5 Signs Your Retaining Wall Is Failing (And What To Do About Each)

1. Forward lean. The most obvious sign — the wall is visibly tilted toward the low side. A lean of up to 15 mm on a 1 m wall is worth monitoring but not necessarily urgent. A lean of 25 mm or more, or a lean that has increased noticeably in a single season, indicates active movement. Cause: almost always drainage failure causing hydrostatic pressure buildup or loss of geogrid engagement. Action: professional assessment to determine whether drainage restoration or rebuild is needed.

2. Efflorescence. White mineral staining running down the wall face is a sign that water is moving through the wall material, dissolving calcium compounds and depositing them on the surface. Efflorescence itself doesn't cause structural failure, but it's a clear signal that the drainage behind the wall is inadequate — the wall is acting as a drainage path when it should be holding back soil, not water. Action: assess drain tile and gravel zone condition; restore drainage.

3. Cracks wider than 3 mm. Hairline cracks in concrete block or mortar joints are normal and largely cosmetic. Cracks wider than 3 mm, especially horizontal cracks running along mortar joints, or cracks accompanied by visible joint opening, indicate structural stress. Diagonal cracks at corners often indicate differential settlement. Action: monitor crack width over time; seek professional assessment if cracks are widening.

4. Weep holes that have stopped weeping. Counterintuitively, the absence of water from weep holes during or after heavy rain can indicate that the drainage system is blocked or has failed. A properly functioning drain should see water flowing through weep holes during significant rain events. If yours don't flow, the drain tile is likely blocked or the gravel zone is contaminated with clay. Action: rod or jet the drain tile from the weep holes; expose the drainage zone from above if necessary.

5. Settlement or step changes in the top of the wall. If one section of the wall has dropped below adjacent sections, it indicates settlement of the leveling pad or subgrade under that section. Most common cause is water accumulation under the footing (from poor drainage) softening the subgrade. Action: excavate the settled section, recompact or improve the subgrade, and relay the affected courses.