Residential permit rules in Missouri
Representative cities: St. Louis, Kansas City. Covers 20 common home projects.
Check a home project's permit in Missouri
Select a project to see its Missouri permit requirement, fee range, timeline, go / no-go, and the official source to verify.
Missouri
Exact permit fees are set by the local building department. WikEst shows the published or code-based range where one exists, linked to its official source — verify the final amount at the source before budgeting.
🏠 Accessory Dwelling Unit (ADU) permit fee in Missouri
Permit requiredCase by casecity authority
Permit fee range
Permit fees set locally by each municipality — verify with the city building department (St. Louis Building Division or KC Permits Division).
Typical timeline
Varies by municipality — simple permits often same-day to ~2 weeks; full plan-review permits several weeks.
Setback
—
Exempt if
Not size-exempt
ADUs require a building permit plus zoning/use approval. Missouri has no statewide residential building code, so allowance and rules are set locally (e.g., St. Louis and Kansas City each have their own requirements). Verify with your municipal building department.
Official sources: American Wood Council — Missouri Adopted I-Codes (local adoption; no statewide mandate) · City of St. Louis — Building Division
Representative cities for Missouri: St. Louis, Kansas City.
All 20 project fee ranges in Missouri
Official-source ranges where published; “By local jurisdiction” means no flat fee is published and the amount is set case by case.
| Project | Permit? | Authority | Fee range | Go / no-go |
|---|---|---|---|---|
| 🏠 Accessory Dwelling Unit (ADU) | yes | city | Permit fees set locally by each municipality — verify with the city building department (St. Louis Building Division or KC Permits Division). | case-by-case |
| 🪵 Deck / Porch | conditional | city | Permit fees set locally by each municipality — verify with the city building department. | allowed |
| 🧱 Fence / Wall | conditional | city | Usually no building permit under the height threshold; zoning setback/height rules apply. Verify locally. | allowed |
| 🛖 Shed / Outbuilding | conditional | city | No fee under the exemption; a permit fee applies if over the local threshold. | allowed |
| 🪜 Basement Finish | yes | city | Building permit fee set locally; trade permits billed separately. | allowed |
| 🚗 Garage / Carport | yes | city | Building permit fee set locally; zoning clearance may be required first. | allowed |
| ☀️ Rooftop Solar PV | yes | city | Electrical/structural permit fee set locally by the municipality. | allowed |
| 🌡️ HVAC Replacement | yes | city | Mechanical permit fee set locally by the municipality. | allowed |
| 🍳 Kitchen Remodel | yes | city | Building permit fee; trade permits (plumbing/electrical) billed separately. | allowed |
| 🛁 Bathroom Remodel | yes | city | Building permit fee; trade permits (plumbing/electrical) billed separately. | allowed |
| 🏗️ Room Addition | yes | city | Building permit fee based on valuation; zoning and plan review apply. | allowed |
| 🪟 Window / Door Replacement | conditional | city | Permit fee if changing the opening; in-kind swap is often exempt. | allowed |
| 🏘️ Roof Replacement | conditional | city | Roof-covering permit fee set locally; in-kind re-roof may be exempt. | allowed |
| 🅿️ Driveway / Parking Pad | conditional | city | No building permit for private flatwork; a right-of-way/curb cut needs a separate permit. | allowed |
| 🏊 Swimming Pool / Spa | yes | city | Building permit fee; barrier fencing required by code. | allowed |
| 🧱 Retaining Wall | conditional | city | No fee under the exemption; a permit applies if over the threshold. | allowed |
| 💥 Demolition / Teardown | yes | city | Demolition permit fee set locally by the municipality; verify with the city building department. | allowed |
| 🚰 Septic System | yes | state | Onsite sewage construction permit fee set by the MO DHSS Onsite Sewage Program; verify with the program (573-751-6095). | allowed |
| 🔌 EV Charger | yes | city | Electrical permit fee set locally by the municipality. | allowed |
| ⚡ Standby Generator | yes | city | Electrical (and gas, if fuel-fired) permit fee set locally by the municipality. | allowed |
| Project | Permit? | Authority | Typical fee | Timeline | Go / No-Go | Key notes |
|---|---|---|---|---|---|---|
