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Key Biscayne · Miami-Dade County

What flood zone is Key Biscayne in, and what does it require?

+1 ft above BFE (new homes)new one- and two-family dwellings

Key Biscayne requires new one- and two-family homes at base flood elevation plus 1 foot (or the Florida Building Code level, if higher), and lowers its substantial-improvement trigger to 49% of market value. Critical facilities go to the 500-year flood elevation plus 1 foot.

Source: Key Biscayne Code of Ordinances Ch. 10 Floodplain Management, Secs. 10-63, 10-73; FEMA Community Status Book, Florida (www.fema.gov/cis/FL.html, report 10/03/2026); 2023 Florida Building Code, Residential R322.2.1, R322.3.2; 44 CFR 59.1; FEMA Flood Map Service Center · Verified 2026-10

The detail

New homesLowest floor or bottom of lowest horizontal member at or above BFE plus one foot, or as in FBC-Residential, whichever is higher - Sec. 10-73(3)a.
Improved/damaged homesElevation per FBC-Residential - Sec. 10-73(3)b.
Critical facilitiesFBC minimum or the 500-year flood elevation plus one foot, whichever is higher - Sec. 10-73(3)c.
Substantial improvement / damage49 percent of market value, no cumulative period - Sec. 10-63, applied by Sec. 10-73(1).
EnclosuresFor one- and two-family dwellings, enclosed areas below elevated buildings: access limited to parking (garage door), limited storage (standard exterior door) or entry (stairway or elevator), and the interior may not be finished or partitioned - Sec. 10-73(2).
Site plansMust show that street flooding and local drainage from and onto neighbouring lots is accounted for - Sec. 10-73(4).
FEMA flood mapFEMA's Community Status Book (report dated 3 Oct 2026) lists Key Biscayne as NFIP community 120648 with a current effective FIRM dated 11 Sep 2009. Zones are set parcel by parcel, so no single zone covers the whole city - check your own address.
NFIP historyFEMA record: first FIRM 29 Sep 1972; regular NFIP program since 29 Sep 1972; entered CRS 1 Apr 1998.
Flood insurance discountCRS class 8 - 10% off NFIP premiums for policies in the Special Flood Hazard Area (class in effect 1 Apr 2021).
State minimum2023 Florida Building Code, Residential R322.2.1 and R322.3.2 - lowest floor (A zones) or bottom of the lowest horizontal structural member (V and Coastal A zones) at BFE + 1 ft or the design flood elevation, whichever is higher.
Look up your zoneEnter the address in FEMA's Flood Map Service Center (msc.fema.gov), the official public source for FIRMs; an elevation certificate shows how your floor compares with the BFE.

Your city's height sheet

The elevation your city requires, the datum it is measured in, and the section of code that says so. One page.

Available for the cities whose rule we have verified and sourced.

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The county rule behind this

What applies across Miami-Dade County, and where each city departs from it.

Miami-Dade CountySeawall requirements county-wide

The same question, nearby

The rule changes at the city line, not the county line.

Miami-DadeMiami BeachMiami-DadeCoral GablesMiami-DadeMiamiMiami-DadeSurfside

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Twelve signs a seawall is failing

What to look for, where to look for it, and what it means when you find it. Walk your wall in twenty minutes.

A screening sheet for owners, not an engineering inspection.

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