enter image description hereI have been experiencing flooding in my basement. I think the water is coming from the pipe installed in slab for radon mitigation. I don't believe the basement was flooding before (I just closed on house in July, the seller did not disclose water issues and they stored a ton of boxes on basement floor and didn't appear to have water damage). Is this normal? I have also attached a picture of the pipe in the slab and there is a pretty large gap- is this standard or shoddy workmanship? Will simply sealing this properly fix the issue?

  • Is it possibly from condensation on the outside of the pipe? We have that, in warm humid weather. It produces quite a bit of water on the floor.
    – George
    Oct 28, 2019 at 2:19
  • you should also clean/improve your gutters; even if you plug the seepage, you don't want that area wetter than needed.
    – dandavis
    Oct 28, 2019 at 17:03

1 Answer 1


The radon pipe should be tightly sealed through the basement floor. If that gap you identified goes though the floor, then it should be sealed up because the system is supposed to vent radon from the soil. That opening would prevent that from happening and if you had a lot of rain, you could get water rising up through that gap.

Wait until the basement dries out and then play detective to see if you can determine where the water comes from. If it comes from some other cracks in the walls or floor, they should be sealed up to increase the effectiveness of your radon system and to stop the water seepage.

  • 1
    Normally sealed with hydraulic cement, this is important not only to prevent water entry but also so the radon can’t find an easy in.+
    – Ed Beal
    Oct 28, 2019 at 0:12

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