Know Your Flood Zone

A Summary of flood zones relevant to Charleston County is provided below. 

Charleston Co. is subject to coastal flood hazards. The Charleston Co. FIRM provides determined Base Flood Elevations (BFEs) during the 1% annual chance flood event ("base flood"). The Charleston Co. FIRM does not contain any mapped floodways.

Zones A-V are within the Special Flood Hazard Area (SFHA). 

Zone X and D is outside of the Special Flood Hazard Area (SFHA).

Flood Insurance Rate Map (FIRM) Zones

AThe base floodplain mapped by approximate methods, i.e., BFEs are not determined. 

A1-30(Old Format) Numbered A Zones. Check the map index for the BFE that corresponds to each zone number . 
Zone A-

The 1% annual chance floodplain, representing the "base flood" event (aka "100 year flood").


(Current Format) The base floodplain where BFE is provided on the FIRM in parenthesis. i.e. "AE(12)" .

AOThe base floodplain with sheet flow, ponding, or shallow flooding. Base flood depths (feet above ground) are provided.

AHShallow flooding base floodplain. BFEs are provided.

Zone V-

Coastal areas subject to wave action greater than 3ft.
VCoastal area subject to a velocity hazard (wave action greater than 3 ft.) where BFEs are not determined on the FIRM.

VECoastal area subject to a velocity hazard (wave action greater than 3 ft.) where BFEs are provided on the FIRM.

Zone X-

Outside the SFHA

Area of moderate flood hazard, usually between the limits of the 1% annual chance flood (base flood or "100 year flood") and the 0.2% annual chance flood ("500 year flood") event. 

UnshadedArea of minimal flood hazard, usually at elevation greater than the 0.2% annual chance flood ("500 year flood") event.

Other FIRM Zones
Zone DDArea of undetermined but possible flood hazards.


Solid, Jagged Line

(see example by following the Link)

Limit of Moderate Wave Action-
Inland limit of the area in an AE zone expected to receive 1.5-foot or greater breaking waves during the base flood event.

Coastal Barrier Resource System


New or substantial improved residential  or commercial development in this zone are not eligible for NFIP coverage or other forms of federal financial assistance (such as small business loans or flood hazard mitigation grants)