Williamson County Permit Expediting
Williamson County is the opposite of Nashville. Instead of one consolidated government, it has a county codes department for unincorporated land and separate permit offices in each of its cities. Franklin, Brentwood, Spring Hill and Nolensville each run their own building departments, with their own portals, fee schedules and review steps.
The county itself will send you to the right city if your address is inside city limits, but that costs time. NashPermits sorts out the jurisdiction first, then prepares and files the application with the office that actually has authority over the parcel.
County or city: where your application goes
- Unincorporated Williamson County is handled by the Williamson County Department of Building Codes, with zoning through the Community Development Department. Plans go through the county's electronic plan review system.
- Franklin issues permits through its Building and Neighborhood Services Department, with all plans submitted as PDFs through the city's online permit portal.
- Brentwood combines planning and codes in one Planning and Codes Department, and applications and plans are submitted electronically.
- Spring Hill runs its own Building Codes and Inspections office for the whole city, including the part that sits in Maury County.
- Nolensville has its own Building Codes Department, with the town engineer and planner involved in review and utility tap fees paid before the permit is issued.
Septic and the unincorporated county
Much of rural Williamson County is on septic rather than sewer, and the county runs its own Department of Sewage Disposal Management under local rules that were most recently amended in 2026. For a new home or a large addition on acreage, the septic side of the approval can take as long as the building permit, and it depends on the soil and the site. We line up both so the house is not waiting on the drain field.
Projects we see most in Williamson County
- Custom homes and large additions on estate lots, often with septic
- Pools, outdoor living and accessory structures in Brentwood and Franklin neighborhoods
- Subdivision homes in the fast-growing areas around Spring Hill and Nolensville
- Office and commercial tenant build-outs in Cool Springs and Maryland Farms
Why Franklin is its own conversation
Downtown Franklin and the surrounding historic areas fall under the city's Historic Preservation Overlay. Exterior changes there need a Certificate of Appropriateness from the Historic Zoning Commission, reviewed against the Franklin Historic District Design Guidelines, and the city recommends an informal design review before a formal submission. Minor work can sometimes be approved by preservation staff. Getting that sequence right is part of our planning and zoning coordination work.
Across the county, the common thread is that every city expects a complete, electronic package the first time. Our building permit service handles the application itself, and plan review coordination covers the comment rounds that follow.
Related services in Williamson County
- Residential permitting: additions, renovations, new homes, pools and accessory structures
- Building permits: application preparation, submission and tracking
- Planning & zoning coordination: zoning requirements, overlays and use approvals
- Plan review coordination: managing comments and resubmittals
Williamson County permit FAQs
My address says Franklin. Is it a city permit or a county permit?
A Franklin mailing address does not always mean the property is inside Franklin city limits. Parcels outside the city are permitted by Williamson County's Department of Building Codes. We check the parcel before filing so the application goes to the right office the first time.
Do I need septic approval before building in unincorporated Williamson County?
If the property is not on sewer, the on-site system has to be approved by the county's Department of Sewage Disposal Management under the county's rules. That work depends on soils and site layout, so we start it at the same time as the building permit rather than after.
Who handles permits for a pool or home addition in Williamson County?
It depends on where the home sits. Brentwood, Franklin, Spring Hill and Nolensville each issue their own residential permits, and unincorporated homes go through the county. We prepare the application for the right office and track it through review.
What is different about building in downtown Franklin?
Properties in Franklin's Historic Preservation Overlay need a Certificate of Appropriateness from the Historic Zoning Commission for exterior changes, alongside the building permit. We plan the design review step into the schedule so it does not surprise you late in the process.
More questions? See our full FAQ page or browse all service areas.
Starting a project in Williamson County?
Send us the project address and scope of work. We'll confirm the jurisdiction and reply within one business day with the approvals you need and a quote.
Call or text 615-815-5499 · team@nashpermits.com