A crack in a seawall is a door, and the tide keeps using it.

Cracks in the Seawall: diagnosed and explained.

Cracks are usually the first sign a seawall gives you, and they rarely stay the size you found them. Every tidal cycle pushes water into the crack and pulls it back out, and the outbound trip carries fine soil from behind the wall with it. Grain by grain, voids form in the ground the wall is supposed to be retaining. As the wall loses that even backing, stress concentrates around the weak point and the crack widens, which moves more water, which moves more soil. That feedback loop is why a crack you could ignore for a year suddenly seems to grow every month. Not every crack is an emergency: concrete shrinks as it cures, and old walls carry hairline lines that have not moved in a decade. The ones that matter tend to announce themselves, widening over time, showing rust stains from the reinforcing steel corroding inside, weeping water after the tide drops, or pairing up with soft, sunken ground behind the wall. Telling the two kinds apart is a measurement job, and it is exactly what a free evaluation is for. The repair follows the diagnosis. Cracks that are leaking soil get sealed and the ground behind them stabilized with marine safe polyurethane, which fills the voids the tide carved and shuts the erosion path. Cracks that came from wall movement need the movement addressed, typically with tie back anchoring. A documented wall evaluation tells you which story your cracks are telling, in writing, before you spend on either.

For the repair side of this, the seawall repair solutions page lists every method Dalinghaus installs, including the ones that fix problems other than cracks in the seawall.