Seawall Height Rules in St. Augustine
A cap elevation needs a named datum and a property-specific design. A tide-chart number, a neighboring wall or a public project is not a ready-made requirement for your parcel.
- Top of the capMeasured from a fixed survey reference.
- WaterlineRises and falls with tides and weather.
- Survey reference (datum)A named reference, such as NAVD88.
Use the survey reference printed beside the elevation.
What does “six feet high” actually describe?
It could mean the exposed face above the water, the cap above the yard or an elevation relative to a survey datum. Those are different measurements. Ask every proposal to label what is being measured, the units and the reference used.
NOAA distinguishes geodetic datums such as NAVD88 and NGVD29 from tidal references such as mean high water. A surveyor must reconcile the references when older plans, new measurements and water-level information use different systems. Do not copy a conversion from another town or estimate it from a photograph. Frequently Asked Questions: Datums
What should you ask the surveyor to document?
| Record | Why you need it |
|---|---|
Datum, units and control reference | Allows the designer to compare elevations consistently |
Cap elevations at identified points | Shows changes along the wall instead of only an average |
Returns and neighboring connections | Reveals how the barrier meets adjoining edges |
Yard, drainage and outlet information | Helps evaluate where water can enter or leave |
Survey date and limitations | Distinguishes current measurements from older records |
This is a discussion checklist, not a substitute for the surveyor’s scope or the authority’s required documents. Give the professional prior permits and plans so unexplained differences can be checked before design progresses.
What do St. Augustine tide records tell you?
NOAA station 8720576 lists a historical mean tidal range of 4.48 feet. That is a difference between water levels, not a seawall cap elevation. NOAA’s station page also records removal of the instrument in 1979; the available tide predictions should not be described as live readings from a working City Dock gauge.
Use tide information as one input for an assessment. Ask the designer what water levels, waves and other loads apply to the parcel and how they relate to the survey. A predicted astronomical tide does not settle storm conditions or the water level beside a particular wall. St. Augustine station 8720576
Can the existing wall support a higher cap?
A higher finish is a structural question as well as an elevation question. Have a qualified professional evaluate the retained panels, supports and connections before selecting a raising method. Ask what can be inspected directly, what remains concealed and how uncertainty affects the recommendation.
- What existing structure will carry the proposed work?
- How will the new section connect to the old one?
- What changes at the neighboring wall and return?
- How will rainfall drain when outside water is elevated?
- What further investigation is needed before committing to the scope?
These questions help compare proposals without treating an extra layer of concrete as a complete solution. The repair-or-replace guide covers the broader decision.
Which requirement applies to this particular project?
Ask the local authority to identify the applicable code provision and the project trigger using the proposed drawings. City bulkhead review includes plans and survey information. Oceanfront work may involve DEP coastal review, and historic-area changes may require additional consideration.
Keep the reply tied to the actual parcel, scope and plan revision. A design elevation from a public seawall project is evidence of that project’s design, not a rule for every home. Similarly, another municipality’s numerical standard should not be imported into a St. Augustine estimate.
Use the permit route to reach the right office and the assessment guide to prepare your records. The useful outcome is a surveyed, reviewed design with its assumptions explained, rather than an unsupported pass/fail number. Building Permit Information: bulkhead/retaining wall Coastal Construction Control Line Program
Send a height question that can be answered
Use the surveyed information
Provide the survey date, stated vertical datum, benchmark reference and the location of each relevant cap elevation. Include low returns and transitions that the surveyor has actually measured. Keep water-level observations labeled separately.
Name the proposed change
Explain whether the project repairs a cap, raises part of the wall or replaces the system. Ask the designer which local requirement and permit condition control that specific scope, and whether drainage or neighboring transitions also change.
For example, “the cap is 5.2 feet” is incomplete without a datum and measured location. Ask the surveyor to supply the missing reference before comparing the number with a requirement. The diagram on this page explains the terms; it does not establish a compliant design elevation.
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.
Seawall cap elevation
- Top of seawall cap
- 6.00 ft
- Survey reference (datum)
- NAVD88
This example shows 6.00 ft NAVD88. Use the number and reference on your own survey.
Match the value and the reference.
- The elevation: use the number for the top of the wall cap, not a building floor, water depth or the wall’s full height.
- The reference: copy the name beside the elevation, such as NAVD88 or NGVD29. You can compare elevations only when they use the same reference.
- Cannot find both? Choose “No / not sure” in the checker. Ask a surveyor to help find them; measuring from the water will give a different result.
Show sourcesHide sources
- Frequently Asked Questions: DatumsSource reviewed 2026-10-26
- St. Augustine station 8720576Source reviewed 2026-10-26
- Building Permit Information: bulkhead/retaining wallSource reviewed 2026-10-26
- Coastal Construction Control Line ProgramSource reviewed 2026-10-26
Ask about local requirements
Identify the property and the question to resolve. Keep any available survey with your planning notes.