Reviewed and updated September 10, 2026. This article provides general public-health and referral guidance, not testing, medical, legal or engineering advice.
Put radon on the inspection timeline early
A radon test needs time under controlled conditions. EPA's buyer and seller guide says all real-estate radon tests should run for at least 48 hours, and some devices require longer. Waiting until the final walk-through can leave no room to resolve invalid conditions or discuss an elevated result.
Ask the inspector or testing professional when the device will be placed, when it will be retrieved and when the written report is expected. Make sure those dates fit the inspection contingency and closing schedule established by your contract and advisers.
Test the level the buyer could use
EPA recommends the lowest level that could be used regularly, even if it is unfinished today. A clean, accessible Elmira basement that could become a workshop or a Corning lower level marketed as future living space may be the appropriate test location.
The tester should avoid crawlspaces, closets, halls, kitchens, bathrooms, laundry rooms and furnace rooms. Closed-house conditions, placement height and interference controls should be documented. A monitor's tamper and environmental records can be especially useful when neither party is present throughout the test.
A result above 4 pCi/L is a problem to solve, not an automatic reason to walk away
EPA recommends fixing a home at 4 pCi/L or higher. Radon-reduction systems are established building systems, and many properties can be mitigated. The buyer and seller can discuss timing and cost, but the available choices depend on the contract and local practice.
Possible transaction paths can include seller-installed mitigation before closing, a credit or price adjustment, escrow arrangements where permitted, or buyer-managed work after closing. Those are negotiation examples, not legal advice and not guarantees. Consult your agent and attorney about the actual agreement.
Evaluate the proposal, not just the promise to ‘fix radon’
A proposal should identify the method, foundation zones, route, fan and monitor, electrical responsibility, sealing, warranty and post-mitigation test. If the seller commissions the work, the buyer should still receive system documents and the follow-up report.
Use the mitigation-cost checklist when comparing scope. The result-above-4 guide helps distinguish confirmation from mitigation, and the installation timeline helps fit the work into closing plans.
Keep the record with the house
Retain the original test, any confirmation test, the proposal, system diagram, warranty and post-mitigation result. EPA says a buyer may request a new test when the previous test is not recent, renovations occurred, testing conditions were not met or the buyer will use a lower level than the one tested.
A functioning mitigation system should not be switched off to see what happens during a sale. Test with the system operating as designed, check its monitor and disclose documents through the transaction process recommended by your advisers.
Sources
Primary guidance used for this article
We use government and public-health sources, distinguish historical datasets from current household measurements, and do not invent local results. Read our editorial policy.