It only applies when adopted.
The 2018 IRC says an appendix is not mandatory unless specifically referenced. Its radon provisions address gas-permeable layers, soil-gas retarders, vent piping and related new-construction measures.2
The county picture
Radon-ready in the cities. Unknown outside them.
Kingsport’s code adopts the 2018 IRC “including appendix F, Q, and J,” making radon-resistant construction effectively mandatory for new one- and two-family dwellings in a Zone 1 county.12 Bristol’s 2020 first-reading record also includes Appendix F, while the county’s own 2018 IRC adoption page publishes no appendix list.34
Radon risk profile
EPA Zone
1
EPA’s highest radon-potential category: predicted average indoor screening levels above 4 pCi/L. Sullivan also appears in the 2024 IRC’s list of Tennessee high-radon counties.67 A zone is a planning signal—not a result for any address.
The state dashboard could not yield a Sullivan County number.
!County tooltip withheld
After about seven attempts, the Tennessee Radon Testing dashboard kept landing on neighboring counties rather than a tooltip whose own label identified Sullivan. Several neighboring values were internally contradictory, including an average above the maximum.8
No average, median or maximum is published here as Sullivan County’s. The map’s pre/post band charts also aggregate by health region, not the selected county.
~7×Attempts without a reliable Sullivan label
2022–23Years covered by the dashboard view
RegionPre/post charts are not county counts
Building codes
A three-way jurisdiction split
Local adoption matters because Tennessee’s state-enforced residential rule adopts the 2018 IRC with Appendix Q only—not Appendix F—and excludes optional standards.5
Jurisdiction
Status
What the record supports
KingsportMandatory
2018 IRC with Appendices F, Q and J for one- and two-family dwellings. Appendix F is “Radon Control Methods.” Ordinance No. 7136 is dated February 20, 2024.12
Bristol, TennesseeEffectively mandatory
Ordinance 20-12 passed first reading October 6, 2020; staff’s appendix list included E, F, H, I, J, K, M, O, P, Q, R and S. Appendix F is included, but second-reading passage was not directly verified in the reviewed minutes.3
Unincorporated Sullivan CountyUnverified
The county says it adopted the 2018 IRC and 2018 Energy Code effective April 1, 2018. The page gives no resolution number or appendix list, so Appendix F status remains open.4
Appendix Q, not F.
Tennessee Rule 0780-02-23 adopts the 2018 IRC with Appendix Q only. That is why Kingsport’s and Bristol’s local Appendix F records go beyond the state minimum.5
How do I find a certified radon professional in Sullivan County?
Tennessee doesn't license radon testers or mitigators, so national certification is the best way to check qualifications. The Tennessee Radon Program points residents to two directories: search them by ZIP code and widen the radius if nothing is listed nearby.
We don't recommend or rank companies. Before you hire, check the certification number in the directory yourself and ask for a follow-up test after any system is installed. Questions to ask a radon professional.
Homebuyer guidance
Radon-ready is not radon-tested.
Tennessee’s standard disclosure asks whether the seller knows of environmental hazards including radon gas. It does not create a statewide radon-testing mandate.13
01
Know the address
Inside Kingsport, the current code expressly includes Appendix F. Bristol’s reviewed adoption record also includes it. In unincorporated Sullivan County, assume nothing until the county confirms the appendix list.
02
Test new construction
A passive radon system reduces risk; it does not establish the home’s actual concentration. Test after occupancy or during the transaction, even when the structure was built under Appendix F.
03
Use the contract
Because Tennessee does not require transaction testing, buyers should negotiate a radon inspection contingency and leave enough time to schedule one of the region’s limited certified professionals.
An active new-home market makes the distinction important. A Kingsport 2025 market recap reported a $266,932 median sale price, about 307 monthly sales, about 24 monthly new-construction sales, 4.0 months of supply and 57.8 days on market. Those index-sourced figures describe market activity—not radon exposure—and were not independently re-verified in the live browser.14
Questions answered
Sullivan County radon FAQ
Short answers grounded in the EPA zone record, official code sources, the state dashboard review and current certification directories.
Yes. Sullivan County is EPA Radon Zone 1, the highest-potential category. The 2024 IRC also lists Sullivan among Tennessee’s high-radon counties. The zone does not predict the result for an individual home.
Kingsport expressly adopts the 2018 IRC with Appendix F, making radon-resistant construction effectively mandatory. Bristol’s first-reading record includes Appendix F, but the final passage is not yet confirmed. The unincorporated county’s Appendix F status remains unverified.
The Tennessee dashboard repeatedly landed on neighboring counties and produced internally inconsistent tooltip values. No Sullivan-labeled tooltip was reliably isolated, so this guide withholds the average, median and maximum.
No. The statewide seller disclosure asks about known environmental hazards including radon gas, but Tennessee does not mandate testing in a transaction. Buyers can negotiate a radon inspection contingency.
No Sullivan County, Kingsport or Bristol radon-specific testing rule for schools or public buildings was found. Tennessee encourages school radon testing but does not require it statewide; the reviewed school-radon bill’s status was not verified and is not treated here as law.
Source ledger
Read the record
Official sources establish the code and risk framework. Directory searches are dated snapshots; index-sourced market figures are clearly labeled. Sources were reviewed October 16, 2026 unless noted.
- Kingsport Code §22-96 — 2018 IRC with Appendices F, Q and J; Ordinance No. 7136 history.
- 2018 IRC Appendix F — scope and radon control methods.
- Bristol City Council minutes, October 6, 2020 — Ordinance 20-12 first reading and appendix list.
- Sullivan County Planning & Codes — 2018 IRC and Energy Code effective April 1, 2018; no published appendix list.
- Tennessee Rule 0780-02-23 — state residential code adopts Appendix Q only.
- EPA Tennessee radon zone map — Sullivan County Zone 1.
- 2024 IRC Appendix BE — Sullivan listed among Tennessee high-radon counties.
- Tennessee Radon Testing dashboard — 2022–2023 map; Sullivan tooltip not isolated and band charts are regional.
- NRSB Find a Professional — no Sullivan County or Tri-Cities measurement listing in the reviewed directory.
- NRPP professional search — three Sullivan County measurement professionals in the reviewed Kingsport-area search.
- NRPP profile: Steven Forbes — measurement and mitigation certifications.
- NRPP profile: Charlie Joshua Faries — measurement and mitigation certifications.
- Tennessee Residential Property Condition Disclosure, RF 201 — radon question and inspection guidance.
- Kingsport 2025 housing recap, Redfin/Stacker via thebesttimes.com — index result only; live URL was not established in the research, so it is not linked.