O'Fallon, MO Building Setbacks & Zoning: Lot Coverage Limits (2026)
Key Facts
- R-1 lot coverage cap
- 35% maximum, Section 400.080(D)(3)
- R-1A lot coverage cap
- 25% maximum, on 22,000 sq ft lots
- R-2 lot coverage cap
- 45% maximum for two-family lots
- What counts
- All principal and accessory building footprints
- What's excluded
- Roads, driveways, parking lots, swimming pools
- First violation fine
- $200, rising to $450 for repeats
Summary
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.
Lot Coverage. The maximum lot coverage shall not exceed thirty-five percent (35%).
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
080(D)(3), governing the 'R-1' Single-Family Residential District, states: 'Lot Coverage. 080 standards, including a 10,000-square-foot minimum lot area, an 80-foot minimum lot width, and 25-foot front and rear yards with 6-foot side yards. 085(D)(3) caps lot coverage there at 'twenty-five percent (25%) of the lot area,' on lots with a 22,000-square-foot minimum area. The 'R-2' Two-Family Residential District, by contrast, allows a maximum lot coverage of 'forty-five percent (45%)' under its own regulations, and other residential districts range as high as 50%. ' The same section confirms the caps apply 'to all property platted either before or after the effective date of this Section,' so older, previously platted lots are not grandfathered out of the current percentage limits.
Violations & Fines
Exceeding a district's lot coverage cap is enforced as a zoning violation under Article XV of the Zoning Code. Section 400.655 sets maximum fines of $200 for a first violation within twelve months, $275 for a second, $350 for a third, and $450 for a fourth or later violation, plus court costs, with an added $250 civil penalty for ignoring a ten-day written correction order.
Frequently Asked Questions
What is the maximum lot coverage in O'Fallon's R-1 district?
Does lot coverage include my driveway or pool?
Do older, previously platted lots get a different lot coverage limit?
What happens if a building exceeds the lot coverage limit?
Sources & Official References
Other rules in O'Fallon
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