Seawall repair and replacement in Miami

Seawalls in the City of Miami

DERM's Class I permit applies inside the City of Miami just as in the rest of the county, and the City adds its own structural and zoning review. Along Biscayne Bay and the Miami River, the bottom in front of most walls is state-owned submerged land, so a wall moved waterward needs the state's consent as well.[1]

The height question

A 2020 City proposal (File 7338) would have set new and reconstructed walls east of US-1 at 6 ft NAVD 88, able to reach 8 ft, and defined a substantial repair as 50% of the wall's length or 50% of the cost of a new wall. We have not confirmed adoption, so we check the rule in force with the City before design.[2]

The tide at the Miamarina gauge

NOAA's Miami Miamarina station on Biscayne Bay records a mean tidal range of 2.17 ft and a great diurnal range of 2.37 ft, with mean higher high water about 0.26 ft above NAVD 88 (1983 to 2001 tidal epoch). Those numbers set how far a lift has to travel, how far a floating dock rises and falls, and how much freeboard a seawall cap really has.

The tide also sets how much of the wall can be worked on dry at low water, which changes crew time.[3]

What makes Miami waterfront work different

Most of Biscayne Bay and its natural tributaries, including the Miami River and Little River, are state-owned submerged lands, so docks over them need the state's consent alongside the DERM permit. The Biscayne Bay Aquatic Preserve is listed by DERM as a permitting contact, and FDEP's free online dock self-certification is not available in aquatic preserves. The federal seagrass range used in dock design reaches central Biscayne Bay.[1][4][5]

City of Miami seawall height

In 2020 the City considered an ordinance (File 7338) to set a 6 ft NAVD 88 minimum for new and rebuilt seawalls east of US-1, outside the Miami River. We have not confirmed that it was adopted, so for every Miami seawall job we confirm the current height rule with the City before design.[2]

Permits for seawalls in Miami

• Miami-Dade DERM, Coastal Resources Section: Class I permit for any work in, on or over tidal water, the Miami River included, with exempt, expedited and short-form routes for small jobs. Phone (305) 372-6575.
• City of Miami Building Department: Structural and zoning approval for seawalls, docks and lifts inside city limits.
• Florida DEP or South Florida Water Management District: State permit or exemption, and consent to use the state-owned bottom of Biscayne Bay, the Miami River and Little River, which DERM grants for most of the bay on the state's behalf.
• US Army Corps of Engineers, Jacksonville District: Federal sign-off for work in the bay and the river. SPGP VI, the small-project route, passed its stated 27 July 2026 expiry, so we confirm the current route for each job.

Which permits does seawall work need?

In Miami-Dade, any work in, on, over or upon tidal waters needs a DERM Class I permit under Section 24-48 of the County Code, including inside cities. Minor repairs are exempt, cap and tieback work gets an expedited authorisation, and rebuilding a wall at the mean high water line or up to 18 inches waterward is a short-form permit approved by staff.

The city building department also issues a structural permit. A state exemption does not remove county and city permits: Florida Statute 403.813 says its exemptions do not relieve anyone from county and municipal requirements, so in Miami-Dade a DERM Class I permit still applies.[1][7]

How long does a seawall last?

Fort Lauderdale's seawall ordinance FAQ assumed a design life of about 50 years, and city engineers described a 30 to 50 year lifespan for a wall built today. Salt water, wave action from boat wakes and rising tides shorten that when cracks and failed joints are left open.[10]

Why heights matter now

Cities are raising the bar. Miami Beach requires new and substantially repaired seawalls to reach 5.7 ft NAVD, Coral Gables sets bulkheads at a minimum of 6 ft NGVD 1929, and Fort Lauderdale requires 5 ft NAVD. A repair that triggers these rules can turn into a raising job, so we check the local standard before we price.[9][11][12]

Frequently asked questions