Radon FAQ for Upstate SC Homeowners

It can be. Greenville County is the only SC county in EPA Zone 1, the highest radon-potential category, and initial tests reported to the state program averaged 3.4 pCi/L through June 2022. Some homes measured far higher. Radon varies from house to house, so testing your own home is the only way to know your level.

Greenville County is EPA Zone 1, meaning predicted average indoor levels above 4 pCi/L, and it is the only Zone 1 county in South Carolina. Spartanburg, Anderson, Pickens and Oconee counties are Zone 2. The EPA recommends testing every home regardless of zone, because individual houses can test well above or below their county.

Elevated radon has been found in almost every county in South Carolina, according to the state's radon program. The Upstate tends to run higher than the rest of the state, with Oconee and Greenville counties showing the highest averages among the counties we serve. Statewide averages are lower, but your home's level is what matters.

Most systems use active soil depressurization. A fan pulls air from under the slab or from beneath a sealed crawl space membrane through PVC pipe and vents it above the roofline. That slight vacuum under the home keeps radon from seeping indoors. A manometer on the pipe shows the system is pulling suction.

Most single-family installs are done in one day, and many take just a few hours. Homes with a combination foundation, a large crawl space that needs full membrane coverage, or an interior pipe route through finished space can take longer. Your written quote includes a time estimate so you can plan around it.

Yes. We cover the crawl space floor with a heavy plastic membrane, seal it at the walls, piers and seams, and draw suction from beneath it. This sub-membrane depressurization method is the standard approach for crawl space homes. Some homeowners add full encapsulation at the same time to manage moisture as well.

Yes. Water from private wells can carry dissolved radon, which escapes into the air when you shower, wash dishes or run laundry. Homes on public water rarely have this issue. If you are on a well, a water test shows whether treatment is worth it. Radon-in-water systems typically run $1,200 to $5,000.

South Carolina's Residential Property Condition Disclosure form, in effect since June 2023, asks sellers about known radon gas. No South Carolina law requires a seller to test. If you know your home's radon level, you disclose it. Talk with your real estate agent or attorney about how this applies to your sale.

There is no fixed rule in South Carolina. It is negotiated between buyer and seller, often after a test during the inspection period. Sellers may install a system before closing, offer a credit, or reduce the price. Your agent can advise on the best approach. We can work within a closing timeline.

There is no reliable evidence that a working radon system lowers home value. Many buyers see an installed system with a recent low post-install test as a problem already solved. A system that is neatly installed, labeled and backed by test results tends to give buyers confidence rather than concern.

South Carolina does not issue a state license for radon testing or mitigation professionals. Instead, look for NRPP or AARST certification, which shows training in recognized standards. Ask any company for the credentials of the technician who will do your work. We are happy to share ours on request.