Building permits and land rules in Buchanan County, Missouri

Yes. Unincorporated Buchanan County requires an application before a building is erected, constructed, reconstructed, moved, demolished or altered¹. The rule applies throughout the county zoning districts regardless of acreage¹. A separate permit is generally required for each structure, and a complete application that meets the Zoning Order must be approved within 30 days of filing¹. Published fees vary by permit and structure type; commercial and industrial buildings are charged $0.20 per square foot, while the listed fee for other structures is 1% of estimated construction cost with a $50 minimum¹. Starting without a valid permit doubles the later permit fee and can expose the structure to demolition for permit, setback, right-of-way or density-table violations¹.

Buchanan County Planning & Zoning issues building permits, enforces zoning, handles onsite-wastewater permits and processes conditional-use requests in unincorporated Buchanan County³. The office is at 411 Jules Street, Room 201, St. Joseph, MO 64501, and its phone number is 816-271-1528³. Planning & Zoning also assigns new county addresses³. The county rules here cover unincorporated land; the city of Dearborn, which lies mainly in Platte County and reaches into Buchanan, issues its own building permits and sets its own zoning^7,8. Bring the parcel's tax map-block-parcel number plus its description, dimensions, location and intended use when preparing the application¹. County building-inspection authority is limited to enforcement of the Nuisance Order, including permitted work and buildings reasonably suspected of being unsafe, dangerous or hazardous⁹. Ask Planning & Zoning whether a separate adopted residential or commercial construction code governs the project; we could not confirm one.

Buchanan County's Zoning Order governs the entire unincorporated area and regulates uses, buildings, lots, density, yards and other dimensions². Published classifications include agricultural, business, industrial, residential and miscellaneous districts, with parcel boundaries established by county zoning maps⁴. For other permitted uses in the A-1, A-2 and A-OR agricultural districts, the table specifies a 50-foot front yard, 15-foot side yards and a 75-foot rear yard; airport, road, solar, floodplain and use-specific rules can add different setbacks³. The A-OR table caps both principal and accessory buildings at 35 feet, subject to separate airport-zone limits and the Zoning Order's exceptions¹. Minimum lot area for a dwelling depends on the district. A permitted dwelling in A-1 General Agricultural needs at least 20 acres, a conditional-use dwelling in A-1 needs at least 1 acre, and the March 25, 2026 amendment sets the A-OR permitted-dwelling minimum at 2 acres^2,5. Single-family dwellings with sewage in the R-1, R-2 and R-3 residential districts need 8,000 square feet². Business and industrial lots are sized per building: 6,000 square feet in B-1 and B-2, 20,000 square feet in B-3², and 1 acre in I-1 and I-2². Farm structures and structures clearly incidental to farm operations are excluded from the A-1, A-2 and A-OR district-specific regulations, though other Zoning Order provisions may still apply¹. Tiny homes are conditionally permitted rather than allowed by right in every listed zoning district⁶. Do not treat acreage as permit-free: the building-permit rule applies regardless of acreage¹.

Buchanan County requires a permit to construct, substantially modify or substantially repair an onsite sewage system¹. The Environmental Inspector administers county permits and inspections under the Missouri statutes and state construction standards adopted by the County Commission¹. The written application must include the required site plan, soil-profile-hole locations, test results, lot lines, specifications and design information¹. If the disposal standards cannot be met, the Zoning Officer cannot issue a building permit for a structure that needs onsite disposal¹. The Environmental Inspector may inspect contractor-built, modified or repaired systems up to 100% of the time¹. Existing systems subject to the county rule must be inspected by a licensed onsite inspector or evaluator and documented for approval by the Environmental Inspector or Zoning Director¹. About 40.6% of county soils lack severe limitations for a conventional drain field, so parcel-specific soil work remains important¹⁰.

Buchanan County regulates vacation vehicles used as temporary dwellings in parks and communities: the cited rules require at least 10 feet of separation and cap density at 35 spaces per gross acre¹. Those park rules do not answer whether one RV may be occupied temporarily on an individual parcel, so ask Planning & Zoning about the parcel's district and proposed duration before moving in. In unincorporated Buchanan County, a tiny home is a residential structure of less than 1,000 square feet, on wheels or a foundation, and is conditionally permitted in every listed zoning district⁶. A tiny home still requires a building permit and must meet applicable setbacks, rights-of-way, density and onsite-wastewater requirements; the listed tiny-home application cost is $350⁶. Manufactured homes are not automatically interchangeable with tiny homes: individual mobile-home placement may go through conditional-use procedures, while parks face additional zoning, platting, utility, separation and density requirements¹.

1. Ask Planning & Zoning to locate the parcel on the county zoning maps and identify its district, allowed-use path, setbacks, density and height limits^1,3,4.
2. If using the A-1 family-dwelling route, confirm that the homesite is at least 2 acres and that the owner-builder is a sibling, parent, child or grandchild of the parcel owner¹.
3. File the building-permit application before work begins, including the parcel identifier, site details and intended use¹.
4. Submit the septic application and required soil, site-plan and design materials when onsite disposal is needed¹.
5. Obtain a floodplain development permit before construction or manufactured-home placement in the regulated floodplain areas¹.
6. Obtain a MoDOT permit if the driveway work enters state right-of-way, and contact the Traffic Specialist at least 48 hours before work begins^11,12.

Start with zoning and legal access: have Planning & Zoning locate the parcel on the county zoning maps, then ask the appropriate road authority about the entrance location^4,13. For a proposed split, verify whether county subdivision review applies; only the cited division into 2 parcels each greater than 5 acres receives the stated exemption¹. Check mapped flood status because Buchanan County requires a floodplain development permit for construction and manufactured-home placement in the regulated areas¹. For an existing septic system, obtain the licensed inspection and county approval documentation required by the local rule¹. Ask Planning & Zoning separately about private-well permitting, utility connections, minimum dwelling size and certificates of occupancy because we could not confirm those points. Typical county home value is about $196,537, the median annual property-tax bill is about $1,253, and farmland value is about $5,382 per acre¹⁰.