Knox County building codes, and all 95 Tennessee counties

Does Knox County have a building code?

Yes. Knox County enforces its own residential building code through a county codes department, on locally adopted code editions rather than the state program. So a Knox County build needs a permit and inspections, and the office you deal with is the county's, not the State Fire Marshal's. Confirmed at the county's own Codes Administration and Enforcement office, which runs plan review, permitting and inspections on a locally adopted ordinance with Knox County amendments, read 2026-08-13. Knox is in the exempt bucket below, which means exempt from the statewide program, not exempt from having a code. Those two readings of the word send people in opposite directions, which is why the table below separates them.

Neighboring counties differ, and the difference is real money on a barndominium: Blount and Sevier also enforce their own residential codes, while several counties in the region have formally opted out and issue no residential permits at all. Find yours in the county table below, then confirm it at the State Fire Marshal's own list before you plan around it. Building in the region: see our Knoxville region page.

What are the residential building codes in Knox County?

Knox County enforces the 2018 International Residential Code with Knox County amendments. The county publishes both the adopted ordinance and the amendment list through its Codes Administration and Enforcement office, and the amendment document was read in full on 2026-08-23. The changes that matter on a barndominium or post-frame build:

Knox County also inserted its own design criteria into code Table R301.2(1). These are the figures an engineer stamps a post-frame or barndominium plan against, and every county sets its own, so read the row for the county you are building in.

Source: Knox County's published amendments to the 2018 IRC, knoxcounty.org/codes, read 2026-08-23. Confirm the current version with the county before you design to it.

Do you need a permit for a shed or a deck in Knox County?

The answer most searches surface is the state's, and the state's answer does not decide it in Knox County. The State Fire Marshal's residential permit page says a state residential building permit is not required for detached garages, sheds, barns or other detached structures that are not used for living purposes, and that additions over 30 square feet to an existing home have required a permit since October 1, 2011 (tn.gov, read 2026-08-23).

That program only runs where a jurisdiction has neither taken an exemption by enforcing its own local codes nor opted out by a two-thirds vote. Knox County enforces its own code, so it sits outside the state program and that state exemption list is not the Knox County rule. Knox publishes its ordinance and amendments as documents rather than a plain-language list of work that skips a permit, and the one exemption it wrote into its own amendments is fences. So a shed, a deck or a detached garage in Knox County is a question for Knox County Codes Administration before you plan around it, and the same holds in every other county running its own codes office. The county table below shows which counties those are.

How Tennessee's three-bucket system works

Tennessee sets a statewide baseline residential code (the 2018 IRC as adopted by the state) for one- and two-family dwellings, and every county and city lands in one of three buckets on the State Fire Marshal's jurisdiction list:

• State program (SRBP): no local codes office, so the State Fire Marshal's residential building program issues the permit and its deputy inspectors inspect the build.
• Exempt, local enforcement: the county or city runs its own codes office with its own adopted code edition. The metro and growth counties live here.
• Opt out: the local legislative body passed a two-thirds resolution opting out of the statewide residential code. No county permit, no required inspections.

Two facts about opt-out surprise almost everyone. First, the scale: per the University of Tennessee's MTAS, opt-out jurisdictions cover roughly 20 percent of the state's population, and the State Fire Marshal's current list marks 37 of the 95 counties as opt out (a 2016 report counted the same number, so the scale has held even as individual counties moved). Second, the expiration: an opt-out resolution lapses 180 days after the next election of the governing body unless re-passed, per T.C.A. 68-120-101, so the list genuinely changes, and it carries an accuracy date for that reason.

Sources: MTAS and CTAS statewide building standards references, University of Tennessee; T.C.A. 68-120-101 (opt-out authorization and its 180-day post-election expiration).

Every Tennessee county, by code status

All 95 counties are below, grouped by the status the State Fire Marshal's Office publishes for each one. The state's list is accurate as of August 6, 2026. Status can change, and an opt-out resolution can lapse after a local election, so treat this as a dated snapshot and confirm with the county office before you buy land or draw plans.

Opt out: 37 counties

State key: the jurisdiction has passed a resolution opting out of the program. No county residential permit, no required county inspection.

