Retaining Wall Maintenance Guide
A retaining wall that is inspected and maintained annually will outlast one that is ignored by decades. Most failures are predictable — and preventable.
1. Annual Inspection: What to Check
Once a year — ideally after the wet season — walk your retaining walls and check the following:
- Plumb and alignment — stand back and sight along the wall face. Any lean forward (away from retained soil) or bulging indicates movement
- Crack patterns — horizontal cracks are serious (bending failure); diagonal cracks indicate differential settlement; vertical cracks are less critical but should be monitored
- Weepholes — are they clear and discharging? Blocked weepholes mean drainage is backing up
- Surface condition — spalling concrete, rusting steel, rotting timber, crumbling mortar
- Cap and coping — missing or damaged caps allow water to penetrate the wall structure
What to look for in a retaining wall →
2. Drainage Maintenance
Drainage is the most critical maintenance item for any retaining wall. Check annually:
- Weephole outlets — clear of soil, debris, grass or wasp nests
- Surface drainage — water should drain away from the wall, not toward it
- Downpipes and surface channels — ensure stormwater is not directed toward the retained soil mass
- Vegetation — tree roots can infiltrate drainage aggregate and block ag-drain; large trees near walls warrant monitoring
Weepholes can be cleared with a garden hose or compressed air. If a weephole that was previously flowing has stopped, the ag-drain or filter fabric behind may be clogged — this warrants an engineering assessment.
3. Vegetation Management
Vegetation on and near retaining walls requires careful management:
- Creeping plants on the wall face — roots penetrate mortar joints and masonry, freeze-thaw or wetting-drying cycles cause spalling and joint failure over time
- Large trees near walls — root systems can undermine footings and infiltrate drainage systems; trees within 2× wall height should be assessed
- Grass on top of retained soil — generally fine and provides some erosion protection; avoid deep-rooted plants close to the wall
4. When to Call an Engineer
Get an engineering assessment if you observe:
- Any measurable forward lean or movement since last inspection
- Horizontal cracks anywhere in the wall
- Bulging in the middle section of the wall
- Weepholes that have stopped flowing
- Signs of movement in the soil above the wall (slumping, cracking)
- A wall that is 15+ years old with no engineering inspection history
Read: Signs your retaining wall is failing →
Need an Engineer for Your Retaining Wall?
RetWall provides AS 4678-compliant structural engineering reports across Australia. Fast turnaround, fixed fees from $600+GST.
Get a QuoteFrequently Asked Questions
As a minimum, a visual inspection by the owner annually and a professional engineering inspection every 5–10 years, or immediately if any signs of movement, cracking, or drainage failure are observed. Older walls and walls on difficult sites warrant more frequent inspection.
Minor shrinkage cracks in concrete walls can be sealed with flexible polyurethane sealant to prevent water ingress. Structural cracks — horizontal, diagonal, or any crack associated with movement — require engineering assessment before any repair. Sealing a crack that is actively moving will not fix the underlying problem.
Try a garden hose or compressed air first. If the blockage doesn't clear easily, the ag-drain behind the wall may be silted up. In this case, the drainage system may need to be replaced — which typically means significant excavation behind the wall. This is an engineering project, not a DIY one.
A well-designed, well-built and properly maintained retaining wall should last 30–50+ years. Timber walls have a shorter practical life (15–25 years depending on timber treatment and conditions). Walls that were never engineered or that have ongoing drainage problems have unpredictable service lives.