St. Louis County, MN Accessory Structures: Shed & Carport Rules (2026)

Section 6.23 of Floodplain Ordinance 69 sets a size cap for accessory structures sited within the Flood Fringe District specifically, not for sheds and garages generally across the county. Subsection A bars using the structure for human habitation, B requires a low flood damage potential, and C caps the structure at 576 square feet and one story, limiting its use to parking and storage. A structure that exceeds 576 square feet, has more than one story, or is put to another use must instead meet the full floodplain standards for a residential structure under Section 6.21 or a nonresidential structure under Section 6.22, whichever applies.

Any accessory structure with two or more rigid walls that stays within the 576-square-foot cap must still be built using one of four methods under Section 6.23.D: wet floodproofing with at least two openings on two sides sized to one square inch per square foot of enclosed area and positioned no higher than one foot above grade; elevation on fill meeting the Section 6.21.A standard, without the 15-foot fill extension required for residential structures; alternative elevation methods meeting Section 6.22.B; or dry, watertight floodproofing meeting Section 6.22.C. Section 6.23.E carves out an exception for structures with fewer than two rigid walls, such as carports, gazebos, and picnic pavilions, which may sit below the Regulatory Flood Protection Elevation and exceed 576 square feet if they otherwise meet Section 4.21's general development standards. Because this standard sits inside the floodplain overlay, it applies only to accessory structures on parcels within the mapped Flood Fringe District; a shed built elsewhere in the county falls under the separate Zoning Ordinance, Ordinance Number 62, not this floodplain rule.