Radon and Home Sales in Indiana — What Buyers and Sellers Need to Know

March 2, 2026

Radon has become a standard part of Indiana home transactions. In Indiana’s high-radon counties — most of the state — buyers, agents, and lenders increasingly expect a radon test during the inspection period. Here’s what both sides need to know.

Indiana Radon Disclosure Law

Indiana does not have a specific radon disclosure statute. However, Indiana’s general property disclosure law (IC 32-21-5) requires sellers to disclose known material defects that affect the property’s value or habitability.

Practical implication: If you as a seller have a prior radon test showing elevated levels and have not mitigated, that test result is likely a required disclosure under the general law. An undisclosed, known-elevated radon level that surfaces post-closing can expose you to legal liability.

If you have a mitigation system: Disclose it. Show the buyer the pre- and post-mitigation test results. A documented, working mitigation system is a selling point, not a liability.

The Inspection Contingency

Most Indiana purchase agreements include a home inspection contingency. Radon testing typically happens during this period. The standard process:

1. Buyer orders radon test. Usually done simultaneously with the home inspection. Cost: $100–$200 for a certified tester, or the inspector may include it.
2. 48–96 hour test period. Doors and windows must remain closed during the test.
3. Results returned. If below 4 pCi/L — transaction continues. If at or above 4 pCi/L — negotiation begins.
4. Negotiation within contingency window. Parties negotiate who installs a system, covers the cost, or adjusts the price.

When the Test Comes Back High

If the test exceeds 4 pCi/L, buyers typically request one of the following:

Option 1: Seller installs and pays for mitigation. The seller hires a licensed Indiana radon mitigator, installs the system, and provides the post-mitigation test result showing levels below 4 pCi/L before closing. This is the cleanest resolution — the problem is verified fixed.

Option 2: Price reduction or closing credit. The buyer accepts the property as-is and receives a price reduction or closing credit to cover mitigation after closing. Expect quotes of $1,200–$2,000 for a standard Indiana home. Buyers sometimes request a larger credit to account for the hassle.

Option 3: Walk away. If within the inspection contingency window and no agreement is reached, the buyer can terminate and receive the earnest money deposit back.

For Sellers: How to Get Ahead of Radon

If your home is in a Zone 1 county — which covers most of Indiana — consider testing before listing. Benefits:

• Eliminates radon as an inspection surprise
• If elevated, you can mitigate at your pace and budget (not under a closing deadline)
• A working system with documented results is a marketing positive for buyers
• Removes negotiating leverage from the buyer

Cost to test yourself: $15–30 for a hardware store short-term kit, or $100–200 for a certified licensed tester (whose results carry more weight in a transaction).

For Buyers: Radon in Your Inspection Offer

If purchasing in Indiana, include radon testing in your inspection contingency. Do not waive it. Indiana’s Zone 1 counties — including Marion, Hamilton, Hendricks, Johnson, and most of the state — have genuine elevated risk.

Key points:

• A certified test (performed by a licensed Indiana tester) carries more weight than a DIY kit in negotiations
• If a system is already present, request documentation of the post-mitigation test result and current system function
• A manometer (U-tube gauge) on the system should show negative pressure — if it is flat, the fan may be off or failed

For Sellers With Existing Mitigation Systems

If your home already has a mitigation system:

• Have a current radon test run ($100–200) showing levels below 4 pCi/L
• Locate the original installation paperwork showing pre- and post-mitigation levels
• Check the manometer on the system to confirm the fan is running
• Disclose the system’s existence in the property disclosure

A properly documented, working mitigation system can accelerate the transaction and remove radon as a negotiation point entirely.

Finding a Licensed Indiana Radon Professional

For real estate transactions, use a contractor with an active Indiana IPLA license. A licensed tester’s certified measurement carries more evidentiary weight in negotiations than a DIY kit. A licensed mitigator’s installation satisfies Indiana’s professional standard.

Browse licensed Indiana contractors by county on this site — every profile shows an IPLA-verified license number and status.