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Seawall height guidance

Bulkhead Height Requirements in Alabama: Mobile Bay

Bulkhead height requirements around Mobile Bay are thin. Most local codes set flood floor levels, not a wall height, so this page lists what each place does say.

The cap level, the water level and the survey zero point are three separate things. A wall separates yard from water. One vertical arrow runs from the top of the cap down to a dashed line that marks the survey zero point. The water surface is drawn on its own. The numbered markers match the key below the drawing. 123
Three numbers people mix up.
  1. Top of the capRead against a fixed survey zero point.
  2. WaterlineRises and falls with tides and storms.
  3. Survey reference (datum)The named zero point, for example NAVD88.

Use the reference printed beside the number on your survey.

Ask about local requirements

How high should your seawall be?

Some cities and counties set a minimum, a maximum or both for the level of a wall top. The rule that applies turns on where the lot is and what work is planned. Stormwater, flood exposure and the walls beside yours also shape the design.

Local height rules refer to the top-of-cap level on your survey. This is the cap measured from a fixed survey zero point. It is neither the wall’s total length from base to top nor the height of the water.

Find two items on your survey.

You need the level of the wall cap and the reference name that goes with it. The mock survey below shows where both tend to be printed.

Find the cap level and the reference name
Survey example

Seawall cap elevation

Top of seawall cap
6.0 ft
Survey reference (datum)
NAVD88

This example reads 6.0 ft NAVD88. Copy the figures from your own survey instead.

Keep each number with its reference.

  • The level: use the figure labeled for the top of the cap. Do not use floor levels, water depth or how tall the wall is.
  • The reference: copy the label printed near the figure, such as NAVD88 or NGVD29. A level means little unless you know which zero point it uses.
  • Not on the page? Pick “No / not sure” in the checker, then ask a surveyor to find it. A reading taken at the waterline would be wrong.

What does NAVD88 mean?

NAVD88 is a standard zero point that surveyors use to state levels. Some surveys use NGVD29 or a tide-based zero instead. Two levels line up only when they share one zero point, and a surveyor can convert between them. NOAA explains survey references.

Look for the cap level on your survey or the as-built plans. An elevation certificate usually covers only the house. If the wall number is absent, a surveyor can provide it without anyone measuring at the water.

Repairs, rebuilds and permits

Ask the permit office which rules apply before you raise or rebuild a wall. An engineer can judge whether the existing wall, its supports and the drainage can handle the change. A taller wall can also redirect stormwater.

Alabama work at or below the high tide line usually needs three approvals: the Corps of Engineers, ADEM's Coastal Program and ADCNR State Lands. The older joint application is ADEM Form 166, and the Corps now also takes requests through its online regulatory page.

Common questions

How should I prepare to change the wall’s height?

Pull together your survey, write down the wall’s condition and decide what you want to change. An engineer can check supports, drainage and how the change touches neighboring walls. Tell us your plans and we will help you decide what to do next.

Do I have to build to the maximum?

No. A maximum is an upper limit, not a target. Ask the permit office if your lot also has a minimum.

What if I do not know the level?

Start with the address and the change you are considering. A surveyor can find the cap level and its reference for you.

Can an existing wall be made taller?

An engineer should first review the wall, its supports and the drainage. The answer might be extending the wall or replacing parts of it.

Does meeting the number prove the wall is sound?

No. Height is just one factor. Supports, drainage and visible damage matter as well. The warning-sign check helps you prepare for an inspection.

Who can help with a height question?

Tell us which city or county you are in and what you want to change. We can discuss whether to start with a survey or an inspection. Get services and cost confirmed first.

What water levels should a wall height be read against?

Tides here are small, and storms matter far more. West shore gauges show a daily tide range of about 1.5 to 1.7 feet. The average higher high tide sits roughly 0.8 to 0.9 feet above NAVD88, the survey zero. NOAA gauges near Fowl River

Minor flooding starts at 2 feet above that high tide, and major flooding at 6 feet. NOAA Dog River Bridge gauge

Keep each number tied to its zero point. A survey cap level means little until it names NAVD88 or another datum.

How high did storm water get?

These are still-water readings. Waves ride on top of them.

What does each place say about height?

No numeric bulkhead height turned up in the local codes that were read. These are the rules that do exist.

Should a new wall allow for sea level rise?

Ask the engineer. The sea at Dauphin Island rose about 10 inches from 1966 to 2024. NOAA scenarios show 1 to 1.6 feet by 2050, measured from the year 2000. Mobile County Shoreline Management Plan

Daphne and Spanish Fort also ask for non-structural shore methods wherever practical, such as marsh or beach restoration. Groins and jetties come only when nothing else works. Daphne land use ordinance Spanish Fort zoning ordinance

For permits see the permit guide. For zones, see the flood zone guide.

What should you ask an engineer about wall height?

  1. Which datum does the design cap level use, and what is the cap level in that datum?
  2. How does that level compare with the storm water levels above?
  3. Will waves splash over the cap in a storm, and what happens behind the wall then?
  4. Does the permit office set any limit on the wall or on buildings next to it?
Show sourcesHide sources
  1. NOAA CO-OPS metadata API: station list, datums (1983-2001 epoch) and flood levels for stations 8735523, 8738043, 8739803Source reviewed 2026-11-04
  2. CO-OPS Metadata API: Dog River Bridge 8735391 datums and flood levelsSource reviewed 2026-11-04
  3. Hurricane Katrina (NWS Mobile event summary)Source reviewed 2026-11-04
  4. NWS Mobile Hurricane Zeta and Hurricane Sally event pages (maximum observed water level tables)Source reviewed 2026-11-04
  5. Mobile County Shoreline Management Plan (December 2025), Section 4.3.2Source reviewed 2026-11-04
  6. Development Permit Application for all properties in V-Zones, A-Zones and X-Shaded (rev. December 2022)Source reviewed 2026-11-04
  7. Building Codes Permit Fee Schedule Ordinance (28-052-2022), Article Seven ASource reviewed 2026-11-04
  8. Bayou La Batre Ordinance No. 2020-002, Article 4 and definitionsSource reviewed 2026-11-04
  9. Town of Dauphin Island Zoning Ordinance No. 105, Article 2 definitions (Flood Protection Elevation; Freeboard)Source reviewed 2026-11-04
  10. Floodplain Management / Flood Zone Info | Baldwin County Building DepartmentSource reviewed 2026-11-01
  11. Daphne Land Use and Development Ordinance (codified through July 3, 2025)Source reviewed 2026-11-04
  12. Zoning Ordinance No. 1253, City of Fairhope (amended June 3, 2025)Source reviewed 2026-11-04
  13. Zoning Ordinance, City of Spanish Fort, Alabama (Ordinance No. 51-96, as amended)Source reviewed 2026-11-04
What to do next

Ask about local requirements

Give the property address and your question. If you have a survey, keep it handy with your notes.

Prefer to talk it through?(251) 850-5560

Getting your form ready…

Need a hand with your wall?

Give us the property location and describe what the seawall, bulkhead or dock needs.

Each page draws on Mobile Bay permit offices, local ordinances, public bids, tide gauges and storm reports.

Plan your project(251) 850-5560
Plan your project(251) 850-5560