Outside city limits, Jefferson County Code Enforcement (part of the Department of County Services and Code Enforcement) at 725 Maple Street, Hillsboro (636-797-5310) reviews plans, issues building, electrical, plumbing, mechanical and septic permits and inspects the work under the 2015 International Codes. Applications, inspection requests and contractor licences all go through the county’s Citizen Portal, and fees follow the schedule adopted by Ordinance 21-0356 in 2021: a new house is charged on its construction cost, with at least $120 per sq ft counted.
Jefferson County building department: who handles permitting
The Code Enforcement Division, formed in 1967, regulates construction, alteration and occupancy of structures in unincorporated Jefferson County. It employs building, plumbing, electrical, sewer and mechanical inspectors as well as plan examiners, and the office is open Monday to Friday, 7:30 a.m. to 5 p.m. Mailed payments go to P.O. Box 100, Hillsboro, MO 63050, with the permit number on the check. Zoning work (zone changes, conditional uses, development plans, site development and variances) belongs to the county’s Planning Division in the same building (636-797-5580, 8 a.m. to 5 p.m.).
Inside city limits the city, not the county, is the place to start: most of the larger cities run their own building departments. Populations below are Census Bureau Vintage 2025 estimates.
| Place | Who permits building work |
|---|---|
| Arnold (20,994) | City Building & Code Compliance Division, City Hall, 2101 Jeffco Blvd.; 636-282-2378. Applications go through the City’s MyGov portal |
| Festus (14,066) | City Building and Planning Department, 950 N. 5th Street; 636-937-6646 |
| De Soto (6,527) | City Building Inspectors Office, 17 Boyd Street (636-586-3326). Applications are filed online in Cloudpermit; the City Code adopts the 2021 International Codes and 2020 NEC, and the City lists new construction at $0.43 per sq ft of living and non-living space, with fees rising 3% every April 1 |
| Pevely (6,239) | City Code Enforcement and Building Department, 401 Main Street; 636-475-4452. The City Code adopts the 2015 International Codes and 2014 NEC, and the department posts its own permit fee schedule |
| Herculaneum (5,402) | City Building Department and Building Official, 1 Parkwood Court; 636-475-4447. 2021 International Codes and 2020 NEC; only City-licensed contractors may work, and occupancy permits are $30 |
| Crystal City (4,694) | City Building and Planning Department; 636-937-4616. Its occupancy inspection is required before water service |
| Hillsboro (3,493) | City Building Department and Planning & Zoning, through the City’s online portal; City Hall, 101 Main Street, 636-797-3334 |
| Byrnes Mill (3,183) | City permits, under the 2021 building, plumbing, mechanical and fuel gas codes and 2020 NEC; administrative fee $40 for homes and $100 for commercial work. City Hall, 141 Osage Executive Circle, 636-677-7727 |
| Kimmswick (133) | City Hall (636-464-7407) sends building permit applicants to the Rock Community Fire District, which the City Code names as its agent for inspections and occupancy permits |
| Eureka (81 here; most of the city is in St. Louis County) | City of Eureka Building Department; 636-938-5233 |
| Olympian Village (710), Lake Tekakwitha (233), Cedar Hill Lakes (203), Scotsdale (198), Parkdale (156), Peaceful Village (97) | The published sources do not say; ask the village or city clerk |
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Get a free quote →What needs a county permit
Besides building permits, the county posts separate applications for electrical, plumbing, mechanical, on-site sewage, demolition, manufactured home, pool and hot tub, sign, generator, solar and floodplain development work, each with a checklist for common projects such as basements, decks, retaining walls and garages.
No permit (county FAQ)
- Detached decks up to 200 sq ft and no more than 30 inches above grade, not serving the required exit door
- Fences up to 8 ft high
- Gas or electric water heater replacement
- One-story detached sheds and playhouses up to 200 sq ft
- Retaining walls up to 6 ft that hold no surcharge
- Prefabricated pools less than 24 inches deep
Still needs a permit
- Repairs that cut walls, beams or bearing supports or change exits
- Moving or replacing wiring, gas, drain, vent or water piping
- Emergency equipment replacement: apply by the next working day
Jefferson County permit fees
Fees are set in Section 500.250 of the county code (Ordinance 21-0356, in effect for all permits since September 6, 2021). Building permits are priced on the cost of construction, labor and materials, and the county counts at least these costs per sq ft: $120 for new homes, $165 for remodels, $65 for finished basements, $38 for utility buildings and $235 for commercial construction. The $40 residential or $200 commercial plan review charge is paid at application and deducted from the total fee.
