St. Louis County, MO Building Safety: Fire Sprinkler Requirements (2026)

St. 103, covering Chapter 3, Building Planning. 2, One- and two-family dwellings automatic fire systems, requires that a builder of one- and two-family dwellings offer to any purchaser, on or before the time of entering into the purchase contract, the option, at the purchaser's cost, to install or equip fire sprinklers in the dwelling. The section further bars builders from denying a purchaser the right to choose or decline a sprinkler system in the unit being bought. 1 both specify that any sprinkler system a buyer does choose to install must be designed and installed in accordance with NFPA 13D, the national standard for one- and two-family dwelling sprinkler systems.

281 preempts counties from imposing a blanket residential sprinkler mandate, which is why the county code frames R313 purely as a disclosure and consumer-choice requirement rather than an installation requirement. 2 will be reviewed by St. 281 RSMo, meaning the opt-in structure was tied to a specific statutory sunset date rather than left open-ended. 05 gpm per square foot, with garage doors not counted as obstructions to sprinkler placement. Building plans reviewed by the County's Department of Public Works must document that the offer to the purchaser was made and either accepted or declined before a permit is finaled.