In a coastal high hazard area, what is the minimum elevation requirement for the lowest horizontal structural member?

In coastal high hazard areas, the minimum elevation requirement for the lowest horizontal structural member is established to protect structures from the risks associated with flooding and wave impacts. The correct choice specifies that this elevation must be at or above the base flood elevation plus an additional foot.

This additional foot serves as a buffer to account for potential fluctuations and uncertainties in flood projections, wave action, and changes in local conditions. This extra measure is critical in enhancing the safety and resilience of buildings situated in such vulnerable environments.

Base flood elevation refers to the height to which floodwaters are anticipated to rise during a base flood event, which is typically the flood with a 1% chance of occurring in any given year. Simply adhering to the base flood elevation without the added foot could leave the structure susceptible to damage from more severe flooding events or unforeseen weather conditions.

Ensuring the lowest structural member is elevated accordingly reduces the risk of flooding and structural failure, thereby protecting both life and property in these high hazard areas.