Not sure this scope needs a permit?
Get a free quote →| Item | Fee |
|---|---|
| Residential permit, cost $100,001–$120,000 | $1,325 |
| Residential permit, cost $220,001–$240,000 | $1,605 |
| Residential permit, cost over $2 million | 0.18% of cost |
| Commercial permit, cost up to $10,000 | $650 |
| Commercial permit, cost over $5 million | 0.23% of cost |
| Deck, cost up to $2,000 | $225 |
| New on-site sewage (septic) system | $295 (field repair $195, tank replacement $155) |
| Residential electrical panel up to 200 A | $115 |
| Residential plumbing | $125 |
| Furnace or air conditioner | $60 per unit |
| Demolition | $185 |
| Floodplain development | $75 |
| Inspection or re-inspection | $50 |
| Planning and zoning fee | $10 |
For example, a 2,000 sq ft house is counted at no less than $240,000, which falls in the $220,001–$240,000 band, so the building permit is $1,605; the $40 paid at application comes off that total. A septic permit ($295 plus the $40 sewage review) and any separate trade permits are extra. ADA ramps for homes are free. Fees can be refunded only on written request within 180 days of payment, and at most 50% when no work has been done.
Trade permits and contractor licences
Code Enforcement issues the electrical, plumbing and mechanical permits for unincorporated work as well as the building permit. The county electrical rules are the 2014 National Electrical Code with the Jefferson County Electrical Code of 2017.
The Code Official licenses contractors, and each new applicant files an application for examination with the fee and a full-face color photograph. Licences cover the electrical, plumbing, mechanical, sprinkler, communications, irrigation and on-site sewage trades. Most licences are $150, the soil evaluator licence is $100, and each application or renewal costs $30. New and renewal applications go through the Citizen Portal; the office keeps a list of licensed contractors (636-797-5310).
Rather talk it over?
Call 1-855-478-4290 →What a new home application needs
The county’s new-construction checklist (dated May 11, 2026) asks for:
- A complete application whose address and parcel ID match the county Property Viewer, with the licensed contractor’s company, licence holder and licence number, and the Ameren premise number
- A 9-1-1 address verification letter (911 business office, 636-285-7102)
- A site plan showing existing buildings, easements, right-of-way and distances to every property line
- Plans at no less than 1/4 inch to 1 foot: floor plan with wall bracing, foundation plan, elevations with grade lines, wall section and electrical plan; walls 12 ft high or 60 ft long need an engineer’s stamp
- Signed and sealed truss drawings and heat loss calculations
- A soil morphology report and sewer design sealed by a Missouri-licensed septic designer, or a sewer district letter if the house will connect to public sewer
- An owner’s affidavit if the deed is not yet in the applicant’s name
Under the Unified Development Order, a lot of 4.99 acres or less where the building will sit within 100 ft of a property line needs a site plan sealed by a licensed surveyor or engineer, with the building and lines staked by the surveyor. Attached decks and structures under 200 sq ft are exempt from the seal and staking.
How to get a Jefferson County permit
Check that the parcel is outside Arnold, Festus and the other permitting cities; inside them, apply to the city.
Get the 9-1-1 address, the soil report and sewer design or sewer district letter, and a driveway permit from Public Works if the lot fronts a county-maintained road.
Create an account before applying.
Pay the $40 or $200 plan review charge; add a floodplain development application if the site is in a flood hazard area.
The permit is issued after plan review, with the deposit deducted from the fee.
Request inspections in the portal at least one business day ahead; older permit numbers that do not start with 25- need “+0” added to find them.
