Bolthole Index

Jefferson County, Missouri

Building permits, zoning and septic rules in Hillsboro, Missouri

Hillsboro, Missouri administers residential building permits through the city building inspector or the city administrator’s authorized officer, and Hillsboro has its own zoning ordinance.12 For land inside Hillsboro in Jefferson County, confirm septic jurisdiction with Missouri DHSS before using the county’s application: incorporated areas may fall outside county wastewater authority.3

At a glance

Building permits
City residential code includes permit exemptions; ask the city building inspector about your project.41
Zoning
City zoning applies inside Hillsboro; permitted uses depend on the district.2
Residential lot area
R-1 single-family lots generally need 12,000 square feet; qualifying older recorded lots have an exception.5
Building coverage
R-1 main and accessory buildings together may cover at most 40% of the lot.6
Septic permits
Most installations and repairs need a construction permit; ask DHSS to confirm the authority for an address inside Hillsboro.73
Rental occupancy
Rental housing generally needs a city occupancy permit, with specified exclusions.8

Who to call

Building permits

City of Hillsboro Building Department / Planning & Zoning

City building and planning/zoning inquiries; ask for the building inspector about residential construction.

(636) 797-3334

[email protected]

101 Main Street, PO Box 19, Hillsboro, MO 63050

Septic permits

Missouri Department of Health and Senior Services, Onsite Wastewater Treatment Program

Confirm onsite wastewater permitting jurisdiction for land inside Hillsboro; the state guidance identifies exceptions to local authority in incorporated areas.

573-751-6095

[email protected]

PO Box 570

Contact details are copied from each office’s official page and were checked against it on October 11, 2026.

Off-grid gear

Going off-grid in Hillsboro means bringing your own water and power. The kit we’d start with:

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Do you need a building permit in Hillsboro, Missouri?

Hillsboro’s residential building code includes work exempt from a building permit, but the city amendment reduces the specified accessory-structure exemption threshold to 100 square feet.4 Do not use that threshold as a blanket exemption for every small structure: ask Hillsboro’s building inspector which exemption covers the proposed work.41 The city identifies the building inspector or an officer appointed by the city administrator as the residential code official.1 Ask that official to confirm the application, inspection schedule and fees before ordering materials.

Who handles building permits and zoning in Hillsboro?

The City of Hillsboro lists a combined Building Department / Planning & Zoning office, reachable through City Hall at (636) 797-3334 or [email protected].9 The city office is at 101 Main Street, PO Box 19, Hillsboro, MO 63050, with office hours Monday through Friday, 8:00 A.M. – 5:00 P.M.9 Ask for the city building inspector when discussing residential code approval.1 For a proposed purchase, bring the parcel identification, intended use and proposed building footprint, and request the district designation and applicable yard requirements.

Does Hillsboro have zoning, lot limits and setback rules?

Hillsboro has an adopted zoning ordinance, and uses and structures inside city limits must comply with the applicable district regulations and minimum yard requirements.2 In Hillsboro’s R-1 Single-Family Residential District, a single-family dwelling generally needs a lot of at least 12,000 square feet; a smaller lot recorded before March 10, 1975 may qualify under the ordinance’s recordation exception.5 R-1 main and accessory buildings together may cover no more than 40% of total lot area.6 Ask the city planning/zoning office to confirm the district, yards and buildable footprint for the particular parcel rather than applying R-1 standards throughout Hillsboro.9

How do septic permits work inside Hillsboro?

Missouri requires a construction permit before installing or repairing most onsite wastewater treatment systems, although some single-family residential lots may qualify for an exemption.7 Missouri DHSS says to determine the permitting agency first and warns that some incorporated areas fall outside the local wastewater authority.3 We could not confirm the septic permitting authority specifically for Hillsboro city limits; contact the DHSS Onsite Wastewater Treatment Program before submitting a county application.3 Ask the city about sewer availability and connection requirements for the address, then confirm any proposed onsite system’s permitting path before starting work.10

Can you live in an RV or tiny home in Hillsboro?

We could not confirm Hillsboro’s rules for living in an RV, occupying a tiny home or camping while building; ask the city Building Department / Planning & Zoning office about the exact proposal.9 Hillsboro’s district use restrictions still apply to land and buildings, so a small footprint alone does not establish an allowed residential use.2 If the proposed home will be rented, Hillsboro generally requires an occupancy permit for rental units used for human habitation, with exclusions for individual hotel, motel and bed-and-breakfast rooms and specified licensed facilities.8

What steps should you take before building a home in Hillsboro?

Start with Hillsboro’s planning/zoning office: request the parcel’s zoning district and applicable yard requirements before settling on a house layout.92 Next, ask the city building inspector which residential building permits and inspections the project needs.1 For onsite wastewater, confirm the permitting authority and obtain a construction permit or confirmed exemption before work begins.10 Ask the city about floodplain status as well: Missouri requires a permit for all floodplain development through the applicable community process.11 For land outside Hillsboro city limits, consult the Jefferson County guide: the county’s onsite sewage code applies to unincorporated land.12

Watch-outs

  • Hillsboro’s smaller-lot exception in R-1 depends on the lot’s historical recordation; ask the city to review the deed and recorded plat before relying on the exception.5
  • We could not confirm a city owner-builder exemption or minimum dwelling floor area; ask Hillsboro’s building inspector before planning a self-built or very small home.1
  • Missouri DHSS onsite wastewater application fees are temporarily suspended effective August 28, 2026; confirm the current charge with the actual permitting authority rather than assuming a local fee is also suspended.13

