Union County, SC: flood zone, zoning and property lines by address
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Towns in Union County: Union, Monarch Mill, Buffalo.
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 Union County has 21 FIRM panels, the newest effective May 2021; 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 an Union 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 county GIS parcel layer (each South Carolina county publishes its own; the state has no statewide parcel map), so an Union lot shows the same lines the county assessor draws. Union County covers about 328,707 acres of land and 1,109 acres of water.
Mapped lines are approximate. The Union County county assessor keeps the parcel record (Union County website); a licensed surveyor sets the true corners.
Zoning
Union County zones its unincorporated land, and Union zones the land inside its limits. ParcelSheet shows the use the county assessor 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
The South Carolina Local Government Comprehensive Planning Enabling Act (Title 6, Chapter 29) lets local governments allow an accessory dwelling unit on a lot with a house. Whether an Union 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. Union County is soil survey area SC087, Union County, South Carolina, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Union County needs a permit from the SC Department of Environmental Services onsite wastewater program for Union County, which tests the soil on the lot itself.
Setbacks
Setbacks in Union 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 Union for land inside its limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near an Union lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Union 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 Union County has 21 panels, the newest effective May 2021. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Union County?
Open the South Carolina map, type the address, and the parcel outline from the county county assessor 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 Union County?
Zoning in Union County is set by the county for unincorporated land and by each city (such as Union) inside its own limits. ParcelSheet shows the use code the county assessor lists and links the office that sets the zoning; the planning office has the final word.
Can I build an ADU in Union County?
The South Carolina Local Government Comprehensive Planning Enabling Act (Title 6, Chapter 29) lets counties and cities allow an accessory dwelling unit, and each sets its own rules. In Union 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 Union County?
Yes. A new or changed septic system in Union County needs a permit from the SC Department of Environmental Services onsite wastewater program for Union County. ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area SC087 (Union County, South Carolina).
Next to Union County: Cherokee County, Chester County, Fairfield County, Laurens County, Newberry County, Spartanburg County, York County.
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