Building Setbacks & Zoning in O'Fallon, MO (2026)
3 verified building setbacks & zoning rules for O'Fallon, Missouri, sourced directly from the municipal code and official government pages.
Verified from official government sources
Setback Rules
O'Fallon requires a minimum 25-foot front yard, 6-foot side yards and a 25-foot rear yard for every R-1 single-family lot, with wider margins in other districts: R-1A needs 40 feet front and rear, and the AG District needs 50 feet on all three sides. City Code § 400.080 sets the base standard most homeowners fall under.
O'Fallon Yard Setback Minimums by Zoning District
Some RestrictionsO'Fallon Code § 400.080(D)(4)
D. Regulations And Performance Standards. The following regulations shall apply: ... 4. Yard Requirements. a. Front Yard. Not less than twenty-five (25) feet. b. Side Yards. Not less than six (6) feet on each side of the dwelling. c. Rear Yard. Not less than twenty-five (25) feet.
Structure Height Limits
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.
O'Fallon Residential Building Height Limits
Some RestrictionsO'Fallon Code § 400.080(D)(5)
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.
Lot Coverage Limits
O'Fallon's Zoning Code sets a maximum percentage of each lot that buildings and structures may cover, and the limit changes by district. Single-family lots in the R-1 district are capped at 35%, while the larger-lot R-1A district allows only 25%, and two-family R-2 lots can reach 45%. Section 400.265 spells out exactly what counts toward that percentage.
O'Fallon Caps Lot Coverage by Zoning District
Some RestrictionsO'Fallon Code § 400.080(D)(3)
Lot Coverage. The maximum lot coverage shall not exceed thirty-five percent (35%).
Looking for St. Charles County county-wide rules?
County ordinances apply to unincorporated areas and may supplement O'Fallon city rules.
Building Setbacks & Zoning in St. Charles County →