Most sellers think about radon when a buyer's inspector brings it up. By then you have a signed contract, a closing date, and a number on a report that you did not see coming. A seller who tests first has the same information the buyer is about to get, and gets to decide what to do with it on their own schedule.
Knox County and the surrounding area sit in a part of East Tennessee where elevated radon is common, so a high result is far from unusual. The surprise is not the number. The surprise is learning it in the middle of a deal, when the buyer's agent has already framed it as a problem and you are negotiating under a deadline.
When you test before listing, three things change. You are not in a rush. You can get quotes from more than one contractor. And if you need a system, it can be installed and tested before the first showing, which turns a negotiating item into a selling point.
For a result a buyer will take seriously, the test should follow standard protocol. The device goes in the lowest lived-in level, away from drafts, vents and exterior walls, and the house stays closed up as much as is practical during the test, which commonly runs from two days to a week depending on the method. Do not run a test while doors are propped open for a move or a project. A continuous radon monitor is a good choice for a sale, because it records the level hour by hour and shows that nothing disturbed the results. Learn more on our radon testing page.
If the home has a finished basement, test there. If it has a crawl space, test the lowest living area above it. Our pages on local radon levels and finished basements give more context.
An elevated result is a repair, not a verdict on the house. The EPA recommends action at 4.0 pCi/L or higher, and a mitigation system is designed to bring the level well under that. On a slab or basement, a typical system uses a pipe through the foundation, a fan, and a vent above the roofline. For crawl spaces, the approach is different, and we cover it on our crawl space radon page. Our radon mitigation and cost pages explain what to expect.
After the system goes in, a follow-up test confirms the number came down. That second result, along with the warranty on the work, is what you hand to buyers.
Tennessee has its own rules about what sellers need to tell buyers, and your real estate agent and attorney are the right people to advise you on your situation. Our Tennessee radon disclosure page explains the basics. In general, having a test result and a mitigation record on hand makes the conversation simpler for everyone. Our home sale radon guide and real estate radon testing page cover the buyer side as well.
Ideally you test a few weeks before the listing photos, so that if a system is needed there is time for scheduling and the post-install test. If you are already on the market, test now. A seller who offers a clean test result and a system with a guarantee usually has a smoother closing than one who waits for the buyer's inspector.
If you are planning to list, call (865) 563-8112. Tell us the address, whether you have a basement or crawl space, and your target listing date. We will explain the testing and what a fix would involve, so you walk into the sale already informed.
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