Radon in a Columbus home sale: a guide for buyers and sellers

A radon result can land halfway through an inspection period and reshape the rest of a Central Ohio sale within days. What you do next depends on which side of the closing table you sit on, so this guide covers the rules both sides share and then splits into a seller path and a buyer path.

The ground rules Ohio sets for both sides

The disclosure form

Ohio sellers fill out the Residential Property Disclosure Form, required under Revised Code 5302.30 and laid out in Administrative Code rule 1301:5-6-10. Section H, item 4 is titled Radon Gas. The seller answers yes, no, or unknown about any known previous or current presence of radon, gives the level if one is known, and describes any mitigation. The same form tells buyers to do their own due diligence on radon and points them toward EPA and ODH.

The test method

A radon test in a real estate transaction under the Ohio Radon Measurement Protocol lasts at least 48 hours. It uses either two passive devices set side by side or a continuous monitor that records 48 unbroken hours. A buyer, seller, occupant, or agent signs a noninterference agreement, and every entrance carries a posted notice that a radon measurement is underway. At 4.0 pCi/L or higher, the protocol says to fix the home.

Who pays

No Ohio rule decides who pays for mitigation; the bill is settled by negotiation, the same as any other inspection item. The who pays FAQ compares the usual arrangements.

The seller path

Answering the radon item honestly

If you have tested, you know something, and the form asks for it: the result, plus any system in the house. Unknown is an honest answer only when you truly have no information, meaning no past result, no old report tucked into the file from your own purchase, and no pipe in the basement. In practice, an unknown on a house in Franklin, Delaware, Licking, or Fairfield County, all mapped by EPA as Zone 1, works as an invitation for the buyer to test. It postpones the radon question rather than settling it. Our radon disclosure FAQ goes deeper, and wording questions belong with your agent or attorney.

Testing before you list

A pre-listing test moves radon onto your calendar instead of the buyer's. If the number comes back high, you can have a system installed before the first showing and hand buyers a finished job with its paperwork, rather than negotiating against a response deadline. Keep in mind that a result you know about is a result you disclose, so test when you are prepared to act on the answer.

If a system is already running

Gather what a buyer's inspector will ask for: the start-up pressure you were given in writing and the manometer marked with it, the most recent post-mitigation result, and the closeout package with its floor plan drawing and license numbers. For a seller, the strongest radon answer is a recent result plus documents, not a checkbox.

The buyer path

Order the test at the start of the inspection period

A radon test needs at least 48 hours of measurement before anyone reads a result, so it belongs at the front of your inspection period, not the tail end. The real-estate timing FAQ shows how the steps fit together. Whoever places the test for you needs an Ohio radon tester or mitigation specialist license, and that includes a home inspector who offers radon as an add-on.

Protect the conditions

In an occupied house the sellers keep living there during your test, which is exactly why the noninterference agreement and the posted notices exist. Closed-house conditions begin at least 12 hours before any test shorter than 96 hours. A continuous monitor's hourly record makes an opened window visible after the fact, which is useful when the house stays occupied.

Read the result for more than pass or fail

A number under 4.0 is not the same as a clean bill: EPA suggests considering a fix between 2 and 4 pCi/L, and ODH recommends retesting a single-family home every two years. A buyer has the most leverage before the inspection response goes in, so have the result and a written scope in hand by then.

When the result is 4.0 or higher

Get a written scope before the response deadline

Ohio requires a visual inspection and a signed proposal before mitigation begins, and that proposal carries the price, the scope, both license numbers, and a guarantee statement. Getting one written before the inspection response is due means both sides bargain over a real document instead of a guess. See how real-estate radon service fits a sale timeline.

Choose how the cost is handled

Since nothing in Ohio rules assigns the bill, the common arrangements are all negotiated:

• The seller installs a system before closing and hands over the paperwork
• The seller lowers the price or offers a credit, and the buyer arranges the work after closing
• The two sides split the cost
• The buyer takes the house as is and mitigates on their own schedule

Each trade has a cost of its own. When the seller installs, the buyer did not choose the design or the fan location. When the buyer installs after closing, the buyer controls the scope but carries the work into the first weeks of ownership.

Plan the post-mitigation test

The follow-up test has a window that opens 24 hours after the fan is switched on and closes 30 days after it. It may be run by the specialist who installed the system or by an independent licensed tester or specialist. If the seller installs before closing, write into the agreement who runs the follow-up test and when, because that result is the document that closes the loop.

A quick checklist for each side

For sellers:

• Find any past radon result and answer the disclosure item from what you actually know
• If a system exists, collect the closeout package, the start-up pressure, and the latest post-mitigation result
• Weigh a pre-listing test so any fix happens on your schedule

For buyers:

• Book the radon test at the start of the inspection period with an Ohio-licensed tester
• Make sure the noninterference agreement is signed and the notices are posted
• At 4.0 or higher, get a written proposal before the response deadline
• Put who runs the post-mitigation test, and when, in writing

Whichever side you are on, the paperwork you hold on deadline day decides how much room you have. Call or text (380) 221-7233 with your result and your deadline, and we will help you map the next move.