Flood Hazard Areas are lands within a floodplain that have a 1% or greater chance of flooding in any given year.
These areas are identified by FEMA Flood Insurance Study and Digital Flood Insurance Rate Maps (DFIRM), regulated discharge floodplain areas, and flood hazard soils shown in the Wake County Soil Survey and soil overlay maps where FEMA mapping is not available. Flood hazard areas are shown on the record plat of subdivisions as well as on the construction drawings for commercial areas.
Properties with the following characteristics typically contain Flood Hazard Areas:
- FEMA-designated flood zones, including Floodway, Flood Fringe (1% annual chance floodplain), and Future Conditions Floodplain (0.2% annual chance)
- Flood-prone soils
- Streams, lakes, or other water features
- Backwater areas created by culverts, bridges, road crossings, or similar structures
Encroachments (fill material, roads, buildings, etc.) into flood areas are strongly discouraged and when allowed must meet rigorous design standards. Wake County prohibits fill or structures in the flood hazard areas; in addition, structures on flood hazard lots shall be elevated at least 1 foot above the base flood elevation.
Wake County staff determines whether a floodplain review is needed as part of the planning and building permitting process.
Items that may trigger a floodplain review include:
- A building lot may have been identified for potential flood hazard during construction plan review and noted with an asterisk *.
- A proposed structure is within 100 feet of flood hazard soils or FEMA flood hazard area.
- There is FEMA floodplain on or adjacent to the lot.
- Development is proposed in or near a stream buffer.
- A road or driveway crosses a flood hazard area.
- Utility lines, power poles and other small encroachments require a Floodplain Encroachment Permit.
Types of floodplain reviews
Flood Certifications
Floodplain Certifications review is required for single lot properties with flood prone areas OR buffer zones. Building permit applications made through the Permit Portal will be sent to Watershed Management staff for review. The applicant will be invoiced $50 for flood certification review. Flood certifications are conducted through the Single Family Residence (SFR) permit.
If a flood certification identifies encroachment into these features, the design plan is subject to development ordinances like Articles 11-22-2 Activities Allowed within Buffers, 14-18 Special Flood Hazard Area Standards, 14-19 Floodways and Non-Encroachment Areas, 14-20 Floodway Fringe, and 14-21 Flood Hazard Soil Area. Change in design can extend permitting time.
Minor Flood Studies
The flood study is conducted in order to define the flood boundaries of the 100-year storm. Proposed developments like roadways, driveways, and other encroachments will be accepted if the flood study shows that the improvement is not in the flood area.
A minor flood study is required for development proposed in flood hazard soil locations involving 25 acres or more of drainage area but less than 100 acres of drainage area.
The analysis may be conducted using NCDOT Hydraulics Guidance. The study shall delineate HW/D backwater area plus 1 (one) foot rise and label as Q100 backwater easement and label FFE on all affected lots with Special Flood Hazard Areas.
A flood study must be performed by a Professional Engineer or Professional Land Surveyor and reviewed by Wake County Floodplain Management Staff.
A Flood Study submittal includes an application, submittal checklist, site plans and calculations.
- Flood Study Plan Checklist
- Application
Fees will be invoiced through the Permit Portal. The fee for each major flood study is $500 per crossing or encroachment area.
Major Flood Studies
The flood study is conducted in order to define the flood boundaries of the 100-year storm. Proposed developments like roadways, driveways, and other encroachments will be accepted if the flood study shows that the improvement is not in the flood area.
A major flood study is required for development in flood hazard areas involving 100 acres or more of drainage area or a FEMA mapped area.
The analysis shall be submitted using HEC-RAS modeling. The study shall delineate HW/D backwater area plus 1 (one) foot rise and label as Q100 backwater easement and label FFE on all affected lots with Special Flood Hazard Areas. The State Model Plan recommends a 4 foot freeboard above BFE.
A flood study must be performed by a Professional Engineer or Professional Land Surveyor and reviewed by Wake County Floodplain Management Staff.
A Flood Study submittal includes an application, submittal checklist, site plans and calculations:
- Flood Study Plan Checklist
- Application
Fees will be invoiced through the Permit Portal. The fee for each major flood study is $1000 per crossing or encroachment area.
CLOMRs and No Rise Certifications
A Letter of Map Revision is required for new development shown to modify FEMA mapped elevations. A No Rise Certification may be requested when the development is shown to result in no change to flood elevations. Review by Local, State and Federal floodplain officials may be required. These are considered a major flood study and shall be uploaded through the Permit Portal.
The fee for No Rise Certifications and CLOMRs is $1000.
What is required for a floodplain approval?
Wake County requires structures to be built outside flood hazard areas and elevated above the regulatory floodplain. Flood studies, prepared at the applicant's expense and reviewed by County staff, must show that the proposed encroachment does not adversely affect existing or proposed on-site structures or off-site properties.
A revised plot plan may be needed which includes a scale drawing of the lot and the proposed impervious features (house footprint, driveway, sidewalks, porches, outbuildings, etc.). The plot plan should include building setbacks, easements, flood hazard areas, riparian buffers or water supply buffers, water features (lakes and streams) or backwater areas from road culverts or pond dams.
All Flood Certifications must be performed by a Professional Land Surveyor and reviewed by Wake County Watershed Management.
A Wake County elevation certificate may be required if any construction activity has been proposed within 100 feet of the Wake County flood hazard soils. Note: the current regulatory flood protection elevation (RFPE) per the State Model Ordinance is 2 feet above base flood elevation (BFE).
For lots with flood hazard soils, two flood surveys are required. The first survey is required prior to any inspections. Your surveyor will complete a flood certification form Flood Hazard Soils Elevation and submit for County review. This survey should state that the structure will be built outside of a flood hazard area. Grade elevations and locations may be needed. The second survey is required prior to the foundation inspection. This survey should show the elevation of the home’s foundation. A third and final as-built survey and/or flood certificate may be required to confirm the location of the structures and/or the finished floor elevation.
For lots with FEMA flood hazard areas, three flood certifications are required. The first elevation certificate is required prior to any inspections. The second certificate is required prior to the foundation inspection. A third and final elevation certificate is required to confirm the finished floor elevation prior to release of the certificate of occupancy.
A FEMA elevation certificate FEMA Elevation Certificate.