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Should I install passive radon system under slab on grade foundation

bill328 | Posted in General Questions on

I am in the process of designing a passive solar home with a slab on grade foundation. I have been finding hints here and there of people installing passive radon systems in slab foundations but I can’t find any definitive resources discussing it specifically. I am in an area with high radon threat. The systems I am seeing are simply perforated pipes located in the crushed stone beneath the slab (along with all the water and electrical lines) which then gets vented from the roof. Does anyone have any definitive resources discussing the efficacy of these types of systems? Waste of time or absolutely worth it? Please help as we are nearing the building permit submission.

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  1. Jon_R | | #1

    They definitely reduce radon. Efficiency depends on getting the system as airtight as possible.

  2. Expert Member
  3. walta100 | | #3

    I think you would be crazy not install a passive system that you could easily add a fan to making it a powered system if your test comes back to high. The install cost should be low before construction.

    Made sure you have a several inches if clean rock under your slab and consider 2 or more passive systems if your home is large and spread out.


  4. Expert Member


    It's also worth checking the requirements of whatever building code you are under. Many make radon mitigation mandatory.

  5. woobagoobaa | | #5

    The cost to add the radon mitigation system to a new build will be well within the noise of your budget.

    BSC's view is here ...

  6. jberks | | #6

    Is a radon system necessary for a slab on grade? (Other than a radon rated poly sheeting under the slab) Certainly it would be worth doing it for a basement.

    Otherwise, how I built a passive system is just using the interior weeping system. I ran them to a venting sump basin and vented it with the plumbing vent. This is with the expectation that the stack effect will draw radon out. So basically other than the radon poly, there isn't really much of an added cost.

  7. bill328 | | #7

    Great stuff! Thanks everyone for helping.

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