
  • Might be a good time to think about perimeter drains too, if you have a leakage/flooding risk. More work, but if you have the equipment and expertise on site anyway it's never going to be cheaper.
    – keshlam
    Jan 28, 2023 at 15:19
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I don't know what "service" such an installation could need that would require access at other than the drain fittings themselves. Here's a floor drain with integral cleanout, seems like an outstanding design to me: https://www.supplyhouse.com/Sioux-Chief-800-PPK-2-PVC-WeldOne-Floor-Drain-White-PVC

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