| 🏠 Accessory Dwelling Unit (ADU) | Permit required | city | Permit fees set locally by each municipality — verify with the city building department (St. Louis Building Division or KC Permits Division). | Varies by municipality — simple permits often same-day to ~2 weeks; full plan-review permits several weeks. | Case by case | ADUs require a building permit plus zoning/use approval. Missouri has no statewide residential building code, so allowance and rules are set locally (e.g., St. Louis and Kansas City each have their own requirements). Verify with your municipal building department. |
| 🪵 Deck / Porch | Conditional | city | Permit fees set locally by each municipality — verify with the city building department. | Varies by municipality — over-the-counter/simple permits often same-day to ~2 weeks. | Generally allowed | Kansas City adopted the 2018 IRC (effective 2020); St. Louis enforces the I-Codes locally. Exact thresholds follow local amendments — verify with your city. Exempt: Freestanding decks low to grade and not attached are generally exempt under the locally adopted IRC R105.2; attached decks and decks over 30 in require a permit. |
| 🧱 Fence / Wall | Conditional | city | Usually no building permit under the height threshold; zoning setback/height rules apply. Verify locally. | Varies by municipality. | Generally allowed | Missouri has no statewide code, so municipalities set fence rules individually. Verify with your local building department. |
| 🛖 Shed / Outbuilding | Conditional | city | No fee under the exemption; a permit fee applies if over the local threshold. | Varies by municipality. | Generally allowed | Larger sheds or sheds with utilities require a permit; thresholds vary by city. Verify with your municipal building department. Exempt: Detached one-story accessory shed ≤120 sq ft is exempt under the locally adopted IRC R105.2. |
| 🪜 Basement Finish | Permit required | city | Building permit fee set locally; trade permits billed separately. | Varies by municipality — typically several weeks for full plan review. | Generally allowed | Finishing a basement into habitable space requires permits for egress, framing, electrical, plumbing and mechanical work; a sleeping room needs an egress window. |
| 🚗 Garage / Carport | Permit required | city | Building permit fee set locally; zoning clearance may be required first. | Varies by municipality — typically several weeks for full plan review. | Generally allowed | A new detached or attached garage requires a building permit. Kansas City requires a residential building permit for all new construction and additions to one- and two-family structures. |
| ☀️ Rooftop Solar PV | Permit required | city | Electrical/structural permit fee set locally by the municipality. | Varies by municipality — often expedited for residential PV. | Generally allowed | Rooftop solar PV requires an electrical and (if the structure is modified) building permit, reviewed under the locally adopted code. |
| 🌡️ HVAC Replacement | Permit required | city | Mechanical permit fee set locally by the municipality. | Varies by municipality — often same-day to ~2 weeks. | Generally allowed | Furnace, AC or heat-pump replacement requires a mechanical permit. Kansas City allows licensed contractors to pull permits for HVAC/water-heater/panel replacements without a full plan review. |
| 🍳 Kitchen Remodel | Permit required | city | Building permit fee; trade permits (plumbing/electrical) billed separately. | Varies by municipality — typically several weeks for full plan review. | Generally allowed | A permit is required when relocating plumbing/electrical, moving walls, or changing fixtures. Cosmetic-only work (cabinets, counters, paint) may be exempt. |
| 🛁 Bathroom Remodel | Permit required | city | Building permit fee; trade permits (plumbing/electrical) billed separately. | Varies by municipality — typically several weeks for full plan review. | Generally allowed | A permit is required when relocating plumbing/electrical, moving walls, or changing fixtures. Cosmetic-only updates may be exempt. |
| 🏗️ Room Addition | Permit required | city | Building permit fee based on valuation; zoning and plan review apply. | Varies by municipality — typically several weeks for full plan review. | Generally allowed | Room additions change the footprint and require a full building permit, zoning approval and usually a site plan. |
| 🪟 Window / Door Replacement | Conditional | city | Permit fee if changing the opening; in-kind swap is often exempt. | Varies by municipality — in-kind swaps often same-day. | Generally allowed | Swapping windows or exterior doors in the same opening is generally exempt; enlarging or adding openings requires a permit. Kansas City exempts windows not exceeding 4 ft in load-bearing walls from plan review. |
