Seawall height and code guidance

How high should your seawall be?

Your city or county may set a lowest or highest allowed elevation for the top of the wall. The rules can change with the property’s location and the work planned. Drainage, flooding and neighboring properties also affect the design.

For local height rules, use the top-of-cap elevation on your survey. This is the top of the wall measured from a fixed survey reference. It is different from the wall’s bottom-to-top height or the water level.

Find these two items on your survey.

Find the elevation for the top of the seawall cap and the survey reference used with it. The example below shows what to look for.

What does NAVD88 mean?

NAVD88 is a fixed survey reference used to measure elevations, like a shared zero point. Another survey may use NGVD29 or a tide-based reference. To compare two elevations, they must use the same reference. A surveyor can help if the references differ. Read NOAA’s explanation of survey references.

Look for the seawall cap elevation on your survey or final construction plans. A flood certificate may show only the building’s elevation. If the wall measurement is missing, ask a surveyor; you do not need to measure beside the water.

Repair, replacement and permits

Before raising or replacing the wall, ask the permitting office which rules apply to the work. An engineer can check whether the existing wall, supports and drainage can handle the change. A higher wall can also change where rainwater flows.

Use the permit guide to find the local, Florida DEP and U.S. Army Corps of Engineers contacts. Describe your location and planned work and ask which permits you need. Florida DEP’s application instructions explain the information needed for shoreline projects.

Common questions

Jacksonville has not adopted a private seawall height standard

The city’s Resilient Jacksonville strategy (October 2023) commits to setting height standards for public and privately owned bulkheads, drawing on practice elsewhere and an upcoming compound flood risk assessment. The city’s 2024 update lists the public-bulkhead action as ongoing but not the private one, and we found no adopted minimum height for private seawalls in the city’s published rules. The same strategy says the city will limit new bulkhead permits on private property along tributaries and favor green or hybrid shorelines where feasible.

Until a standard is adopted, your cap height is a design decision. Confirm with the city before you design, and ask your engineer whether the wall can be raised later without rebuilding it.

Resilient Jacksonville, Action 16 'Invest strategically in hardened shorelines' · Office of Resilience (with 2024 and 2025 Annual Updates) · Resilient Jacksonville, Action 8

Reference numbers to discuss with your engineer

• Normal high water is about 1.96 ft NAVD88 at Mayport, 0.65 ft downtown and 0.39 ft at the Buckman Bridge.
• Irma reached 4.89 ft above normal high water at the Main Street Bridge and 5.2 ft at the Buckman Bridge.
• Jacksonville requires new buildings in flood zones to be two feet above base flood elevation, in NAVD88.
• St. Augustine targets +7.1 ft NAVD for its bayfront wall.

None of these is a seawall rule for your property. They help you and your engineer choose a height with known margins.

Mayport (Bar Pilots Dock) 8720218 datums · Southbank Riverwalk 8720226 datums · I-295 Buckman Bridge 8720357 datums · Main Street Bridge historic crests · NWPS historic crests (BKBF1, DMSF1, MYPF1, SRPF1, GCEF1, FRDF1) · Ordinance 2023-615-E (Chapter 652 Floodplain Management amendments) · Floodplain Definitions · Avenida Menendez Seawall Project Fact Sheet

Give the designer a survey that resolves the transitions

• Identify the survey date, vertical datum (NAVD88) and benchmark used for the cap elevations.
• Measure enough points to show low spots, returns and connections to neighbors’ walls; one average cap number can hide a low transition.
• Show yard grades, drains, dock connections and the proposed scope on the same drawing.

Higher walls can trap rain behind them. The city’s resilience strategy notes bulkheads often need tide valves and pumps for that reason, so plan drainage with the height.

Frequently Asked Questions: Datums · Resilient Jacksonville, Action 16