Date: June 5, 2024
From: Charlotte County Community Development
Subject: Flood Map and Design Datum Reminder
Charlotte County’s current Federal Emergency Management Agency (FEMA) flood maps became effective on Dec. 15, 2022. The new maps ushered in the new Coastal A Zone, which has the same construction standards as the V/VE flood zone.
The maps changed the vertical datum from the National Geodetic Vertical Datum of 1929 (NGVD 29) to the more current North American Vertical Datum of 1988 (NAVD 88). This change is important for the design and construction of buildings. Design professionals and surveyors should be aware of this change and use the NAVD 88 datum. Here are some guidelines:
- For surveyors, elevation certificates and property surveys must use NAVD 88 datum.
- If an elevation certificate was issued in the older NGVD 29 datum, or if the property was in an X zone prior to Dec. 15, 2022, and is now in a Special Flood Hazard Area (SFHA), then previous FEMA Flood Insurance Rate Maps (FIRM) data and, if appropriate, the conversion factor from NGVD 29 to NAVD 88 must be shown in comments under Section D.
Design professionals and contractors should use the NAVD 88 datum in their design and construction documents.
For additional information on datums, visit https://tinyurl.com/VerticalDatum. For questions, call Donna Bailey, CFM, Floodplain Coordinator, at 941.623.1080.
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