Radon and Real Estate: What Buyers and Sellers Need to Know

Radon comes up in real estate transactions more often than most people expect, and when it does, both sides tend to be unprepared. Buyers worry they are walking into a money pit. Sellers worry a high reading will kill the deal. Neither reaction is warranted if you understand how this works.

This guide covers what buyers and sellers each need to know, how to handle test results during a transaction, and what Tipper would do on either side of the table.

🏠If you are buying

Request a radon test as part of your home inspection. This is standard practice in most of the country and should be non-controversial. A short-term test during the inspection contingency period gives you a result before you close.

• •Who runs the test? Your home inspector may offer radon testing as an add-on, or the seller may have recent results. If neither, you can place a kit yourself during the inspection window. A professional inspector using a continuous monitor is the gold standard for transactions.
• •What if the result is high? A reading above 4 pCi/L is not a deal-killer. Mitigation systems cost $800 to $2,000 and reliably bring levels below 2 pCi/L. You can ask the seller to install a system before closing, negotiate a credit, or handle it yourself after purchase.
• •What if the seller refuses? That is their right. But a high radon reading that the seller will not address is useful information. Factor the cost of mitigation into your offer price, or walk away if the numbers do not work.

🏷️If you are selling

Test before you list. Knowing your number ahead of time eliminates the most common radon-related disruption in a sale: a surprise high reading during the buyer's inspection.

• •If the result is low: Disclose it. A recent test showing levels below 4 pCi/L is a genuine selling point, especially in high-risk areas where buyers know to ask.
• •If the result is high: Fix it before listing. A mitigation system installed before sale is cheaper and cleaner than negotiating a credit mid-transaction. Most systems are installed in half a day and cost $800 to $2,000. A post-installation test proving levels are below 2 pCi/L turns a liability into a feature.
• •Disclosure laws vary by state. Some states require sellers to disclose known radon test results. Others require testing at sale. Your real estate agent or attorney should know the rules in your state.

🤝How radon fits into negotiation

When radon comes up during a transaction, the conversation usually follows one of three paths:

• •Seller installs mitigation before closing. The cleanest outcome. The system is in place, a post-install test confirms it works, and both sides move forward with confidence.
• •Seller provides a closing credit. The buyer handles mitigation after purchase. The credit should cover the full expected cost: $800 to $2,000 depending on the home. Make sure the credit amount is based on an actual contractor quote, not a guess.
• •Buyer accepts and handles it independently. If the price already reflects the condition, or if the buyer wants to choose their own contractor, this works too. Just budget for it.

Radon mitigation is a known, bounded cost. It is not like a structural issue where the scope can surprise you. A certified contractor gives you a fixed quote, does the work in a few hours, and you test to confirm. The unknowns are small.

🧪Testing protocols during a sale

Radon testing during a real estate transaction has specific requirements beyond what a homeowner would do for their own purposes:

• •Closed-house conditions. Windows and exterior doors must be closed for at least 12 hours before and during the test. Both parties should agree to maintain these conditions. A test run with windows open is not valid.
• •Tamper-resistant testing. Professional inspectors often use continuous monitors with tamper detection or sealed short-term kits to prevent interference. This protects both buyer and seller.
• •Placement. The test goes in the lowest livable area, meaning the lowest floor where someone would actually spend time, not an unfinished crawl space. Placement should follow EPA protocol.
• •Duration. A short-term test during a transaction is typically 48 hours. Some lenders or state programs may require longer testing periods.