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Floodplain Construction FAQs

Can I build on property in a floodplain?

It depends.  Building codes are different inside the floodplain than outside of the floodplain.  Floodplain development restrictions apply to grading, new construction and some renovations.

Do I need a special permit to grade, build or renovate in a floodplain?

Yes.  A Floodplain Development Permit is needed to make sure the changes comply with floodplain regulations.

What if my property is in a Community Floodplain, also known as a Future Flood Zone?  Do the additional restrictions apply?

Yes.  Local floodplain ordinances apply to both Federal Emergency Management Agency (FEMA)-regulated floodplains and future or community flood zones.

Map of floodplains in Mecklenburg County.

Local floodplain ordinances require that the lowest floor of a structure be at least a foot* above the expected depth of floodwater in a 100-year flood.  What is defined as the lowest floor elevation depends on the foundation type. 

FEMA also requires an Elevation Certificate (form 086-0-33). The FEMA Elevation Certificate to be submitted and approved before electrical power can be turned on.  This form must be filled out by an engineer, architect, or surveyor registered in the State of North Carolina.

*Matthews and Cornelius require more than one foot above the Future 100-Year Floodplain Elevation and the 100-Year Elevation on the smaller creeks.

*Davidson does not allow development in the FEMA Floodplain or "area of special flood hazard."

View local Floodplain Regulations

What are the basic construction requirements in a 100+1 floodplain?

Creeks in the minor system that drain less than one square mile and are referred to as 100+1 creeks and are subject to floodplain regulations contained in the local ordinances.

According to local ordinances, the building pad in these areas must be at least one foot* above the 100 year flood elevation or shown by survey, to be outside the 100+1 Floodplain Line (also called the Building Restriction Flood Line).  If the building is located within the 100+1 Floodplain an Elevation Data Sheet or physical survey must be used to show the following elevation information: 100+1 Elevation, Finished Floor Elevation, Elevation of Lowest Mechanical Equipment, Lowest Adjacent Grade and Lowest Elevation on Lot.

*Matthews and Cornelius require more than one foot above the Future 100-Year Floodplain Elevation and the 100-Year Elevation on the smaller creeks.

My house is in the floodplain. What do I do if I want to build an addition or otherwise improve my home? (Multiple-part answer)

Regardless the extent of your repairs or improvements, you will need a building permit before work begins. Building activity in the floodplain depends on where the house is located in the floodplain and the cost of the improvement in relation to the value of the house.  

 Construction in a floodplain.

If you are in the Community Floodplain (Future Floodplain), you could rebuild on the current footprint if you brought the structure into compliance with the new Future 100-Year Floodplain elevations. Any development inside the FEMA floodplain carries additional restrictions and requirements.

If the value​ of the addition or improvement to the house is less than 50 percent of the market value of the existing structure, you need only make sure that the improvement meets the requirements described in the current local floodplain regulations.  Additions or other improvements valued at 50 percent or more of the market value of the existing structure are considered substantial improvements. In such cases, the entire structure must be brought into compliance with the elevations shown on the current flood map. 

If my floodplain property is severely damaged by a flood, would I be able to make repairs?
If your house receives "substantial damage" within a ten-year period (meaning any damage where the cost to restore the structure to how it was before it flooded equals or exceeds 50 percent of the structure's market value), then you will not be able to rebuild. For a property valued at $150,000 this would mean if you sustained $75,000 worth of damage, you could not repair any wall, ceiling, floor or other structural part of the house.

"Substantial improvement" means any repair, reconstruction, or improvement of a structure, where the cost equals or exceeds fifty percent of the market value of the structure, either (1) before the improvement or repair is started, or (2) if the structure has been damaged and is being restored, before the damage occurred.

"Substantial improvement" also means any repair, reconstruction, or improvement to a structure on two separate occasions during a 10 year period beginning after September 8, 1999, for which the cost of repairs, reconstruction, or improvement at the time of each alteration equals or exceeds 25 percent of the market value of the structure before the alteration occurred.

For the purposes of this definition, "substantial improvement" is considered to occur when the first alteration of any wall, ceiling, floor, or other structural part of the building commences, whether or not that alteration affects the external dimensions of the structure.  The term does not, however, include either (1) any project for improvement of a structure to comply with existing state and local health, sanitary, or safety code specifications which are solely necessary to assure safe living conditions, or (2) any alteration of a structure listed on the National Register of Historic Places or a State Inventory of Historic Places. However, should your house be substantially damaged (damage is 50 percent or more of the pre-damage market value) and you wish to repair it, you be required to bring the entire structure into compliance with the zone designation and flood elevations in effect at the time the repairs take effect.

Questions? Contact:
Charlotte-Mecklenburg Storm Water Services Floodplain Permitting Office
704-432-RAIN (7246)