Radon Testing for a Home Sale in Knoxville: Who Pays, What It Costs, How Long It Takes

If you are buying or selling in Knox County and radon just came up, here is the whole picture in one page.

Nobody is legally required to test

Tennessee has no radon testing mandate for home sales. Radon testing happens here because buyers ask for it in the contract, and in an EPA Zone 1 county most buyer's agents do ask. Separately, sellers have a duty to disclose known environmental hazards under the Residential Property Disclosure Act, and radon is named on the standard form. Knowing and not saying is the problem. Not knowing is not. Our disclosure guide goes deeper.

Who pays

Whoever orders it, and that is usually the buyer, as part of the inspection period. Cost is typically $150 or less for a professional 48-hour continuous-monitor test. Sellers who test before listing pay for their own test and generally consider it money well spent, because it converts a late-stage surprise into a planned decision.

The timeline that actually matters

• Day 0: you call, we schedule. Placement usually happens within a day or two.
• 12 hours before: closed-house conditions begin. Windows and exterior doors shut, HVAC running normally.
• Days 1 to 2: the monitor logs hourly for a full 48 hours.
• Day 3: pickup, and the written report the same day.

Total elapsed time is three to four days from the call. That fits inside a normal inspection period, but it does not fit inside the last afternoon of one. Call early.

What a passing and failing result looks like

Under 2.0 pCi/L, nothing to do. Between 2.0 and 4.0, the EPA says consider action, and in a transaction this usually gets noted and left alone unless there is a bedroom on the lower level. At or above 4.0, expect the buyer to ask for mitigation or a credit.

What mitigation costs, and how deals usually handle it

$900 to $2,500 in the Knoxville area, one day of work, guaranteed result. The three common resolutions are: the seller mitigates before closing and provides the post-mitigation report, the seller credits the buyer at closing and the buyer handles it after, or the price is adjusted. All three are routine. What is not routine is a deal falling apart over radon, and it mostly happens when the number shows up too late for anyone to get a real quote.

For agents

Tell us the deadline when you call and we will tell you honestly whether we can make it. Reports come back with hourly data attached in a format you can put straight in the file, and we can turn a mitigation quote around off the result the same week so your client is negotiating over a real number. Call (865) 563-8112.