What is the required elevation for a large addition if the building's original lowest floor was built to 4 feet and the new BFE is 6 feet?

The correct answer is based on the requirement that any new construction or substantial improvement must meet or exceed the Base Flood Elevation (BFE). For this particular scenario, the original lowest floor was built to an elevation of 4 feet, but the updated BFE is now set at 6 feet.

To comply with floodplain management requirements, any new addition needs to be elevated to at least the BFE to mitigate flood risk effectively. Therefore, since the new BFE is 6 feet, the large addition must be constructed at least at this elevation to ensure protection against flooding.

This requirement aims to help reduce the potential for flood damage and protect the safety of occupants, aligning with NFIP regulations. Understanding the context of the BFE is crucial, as it serves as a standard for ensuring that any structures are appropriately elevated in flood-prone areas.

In summary, to adequately respond to the floodplain management needs and regulations, the addition must be at least 6 feet above grade, corresponding to the BFE established for the location.