Radon when buying or selling a home

Many radon tests happen during a home sale. That is a good moment: the buyer learns the level before closing, and a fix can be negotiated like any other repair.

For buyers

EPA’s Home Buyer’s and Seller’s Guide to Radon recommends that buyers ask whether the home has been tested and, if it has, whether the test was done correctly and recently. EPA notes a buyer may reasonably ask for a new test if:

• the earlier test did not follow EPA’s testing checklist,
• the last test is not recent (EPA gives the example of within two years),
• the house was renovated or altered after the test, or
• the buyer plans to live in a lower level than the one tested, such as a basement that could be finished.

Radon testing is often an optional add-on to a home inspection. Include it in the contract with a clear timeline and a plan for what happens if the result is 4 pCi/L or higher, such as a seller-installed system or a credit.

For sellers

If you have tested, EPA suggests reviewing whether the test followed its checklist, then sharing the results with buyers. If your home has a mitigation system, share its details, the post-installation test result, and any maintenance records. A working system with a recent low result is a selling point.

Fast test options

Real estate timelines rarely allow a three-month test. EPA’s guide describes approaches that deliver results within days, such as:

• two short-term tests placed side by side at the same time, averaged, or
• a continuous radon monitor run by a professional for at least 48 hours.

The decision point is the same as for any home: fix if the average is 4 pCi/L or higher.

Protecting the test

A seller’s activity can affect a result, for example by opening windows. Professionals often use tamper-evident devices or monitors that log movement and conditions. Many states require that real estate radon tests be performed by credentialed testers; check with your state program on our state pages.

Disclosure rules vary by state

Some states require sellers to disclose known radon test results or provide buyers with radon information; others do not. Your state radon program and your real estate agent can tell you the local rules.

New construction

If you are buying a newly built home, ask whether it has radon-resistant features and whether it was tested after completion. See radon-resistant new construction.

Quick checklist

• Ask for existing results and mitigation records.
• Put a radon test and a remedy plan in the contract.
• Use a credentialed tester where required.
• Plan on retesting after moving in if you will use a lower level as living space.

Other checks before you make an offer

Radon is one of several things worth checking before you commit. If the house is on a private well and septic system, see buying a house with septic and well for the inspections to order. If it is in a homeowners association, read buying a home in an HOA before the review period ends. For how a radon fix, an HOA assessment, or a septic repair should change the price, the pre-offer checklist walks through the numbers.