Florissant, MO Accessory Structures: Shed & Carport Rules (2026)

215(A)(2)(c) sets the core numbers: no accessory building may top eighteen feet or exceed the height of the principal house, and it cannot cover more than thirty percent of a required rear yard. The setback scales with height. A shed up to thirteen feet tall needs only a three-foot gap from the property line, but for every foot taller than thirteen feet, add another foot of setback, so an eighteen-foot shed needs at least an eight-foot buffer. 250(A)(3)(d) layers on exterior design rules: siding must be painted aluminum, steel or vinyl lap siding, masonry, hardboard, stucco or exterior plaster, or wood siding or shingles, and the roof must use a BOCA-approved material such as asphalt or fiberglass shingles, wood shingles or shakes, slate, or copper.

For an isolated single-family accessory structure the Building Commissioner reviews the plans directly and can issue the Building Permit; larger commercial, industrial, institutional or multi-family projects go to the Planning and Zoning Commission, which has thirty days to act before the Building Commissioner may issue the permit on its own authority. If the Commission disapproves and the applicant will not make the required changes, the Building Commissioner must refuse the permit, and the applicant can appeal that refusal to the Board of Adjustment or, if the Commission itself rejected the plans, to the City Council sitting as an administrative appeals body.