Putting your Ohio home on the market is stressful enough without unexpected surprises during inspection. If your home has elevated radon, or you suspect it might, here is exactly what Ohio law requires of you, what buyers will expect, and how to keep your closing date on track.
Under Ohio Revised Code Section 5302.30, sellers must disclose the known presence of radon gas on the Residential Property Disclosure Form. While testing is not legally required, any prior radon test results, even old ones, must be shared with potential buyers. A documented mitigation system can resolve buyer concerns and preserve your closing timeline.
Radon is the silent variable in many Ohio home sales. It is invisible, odorless, and naturally occurring. Ohio sits in EPA Radon Zone 1, the highest-risk category in the country. According to the Ohio Department of Health, approximately 1 in 3 Ohio homes has elevated radon levels above the EPA action level of 4.0 pCi/L.
For sellers in Columbus and across Central Ohio, that means the question is rarely if radon will come up during your sale. It is when, and how prepared you are when it does.
What Ohio Disclosure Law Actually Requires
Disclosure applies only to known information. Ohio law does not require sellers to test for radon. But if you have ever tested, or if you know radon is present, that information must be disclosed in good faith. Failing to disclose known elevated levels can expose sellers to legal liability after closing, including rescission of the sale.
Ohio Revised Code Section 5302.30, known as the Residential Property Disclosure Act, requires sellers of residential property with one to four units to deliver a completed disclosure form to prospective buyers before the purchase agreement is finalized.
The form, prescribed under Ohio Administrative Code 1301:5-6-10, requires sellers to disclose the presence of hazardous materials including radon gas, lead-based paint, asbestos, and urea-formaldehyde foam insulation.
Translation: if a previous owner installed a mitigation system, or if you tested two years ago and got a high reading, that result follows the home. The Ohio Association of Realtors notes that real estate professionals who know about elevated radon and fail to disclose it also risk liability.
Should You Test Before Listing?
Yes, and the reasoning is strategic, not just legal.
Most buyers in Central Ohio request a radon test as part of their inspection contingency, which Ohio purchase agreements typically allow for 10 to 14 days. If your home tests high during that window, you have a tight clock to negotiate, mitigate, and verify results before closing.
Testing before you list flips the timing in your favor:
- You control the testing company, the timing, and the documentation
- If levels are elevated, you can mitigate calmly, not under closing pressure
- You enter the market with a “documented & resolved” story, not a “buyer-discovered problem”
- You remove the single most common inspection-period renegotiation in Central Ohio
Ohio homes test above the EPA action level of 4.0 pCi/L. Ohio ranks 4th nationally for average radon levels.
What If My Home Tests High?
Elevated radon is not a deal-breaker. The National Radon Program Services (operated by the EPA and Kansas State University) is explicit on this: “Any level should not be a deterrent to buying a home because radon can almost always be reduced.”
A professionally installed mitigation system reduces radon by up to 99 percent, typically bringing levels below 2.0 pCi/L, well under the EPA’s 4.0 action threshold.
Most Central Ohio homes use sub-slab depressurization, which routes a PVC pipe and fan from beneath the foundation through the home or along an exterior wall, terminating above the roofline. Installation usually takes 4 to 8 hours. A post-mitigation test runs 48 hours to verify the system is working.
The 5-Step Seller's Process
Whether you find out about radon before listing or during the buyer’s inspection, here is the path forward:
Test the home
A licensed Ohio professional uses a continuous radon monitor to measure levels over 48 hours under closed-building conditions. Results are documented for disclosure and negotiation purposes.
Review the results
Below 4.0 pCi/L, no action is legally required, but document the result for disclosure. At 4.0 or higher, the EPA recommends mitigation. Between 2.0 and 4.0, mitigation is optional but increasingly common.
Mitigate if needed
A certified Ohio Department of Health-licensed contractor designs a system based on your home’s foundation type, structure, and radon levels. Installation typically takes a single day.
Verify with a post-mitigation test
A second 48-hour test confirms radon levels are below the EPA action level. Reputable contractors include this in their installation package and provide written results.
Disclose and document
Note the test results and mitigation system on the Residential Property Disclosure Form. Provide buyers with the system warranty and post-mitigation test report. These turn a concern into a selling point.
Who Pays for Mitigation: Buyer or Seller?
This is one of the most common Ohio real estate questions, and there is no single answer. It depends on market conditions and negotiation.
The most common scenarios in Central Ohio:
- Seller installs the system before closing. Most common when results come back at or above 4.0 pCi/L. The seller controls the contractor, timing, and warranty, and the home closes with documented mitigation in place.
- Seller provides a credit at closing. The buyer receives funds (often the full estimated mitigation cost plus a buffer) and arranges installation after closing. Buyers sometimes prefer this because they can choose their own contractor.
- Cost split. In hot seller’s markets, buyers may absorb part of the cost to keep their offer competitive. Less common in cooler markets.
- Pre-listing mitigation. The seller mitigates before listing, eliminating the negotiation entirely. Buyers in Zone 1 areas often prefer homes with documented mitigation already in place.
Does Radon Mitigation Affect Home Value?
A documented mitigation system is an asset, not a liability. It signals to buyers that the home has been tested, addressed, and protected. In a region where roughly one in three homes tests above the action level, that documentation removes uncertainty, and uncertainty is what kills deals.
Homes with untested or unaddressed radon often see a drop in market value because buyers factor in both the cost of mitigation and the perceived risk. Homes with installed and verified systems do not carry that discount
Common Seller Mistakes to Avoid
- Hoping the buyer won’t test. Most Central Ohio buyers test. Pretending the issue does not exist almost guarantees a rushed renegotiation later.
- Hiding prior test results. Old test results are still material disclosure items under Ohio law. Concealment creates legal exposure long after closing.
- Hiring an unlicensed contractor. Ohio requires radon mitigation contractors to be licensed by the Ohio Department of Health. Unlicensed work may not be accepted by buyers, lenders, or insurers.
- Skipping the post-mitigation test. Without verified results showing levels below 4.0 pCi/L, the work is incomplete. Buyers will ask for that document.
- Waiting until inspection week. By the time the buyer’s test comes back high, you have days, not weeks, to resolve it without delaying closing.
Selling Your Home? Don't Let Radon Delay Your Closing.
Our state-licensed, NRPP-certified team understands real estate timelines. We test, mitigate, and verify. Fast, accurate, and ready for closing.