Raleigh, NC Hurricane Preparedness: Flood Elevation (2026)

Under UDO Sec. 6, no building permit may issue for new construction or substantial improvement of a residential structure in a SFHA unless the lowest floor, including the basement, plus all attendant mechanical, electrical, heating, ventilation and air-conditioning equipment, is elevated at least to the RFPE. A registered professional engineer or architect must certify on the building plans that everything below the RFPE is designed to withstand the depth, pressure, velocity, impact and uplift forces of a 100-year flood, and enclosed areas below the RFPE used only for parking, access or storage must be engineered to automatically equalize hydrostatic pressure by allowing floodwater to enter and exit.

Before the structure is occupied, a registered land surveyor must certify the elevation of the lowest floor to the nearest 1/10 of a foot in mean sea level datum. Nonresidential structures and residential accessory structures face the same elevation duty or may instead be dry-floodproofed to the RFPE under a Corps of Engineers Class W2 standard, wet-floodproofed under FEMA Technical Bulletin 85-1, or exempted for accessory structures costing under $5,000. The RFPE itself is defined in Sec. 4: for areas within a FEMA-designated SFHA, it equals the FEMA base flood elevation (BFE) plus two vertical feet, and the same two-foot add-on applies to SFHAs mapped from City drainage basin studies or site-specific flood studies.

All backflow preventers on potable water lines and sanitary sewer connections below the RFPE must include automatic backwater valves, and sewer vents and non-watertight manholes must sit at least one foot above the RFPE. The Floodplain Administrator, housed in Engineering Services, administers these permit conditions citywide, including in Wake County and Durham County FIRM areas that fall inside Raleigh's jurisdiction.