Seawall caps in Miami

When a new cap is the right fix

A cap replacement suits a wall whose panels are sound but whose cap is cracked, spalled or too low.

• Cracked or spalled cap with rust staining
• Wall a little below the city's new height
• Panels separating at the top

Two seawall heights split by the Rickenbacker Causeway

The City code text that File 7338 set out to replace puts seawall tops at +5.00 ft NGVD north of the Rickenbacker Causeway and +6.00 ft NGVD south of it, so the same job can have a different minimum depending on which side of the causeway the lot sits. The 2020 proposal would have moved every wall east of US-1 to 6 ft NAVD 88, with the Miami River left to its own section of the code.

A new cap is often the cheapest way to reach that height, if the old wall can carry the extra weight.[1]

What would count as a substantial repair

The 2020 Miami proposal defined a substantial seawall repair three ways: work on 50% or more of the barrier length, work costing 50% or more of a new wall, or a change in elevation along 50% or more of the length. It also asked for new walls that can be raised to at least 8 ft NAVD 88 later, with a variance route for undue hardship.

A cap replacement can count as substantial work, so we check the trigger before design.[1]

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.

Caps are formed and poured above the water, but the tide decides how high the new cap must sit to give real freeboard.[2]

What DERM charges in Miami

A DERM short-form permit costs $470 plus $25 for each $1,000 of construction above $10,000, and every fee carries a 7.5% surcharge. A seawall cap or tie rod job on DERM's expedited track has a $75 review fee, and after-the-fact applications for work already done pay double.

Cap repairs and cap replacements usually take a lighter permit route than a full wall.[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.[3][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.[1]

Permits 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.

Can the wall take a new cap?

Not always. Whether a cap can be added depends on whether the existing wall can bear the weight, which a marine or structural engineer must assess. A wall that cannot take it needs replacing instead.[9]

Permits for cap work

Miami-Dade DERM gives cap repair or replacement an expedited administrative authorisation when the building department has approved the structural plans. At the state level, seawall caps, batter piles and king piles used only to stabilise and repair seawalls fall under an exemption in rule 62-330.051(12)(d).[3][5]

Caps and city height rules

In Miami Beach a wall may be built to 4 ft NAVD if it is designed to support a future 5.7 ft NAVD, so the cap and footing need to be designed for that later raise. In Boca Raton the city must approve a location survey before the cap is poured, and a final engineer report confirms the cap elevation.[10][11]

Frequently asked questions