Spotsylvania County, VA Environmental Rules: Flood Elevation Requirements (2026)

Sec. 23-7.2.5 defines freeboard as a factor of safety usually expressed in feet above a flood level for floodplain-management purposes, and defines base flood elevation (BFE) as the water surface elevation of the base flood shown on or determined from the current FEMA Flood Insurance Rate Map. Sec. 23-7.2.12(D), the Floodplain Overlay District's elevation and construction standards, turns that safety margin into a hard number: new construction or substantial improvement of any principal residential structure, including manufactured homes, in Zones A1-30, AE, AH, and A with detailed base flood elevations must have the lowest floor, including the basement, elevated to or above the base flood level plus eighteen inches. The same eighteen-inch freeboard applies to new construction or substantial improvement of any commercial, industrial, or nonresidential structure.

Nonresidential buildings have an alternative to elevation: Sec. 23-7.2.12(D)(3) lets them be floodproofed instead, provided every component below the BFE plus two feet is watertight, with walls substantially impermeable to water and structural components able to resist hydrostatic and hydrodynamic loads, a standard a certified professional engineer or architect must certify. Accessory structures are prohibited within the floodplain outright, with a narrow exception for water-dependent structures like docks and boat houses built on pilings, whose tops must sit at least eighteen inches above the base flood elevation. Fully enclosed areas below the flood-protection elevation cannot be used for habitation and must include flood-vent openings totaling at least one square inch per square foot of enclosed area, with at least two openings on different walls and no opening more than one foot above grade.