Coastal A Zone Determinations

What is a Coastal A Zone?

A FEMA Coastal A Zone is a high-risk flood area in coastal regions where wave heights are expected to be between 1.5 and 3 feet during a base flood event (1% annual chance of flooding). This zone falls between high-velocity Zone V (with waves over 3 feet) and inland Zone A. Properties here are vulnerable to both rising floodwaters and moderate wave action, which increases the potential for structural flood damage. Coastal A Zones are identified by the Limit of Moderate Wave Action (LiMWA) on FEMA flood maps, indicating areas where wave energy could be impactful.

Why Coastal A Zones Matter

Properties in Coastal A Zones face unique risks due to moderate wave action, making them more vulnerable than standard Zone A areas. FEMA designates these zones to guide flood insurance requirements, building regulations, and community planning measures that can mitigate coastal flood damage.

Key Characteristics of Coastal A Zones

• Wave Action: Expected wave heights between 1.5 and 3 feet during a base flood, leading to potential structural impacts and damage.
• Building Standards: FEMA recommends constructing to Zone V standards in Coastal A Zones, which includes elevated foundations and flood-resistant materials to help withstand wave forces.
• Flood Insurance: Required for properties with federally backed mortgages; premiums may reflect the added risk of wave action.