Maryville
City Building Official
2024 IRC
Ord. #2025-23 · Dec. 2025
Appendices BA and BO only. Appendix BE is not adopted; RRNC is optional.
01
The average clears the action line
These are the Tennessee Department of Health dashboard’s Blount County tooltip values with Year set to “All,” covering 2022–2023 tests.
Average6.7pCi/L
Median2.2pCi/L
Maximum18.2pCi/L
0 pCi/L20 pCi/L
The 6.7 average sits above the 4.0 pCi/L action level and well above the 2.2 median, indicating a right-skewed set of readings with high outliers. The tooltip showed no county test count, so sample size is unknown. The dashboard’s pre/post-mitigation bars are East Region aggregates and did not filter to Blount County. Open the Tennessee dashboard.
A county average cannot clear a house.
EPA recommends testing every home regardless of zone. Zone 1 describes broad potential; only a properly run test can describe the air in a specific home. Read EPA’s zone guidance.
02
The city rules are clear. The county rule is not.
Maryville and Alcoa each publish a closed appendix list that excludes radon. Unincorporated Blount County’s current radon-appendix status remains an open question.
Alcoa
City Building Official
2018 IRC
Ord. #18-464 · Nov. 2018
Appendices E, H and J only. Appendix F is not adopted; RRNC is optional.
Unincorporated Blount County
County Environmental & Codes
Public record: 2014 adoption
2012 building/fire codes referenced
Current IRC edition and radon appendix status could not be verified publicly.
Sources: Maryville code extract and 2024 IRC modifications; Alcoa code, §§12-201/12-202; April 17, 2014 county commission minutes; and the county’s permit process checklist. Each jurisdiction enforces its own codes rather than the State Fire Marshal’s residential program.
One call closes the county gap
For an address outside Maryville and Alcoa, ask which IRC edition and appendices govern the permit—and whether the radon appendix was adopted. Blount County Building Commissioner / Environmental & Codes: 865-681-9301.
03
Four questions before you own the air
“Built to code” is incomplete. In Maryville and Alcoa, code does not require the radon appendix; in the unincorporated county, the answer was not publicly verifiable.
Test during due diligence
Make the offer contingent on radon testing and preserve enough time to review a follow-up test or mitigation estimate. A seller disclosure or disclaimer is not a measurement.
Name the jurisdiction
Confirm whether the parcel is inside Maryville, inside Alcoa, or unincorporated Blount County. The mailing city alone may not tell you which code office governs the home.
Ask for system evidence
For a new home, request plans and permit records showing any gas-permeable layer, sealed slab penetrations, vent route, and fan-ready provision. Do not treat a pipe as proof of a safe result.
Retest after the fix
If a result is elevated and the system is activated or upgraded, use a post-mitigation test to confirm performance. Regional post-mitigation totals cannot substitute for the home’s result.
Tennessee transaction rule
Sellers of one-to-four-unit residential property must provide a disclosure statement or disclaimer under T.C.A. § 66-5-202. The state form advises buyers to use radon inspection contingencies.
Homeowner test kits
TDEC offers free radon test kits to Tennessee homeowners. Request a kit from the state program.
How do I find a certified radon professional in Blount 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.
04
Quick answers
What the available records establish—and what they do not.
Is Blount County a high-radon area?
Yes. EPA maps Blount County as Zone 1, its highest-potential category. The Tennessee dashboard reports a 6.7 pCi/L average, 2.2 median, and 18.2 maximum for 2022–2023 tests. Those figures describe submitted tests, not every home.
Are new homes in Maryville radon-ready by code?
Not as a result of the radon appendix. Maryville’s 2024 IRC adoption names only Appendices BA and BO, explicitly excluding all other parts; Appendix BE for Radon Control Methods is not adopted.
Are new homes in Alcoa radon-ready by code?
Not as a result of the radon appendix. Alcoa’s 2018 IRC adoption includes Appendices E, H and J only, not Appendix F for Radon Control Methods.
What about unincorporated Blount County?
The public record reviewed shows a county adoption action on April 17, 2014, but did not establish the current IRC edition or whether the radon appendix was adopted. Confirm the project address with the county code office.
Did this review find a local radon ordinance?
No Blount County, Maryville, or Alcoa radon-specific ordinance for public buildings, schools, or real-estate transactions was found. That is a research finding, not proof that no unpublished policy exists. Statewide disclosure norms and voluntary school-testing guidance still apply.
Sources & verification notes
- Tennessee Department of Health, Tennessee Radon Testing dashboard — Blount tooltip verified on two page loads, October 16, 2026.
- EPA Map of Radon Zones — zone definitions and testing guidance.
- EPA Map of Radon Zones: Tennessee and EPA Map of Radon Zones: Tennessee — both identify Blount County as Zone 1. This page does not use the marketing site’s unverified county-average figure.
- MTAS Maryville code extract and Maryville 2024 IRC local modifications.
- MTAS Alcoa combined code, Change 17, August 13, 2024.
- Blount County Commission minutes, April 17, 2014; county Building Safety Codes page; and county permit process checklist.
- MTAS statewide building standards — State Fire Marshal adoption context.
- 2024 IRC Appendix BE, Radon Control Methods.
- NRPP Find-a-Pro results for Maryville 37801 and NRSB Find A Professional — reviewed October 16, 2026.
- TDEC Radon Program free test-kit request.
Research completed October 16, 2026. Open questions: the current IRC edition and radon-appendix status for unincorporated Blount County; the status of TN SB660/HB1269; and the dashboard’s county sample size. No county test count was shown.