Radon often comes up during the home inspection window, when there’s little time and a lot of money at stake. Here’s how to handle it without blowing your deadline.
For buyers
1. Ask for existing results first. Ask the seller for any radon test results and, if there’s already a system, any paperwork about it [EPA-4].
2. Decide whether to accept the seller’s test. The EPA’s buyer and seller guide suggests asking for a new test if, for example, the last test isn’t recent (within about two years), the house has been renovated since, or you plan to use a lower level than the one that was tested [EPA-4].
3. Put radon in the contract. The EPA suggests the contract spell out who tests, when, who pays, how results are shared, and what happens if the result is high [EPA-4].
4. Use a short-term test that fits the timeline. The EPA describes short-term options for real estate tests, including continuous monitors and simultaneous tests, done under closed-house conditions [EPA-4]. Ohio’s health department adds: test in the lowest level that could be lived in, for at least 48 hours [OH-1].
5. If the result is 4 pCi/L or higher, negotiate. Common options are (a) the seller installs a system using a certified installer before closing and provides a post-mitigation test, (b) a price credit, or (c) an escrow holdback. Each has trade-offs. With a credit, you choose the installer and control the quality.
6. If the seller installs the system, ask for the installer’s credential number, the system design, the warranty (and whether it transfers to you), and a post-mitigation test done no sooner than 24 hours after the system starts and within 30 days [EPA-3].
For sellers
- Testing before you list avoids surprises in the middle of a deal. The Ohio Department of Health recommends sellers test before selling [OH-1].
- Keep your records. Many states require you to disclose what you know (see below).
- If you already have a system, retest if the last test is more than two years old [OH-1][EPA-3], and gather the installer’s paperwork.
- If you need a system quickly, filter RadonCosts listings by “real estate / fast turnaround” (shown when the installer says so on their website).
State disclosure rules (selected states)
| State | What the law requires | Source |
|---|---|---|
| Illinois | Before the buyer is bound by a contract, the seller must give the buyer the IEMA pamphlet “Radon Testing Guidelines for Real Estate Transactions” and the Illinois Disclosure of Information on Radon Hazards. The seller must also share any records showing elevated radon that they have. Testing and mitigation are not required. | 420 ILCS 46/10 [IL-2] |
| Minnesota | Before signing a sale agreement, the seller must disclose in writing what they know about radon: whether tests were done, the latest records, any mitigation and system details. The disclosure includes a radon warning statement, and the seller must provide MDH’s “Radon in Real Estate Transactions” publication. Effective for agreements from Jan 1, 2014. | Minn. Stat. § 144.496 [MN-3] |
| Ohio | The state Residential Property Disclosure Form asks whether the seller knows of radon gas and the level, if known. | Ohio Residential Property Disclosure Form [OH-3]; ORC 5302.30 [OH-4] |
| Pennsylvania | The seller’s property disclosure must cover the “presence of hazardous substances.” Radon testing and mitigation must be done by DEP-certified people when done for others. | 68 Pa.C.S. § 7304 [PA-5]; 25 Pa. Code § 240 [PA-6] |
| Iowa | Credentialed testers and mitigators must report test results and work to Iowa HHS. State law ties radon test disclosure to real estate transactions under Iowa Code § 558A.4(2). | Iowa Code §§ 136B.1–136B.2 [IA-3][IA-4] |
This is a summary, not legal advice. Disclosure forms change, so confirm current requirements with your agent or attorney.
Timeline tips
- Book the test the day your offer is accepted. Many inspection windows are 7–10 days. (This is a typical range, so check your contract.)
- Line up two or three installer quotes as soon as you have a high result, even before you finish negotiating.
- Ask installers how soon they can install and test. A post-mitigation test can’t start until 24 hours after the system is running [EPA-3].