Why seawalls fail
A seawall holds back soil on the land side and tidal water on the other, twice a day, every day. Most failures come from a few root causes: saltwater reaching the steel inside the concrete, joints and cracks that let soil escape, tiebacks or anchors that corrode or pull loose, and scour at the base of the wall. Each leaves visible clues.
The warning signs
- Sinkholes or soft spots behind the wall. Soil is escaping through or under the wall, usually through an open joint or crack. The hole tends to grow with each tide. Urgency: get it inspected soon, and keep people and heavy loads back from the edge.
- Sand or soil washing out at low tide. Look for fans of sand at the base of the wall, cloudy water at a joint as the tide drops, or new gaps behind the cap. Urgency: soon. This is the usual cause of sinkholes.
- Panels leaning toward the water, or a wavy cap line. Often a sign that a tieback or anchor has failed or that the toe of the wall is moving. Urgency: high. Leaning walls can move quickly in a storm.
- Cracks with rust stains. Orange or brown streaks mean water is reaching the reinforcing steel. Rusting steel expands and splits the concrete further. Urgency: schedule an inspection.
- Spalling: chunks of concrete popping off with rebar showing. The steel is corroding and losing section. Urgency: schedule soon, especially on the cap where tiebacks connect.
- Gaps opening between the cap and the panels. The cap ties the wall together. Separation means movement. Urgency: high.
- Water coming over or through the wall at high tide. Beyond the flooding itself, Broward cities' tidal flood barrier rules treat a wall that lets tidal water through onto a neighbor's property or the street as in disrepair and citable (Fort Lauderdale Ordinance C-23-05, Pompano Beach Sec. 151.05). Urgency: plan a fix before the next king tide season.
- Cracks in the pool deck, patio or driveway near the wall. Settlement behind the wall often shows up in hard surfaces first. Urgency: inspect.
- Scour or missing rock at the base of the wall. Boat wake and currents can undermine the toe. Walls on the open Intracoastal and near inlets see more of this. Urgency: inspect, and ask about rip-rap.
- Clogged or missing weep holes or filters. Tidal barriers are meant to stop tidal water while still relieving water pressure from the land side (Fort Lauderdale Ordinance C-23-05). Trapped water pushes on the wall after heavy rain. Urgency: mention it at your next inspection.
- A wall that is simply old and low. Many Broward canal walls are decades old and sit below today's high tide levels. Even without visible damage, it is worth knowing your wall's elevation and condition before a sale, a storm or a major repair. Urgency: baseline inspection.
How to document what you see
- Photograph at low tide from the water side if you safely can, or lean out from a dock. Most clues sit near the waterline.
- Take one wide photo of the whole wall and close-ups of each problem with a tape measure or common object for scale.
- During king tides, photograph any overtopping with the date and time. Fort Lauderdale publishes its predicted king tide dates each year (city king tide page).
- Note when you first saw each sign and whether it is getting bigger.
Those photos are exactly what a contractor needs to give you a useful first opinion. You can attach up to three to a free quote request.
What not to do
- Do not just fill a sinkhole and move on. Filling hides the symptom while soil keeps escaping through the wall.
- Do not park vehicles, stack pavers or run heavy equipment near a leaning or undermined wall.
- Do not attempt structural repairs yourself. Structural seawall work generally needs a licensed contractor, a city permit and a Broward County license for work in county waters (Broward 311).
Not sure whether what you see is serious? Read our seawall inspection guide, or send photos and we will connect you with a licensed, insured local seawall contractor.