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Get a free quote →County inspections
Requests made in the Citizen Portal after 3:30 p.m. are scheduled for the following business day. The county lists these required inspections:
- Site: after applying, with the area cleared and the building and septic components staked
- Footing and foundation: excavations clean, with only forms and reinforcing steel in place
- Under-floor or slab: before sheathing or concrete covers piping and conduit
- Framing and rough-in: framing, electrical, plumbing and mechanical work before it is covered
- Gypsum board: before taping and plastering
- Septic: with the system in place and the excavation clean
- Final: after finish grading, with the building ready to occupy
A second visit for incomplete work can carry the $50 re-inspection fee. Permanent electric service is released only when the building is secured, with roofing, windows, doors and exterior cladding finished.
Floodplain, septic and zoning rules
Floodplain: the county adopted a new Flood Damage Prevention chapter on December 4, 2025 (Ordinance 25-0406), after FEMA’s revised flood maps for the county took effect on October 2, 2025. The Director of County Services and Code Enforcement is the floodplain administrator. New and substantially improved homes, including manufactured homes, must have the lowest floor, basement included, 3 ft above the base flood elevation; businesses must meet the same height or be floodproofed. The floodplain development permit ($75) is a separate application with a site or grading plan sealed by an engineer or surveyor and the market value of the building and of the work.
Septic: Code Enforcement is the onsite wastewater permitting authority for the county under its own On-Site Sewage Treatment Code (Chapter 705), and it licenses the on-site sewage installers, designers and soil evaluators who work on these systems.
Zoning and data centers: the Unified Development Order (Chapter 400) sets the zoning districts. On April 27, 2026 the County Council added Article X, which allows data centers only with an approved development plan in the Planned Business Park (PB) and Planned Industrial (PI) districts, set back 200 ft from non-residential property and 500 ft from residentially developed property. A full rewrite of the Unified Development Order is under way with the county’s planning consultant.
Missouri building code
Missouri has no mandatory statewide building code for private construction: a county, fire protection district or municipality may adopt one (usually by reference under RSMo 67.280), and in parts of the state none has. Building codes in Missouri
Want this handled start to finish?
Get a free quote →Jefferson County permit FAQs
Who issues building permits in unincorporated Jefferson County?
Jefferson County Code Enforcement, 725 Maple Street, Hillsboro (636-797-5310), through the online Citizen Portal.
How much is a building permit for a new house?
It depends on the construction cost, counted at no less than $120 per sq ft. A 2,000 sq ft house falls in the $220,001–$240,000 band, so the permit is $1,605, including the $40 paid at application.
Do I need a permit for a shed or deck?
Not for a one-story detached shed of 200 sq ft or less, or a detached deck of 200 sq ft or less no more than 30 inches above grade. Larger ones need a permit; decks start at $225.
Does the county issue permits in Arnold, Festus or Pevely?
No. Arnold, Festus, Pevely, De Soto, Herculaneum, Crystal City, Hillsboro and Byrnes Mill permit work inside their own limits.
Which building codes does the county use?
The 2015 International Building, Residential, Plumbing, Mechanical, Fuel Gas, Fire, Energy Conservation and Pool and Spa codes, with the 2014 National Electrical Code and the 2017 county electrical code.
How do I schedule an inspection?
In the Citizen Portal, at least one business day ahead; requests after 3:30 p.m. go to the next business day.
Inspections are where schedules slip.
Get a free quote →Jefferson County permit search and official resources
- Jefferson County building permits and Citizen Portal
- Jefferson County Citizen Portal
- Jefferson County adopted codes and ordinances
- Jefferson County Building Code and fee schedule (Chapter 500)
- Jefferson County permit applications and checklists
- Residential new construction checklist (May 2026)
- Jefferson County inspections
- Jefferson County contractor licences
- Jefferson County Flood Damage Prevention (Chapter 405)
- Jefferson County Unified Development Order (Chapter 400)
- Jefferson County Planning Division
- FEMA Community Status Book: Missouri
- City of De Soto Building Inspectors Office
- City of Pevely Code Enforcement and Building Department
- City of Herculaneum permits and licences
- City of Crystal City Building and Planning Department
- City of Byrnes Mill building permits
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More Missouri permitting guides
Arnold
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Read guide →Joplin Building Permit Guide
Read guide →This guide is provided by Alliance Permitting for general information about Jefferson County permitting. Requirements, fees, and procedures change; confirm details with the permitting authority before relying on them.