ADU Permits: Olathe vs Overland Park
How do adu permits rules compare between Olathe, KS and Overland Park, KS?
Olathe and Overland Park have similar restriction levels.
Olathe, KS
Johnson County
Olathe permits accessory dwelling units (ADUs) accessory to a principal single-family dwelling in all residential, downtown, and planned districts under Section 18.50.025 of the Unified Development Ordinance. ADUs require a building permit through the Olathe Building Codes Division and must meet size, height, setback, and architectural-compatibility standards administered by the Planning Division.
View full Olathe rules →Overland Park, KS
Johnson County
Overland Park regulates accessory dwelling units under the Unified Development Ordinance (Title 18 of the Overland Park Municipal Code), administered by Planning + Development Services. An Accessory Unit is defined as a building or addition for living purposes with a maximum footprint of 650 square feet (or the principal-structure footprint for English Basement types). Building permits are issued under the City-adopted 2018 IBC/IRC. Kansas has no statewide ADU statute — KSA 12-741 et seq. delegates zoning to home-rule cities.
View full Overland Park rules →Key Facts Comparison
| Fact | Olathe | Overland Park |
|---|---|---|
| Authority | Olathe UDO Sec. 18.50.025 | - |
| Max Size | 1,000 sq ft or 50% of principal | - |
| Max Bedrooms | Two | - |
| Height Limit | Two stories / principal height | - |
| Setbacks | 6 ft behind front / 10 ft rear | - |
| Districts | Residential, downtown, planned | - |
| Zoning Authority | - | OPMC Title 18 (UDO) |
| Filing Office | - | Planning + Development Services |
| Max Footprint | - | 650 sq ft (Accessory Unit) |
| Setbacks (rear yard) | - | 3 ft interior / 20 ft ROW |
| Building Code | - | 2018 IBC/IRC (OPMC Title 16) |
| State Framework | - | None — KSA 12-741 local |
Highlighted rows indicate differences between cities.
Olathe FAQ
Can I build an ADU in Olathe?
Yes. UDO Sec. 18.50.025 permits ADUs as accessory to a principal single-family dwelling on the same lot in all residential, downtown, and planned districts. ADUs are capped at 1,000 sq ft or 50% of the principal structure's floor area (whichever is less), with a maximum of two bedrooms and two stories.
What permits do I need and must the ADU match the main house?
A building permit from the Olathe Building Codes Division covering structural, mechanical, plumbing, and electrical work. Olathe enforces the 2018 IRC with Kansas amendments. UDO Sec. 18.50.025 also requires the ADU's architectural style and exterior materials to conform to those of the principal structure.
Overland Park FAQ
Do I need a permit to build an ADU in Overland Park?
Yes. A building permit is required for any habitable accessory dwelling unit, plus separate electrical, plumbing, and mechanical trade permits. Applications are filed with Overland Park Planning + Development Services at 8500 Santa Fe Drive. The Unified Development Ordinance (Title 18 OPMC) caps the accessory unit footprint at 650 square feet and applies the OPMC 18.180.070 rear-yard setbacks (3 ft interior, 20 ft from street right-of-way). Construction must meet the 2018 IBC/IRC adopted under OPMC Title 16.
Does Kansas have a state ADU law?
No. Kansas does not have a statewide ADU framework. KSA 12-741 et seq. delegates zoning to home-rule cities, so all ADU rules are local. Overland Park's standards live in the Unified Development Ordinance (Title 18 OPMC) and are administered by Planning + Development Services. The City began updating the UDO in 2024 — check the current version before designing.
Compare other topics
See how Olathe and Overland Park compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool