O'Fallon, MO Building Setbacks & Zoning: Structure Height Limits (2026)
Key Facts
- R-1 dwelling height cap
- 2.5 stories / 35 feet
- R-1 accessory building cap
- 25 feet
- Accessory height rule
- never taller than main house
- Commercial max with approval
- 6 stories
- First zoning fine
- up to $200
Summary
O'Fallon caps single-family homes in the R-1 District at two and one-half (2 1/2) stories or thirty-five (35) feet under City Code § 400.080(D)(5). Detached accessory buildings are capped lower still, at twenty-five (25) feet, and can never be taller than the main house.
5. Height Requirements. a. For Buildings And Structures. No building or structure shall exceed a height of two and one-half (2 1/2) stories, or thirty-five (35) feet. b. For Accessory Buildings. No detached accessory building shall be higher than twenty-five (25) feet, nor higher than the main building.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4860992; v58 updated 2026-05-14; through 05-14-2026).
Full Breakdown
085, where accessory buildings are likewise limited to twenty-five (25) feet and cannot exceed the height of the main structure. 125(D)(5) if the added height will not interfere with St. Charles County's emergency microwave communications system and the local fire district can still provide protection. For a homeowner building a house or detached garage in the City's core single-family districts, however, the operative ceiling is the R-1 standard: 35 feet for the house, 25 feet for any detached accessory structure, and the accessory structure can never out-top the house itself.
Violations & Fines
Exceeding the height limit in Chapter 400 is a zoning violation subject to the City's general penalty at § 100.010(A)(4): under the RSMo §§ 89.120/89.490 zoning schedule, a first violation within twelve months draws a fine up to $200, rising to $275, $350 and $450 for the second, third and fourth-plus violations, and the City can require the excess height to be removed.
Frequently Asked Questions
How tall can I build a house in O'Fallon's R-1 District?
How tall can my detached garage or shed be?
Can buildings ever go taller than 35 feet in O'Fallon?
Sources & Official References
Other rules in O'Fallon
Compare O'Fallon to another location·View the Missouri building setbacks & zoning overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.