GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

radon mitigation; climate zone 6 in central Maine, HRV?

maine_dorothy | Posted in General Questions on
We are selling 1.5 story 1989 home (yikes, our closing is in 3 weeks), 645 sq ft dry basement with concrete floor /walls. Basement radon level is 11.7. The house was relatively tight for 1989, but not by current standards. Concrete is over native very deep sandy soil–no gravel, no plastic. Unfortunately, the basement has about 40 sq ft of exposed earth floor (for a root cellar that was never added.) No apparent cracks, one drain (never needed) and and one incoming pipe from our well. In 2006, house was enlarged with 2 slabs/frost walls that flanked opposite sides of the basement. There is plastic and foam under these slabs. Slabs add about 500 sq ft to house. Mitigator has requested 2 more radon tests on main floor (being done today) over the slab additions before finalizing recommendation, but I think he is leaning towards HRV. If we do sub-slab depressurization of basement, it may require outside vent and fan given difficulty getting vent pipe to attic (there is one iffy route up through theĀ  house). I would like to hear your thoughts and recommendations. Thank you.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Tim_O | | #1

    We recently had Radon mitigation done at my house. Level was about 18 beforehand. In our case, they sealed off the sump, extracted from there and ran a tube out into the garage and through the attic. Pretty simple approach. Our level is around 0.5-1 now.
    With that said, it doesn't need to exit through the attic, it can go out the side of the house. Unfortunately, you'll be stuck with a pipe running up the side of your house then. It does need to exit above the roof. It sort of sounds like none of this is an option for you though?

    My initial thought with the HRV is that you are not addressing it at the source, which would be the ground. But with your exposed dirt area, having the HRV right there might be basically attacking at the source.

    These guys had pretty good luck with an HRV. It does sound like they put it at max ventilation. Even with an HRV, you are exhausting a decent chunk of heat then.

    One final note - when I found my issue, I had bought a digital meter. I put it in different areas of the basement, eventually putting it right next to the sump where it read by far the highest value. Maybe something to consider? Verify that your exposed dirt is truly the source.

  2. maine_dorothy | | #2

    thanks Tim_O;
    radon test levels main floor over slabs averaged 2.2. I bought my meter. I think I found a route from basement to roof.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |