Jefferson County, MO Building Setbacks & Zoning: Setback Rules (2026)
Key Facts
- Governing table
- Table 5-3, Section 400.1670
- RA-5/LR-2 front yard
- 100 feet (or existing home line)
- R-20/R-10/R-7 front yard
- 50 feet
- Alley-access garage reduction
- 5 feet off front setback
- Applies to
- Unincorporated Jefferson County only
Summary
Jefferson County's Unified Development Order fixes minimum front, side and rear yard setbacks by zoning district in unincorporated areas, measured from the street right-of-way or access easement line, whichever is more restrictive, under Table 5-3.
All buildings on a lot shall be set back from the street right-of-way lines (property lines) or the edge of the access easement, not less than the distances shown in Table 5-3. The measurement shall be taken at the right-of-way line or the edge of an access easement, whichever is more restrictive. Note: minimum distance between detached buildings is dependent upon the International Fire Code.
Full Breakdown
1670 requires every building on a lot in unincorporated Jefferson County to sit back from the street right-of-way or the edge of an access easement no less than the distance shown in Table 5-3, with measurement taken at whichever line is more restrictive. The table sets separate front, side and rear yard minimums by district. In the large-lot "RA-5" and "LR-2" districts, front and side setbacks default to 100 feet and 65 feet respectively (or the line established by existing homes on the same side of the street), with a 25-foot rear yard; "R-40" reduces those to 70 feet front and 50 feet side.
The denser single-family districts "R-20", "R-10" and "R-7" require a flat 50-foot front yard, 35-foot side yard and 25-foot rear yard, while planned residential districts "PR-1" and "PR-2" require 35-foot front yards with rear yards of 25 feet and 15 feet respectively. Commercial and industrial districts ('NC-1", "CC-2", "PC", "PB", "NPI", "PI") carry smaller front setbacks of 20 feet, with side and rear yards ranging from 5 to 60 feet depending on district and adjacency. Along a County-maintained major street the front setback increases further, while a footnote lets the front yard shrink by 5 feet where the garage is accessed from an alley, and corner lots must satisfy two front-yard and two side-yard setbacks.
Setbacks in "PM" planned developments are set individually as part of zoning approval rather than by table. Minimum separation between detached buildings on the same lot is governed instead by the International Fire Code, not this section. 1690 layers additional yard exceptions on top of Table 5-3: sills, cornices, chimneys and eaves may project into a required yard by up to half its width (capped at 6 feet into a rear yard), and irregular or 'flag' lots in "R-20", "R-10", "R-7", "PR-1" and "PR-2" may use an averaging method to meet a 30-foot (or 20-foot in PR districts) rear-yard target, provided no point of the structure comes within 10 feet of the rear lot line.
Violations & Fines
Building without meeting Table 5-3 setbacks is a zoning violation enforced by the County's Department of Land Use, Development and Code Enforcement, which can require relocation or removal of a nonconforming structure and withhold or revoke occupancy approval. Owners who need relief from the stated minimums must seek a variance from the Board of Zoning Adjustment; encroachments discovered after construction can force costly remediation.
Frequently Asked Questions
What is the minimum front yard setback in Jefferson County's R-20 district?
Does Jefferson County's setback rule apply inside Arnold or Festus?
Can a corner lot in Jefferson County reduce its setbacks?
Sources & Official References
Other rules in Jefferson County
Compare Jefferson County to another location·View the Missouri building setbacks & zoning overview
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