The four signs a retaining wall is about to fail

A retaining wall holds back soil and water at the same time, and most failures are really a water problem that shows up as a wall problem months or years later.

The first sign is usually a lean, even a slight one — stand at one end and sight down the face. The second is a horizontal crack running across it, which means the wall is bending under pressure it wasn't built to take. The third is a gap opening at the base or between courses, which often means the base itself has shifted. The fourth is water actively seeping or pooling at the bottom after a rain, which tells you exactly where the pressure is coming from.

Any one of these on its own is worth a look. Two or more together usually means the drainage behind the wall has failed, not just the wall — which is why the fix is often a French drain or regrading behind the wall, with the face rebuilt afterward rather than instead of that work.

Caught early, most of this is a repair. Left alone, the wall eventually has to come out completely, which costs several times what the early fix would have.