| 🏘️ Roof Replacement | Conditional | city | Roof-covering permit fee set locally; in-kind re-roof may be exempt. | Varies by municipality — in-kind re-roofs often same-day. | Generally allowed | Roof covering replacement is typically permitted; structural deck replacement triggers a full building permit. |
| 🅿️ Driveway / Parking Pad | Conditional | city | No building permit for private flatwork; a right-of-way/curb cut needs a separate permit. | Varies by municipality. | Generally allowed | Kansas City requires a permit only for a drive approach located in the public right-of-way. Other municipalities may differ — verify locally. |
| 🏊 Swimming Pool / Spa | Permit required | city | Building permit fee; barrier fencing required by code. | Varies by municipality — typically several weeks. | Generally allowed | Pools need a permit and barrier fencing. Kansas City issues residential swimming-pool permits; verify your municipality’s threshold and barrier rules. |
| 🧱 Retaining Wall | Conditional | city | No fee under the exemption; a permit applies if over the threshold. | Varies by municipality — if required, typically several weeks. | Generally allowed | Walls over 4 ft or supporting a surcharge require design and a permit. Verify with your municipal building department. Exempt: Retaining walls ≤4 ft (not supporting a surcharge) are exempt under the locally adopted IRC R105.2. |
| 💥 Demolition / Teardown | Permit required | city | Demolition permit fee set locally by the municipality; verify with the city building department. | Varies by municipality — typically 1–3 weeks for review and utility disconnect. | Generally allowed | Full or structural demolition requires a building permit from the local building department. A pre-demolition asbestos and lead-paint survey is generally required, and all utilities must be disconnected. Interior non-structural demolition may be exempt where it does not affect structure or egress — verify with your city. |
| 🚰 Septic System | Permit required | state | Onsite sewage construction permit fee set by the MO DHSS Onsite Sewage Program; verify with the program (573-751-6095). | Soil morphology evaluation and plan review typically several weeks; a Registered Onsite Soil Evaluator is required. | Generally allowed | Septic (onsite wastewater) systems in Missouri are permitted by the MO Department of Health & Senior Services Onsite Sewage Program under RSMo 701.025–701.059 / 19 CSR 20-3.060 — NOT the building department. A permit is required for new systems on lots under 3 acres (and other triggers). Contact DHSS or your county health department. |
| 🔌 EV Charger | Permit required | city | Electrical permit fee set locally by the municipality. | Varies by municipality — electrical permits often same-day to 1–2 weeks. | Generally allowed | Installing an EV charging circuit (NEC Art. 625) requires an electrical permit; a dedicated branch circuit is needed. Where adopted, the 2021 IRC Appendix T and 2023 IECC require EV-ready circuitry in new dwelling garages — verify local adoption with your city. |
| ⚡ Standby Generator | Permit required | city | Electrical (and gas, if fuel-fired) permit fee set locally by the municipality. | Varies by municipality — electrical/mechanical permits often same-day to 2 weeks. | Generally allowed | A standby generator requires an electrical permit; fuel-fired units also need a gas/mechanical permit. Review NEC Art. 445 (Generators) and Art. 702 (Legally Required Standby Systems); verify load calc, transfer switch, and placement with your city. |
Homeowner Tools
Frequently asked questions
Do I need a building permit for home projects in Missouri?
Most structural, electrical, plumbing, and mechanical work does. The project table above shows Missouri-specific permit requirements for 20 common home projects. Always confirm with the local building department before starting.
Who issues building permits in Missouri?
Missouri permit authorities are typically city or county building departments. Use the county permit authority lookup to find the exact office for your property.
Which home projects are exempt from permits in Missouri?
Common baseline exemptions apply widely: detached sheds ≤120 sq ft, fences ≤6–7 ft, decks ≤30 in above grade, same-footprint re-roofs, and in-kind window/door swaps. Missouri or your city may amend these — verify locally.
How much does a permit cost in Missouri?
Permit fees are set by each city or county and scale with project valuation; there is no single Missouri statewide fee. Open the official authority link on this page for the local fee schedule.