St. Clair County, IL Building Setbacks & Zoning: Setback Rules (2026)

The table splits lot size and setbacks by district. "A" Agricultural, "RR-3," and "RR-1" each require 40 feet of combined side yard with 15 feet minimum on either side and a 25-foot rear yard. "SR-1," the district behind the county's most common single-family lots at 20,000 square feet minimum, needs 30 feet combined side yard with a 15-foot minimum per side; "SR-2" (15,000 square feet) drops to 25 feet combined with a 10-foot minimum; "SR-3" (10,000 square feet) needs only 15 feet combined with a 5-foot minimum per side.

" Section 40-2-2 defines "Yard, Front" as the space across the full lot width between the front lot line and the nearest point of the principal building, "Yard, Side" as running between the side lot line and the building from front yard to rear yard, and "Yard, Rear" as the space across the full lot width between the rear lot line and the building. Commercial and industrial districts (Highway Business, B-1, B-2, I-1, I-2) instead carry a 75-foot front yard, with side yards reduced under Note 3 to zero feet or a 12-foot minimum unless the lot abuts an "A," "RR," "SR," "MH," "MR," or "NB" district, which restores the 25-foot buffer.

A property owner who cannot meet the table may apply to the Zoning Board of Appeals for an area/bulk variance under Sections 40-11-19 through 40-11-22; the Board must find undue practical difficulty not caused by the owner, no reasonable alternative, and that the variance is the minimum deviation needed to allow reasonable use.