Benton, Bledsoe, Carroll, Claiborne, Cocke, Decatur, Fentress, Franklin, Grainger, Grundy, Hardin, Henderson, Henry, Houston, Humphreys, Jackson, Johnson, Lake, Lawrence, Lewis, McMinn, McNairy, Monroe, Moore, Morgan, Obion, Overton, Perry, Pickett, Polk, Scott, Sequatchie, Stewart, Unicoi, Van Buren, Wayne, Weakley.

The fine print matters here: cities inside an opt-out county can still run their own codes office, and statewide electrical and TDEC septic permitting applies everywhere regardless.

Exempt: 50 counties

State key: the jurisdiction has received an exemption from the state program. In practice these counties run their own inspection program, which is where the metro and growth counties sit. Confirm the office and the adopted code edition locally.

Anderson, Bedford, Blount, Bradley, Cannon, Carter, Cheatham, Clay, Coffee, Crockett, Cumberland, Davidson, DeKalb, Dickson, Dyer, Fayette, Gibson, Greene, Hamblen, Hamilton, Hancock, Haywood, Hickman, Jefferson, Knox, Lincoln, Loudon, Macon, Madison, Marion, Marshall, Maury, Montgomery, Putnam, Rhea, Roane, Robertson, Rutherford, Sevier, Shelby, Sullivan, Sumner, Tipton, Trousdale, Union, Warren, Washington, White, Williamson, Wilson.

State Residential Building Program: 8 counties

State key: the jurisdiction will participate in the State Residential Building Program, so the state inspects.

Campbell, Chester, Giles, Hardeman, Hawkins, Lauderdale, Meigs, Smith.

Source: TN State Fire Marshal's Office, Residential Jurisdictions and Inspectors, accurate as of August 6, 2026, read August 13, 2026. Four consolidated city-county governments appear on the state table under a combined name: Moore County/Lynchburg, Davidson County/Nashville, Shelby County and Memphis, and Trousdale County/Hartsville. The same table lists each participating city and the assigned inspector.

Found your county? The status changes what your build looks like on paper, not whether it can happen. Opt-out counties tend to move faster and put more weight on your builder's own standards, which is why the barndominium construction page covers what to hold a builder to when no inspector will. Exempt counties add a permit desk and a review timeline, which belongs in your budget alongside the Tennessee cost ranges. Either way, financing is the step that surprises people most, and the appraisal-gap guide explains why. Tell us the county and a licensed builder who works it prices the build.

Verified local-enforcement counties and their code editions

Sources: each county's building or codes office pages, verified 2026-07-12, for the offices and code editions; TN State Fire Marshal's Office jurisdiction list, accurate as of August 6, 2026, for the status column.

What opt-out does not exempt

Opt-out removes the county building permit and inspections. Everything else still applies:

• State electrical permits and inspections, which run statewide through the state's deputy electrical inspectors.
• TDEC septic (SSDS) permits, statewide, on every lot without sewer. The lot-level details are on the land and lot evaluation page.
• FEMA floodplain designations, enforced in practice by lenders and insurers regardless of county policy.
• Recorded deed restrictions and subdivision covenants.
• City codes offices inside opt-out counties; the county's status does not decide the city's.
• Tennessee's contractor licensing law: the $25,000 license threshold and monetary limits apply in every county, opt-out or not.

And one option runs the other direction: under a 2017 state law, an owner building in an opt-out or non-code area can voluntarily request an inspection from the State Fire Marshal's Office against the statewide standards, and a passing build receives a certificate of occupancy, per the SFMO's opt-out jurisdictions page. Lenders like seeing it; so do future buyers.

How to check your county in five minutes

1. Open the State Fire Marshal's residential jurisdictions and inspectors list (the same office also publishes an opt-out areas page). Note the "accurate as of" date; the version behind the roster on this page is stamped August 6, 2026.
2. Find your county and, separately, your city if the parcel is inside city limits. The two can differ.
3. Call the office the list points to, county codes, city codes, or the state program, and ask what a new residential build requires on your specific parcel.
4. If the county shows opt out, plan your own documentation standard with your lender and builder, because design and engineering still carry the project even where nobody inspects it.

The permit question is one leg of the full project path; costs, financing, land, and timeline are the rest, and they live in the Tennessee Barndominium Guide. For how the split plays out on the ground, the Knoxville region page covers enforced-next-to-opt-out country, and West Tennessee covers the state's thickest opt-out territory.