GUEST AUTHOR: Ryan Paris, Virginia Department of Health

*This is the third of a 4-part weekly series on radon in real estate

Virtually every home can be successfully mitigated. No mitigation system can bring the indoor radon level down to zero, but about 75% of the time, a well-designed system will reduce the radon level below 2.0 pCi/L. Most professional mitigators will only guarantee getting the level below the EPA action level of 4.0 pCi/L.

The most common method uses a collection pipe which penetrates the material located under your slab or crawlspace. This pipe is attached to an electric fan that runs continuously to supply suction. The fan cannot be located in livable space or in any space below livable space, like a basement or crawlspace. The discharge pipe must eventually terminate a minimum of 12 inches above the gutter edge of the roof. Mitigation guidance documents list several other restrictions which help prevent the discharge gas from reentering the house or exiting within anybody’s potential breathing zone. Although it is most efficient to run the pipe through the interior or the home, in most cases, most of the pipe and fan will be attached to the outside of the home. The end of the discharge pipe should be straight up—no cap or deflector is necessary. A screen over the opening is recommended to keep out debris and animals. After the system is running for a minimum of 24 hours, the home should be retested to verify that it has lowered the indoor radon to an acceptable level.


This information and more is presented in greater detail in 1 or 2 hour CE courses that are designed for Virginia REALTORS®. For more information, click here.