How to Test for Radon and Fix It in Your South Carolina Home

What radon is and why it matters in South Carolina

Radon is a colorless, odorless radioactive gas that seeps into homes from soil and rock beneath the foundation. It forms naturally as uranium breaks down underground and moves up through cracks, gaps, and porous materials into your basement or crawl space. South Carolina's geology—particularly in the Piedmont region and areas with granite bedrock—creates conditions where radon accumulates in some homes and not others, even on the same street.

The U.S. Environmental Protection Agency (EPA) considers radon the second leading cause of lung cancer after smoking. You cannot see, smell, or taste it, which is why testing is the only way to know if your home has a problem. Many South Carolina homes have radon levels above the EPA's action level of 4 picocuries per liter (pCi/L), but the gas is entirely fixable with the right system.

Key Takeaways

• Radon testing takes two to seven days and costs between $100 and $300; a short-term test gives quick results, while a long-term test over 90 days shows your average exposure.
• If your home tests above 4 pCi/L, a radon mitigation system—usually a vent pipe and fan in the basement or crawl space—can reduce levels by 50 to 99 percent.
• Radon mitigation systems cost $800 to $2,500 depending on your home's foundation type and soil conditions, and many can be installed in one to three days.
• South Carolina does not require radon testing before a home sale, but many buyers request it as part of the inspection process.
• A certified radon professional can test your home, interpret results, and design a system tailored to your foundation and soil.

How to test your home for radon

You have two main testing options: a short-term test lasting two to seven days, or a long-term test lasting 90 days or more. A short-term test gives you quick information and costs less, but a long-term test captures seasonal variations and gives a more accurate picture of your year-round exposure. Many homeowners start with a short-term test to see if further investigation is needed.

You can purchase a do-it-yourself radon test kit from hardware stores or online retailers for $15 to $50, then mail it to a lab for analysis. The kit sits in your lowest lived-in area—usually the basement—away from drafts and exterior walls. If you prefer professional testing, a certified radon professional will place monitors, retrieve them after the testing period, and send them to a lab. Professional testing costs $150 to $300 but removes the guesswork about placement and handling.

Test results come back as picocuries per liter (pCi/L). The EPA recommends taking action if your home averages 4 pCi/L or higher. If your first test is between 2 and 4 pCi/L, the EPA suggests considering a mitigation system, especially if you have young children or plan to stay in the home long-term. Some homeowners in the 2 to 4 range choose to retest or install a system for peace of mind.

Radon mitigation systems and how they work

A radon mitigation system works by creating a pressure difference that pulls radon from beneath your foundation and vents it safely outside above your roofline, where it disperses into the atmosphere. The most common system is an active soil depressurization (ASD) system, which uses a vent pipe running from below the foundation through your home to the roof, with a fan that continuously draws radon out.

The system's design depends on your foundation type. Homes with basements typically have a pipe running along an interior wall or through a closet to the roof. Crawl space homes may have the pipe running along an exterior wall or through the rim joist. Slab-on-grade foundations require drilling through the slab to access the soil beneath. A certified radon professional will assess your home's layout, soil type, and ventilation to recommend the best placement.

Most systems reduce radon levels by 50 to 99 percent. After installation, you should retest your home to confirm the system is working. Testing typically happens two to four weeks after installation, once the system has run continuously. If levels remain above 4 pCi/L, the professional can adjust the system or add additional measures.

Cost and timeline for radon mitigation

Radon mitigation systems in South Carolina typically cost $800 to $2,500, depending on your foundation type, soil conditions, and system complexity. A straightforward basement system in a single-story home may cost closer to $800 to $1,200, while a multi-level home or one requiring sub-slab depressurization may run $1,500 to $2,500. Some contractors offer payment plans or financing options.

Installation usually takes one to three days. The contractor will run the vent pipe, install the fan, seal any gaps in your foundation, and test the system before leaving. You may hear the fan running—most modern systems are relatively quiet, though some homeowners notice a low hum. The fan runs continuously and uses electricity similar to a small appliance, adding roughly $10 to $20 per month to your utility bill.

After installation, the system requires minimal maintenance: an annual inspection to check for cracks or damage, and occasional cleaning of the vent pipe if debris accumulates. If the fan fails, replacement typically costs $300 to $600. Many contractors offer warranties on parts and labor, usually one to five years.

Finding a certified radon professional in South Carolina

South Carolina does not license radon professionals at the state level, but the EPA recognizes the National Radon Proficiency Program (NRPP) and the American Association of Radon Scientists and Technologists (AARST) as credible certifications. When hiring someone to test or mitigate radon, ask for their certification number and verify it on the NRPP or AARST website. A certified professional has passed an exam and agrees to follow EPA protocols.

Many home inspectors in South Carolina offer radon testing as part of their services, and some specialize in mitigation as well. You can also search the EPA's list of certified professionals by state, or contact your local health department for referrals. Get at least two quotes before deciding, and ask each contractor to explain their recommended system and why it suits your home.

When comparing quotes, look beyond price. Ask about the contractor's experience with your foundation type, whether they offer a warranty, and how they handle post-installation testing. A contractor who takes time to explain the system and answer your questions is usually a safer choice than one offering the lowest bid without detail.

Radon and home sales in South Carolina

South Carolina has no state law requiring radon testing before a home sale. However, many buyers request radon testing as part of the home inspection process, and some sellers choose to test and mitigate before listing to make their home more attractive. If you are selling, disclosing a radon problem and showing that you have installed a mitigation system can actually strengthen your position, since buyers know the issue is addressed.

If you are buying, radon testing is a reasonable addition to your inspection. Many home inspectors can arrange it, or you can hire a separate certified radon professional. The test results belong to you and inform your decision about the purchase or your negotiating position with the seller.

Radon in different South Carolina regions

Radon risk varies across South Carolina based on geology. The Piedmont region—including areas around Greenville, Spartanburg, and Columbia—sits on granite and metamorphic rock that produces higher radon levels. The Lowcountry and coastal areas, built on sandy soils and marine sediments, typically have lower radon risk, though testing is still worthwhile since individual homes can vary. The EPA publishes radon zone maps by county; you can check your county's risk level on the EPA website, though a map is not a substitute for testing your actual home.

Older homes and those with basements or crawl spaces are more likely to have radon issues than newer construction or homes on slabs, but age and foundation type are not guarantees. The only way to know your home's radon level is to test it.

Frequently Asked Questions

How long does radon testing take?

A short-term test takes two to seven days; a long-term test takes 90 days or more. Short-term tests are faster and cheaper but may not capture seasonal variations. Long-term tests give a more accurate picture of your year-round radon exposure.

Can I install a radon mitigation system myself?

Technically yes, but it is not recommended. A professional knows how to design a system that actually works for your foundation type and soil conditions. Poor installation can leave radon levels unchanged or create other problems. Hiring a certified professional ensures the system meets EPA standards.

Will a radon mitigation system affect my home's resale value?

No—in fact, having a working mitigation system can be a selling point. Buyers are increasingly aware of radon risk, and knowing the problem is solved gives them confidence. Always disclose the system to potential buyers.

Do I need to retest after installing a mitigation system?

Yes. Retesting two to four weeks after installation confirms the system is working and your radon levels have dropped below 4 pCi/L. Most contractors include this retest in their service or offer it at a reduced cost.

What if my radon level is between 2 and 4 pCi/L?

The EPA suggests considering mitigation in this range, especially if you have young children or plan to stay in your home long-term. Some homeowners retest to see if levels fluctuate seasonally, while others install a system for added safety. The decision depends on your comfort level and how long you plan to live there.