Buying a Home in Indiana? What to Know About Radon Testing

Indiana doesn't get as much attention as some states when people talk about radon, but it should. The majority of Indiana counties fall into EPA Zone 1 or Zone 2, meaning predicted indoor radon levels are moderate to high across most of the state. And unlike Illinois next door, Indiana has no mandatory seller disclosure requirement for radon. That puts the responsibility squarely on you as the buyer.

Indiana's Radon Landscape

The bedrock and glacial soils across Indiana create favorable conditions for radon production. Central and southern Indiana sit on limestone and shale formations that contain naturally occurring uranium. Northern Indiana's glacial till deposits add another layer of radon source material. The Indiana State Department of Health (ISDH) runs the state's radon program and has published county-level data showing that many areas consistently test above the EPA's 4.0 pCi/L action level.

Counties like Hamilton, Hendricks, Johnson, and Marion -- essentially the Indianapolis metro area -- have significant numbers of homes testing above 4.0 pCi/L. But this isn't just an urban issue. Rural counties across the southern half of the state see elevated readings too. The pattern is statewide.

No Disclosure Law Means You're on Your Own

Here's what most Indiana homebuyers don't realize: the seller isn't required to tell you anything about radon. There's no state mandate to test before selling and no requirement to share past results. Some sellers voluntarily disclose, and some listing agents recommend it, but there's no legal obligation.

That means if you skip radon testing during your inspection period, you could move into a home with dangerously elevated levels and not find out until you test on your own later. Don't make that mistake. Add radon testing to your inspection list right alongside the structural inspection and the HVAC check.

How to Get a Radon Test During Your Purchase

The process is straightforward. A certified tester places a continuous radon monitor in the lowest livable level of the home -- typically the basement or ground-floor room over a slab. The test runs for a minimum of 48 hours under closed-house conditions. Results are available shortly after the device is retrieved.

Professional testing in Indiana runs about $100 to $200. Many home inspectors in the state offer radon testing as an add-on service, which can save you the hassle of coordinating a separate appointment. Just confirm the tester holds valid credentials through NRPP, NRSB, or the ISDH radon program.

For a deeper dive into testing methods and what the numbers mean, our complete radon testing guide walks through everything step by step.

Where to Place the Test

Placement matters more than people think. The test device should go in the lowest level that could be used as living space -- even if it's currently unfinished. If the basement has any chance of becoming a rec room, office, or bedroom in the future, test there. Radon levels are highest closest to the soil, so testing an upper floor would give you a misleadingly low result.

Interpreting Results and Next Steps

If your test comes back below 2.0 pCi/L, you're in good shape. Between 2.0 and 3.9, the EPA says to consider mitigation -- especially if you'll spend significant time in that level. At 4.0 pCi/L or above, the EPA recommends taking action to reduce levels.

According to the EPA, radon exposure is the number one cause of lung cancer among non-smokers in the United States. Long-term exposure to elevated levels increases risk progressively. This is a health hazard with a well-established scientific basis, not a theoretical concern.

Negotiating Radon Mitigation Into the Deal

When test results come back elevated, you have leverage. Radon is a documented, measurable health risk, and mitigation has a clear, predictable cost. Most buyers in Indiana handle this one of three ways:

• The seller hires a certified mitigator to install a system before closing and provides post-mitigation test results showing levels below 4.0 pCi/L.
• The buyer receives a credit at closing -- typically $800 to $1,500 for a standard system -- and handles the installation after moving in.
• The purchase price is adjusted downward to account for mitigation costs.

All three approaches are common and reasonable. The key is to have the conversation early, backed by certified test results and a written estimate from a licensed mitigator. Our mitigation cost guide breaks down pricing by system type and foundation.

What Mitigation Looks Like in Indiana Homes

Most Indiana homes have basements, which means sub-slab depressurization is the standard approach. A contractor drills through the basement slab, installs a PVC pipe run to the roof, and attaches an inline fan that creates negative pressure under the foundation. The entire install usually takes less than a day.

Costs range from $800 to $2,500, depending on the home's layout and foundation complexity. Homes with crawlspaces or mixed foundations may cost more due to the additional membrane work involved. Check our Indiana radon page for contractor listings and local pricing context.

After the Purchase: Long-Term Monitoring

Radon levels fluctuate seasonally. Winter readings tend to be higher because closed houses create stronger stack effect, pulling more soil gas indoors. The EPA recommends retesting every two years, and that advice applies whether or not you have a mitigation system installed.

If your home has a mitigation system, verify that the fan is running by checking the system's manometer -- the small U-tube gauge on the pipe. A flat reading means the fan may have failed. Replacement fans are affordable, but you need to catch the problem before radon levels climb back up.

To find certified testers and mitigators in any part of Indiana, visit radon testing near me for a searchable directory of verified professionals.

FAQ

Is radon a deal-breaker when buying a home in Indiana?

No. Elevated radon is common and fixable. A mitigation system is straightforward to install, and the cost is modest compared to most home repairs. The issue is only a deal-breaker if it goes undetected.

Should I test even if the home has a crawlspace instead of a basement?

Yes. Radon enters through any soil contact point, including crawlspaces. Homes with crawlspaces can have elevated radon levels just like homes with basements.

Does a new-construction home need radon testing?

Absolutely. New homes can have high radon levels. Some are built with passive radon-resistant features, but these still need to be verified with a test after the home is occupied.