Dallas County, TX Environmental Rules: Flood Elevation Requirements (2026)

Chapter 42, Article V of the Dallas County Code (Provisions for Flood Hazard Reduction) sets the county's freeboard standard. For residential construction, "new construction and substantial improvements of any residential structure shall have the lowest floor (including basement), elevated to or above two (2) feet above the base flood elevation, based on a fully-developed watershed (if available)." A registered professional engineer, architect, or land surveyor must certify to the Floodplain Administrator that this standard was met.

Commercial, industrial, and other nonresidential structures have a choice: elevate the lowest floor the same two feet above base flood level, or flood-proof below that line so the structure is watertight, "with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy." A registered engineer or architect must design and certify the flood-proofing, and the Floodplain Administrator keeps the certified elevation, referenced to mean sea level, on file.

Manufactured homes get the same two-foot cushion: units placed or substantially improved in Zones A1-30, AH and AE must have their lowest floor elevated to or above two feet above the base flood elevation on a permanent, anchored foundation, or on some existing manufactured-home-park sites, be supported on reinforced piers at least 36 inches above grade. Enclosed areas built below the elevated lowest floor may only be used for parking, building access, or storage, must use flood-resistant materials, and in A Zones need openings that let floodwater equalize automatically. Compliance is measured from the elevation certificate a licensed surveyor prepares for every new or substantially improved structure in the flood hazard area.