Posey County, IN zoning map, flood zone and property lines by address
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Towns in Posey County: Mount Vernon, Poseyville.
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 Posey County has 35 FIRM panels, the newest effective November 2014; 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 Posey 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 Indiana statewide parcel layer (IndianaMap, from each county), so a Posey lot shows the same lines the county assessor draws. Posey County covers about 262,006 acres of land and 6,550 acres of water.
Mapped lines are approximate. The Posey County assessor keeps the parcel record (Posey County website); a licensed surveyor sets the true corners.
Zoning
Posey County zones its unincorporated land, and Mount Vernon, Poseyville each zone the land inside their limits. ParcelSheet shows the use the county assessor lists for the lot and links the county plan commission for the district, the uses it allows and the lot size it needs.
ADU and guest houses
Under Indiana's planning and zoning law (Indiana Code 36-7-4), local governments can allow an accessory dwelling unit on a lot with a house. Whether a Posey lot can add one depends on its district; the county plan commission 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. Posey County is soil survey area IN129, Posey County, Indiana, last updated August 2026, on Web Soil Survey.
A new or changed septic system in Posey County needs a permit from the Posey County health department (Indiana Department of Health onsite sewage program).
Setbacks
Setbacks in Posey 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 Mount Vernon and Poseyville for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Posey lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Posey 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 Posey County has 35 panels, the newest effective November 2014. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Posey County?
Open the Indiana map, type the address, and the parcel outline from the Posey 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 Posey County?
Zoning in Posey County is set by the county for unincorporated land and by each city (such as Mount Vernon, Poseyville) 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 Posey County?
Under Indiana's planning and zoning law (Indiana Code 36-7-4), counties and cities can allow an accessory dwelling unit, and each sets its own rules. In Posey 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 Posey County?
Yes. A new or changed septic system in Posey County needs a permit from the Posey County health department (Indiana Department of Health onsite sewage program). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area IN129 (Posey County, Indiana).
What can I build on 5 acres in Posey County?
Zoning in Posey County is set by the county for unincorporated land and each city inside its own limits (such as Mount Vernon, Poseyville). 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 Posey County website.
What are the residential setbacks in Posey County (2026)?
Setbacks in Posey 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 Posey County website.
Next to Posey County: Gibson County, Vanderburgh County.
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