Community Planners, Local Officials, Engineers, Builders
As of January 30, 2011, all surveys and plans for Environmental Engineering and Permitting applications must utilize the new vertical datum.
Measurements on flood maps have changed. The National Geodetic Vertical Datum of 1929 (NGVD 29) has been been replaced by the North American Vertical Datum of 1988 (NAVD 88). The Federal Government as well as many state and local governments throughout the country have adopted the more accurate NAVD 88 datum as the new standard for vertical measurement.
There is a significant difference between the two datums, which means a conversion factor must be used when comparing elevations. FEMA has computed the official conversion factor for Broward County to be -1.51. Please see the NAVD Conversion Factor Letter for an explanation.
Conversion Factor Example
A building's finished floor elevation is shown on an existing elevation certificate as 10.0’ NGVD. The equivalent NAVD 88 elevation can be obtained using the FEMA-approved average conversion factor in the following formula:
NAVD 88 = NGVD 29 + conversion factor
NAVD 88 = 10.0’ NGVD + (-1.51 Broward County Conversion Factor)
NAVD 88 = 8.49
View enlarge graphic
New required elevations might affect construction projects. Most parcels in the Special Flood Hazard Area have required minimum finished floor elevations. That means the lowest floor of livable space must meet a minimum height requirement. Plans for all new buildings will be subject to any new elevation requirements proposed in the preliminary flood maps. Some additions to existing structures as well as some storage buildings might also be subject to new requirements. All applications for building permits and environmental licenses will be reviewed for compliance with the new elevation requirements after the updated maps become effective.