Passive Radon System in New Home
3900 ft2 house with half of the ft2 in the basement with balanced ventilation and a 0.76 ACH50.
I just finished my home this summer and have been tracking radon levels for a couple of months. My basement was averaging 4.1 pci/L.
We installed 10’ of perforated pipe under slab in the center of the house teed with a 4” pipe that we left plugged in the attic. We just removed the plug and extended this pipe through the roof. I have been monitoring my radon of levels and they have decreased by just over 50%, averaging 1.7 pci/L now.
Should I plan on installing a fan as well or is natural draft likely to sustain these lower radon levels I have experienced since extending my pipe through the roof?
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Any home I design located on the EPA's radon zones 1 & 2, I'll always specify perforated pipe at the interior footing perimeter and attached to a centerly located PVC pipe, and a good idea for zone 3, just in case.
There is really no level of exposure to radon gas that is considered safe, although according to the EPA, anything bellow 4.0 pCi/L is considered "ok". I do believe any level of exposure to radon gas is worth mitigating, and installing a radon vent fan in the attic is usually a good inexpensive solution.
utah_matt,
If the passive system is delivering results you are comfortable with, I don't see why it shouldn't continue to work as it is now.
I would continue to track your radon levels; they change over time. Often wet weather brings higher readings. I always include a passive system and have never needed to add a fan. As Armando said, the 4.0 pCi/L is not a magic line. It was heavily extrapolated from higher levels that were known to cause cancer. Some sources say 8.0 is a safe limit; some say 2.0, some say no level is safe.
Hey Utah Matt, Utah Ryan here.
The fan costs like 100 dollars. Consider now sunk cost on the pipe...the fan will net the biggest gain at this point. My electronic reader is more expensive than the fan, which was by accounts way better information than the single test pads.
I joke with you, but a 4K ft house in Utah is like what, a million dollars? I'd hope on Amazon right now and buy it.
Geology.Utah.gov has it at 2.7 needs remediation, which conveniently is in the middle of the EPA 2-4 suggesting some monetary decision making in the analysis to state 2.7.
American Lung says Utah is small and large area high for radon.
EPA has a really cool view at relative risk rates by concentration of radon between smokers and non smokers.
I'm err on the side of there is nothing wrong with having a desire for 0 and as close as that is success.