Sources

  1. Hillsboro Building Code Amendments (Hillsboro), quoted and re-checked
  2. Hillsboro Zoning Code, R-1 Use Regulations (Hillsboro), quoted and re-checked
  3. Missouri Department of Health and Senior Services, Onsite Wastewater Treatment Program (health.mo.gov)
  4. Hillsboro Building Code Amendments (Hillsboro), quoted and re-checked
  5. Hillsboro Zoning Code, R-1 Area Regulations (Hillsboro), quoted and re-checked
  6. Hillsboro Zoning Code, R-1 Area Regulations (Hillsboro), quoted and re-checked
  7. OWTS Construction Permit Process (Missouri statewide rule), quoted and re-checked
  8. Hillsboro Occupancy Permits (Hillsboro), quoted and re-checked
  9. City of Hillsboro Building Department / Planning & Zoning (hillsboromo.gov)
  10. OWTS Construction Permit Process (Missouri statewide rule), quoted and re-checked
  11. Floodplain Forms (Missouri statewide rule), quoted and re-checked
  12. Chapter 705, Article I — On-Site Sewage Treatment Code, quoted and re-checked
  13. OWTS Construction Permit Process (Missouri statewide rule), quoted and re-checked

Written October 11, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

Answers from the rulebook for Hillsboro

Hillsboro’s own rules

  • Building permitLimited

    Residential construction governed by the city's adopted residential building code inside Hillsboro city limits.

    • The code section identifies work exempt from permit and changes the exemption threshold for specified IRC items to 100 square feet; the complete permit table was not available in the opened excerpt.

    specified accessory-structure permit exemption threshold: <= 100 square feet (The excerpt states the IRC exemption item is amended from 200 square feet to 100 square feet.)

    “Section R105.2 "Work exempt form permit" is amended by deleting "200 square feet" on item 1 and 10 under Building and substituting "I 00 square feet". Also by deleting item 2.”
  • InspectionsLimited

    Nonowner-occupied rental dwellings inside Hillsboro city limits.

    • The occupancy-permit process includes inspection before issuance and applies to rental units used for human habitation; hospitals, nursing homes, and units subject to other licensing are excluded.
    “The occupancy permit so issued shall state that the condition of the premises and its proposed occupation complies with all of the provisions of this Code as far as can be determined by a visual inspection of the premises and a review of the records.”
  • Certificate of occupancyRequired

    Rental units used for human habitation inside Hillsboro city limits.

    • Applies to rental units; individual hotel, motel, and bed-and-breakfast rooms are excluded, as are specified medically licensed facilities.
    “It shall be unlawful for any person, firm or corporation to conduct or operate or cause to be rented either as owner, lessee, agent or manager within the city, any rental units used for human habitation (occupancy of individual hotel, motel, or bed and breakfast rooms excluded) without having first obtained an occupancy permit to do so as provided in this section.”
  • Local zoningPresent

    Land inside Hillsboro city limits; the city administers an adopted zoning ordinance with R-1 and other districts.

    • Uses and structures must comply with the district regulations and minimum yard requirements.
    “In the "R-1" District no building or land shall be used and no building shall be erected or structurally altered (unless otherwise provided in the Municipal Code or set forth elsewhere in this ordinance when referred to in this section) except for one or more of the following uses:”
  • Minimum lot sizeSpecified

    Single-family dwellings in the R-1 Single-Family Residential District.

    • A recorded lot existing before March 10, 1975 may be used for a single-family dwelling if it has less area and was duly plotted and recorded in the county recorder's office.

    minimum lot area: >= 12000 square feet (Pre-March 10, 1975 recorded lots may be smaller if the stated recordation conditions are met.)

    “Every lot for single-family dwelling shall have an area of not less than 12,000 square feet, except that if a lot of record prior to the adoption of the order on March 10, 1975, has less area and has been duly plotted and recorded in the office of the recorder of deeds of the county, such lot may be used for a single-family dwelling.”
  • Lot coverageSpecified

    Lots in the R-1 Single-Family Residential District.

    maximum combined building coverage: <= 40 percent of total lot area (Includes the main building and accessory buildings.)

    “The combined building area of the main building and accessory buildings shall not cover more than 40 percent of the total lot area.”
  • Permit processPartial

    Residential building-code permit administration inside Hillsboro city limits.

    • The code identifies the building inspector or city-administrator designee as code official; the complete application and inspection workflow was not available in the opened materials.
    “The "code official" under this Code shall be the building inspector or the duly authorized officer appointed by the city administrator.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Hillsboro or Jefferson County directly.

  • Owner-builder exemption — Owner-builders performing residential construction inside Hillsboro city limits.
  • Minimum dwelling size — Single-family dwellings in Hillsboro city limits, including the R-1 district.
  • Building height — Buildings inside Hillsboro city limits.
  • Camping on your land — Temporary camping on private land inside Hillsboro city limits.
  • Tiny homes — Tiny-home occupancy inside Hillsboro city limits.
12 more unanswered
  • Accessory dwellings
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Mandatory utility hookup
  • Agricultural exemption
  • Subdividing land
  • Driveway access
  • Short-term rentals
  • Permit fees

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Unanswered questions are usually a sign that Hillsboro publishes no rule on the point, not that none exists. Jefferson County’s page lists the county offices to call.

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