What riprap does
Waves and boat wakes scour the soil at the foot (toe) of a seawall. Over time that undermines the wall. Riprap is a sloped bank of large rock placed in front of the wall, or on its own along a shoreline, to break up the waves and hold the bottom in place. It also gives fish and other marine life somewhere to live.
Florida's rule on riprap
Florida's rule on permitting shoreline stabilization (62-312.440, Florida Administrative Code) sets out how the state treats riprap in the waters it covers:
- Plants first: native aquatic vegetation is the default for stabilizing a shoreline. Riprap and other sloping revetments are allowed when the applicant shows vegetation won't stop the erosion.
- Rock size: the outer layer must be rocks two feet in diameter or larger.
- Slope: no steeper than 2 horizontal to 1 vertical.
- Filter cloth: required under every revetment.
- Seagrass: riprap can't be placed over or within a seagrass bed.
- Dredging and fill: limited to what's needed to install it safely.
The same rule says new vertical seawalls aren't permitted in those waters except where state law makes exceptions. That's one reason permits for work in natural waters are often stricter than for man-made canals.
When you may not need it
- Broward: the county's guidance says over-water structures under 500 sq ft, or exact replacements of existing docks, don't require riprap. Other projects may. See Broward permits.
- Living seawalls: in Fort Lauderdale, a "living" seawall project on Bryan Place was described by its maker as the first in Broward approved without riprap. The city also waives permit base fees for qualifying living seawalls. See Fort Lauderdale.
Living shorelines and oyster reefs
Pinellas County's Water and Navigation section lists living shorelines and oyster reefs alongside seawalls and riprap among the projects it reviews. These softer options use plants, shell and natural materials to hold the shore while adding habitat. See Pinellas permits.
Not to be confused with
Cape Coral's alternative seawalls are stabilized, usually sodded, slopes allowed instead of a wall on freshwater canals. They aren't rock revetments, and they have their own slope limits.
Getting it priced
Riprap is usually quoted with the seawall or dock work it protects. Ask for the rock size, the slope, the filter cloth and the length covered to be listed separately. Use the form below for a quote.
Sources: Fla. Admin. Code R. 62-312.440. Broward County riprap requirements guide. Kind Designs on the Bryan Place living seawall.
This page summarizes published rules and prices for general information. It isn't engineering or legal advice, and codes change. Your contractor, engineer and building department have the final word for your property.
Common questions
How big does riprap have to be in Florida?
Under Florida's rule on shoreline stabilization (62-312.440), the outer layer of riprap must be rocks two feet in diameter or larger, placed over a filter cloth, at a slope no steeper than 2 horizontal to 1 vertical, and not over seagrass. That rule covers the waters it regulates. Local rules can add their own requirements.
Do I need riprap in front of my seawall or dock in Broward?
Not always. Broward County's guidance says an over-water structure under 500 square feet, or an exact replacement of an existing dock, doesn't require riprap. Other projects may. Your contractor will find out when applying for the county licence.