Signs Your Retaining Wall Is Failing

1. Forward Lean or Bulging

A wall leaning away from the retained soil (forward lean) or bulging in the middle is experiencing lateral earth pressure it cannot resist. This is a serious sign requiring urgent engineering assessment.

How to check: hold a plumb bob or a level against the wall face and measure the deviation from vertical at the top. Any measurable forward lean warrants investigation. Photograph the lean against a fixed reference (plumb bob, spirit level) with a date stamp so any progression can be monitored.

Bulging in the middle of a wall typically indicates that the mid-span is the weak point — common in walls without adequate vertical reinforcement or with poorly anchored tops.

2. Crack Patterns and What They Mean

• Horizontal cracks — the most serious type. Indicate bending failure or loss of vertical support. Require immediate engineering assessment
• Diagonal cracks — indicate differential settlement. One section of the wall is moving more than adjacent sections. Investigate the cause — often differential soil conditions or drainage failure on one side
• Vertical cracks — may be shrinkage or thermal movement (often benign) or separation joints opening up (less benign). Investigate if wide (>2mm) or if associated with wall movement
• Stair-step cracks in masonry — mortar joint failure, often due to movement. Less immediately structural than horizontal cracks but indicates the wall is experiencing forces

3. Drainage Changes

Changes in drainage behaviour are one of the earliest and most reliable indicators of developing problems:

• Weepholes that have stopped flowing — drainage is backing up behind the wall. The wall is now experiencing hydrostatic pressure it wasn't designed for
• Water seeping from joints or cracks — drainage system is overwhelmed and water is finding other paths through the wall
• Efflorescence (white mineral deposits) — indicates water has been passing through the wall and depositing minerals. Not immediately structural but confirms drainage failure
• Damp patches appearing on the wall face — seasonal changes in wall dampness indicate groundwater fluctuations that are stressing the structure

Understanding retaining wall drainage →

4. Soil and Surface Movement

Movement of the retained soil itself can precede or accompany wall movement:

• Cracking in the soil surface above the wall — particularly if parallel to the wall, indicates the soil mass is moving
• Settlement or slumping of paths, driveways, or garden beds above the wall
• Exposure of footings — if the base of the wall is becoming exposed, the soil in front is eroding and passive resistance is being lost
• Movement of posts or structures near the top of the wall

Any visible soil movement near a retaining wall warrants immediate engineering assessment. Do not wait to see if it gets worse.