Retaining wall leaning, bulging, or cracking

Symptoms

• Wall visibly leans or bulges outward
• Cracks running horizontally or diagonally across the wall
• Soil or mulch spilling over the top or through gaps

Likely causes

• CommonPoor or blocked drainage behind the wallWater buildup behind a wall adds significant hydrostatic pressure it wasn't designed to hold.
• CommonWall not originally built with adequate drainage or reinforcementSome walls, especially DIY or older ones, lack proper gravel backfill and drain pipe.
• PossibleSoil settling or erosion undermining the wall's baseLoss of supporting soil at the footing can destabilize the whole structure.
• PossibleWall exceeding its height rating for the retained soil loadTaller retaining walls need engineering design; DIY walls are often limited to a few feet safely.

What to do

1. Observe the wall after heavy rain to see if leaning or bulging worsens, which points to drainage as a major factor.
2. Check for and clear any visible drainage weep holes at the base of the wall that may be blocked.
3. Avoid adding significant new weight (like a structure or heavy planting) behind or on top of a wall showing distress.
4. For minor cracks in a small wall, monitor for progression by marking the crack and checking width over several weeks.
5. For any wall over a few feet tall that's visibly leaning or bulging, treat this as a structural safety concern rather than a cosmetic one.
6. Contact a structural or landscape engineer to assess whether the wall needs rebuilding with proper drainage and reinforcement.

Tools and parts

• None for initial assessment

When to call a pro

A structural engineer or retaining wall contractor should assess any wall showing significant lean, bulging, or cracking before it worsens or fails.

Safety