Radon in Real Estate: What Buyers and Sellers Need to Know
Radon comes up in about 40% of home transactions, and it derails closings when people don't know how to handle it. The good news? It's completely manageable. A radon issue shouldn't kill a deal — but handling it poorly can.
For Buyers
Should you test before buying?
Yes. Always. Even if the seller already tested. Their test might be old, conditions might have changed, or honestly they might have tested with windows open (it happens). Your lender might require it, your inspector might recommend it, and regardless — you're the one who'll be breathing the air.
When to test
During the inspection period. Most purchase agreements give you 7-14 days for inspections. A continuous radon monitor (CRM) test takes 48 hours, which fits comfortably in that window. Don't wait until the last minute — if the test comes back high, you'll need time to negotiate.
What if the test comes back high?
Don't panic and don't walk away from the house. Radon mitigation is straightforward, takes one day to install, and costs $800-$2,500. That's a rounding error on a home purchase. Instead:
- Get 2-3 quotes from certified contractors in the area
- Negotiate with the seller (see "Who Pays" below)
- Get the work done before closing, or negotiate a credit
- Re-test after mitigation to confirm levels dropped
For Sellers
Should you test before listing?
There's a case for it. If your home tests low, you can market it as radon-tested — that's a selling point in high-radon areas. If it tests high, you can mitigate before listing and avoid the negotiation entirely. Buyers love seeing a system already installed with a passing re-test.
What if the buyer's test comes back high?
You've got options. You can pay for mitigation, split the cost, offer a credit, or reduce the sale price. What you shouldn't do is argue that radon isn't a real problem — that'll cost you the deal faster than the mitigation would have cost you in dollars.
Who Pays for Mitigation?
There's no universal rule — it's part of the negotiation, same as any other inspection finding.
Most common arrangements:
- Seller pays: Seller hires a contractor, system is installed before closing. Buyer gets a mitigated home. This is the most common arrangement.
- Buyer gets a credit: Seller credits $800-$1,500 at closing. Buyer handles installation after moving in. Good when the seller doesn't want to deal with contractors.
- Split it: Both parties share the cost. Common in competitive markets where buyers don't want to push too hard.
- Price reduction: Purchase price drops by the estimated mitigation cost. Effectively the same as a credit but structured differently.
In a hot market, buyers often eat the cost to keep their offer competitive. In a buyer's market, sellers usually cover it. But everything is negotiable.
The Timeline
This is where deals get tight. Here's a realistic timeline:
- Day 1-2: Radon test placed (CRM or short-term)
- Day 3-4: Test results back
- Day 4-5: Get mitigation quotes (if needed)
- Day 5-7: Negotiate who pays
- Day 7-10: Mitigation installed (usually 1 day of actual work, but scheduling the contractor takes a few days)
- Day 10-11: Wait 24 hours for system to stabilize
- Day 11-13: Post-mitigation test (48 hours minimum)
- Day 13-14: Re-test results confirm levels are below 4.0 pCi/L
So you need at least 2 weeks from the start of testing to a confirmed passing re-test. If your closing is sooner than that, talk to your agent and lender about options — sometimes closing can be pushed, or mitigation can be a condition of sale handled after closing with funds held in escrow.
What to Put in the Purchase Agreement
Get these items in writing. Verbal agreements don't hold up:
- Who pays for the initial radon test
- The action level that triggers mitigation (usually 4.0 pCi/L, matching EPA guidance)
- Who pays for mitigation if needed
- Requirement that work be done by a certified professional (NRPP or NRSB)
- Post-mitigation re-test requirement
- What happens if the re-test still shows elevated levels (second mitigation attempt, extended timeline, etc.)
- Deadline for all radon work to be completed
State-Specific Requirements
Some states have disclosure laws about radon:
- Several states require sellers to disclose known radon test results
- Some states require certified testers for real estate transactions
- A few states mandate radon testing in certain situations
Check your state page for local regulations, or ask your real estate agent.
Sources: EPA "Home Buyer's and Seller's Guide to Radon," National Association of Realtors radon guidelines.