St. Peters, MO Building Setbacks & Zoning: Setback Rules (2026)

Section 405.130(H)(1) of the St. Peters Municipal Code lays out the yard requirements that apply to every lot in the "R-1" Single-Family Residential District. The minimum front yard depth is twenty feet unless a different line is set by the recorded plat, and roofs, canopies, and covered entranceways, including their support posts, may project no more than four feet over that front building line. Each side yard must be at least ten percent of the lot's width as measured at the front building line, except that lots on a cul-de-sac, and lots on plats approved before January 1, 2001, need only a six-foot side yard.

The rear yard must be at least twenty-five feet deep, dropping to fifteen feet on a corner lot, though swimming pools, decks, and open-air porches are excluded from that twenty-five/fifteen-foot measurement as long as they stay at least six feet from the rear lot line; in no case may the City require a rear yard deeper than twenty-five feet or accept one shallower than fifteen feet. Where irregular lot shape makes the rear line unclear, the Administrative Officer decides which line governs. Subsection (H)(2) adds an averaging rule: if more than half of existing homes on the same side of the street within five hundred feet (or to the nearest cross street) have front setbacks within ten feet of each other, a new home's required front setback matches that neighborhood average, never less than fifteen feet, though the averaging rule does not apply to new streets in a fresh subdivision plat.