Charleston County, SC Environmental Rules: Flood Elevation Requirements (2026)

Sec. 9-40(a)(2) sets the baseline: new construction and substantial improvements must be built to meet or exceed the design flood elevation (DFE), which the code defines as the base flood elevation (BFE) plus two feet of freeboard, and mechanical, electrical and HVAC equipment must be protected against water intrusion at that same base-flood-plus-two-feet level under Sec. 9-40(a)(8). Sec. 9-41(a) applies that standard directly to homes: residential new construction and substantial improvements in unnumbered A zones and AE zones must have the top of the lowest floor, including any basement, elevated to or above the DFE.

Non-residential buildings in those zones may instead be dry-floodproofed watertight below the DFE if a South Carolina-licensed engineer or architect certifies the design under Sec. 9-41(b). Coastal high-hazard VE zones and coastal A zones carry a stricter rule: Sec. 9-42(a) requires new construction to sit landward of two feet above the recognized mean high tide and to be elevated on pilings or columns so the bottom of the lowest horizontal structural member reaches the DFE, anchored to resist wind and water loads acting together. The building official enforces elevation compliance with a staged certificate process under Sec.

9-40(b): an under-construction elevation certificate before vertical framing continues, a floodproofing certificate for any non-residential dry-floodproofed structure, and a finished-construction elevation certificate after final grading, without which no final inspection or certificate of occupancy can be issued. All certificates must be prepared by a registered land surveyor, engineer or architect.