Flood vents in Key Largo

Who needs flood vents

Owners with garages, storage rooms or crawlspaces below base flood elevation in A zones.

Class 3 for unincorporated Monroe

Key Largo is unincorporated, so it shares Monroe County's flood insurance rating, and the County lists its current Community Rating System class as 3. Monroe takes part in the program on behalf of homeowners in unincorporated areas, and the discount depends on whether a home is inside the Special Flood Hazard Area.

Vents are sized to FEMA's one square inch per square foot rule for the enclosed area in your zone.[1]

Where a seawall is allowed at all

Monroe County allows vertical seawalls only to stabilise severely eroding shorelines on man-made canals, channels or basins, and never on open water. Lawfully existing walls may be repaired or replaced on the same footprint, the yard behind must sit at least 6 in below the top of the wall, and riprap goes at the toe wherever feasible.

Vent openings sit within 1 ft of grade, so local elevation datums matter when they are placed.[2]

Ocean side tide at Rock Harbor

NOAA's Rock Harbor station on the Atlantic side of Key Largo records a 2.09 ft mean range and a 2.37 ft great diurnal range, with mean higher high water about 0.25 ft above NAVD 88 (1983 to 2001 epoch). There is no NOAA datum station on the bay side near Key Largo, so for bay side lots we measure the water on site.

Those tide levels show how close high water already gets to the enclosure.[3]

What makes Key Largo different

The special exception application asks owners to describe the submerged lands the dock crosses, such as sand, seagrass or coral, and the minimum extra length needed to reach adequate water depth. The site plan must be prepared by a Florida registered architect, engineer or landscape architect and show the mean high water line and shoreline setbacks.[4]

Sanctuary, seagrass and manatees

Projects inside the Florida Keys National Marine Sanctuary needed prior Sanctuary approval under SPGP VI. The same permit let boat lifts and minor structures in Monroe County go into existing boat slips without a seagrass survey. All in-water work follows the state manatee conditions.[5][6]

Permits in Key Largo

• Monroe County Planning and Environmental Resources Department: Dock length special exceptions under County Code section 118-12(m)(15).
• Florida Keys National Marine Sanctuary: The Sanctuary starts at mean high water, so Key Largo canal and bay work is inside it; SPGP VI required its prior approval.
• Florida DEP or South Florida Water Management District: State permit or exemption, which Monroe County needs to see before it issues a Notice to Proceed for docks, seawalls and ramps.
• US Army Corps of Engineers, Jacksonville District: Federal permit, also required before the County's Notice to Proceed.

Sizing flood vents

A 400 sq ft garage needs at least 400 square inches of net open area, split across at least 2 walls, unless engineered vents carry a design certification for a smaller area. FEMA says designs must either carry a certification or meet the prescriptive criteria.[7][8]

Frequently asked questions