Should you test for radon in Tennessee? The state of Tennessee says yes, but in my experience the answer is a little more nuanced. Let’s dive in.
Should you Pay for Radon Testing in Middle Tennessee?
The Tennessee Department of Environment and Conservation (TDEC) considers radon to be a serious problem statewide, and it’s true that Tennessee’s in-home radon levels average higher than the national baseline. For that reason, the state, the EPA, and most home inspectors highly encourage homebuyers to invest in radon testing.
In my experience working with buyer-clients, I encourage them to do their own research on radon testing. Most home inspection companies will try to upsell a standard 48-hour test. This test will probably show if radon levels are off the charts but it’s not a great overall “one-and-done” test for accuracy over time, as time, weather, the condition of the crawlspace, and even whether the home already has a passive or active radon system can greatly impact 48-hour readings.
Passive and Active Radon Systems in Middle Tennessee
Many newer homes in areas like Nolensville are built with a passive radon pipe system already in place. It’s a simple ventilation setup installed during construction that helps vent radon gas from beneath the home. Many local builders began adding them voluntarily in the mid-2010s.
The 2024 Nolensville building code requires a passive radon system to be installed, including gravel beneath any sealed vapor barrier in crawlspace areas.
I want to reiterate that including a passive radon system is not a statewide mandate, but it’s something to research and consider when deciding your approach to radon testing.
When we built our home in 2020, our inspector advised us to skip radon testing since our builder (Drees) had already included a passive system and an encapsulated crawlspace. Encapsulated crawlspaces add another layer of protection because they reduce radon infiltration by sealing soil contact and improving ventilation balance.
What is a passive radon system?
To rewind a bit, let’s define what a passive system is. A passive system consists of piping and venting installed during home construction (or added later) that allows soil gas, including radon, beneath the home to vent outside naturally. It’s that simple. An active system takes it a step further by adding a small fan that actively pulls radon gas out through the vent pipe.
Mitigation and active radon systems
If a higher radon level is found during your home inspection test, you can ask the seller to mitigate the issue. If the home already has a passive system, it can be converted to an active system fairly easily.
According to TDEC, homes with a passive system can be upgraded to an active system by adding a small fan that helps further reduce radon levels, typically along with sealing the system and adding a monitor.
The cost of converting a system from passive to active is lower than installing a full mitigation system from scratch. Recent quotes I’ve seen in our area range from around $600 for a conversion to about $2,000 for a full installation, depending on the home’s layout and foundation type.
Thoughts about 48-Hour Radon Testing
Radon testing through a home inspection company generally costs around $250 and uses a short term measurement (often 48 hours). In Tennessee, readings tend to be higher when it’s cold and raining, and even with our volatile weather a single 48-hour snapshot may not give the full picture.
Alternatives to the Standard 48-Hour Test
In speaking with the experts at Radon 1—a Tennessee-based radon mitigation service provider—I learned they typically recommend monitoring radon levels for a full year using an at-home continuous radon monitor such as the Airthings View Plus.
An at-home monitor offers ongoing tracking so you can observe trends, seasonal spikes, and get a more accurate picture of your home’s radon levels. For example, it’s not uncommon for a home’s radon level to spike well above acceptable levels from time to time, but it’s not brief spikes that pose the greatest risk. What matters most are consistent, long term elevated levels.
What to do if Levels Are High
According to the state of Tennessee, radon levels indoors that are above 4 pCi/L require action. TDEC and the United States Environmental Protection Agency (EPA) recommend further radon testing if the first test exceeds 4 pCi/L. If the follow-up (or the average of two tests) still exceeds 4 pCi/L, then mitigation is recommended.
Moreover, the EPA says if your radon level sits between 2 and 4 pCi/L, you should consider steps to reduce it to below 2 pCi/L.
If high levels are found during a Middle Tennessee home inspection, you can negotiate with the seller to cover the cost of mitigation or request that a system be installed before closing. If the issue is discovered after you own the home, contact a qualified mitigation company. You will want to find a professional certified through the National Radon Proficiency Program (NRPP) or the American Association of Radon Scientists and Technologists (AARST).
Summary
To sum it up:
- Radon is a real risk in Tennessee.
- The EPA and state suggest all homes be tested for radon and yet some homes in Tennessee will already have active or passive systems in place.
- If your home has a passive radon system, that’s a bonus, but testing will tell you if it needs to be converted to an active system.
- Continuous, long term monitoring can provide more reliable data than the standard 48-hour test offered by most home inspectors. Keep in mind, post-sale mitigation becomes the new owner’s financial responsibility, while issues discovered before closing can often be negotiated with the seller.
- If radon levels exceed 4 pCi/L (or even between 2 and 4 pCi/L), mitigation is strongly advised.