Building Code Editions Around Nashville, Town by Town

Every city and town in Middle Tennessee builds to the International Residential Code (IRC), but not to the same edition. The ICC publishes a new edition every three years, and each city adopts one when its council passes an ordinance, often with local amendments. Right now, homes a few miles apart can be built to codes six years apart. This affects your project more than you might expect.

Who's on what (as posted by each city)

A dash means the city's page didn't state it clearly. We couldn't confirm a current residential code edition for Murfreesboro or Franklin from their public pages, so they're not in the table. Ask those departments directly.

Why the edition matters to you

Bids should be priced to the same code. If you're getting bids from contractors who work all over the region, ask each one which edition and amendments they priced to. A builder used to a 2018-code town may not have priced what a 2024-code town requires, and the difference shows up as a change order.

Plans have to match where you build. Designers working across county lines need to check every town. Thompson's Station's notice is a good example of how mixed it can be: a 2021 residential code, a 2018 energy code and a 2023 electrical code, all at once.

Cutover dates decide which rules apply. Codes generally apply based on when you apply for the permit. Gallatin spells it out: permits pulled before November 20, 2024 stay under the older 2018 codes, 2015 energy code and 2017 NEC, while later permits fall under the 2024 set. If a city is about to change editions, the application date can change your design requirements.

Local amendments can matter more than the edition. Nolensville's 2024 adoption is a good example. It added items to the exempt-work list (including non-structural re-roofs), set minimum footing dimensions and reinforcement, required a Tennessee-licensed engineer to design certain slabs, set deck footing sizes, and required a positive drain for crawl spaces. Thompson's Station added its own rule that gas vent pipe must be UL 1738 listed, so ordinary schedule 40 PVC isn't accepted for fuel-fired appliance vents. Neither rule is obvious from the edition number.

Questions to ask the building department

1. Which IRC edition, energy code and electrical code apply to a permit I submit this month?
2. Are there local amendments, and where are they posted?
3. Is a code change coming, and from what date?
4. Who handles electrical permits here: the city, Metro, or the state?

Questions to ask your contractor

1. Which code edition did you price this bid to?
2. Have you built under this city's amendments before?
3. Will you pull the permit and schedule every inspection? (See our contractor checklist.)

Older homes and newer codes

A newer code doesn't make your existing house illegal. Codes mostly apply to new work: an addition, a converted basement, a replaced deck. But the new part has to meet today's rules, and that sometimes forces upgrades where old and new connect. Expect it on additions (see home additions) and decks (see decks and porches).

Area pages with more detail: Nolensville, Gallatin, Smyrna, Brentwood, Thompson's Station.