My house has slab heat and the pipes come out of the dirt and go to the heating unit. This is located in my basement and I'm wondering how to seal it to help reduce radon entering the house.

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    What dirt? A photo of what we're talking about would really help. I picture a set of 1/2" pex pipes coming through concrete, which should be naturally sealed pretty well already. It's not clear what the problem is.
    – isherwood
    Jul 30, 2019 at 15:24

2 Answers 2


Unless you have had your house professionallly tested for radon and got a positive (i.e bad) result, do nothing.

If you do have high levels of radon, it's much simpler to install an exhaust fan system, either in the basement or (more properly) by cutting a hole in the basement floor and dropping a 6-inch pvc tube down into the dirt. That acts as the source for a closed-system exhaust fan that should be ducted to the outside.

  • Sticking your head in the sand is not a good answer. You say, “Unless you have had it tested and got a positive result, do nothing.” Wow, I disagree. I’d error on the side of caution and have it tested...and rest easy at night.
    – Lee Sam
    Aug 30, 2019 at 1:44
  • @LeeSam You might want to dial down your paranoia there. Radon risk to non-smokers who don't live in their basement is minimal even when there is radon in the bedrock. Aug 30, 2019 at 11:42
  • Here’s a link to Wikipedia that indicates it’s the second leading cause of lung cancer after smoking. en.m.wikipedia.org/wiki/Radon
    – Lee Sam
    Aug 30, 2019 at 15:00

Most hydronic heating lines have a vapor barrier and insulation below the concrete slab with these layers I doubt you would have a radon problem from the ground but it is always a good idea to test.

A few years back I installed a radon abatement system because of a positive test. The company did the test again and it came back positive, I asked to see the results, no radon in the basement, high levels on the main floor and acceptable levels in the up stairs. The radon was coming from the natural stone counter tops, so if you have a positive report ask to see the test results. I don’t remember where they got the granite but it was a pale rose and they had ~40’ or more in the kitchen. I wish I remembered where they got it from, or if it was because of the color. I have installed darker granite since then and had it tested (negative). I started doing concrete counter tops after that but that is off topic.

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    so the original pale rose granite was 50% U-235 ? :-) Jul 31, 2019 at 18:43
  • @carl witthoft, I do not remember the amount but had never heard of granite being radioactive prior to this ok thinking back it was in the 90’s, the levels were 4-6x the acceptable level, the owner was a lawyer and he got the counters replaced by the company because of the health hazard, I never saw the new counters but a friend did some work for them and said they looked white that’s all I know. Just wanted to put this information out there as I have only seen it 2x in 40 years and both were pale rose (my guess on the color).
    – Ed Beal
    Aug 1, 2019 at 14:30
  • I was joking, a little... certainly in VT and NH there is a lot of granite bedrock with measurable uranium content. Measurable, not even close to health-concerns. Aug 1, 2019 at 15:18
  • @EdBeal I doubt a vapor barrier below a concrete slab would be much resistance against radon. First, the laps are not sealed, and second, it’s punctured with a zillion holes for the grade stakes. (Also, insulation is not a radon barrier.)
    – Lee Sam
    Aug 29, 2019 at 23:15
  • Wow keep on doubting and guessing I have installed radon abatement systems and as of this date 3 systems that were thought to be needed but ended up to be the natural stone that was the source ,,, yessssss keep on guessing because you have not read actual reports , I don’t know what laps are but, I do know grade stakes are at the perimeter. Not in the center of the slab you Do not know anything and I doubt you have ever put in a vapor barrier below a slab that is 100% a radon block and has been required by my state for many years so keep on being an ass Sam I have answered lots of questions u?
    – Ed Beal
    Aug 30, 2019 at 2:16

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