Radon testing
Professional air tests for the house you live in, placed and timed so the number means something
Open the radon testing pageJohnson City, TN · Radon testing and mitigation
Washington County is Zone 1. Your neighbor's kit is not your house.
We test and mitigate radon in Johnson City and the Tri-Cities.
Johnson City Radon does professional radon testing and mitigation in Johnson City, Jonesborough, Kingsport, Bristol TN, and the rest of Washington and Sullivan Counties. We write reports a realtor can read and we build fan systems that match the crawl, the hillside basement, or the split foundation you actually have.
You're in the Ridge-and-Valley. The rock under Johnson City is folded limestone, dolomite, and shale. Some of that shale, including the Chattanooga, carries a little uranium. Uranium decays. Radon shows up. The EPA put Washington County in Zone 1 for a reason, and it put Carter and Unicoi in Zone 2 right next door. None of that is a reading for your bedroom.
We test the lowest lived-in level the way the protocol says: closed house, device off the floor, away from a supply vent. If you're buying, we run a continuous monitor so the file has a time stamp. If you already live here, a careful short-term test or a TDEC kit can be the first look. Then we talk mitigation only if the number earns it.
Mitigation around here is usually a sealed crawl membrane with a fan, or a pipe through a basement slab. Hillside houses toward Buffalo Mountain and Boones Creek often need both. We do not hang a bathroom fan in a foundation vent and call it a system.
Tennessee does not issue a state radon license. That's the law, not a loophole we hide. We work to NRPP and NRSB standards and we expect you to ask. Request a quote and tell us the town and the foundation.
What we do
Radon mitigation
Fan systems for crawls, slabs, and the split hillside basements this valley builds
Open the radon mitigation pageReal estate testing
Continuous monitors and written reports when a purchase contract is on the clock
Open the real estate testing pageWashington County radon risk explainer
This is a geology and housing guide, not a test result. It will not invent a pCi/L number for your address. Pick what you know. We will tell you what usually matters here, then you can request a real measurement.
Context only · not a radon reading
Washington County is EPA Zone 1
The EPA map puts Washington County in Zone 1, the highest predicted indoor-radon band (average screening above 4 pCi/L). That is a planning map from geology and older measurements, not a reading for your street. Carter and Unicoi next door are Zone 2. The line does not stop radon at the county sign. Test the house you actually sleep in.
Crawl space is the common Johnson City story
Most of the housing stock we see is a crawl over soil. Radon moves through that dirt, then through the floor and the return leaks. Mitigation is usually a sealed polyethylene membrane plus a fan that pulls from under the plastic (sub-membrane depressurization), not a box fan in a vent. Mid-century ranches around here usually sit on a crawl with a dirt floor and a few foundation vents that do not count as a mitigation system.
City water: the job is indoor air
If you are on Johnson City, Jonesborough, Kingsport, or Bristol utility water, the radon conversation is the air in the house. Utility water is treated and is not the usual indoor-radon driver here. Test the lowest lived-in level. Leave the geology map for context.
Living there: a careful kit or a professional test
If you just want a number, Tennessee's radon program will mail a free short-term kit. Follow the 3 to 5 day window and mail it back immediately. If you want us to place a monitor and write it up, request a quote. Either way, this tool will not invent a pCi/L reading for your address.
- Zone 1 here. Useful for why we take the county seriously. Useless as a substitute for a test.
- Expect a crawl-space membrane system if you mitigate, not a hardware-store fan in a vent.
- Utility water: skip the water scare. Book an air test in the lowest lived-in room.
- Occupied home: TDEC kit for a first look, or hire us to run a professional test.
Dedicated page: Washington County radon risk explainer.
Towns we write about
Four unique pages, not the same paragraph with a city swap.
Johnson City
Tree Streets crawls, Boones Creek slabs, Buffalo Mountain walkouts.
Jonesborough
Founded 1779. Stone, brick, and dirt crawls in the historic district.
Kingsport
Sullivan County Zone 1. Colonial Heights, Bloomingdale, Bays Mountain.
Bristol TN
Tennessee side of the split city. State Street, South Holston slopes.
Questions people ask first
Is Washington County really a high-radon county?+-
The EPA maps Washington County as Zone 1, the highest predicted indoor-radon band (average screening above 4 pCi/L). Sullivan County is Zone 1 too. Carter and Unicoi next door are Zone 2. The map is why we take the county seriously. It is not a reading for your hallway. Test the house.
Can I just use the free TDEC kit?+-
Yes, if you already live there and you want a first look. Order from the Tennessee Radon Program, run it 3 to 5 days, and mail it back immediately. If you're buying or selling, use a professional continuous test so the other side has a time-stamped report.
Does Tennessee license radon testers?+-
No. Tennessee does not issue a state radon measurement or mitigation license. TDEC points people to national credentials: NRPP and NRSB. Ask for the credential and look it up on the directory.
What's the EPA action level?+-
4 pCi/L. EPA also says think about fixing between 2 and 4. We treat 3.8 and 4.2 as the same conversation. A 12 is a different one. We will not invent a number from your zip code.
Do crawl-space houses need a different system?+-
Usually yes. A dirt crawl gets a sealed membrane and a fan pulling from under the plastic. A basement or slab gets a pipe through the concrete. Hillside houses that have both often need both. A box fan in a foundation vent is not a system.
Should I test well water?+-
Test the air first. If you're on a private well or spring, especially in northern Washington County, a water sample can be a second step. City water in Johnson City, Jonesborough, Kingsport, or Bristol is not the usual indoor-radon driver. We will not guess a water number from a geology paper.
How fast can you test a house under contract?+-
A continuous monitor usually needs a closed house and about 48 hours on site, plus scheduling. Tell us the inspection window in the quote form. We will say if the calendar works. Do not wait until the last Wednesday on a split-foundation house.
Do you work Kingsport and Bristol, or only Johnson City?+-
Johnson City and Washington County first. We also cover Kingsport and Bristol TN (Sullivan County) and Jonesborough. Elizabethton and Unicoi when the drive makes sense. Say the town in the form.
What does mitigation usually cost?+-
Straightforward crawl or slab jobs in this region often land somewhere between $800 and $2,500. Split hillside foundations and historic stone crawls run more. That is a market range, not a bid. Send the foundation and the test number if you have one.
Will this website tell me my radon level?+-
No. The Washington County risk explainer talks geology and housing. It will not print a fake pCi/L. The only reading we stand behind is a device in the room.
Same answers on a dedicated page: FAQ.
Request a quote
Tell us the town, the foundation, and whether this is a home test or a real-estate deadline. We'll follow up by email.