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.

What EPA's home buyer guidance says about recent tests

EPA's Home Buyer's and Seller's Guide to Radon says sellers who have already tested should review the testing checklist to make sure the test was done correctly, and provide results to the buyer. A buyer may want a new test, especially if:

• the testing checklist items weren't met;
• the last test isn't recent, for example within the past two years;
• the home has been renovated or altered since the test;
• the buyer plans to live in a lower level of the house, such as a basement, that wasn't tested.

Contract language to discuss with your agent

Common radon provisions in purchase contracts include:

• A testing contingency: the buyer may test within a set number of days.
• A threshold: for example, 4 pCi/L, EPA's action level.
• The remedy if results are high: the seller installs a mitigation system before closing, the parties agree on a credit or price reduction, or the buyer may cancel.
• Who chooses the mitigator, and the requirement for a post-mitigation test.
• Access and non-interference: the seller agrees to maintain closed-house conditions and not disturb the test.

Your agent will know what's standard in your market, and some states have standard radon addenda.

Mitigation costs and timing in a deal

EPA says most homes can be fixed for about the same cost as other common home repairs, and that costs vary with the home's size and design. In a transaction, the bigger issue is often timing. Installation usually takes a day or less, but scheduling a contractor and completing a post-mitigation test can take a week or more. Options include:

• the seller installs before closing, with a post-mitigation test result provided to the buyer;
• an escrow holdback, so the buyer can install after closing with funds set aside;
• a price credit, with the buyer arranging mitigation.

If the seller installs, buyers should ask for documentation: the contractor's credentials, the system design, the manometer reading, warranty terms, and the post-mitigation test.

Understanding the risk you're negotiating about

EPA estimates that among 1,000 people who never smoked and were exposed to 4 pCi/L over a lifetime, about 7 could get lung cancer, and among smokers about 62. Those numbers explain why EPA recommends fixing at 4 pCi/L and considering a fix between 2 and 4. A mitigation system is a modest cost compared with the long-term risk, which is why most radon findings are resolved rather than deal-breaking.

For sellers: getting ahead of it

• Test before listing. A recent, properly done test, or an existing working mitigation system with a recent post-mitigation result, removes uncertainty.
• If you already have a system, gather the installation paperwork and the latest test, and confirm the fan runs and the manometer shows suction.
• Disclose what you know. Many states require disclosure of known radon test results or radon hazards.

After you move in

Even with a good pre-purchase test, EPA's retest guidance suggests testing again if you start using a lower level, after renovations, and periodically over time. If you inherited a mitigation system, learn how to check it. See living with a radon mitigation system.