Williamson County, TN zoning map, flood zone and property lines by address
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Towns in Williamson County: Franklin, Brentwood, Brentwood Estates.
Flood zone by address
ParcelSheet reads FEMA's National Flood Hazard Layer at the lot: the zone, whether it is a high risk area where lenders ask for flood insurance, and the base flood elevation where FEMA lists one. FEMA's countywide study for Williamson County has 94 FIRM panels, the newest effective December 2024; no coastal V zones are mapped in it.
The official panel and any Letter of Map Amendment are at FEMA's Map Service Center. An elevation certificate for a Williamson house comes from a licensed surveyor and is often on file with the county or city building office.
Property lines
The parcel outline, parcel number and mapped size come from the Tennessee Comptroller property boundaries layer (from each county assessor of property), so a Williamson lot shows the same lines the assessor of property draws. Williamson County covers about 373,063 acres of land and 744 acres of water.
Mapped lines are approximate. The Williamson County assessor of property keeps the parcel record (Williamson County website); a licensed surveyor sets the true corners.
Zoning
Williamson County zones its unincorporated land, and Franklin, Brentwood each zone the land inside their limits. ParcelSheet shows the use the assessor of property lists for the lot and links the county planning office for the district, the uses it allows and the lot size it needs.
ADU and guest houses
Under Tennessee's zoning laws (Tennessee Code Title 13, Chapter 7), local governments can allow an accessory dwelling unit on a lot with a house. Whether a Williamson lot can add one depends on its district; the county planning office has the rule. ParcelSheet shows the mapped lot size and the ground's slope, the first two things the question turns on.
Septic and soil
ParcelSheet reads the USDA soil survey at the lot: the soil's name, its septic absorption rating and whether it is prime farmland. Williamson County is soil survey area TN187, Williamson County, Tennessee, last updated August 2026, on Web Soil Survey.
A new or changed septic system in Williamson County needs a permit from the TDEC Division of Water Resources, or the county health department in a county that runs its own septic program, which tests the soil on the lot itself.
Setbacks
Setbacks in Williamson County come from the zoning district: the front, side and rear distances a house must keep. ParcelSheet does not draw setback lines; the county zoning office gives them for the lot's district, and Franklin and Brentwood for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Williamson lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Williamson County?
Type the address in the box above and ParcelSheet reads FEMA's flood zone at the lot's center. FEMA's countywide flood map for Williamson County has 94 panels, the newest effective December 2024. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Williamson County?
Open the Tennessee map, type the address, and the parcel outline from the Williamson County assessor of property shows on the map with its parcel number and mapped size. Mapped lines are approximate; only a licensed surveyor sets the true corners.
What is my property zoned in Williamson County?
Zoning in Williamson County is set by the county for unincorporated land and by each city (such as Franklin, Brentwood) inside its own limits. ParcelSheet shows the use code the assessor of property lists and links the office that sets the zoning; the planning office has the final word.
Can I build an ADU in Williamson County?
Under Tennessee's zoning laws (Tennessee Code Title 13, Chapter 7), counties and cities can allow an accessory dwelling unit, and each sets its own rules. In Williamson County ask the zoning office for the lot's district first; ParcelSheet shows the lot size as mapped so you can see the room you have.
Do I need a septic permit in Williamson County?
Yes. A new or changed septic system in Williamson County needs a permit from the TDEC Division of Water Resources, or the county health department in a county that runs its own septic program. ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area TN187 (Williamson County, Tennessee).
What can I build on 5 acres in Williamson County?
Zoning in Williamson County is set by the county for unincorporated land and each city inside its own limits (such as Franklin, Brentwood). The zoning district decides the uses, how many homes and the smallest lot it allows on 5 acres. ParcelSheet shows the lot size as mapped and the use code on the parcel record; the planning office has the district and its rules. See the Williamson County website.
What are the residential setbacks in Williamson County (2026)?
Setbacks in Williamson County come from the zoning code of the county, or of the city when the lot is inside city limits: the front, side and rear distances depend on the lot's district. ParcelSheet does not draw setback lines or give a number it did not read; the zoning office gives them for the district. See the Williamson County website.
Next to Williamson County: Cheatham County, Davidson County, Dickson County, Hickman County, Marshall County, Maury County, Rutherford County.
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