Retaining Wall Inspection

Drainage is the most critical element of retaining wall design. Water pressure behind the wall (hydrostatic pressure) is the #1 cause of failure.

1. Check for weep holes at the base of the wall — should be every 4-6 feet

2. Verify drain pipe behind the wall (should be perforated pipe in gravel)

3. Check that drain pipe exits to daylight or storm system

4. Look for water stains on the wall face (indicates drainage issues)

5. After rain: check for water flowing through weep holes (good sign — drainage is working)

6. Verify gravel backfill behind wall (not native clay soil)

7. Check filter fabric between gravel and native soil

- No drainage behind wall (hydrostatic pressure builds — wall fails)

- Weep holes blocked or missing

- Drain pipe with no outlet

- Clay soil backfill instead of gravel (holds water behind wall)

- No filter fabric (soil migrates into gravel, clogs drain)

- Water stains indicating drainage problems

Wall must be plumb or leaning slightly into the retained soil. Cracks, bulges, or leaning away from soil indicate potential failure.

1. Check wall plumb — should be vertical or leaning slightly toward the soil (battered face)

2. Any lean AWAY from the soil is a warning sign — measure and monitor

3. Look for horizontal cracks (most dangerous — indicates bending failure)

4. Check for vertical cracks — may indicate settlement

5. Inspect for bulging or displacement at any point along the wall

6. Check top of wall alignment — should be straight with no waves

7. For block walls: check for movement at mortar joints or shifted blocks

8. For timber walls: check for rot, splitting, or displaced timbers

- Wall leaning away from soil (active failure)

- Horizontal cracking (bending failure from lateral pressure)

- Bulging section (localized failure imminent)

- Top of wall displacing outward

- Mortar joints cracked or displaced

- Timber walls rotting at ground contact

- Wall higher than 4 feet without engineering (most jurisdictions require engineered design above 4')