Ralls County, MO zoning map, flood zone and property lines by address
Free, no account. Or open the Missouri map and tap a lot.
Towns in Ralls County: New London.
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 Ralls County has 23 FIRM panels, the newest effective April 2010; 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 Ralls 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 Missouri county parcel layers (each county publishes its own), so a Ralls lot shows the same lines the county assessor draws. Ralls County covers about 300,668 acres of land and 8,986 acres of water.
Mapped lines are approximate. The Ralls County assessor keeps the parcel record (Ralls County website); a licensed surveyor sets the true corners.
Zoning
Ralls County zones its unincorporated land, and New London zones the land inside its limits. ParcelSheet shows the use the county assessor lists for the lot and links the county planning and zoning office for the district, the uses it allows and the lot size it needs.
ADU and guest houses
Under Missouri's county planning and zoning law (Revised Statutes of Missouri Chapter 64), local governments can allow an accessory dwelling unit on a lot with a house. Whether a Ralls lot can add one depends on its district; the county planning and zoning 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. Ralls County is soil survey area MO173, Ralls County, Missouri, last updated August 2026, on Web Soil Survey.
A new or changed septic system in Ralls County needs a permit from the Ralls County health department, or the county's other designated onsite authority (Missouri Department of Health and Senior Services onsite wastewater program).
Setbacks
Setbacks in Ralls 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 New London for land inside its limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Ralls lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Ralls 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 Ralls County has 23 panels, the newest effective April 2010. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Ralls County?
Open the Missouri map, type the address, and the parcel outline from the Ralls 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 Ralls County?
Zoning in Ralls County is set by the county for unincorporated land and by each city (such as New London) 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 Ralls County?
Under Missouri's county planning and zoning law (Revised Statutes of Missouri Chapter 64), counties and cities can allow an accessory dwelling unit, and each sets its own rules. In Ralls 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 Ralls County?
Yes. A new or changed septic system in Ralls County needs a permit from the Ralls County health department, or the county's other designated onsite authority (Missouri Department of Health and Senior Services onsite wastewater program). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area MO173 (Ralls County, Missouri).
What can I build on 5 acres in Ralls County?
Zoning in Ralls County is set by the county for unincorporated land and each city inside its own limits (such as New London). 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 Ralls County website.
What are the residential setbacks in Ralls County (2026)?
Setbacks in Ralls 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 Ralls County website.
Next to Ralls County: Audrain County, Marion County, Monroe County, Pike County.
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