What a radon test result means for your home sale

A high radon reading during the inspection period is one of the most common last-minute deal snags — and one of the most fixable. Here's how it plays out and how to keep your closing on track.

The radon contingency, explained

During a typical real-estate transaction, the buyer's inspection includes a short-term radon test. If the result is at or above the EPA action level of 4.0 pCi/L, the buyer usually has the right — under the inspection or a dedicated radon contingency — to request that the seller mitigate, credit the cost, or renegotiate. Because the test happens late in the process, a high number can feel like it threatens the whole deal.

Why it rarely kills the sale

Radon is unusual among inspection findings: the fix is well-defined, fast, and relatively inexpensive. A certified mitigation contractor can often install a sub-slab depressurization system in a single day for $800–$2,500, and a post-mitigation retest documents that the home is now below the action level. That paper trail is exactly what buyers, agents, and lenders want to see.

Who pays

It's negotiable and local custom varies. Common outcomes: the seller installs a system before closing, the seller credits the buyer to install one after, or the parties split the cost. The dollar amounts are small relative to the transaction, which is why radon findings usually resolve rather than collapse a deal.

The move if you're the seller

Get a certified mitigation contractor out quickly — speed preserves your timeline. A documented, certified system plus a passing retest turns a scary red flag into a routine repair the buyer feels good about.