Williamson County is currently under the 2015 edition of the International Building Code for all commercial, educational, and assembly occupancies. For all residential construction, the 2015 International Residential Code
- 2015 International Building Code
- 2015 International Mechanical Code
- 2015 International Plumbing Code
- 2009 International Energy Conservation Code
Plans submitted for residential occupancies covered by the 2015 International Building Code that are one (1) or two (2) story(s) in height having a gross area of less than five thousand (5,000) square feet must be significantly detailed and describe the site, foundation, framing, electrical, plumbing, mechanical, and sprinkler systems,
: Plans are not required to be designed by registered design professionals unless the project's complexity warrants otherwise. Buildings larger than this require plans to be developed by a registered design professional.
All Educational occupancies, Daycare facilities and large assembly occupancies must have plans approved by the Tennessee State Fire Marshals Office prior to permitting.