What to Look For in a Retaining Wall

What to Look For: A Visual Checklist

You can do this yourself in 10 minutes during a property inspection. No tools needed beyond your eyes and a phone camera.

1. Check for Lean

Stand at the end of the wall and sight along it. Is it vertical? Even a small amount of visible forward lean is a concern. For precision, hold your phone vertically against the wall face and use a spirit level app.

• No lean: Good — wall is stable
• Slight lean (<10mm per metre of height): Monitor — may indicate early-stage movement
• Visible lean (>10mm per metre): Red flag — get engineering assessment
• Severe lean (>25mm per metre): Major red flag — wall likely needs rebuilding

2. Check for Cracking

Walk along the wall and examine the face closely:

• Horizontal cracks: Indicate bending failure — the wall is being pushed harder than it can resist. Red flag.
• Vertical cracks: Indicate differential settlement — different parts of the footing are moving differently.
• Stair-step cracks (in masonry): Indicate movement along mortar joints — the wall is shifting.
• Hairline surface cracks: Often cosmetic (shrinkage) — usually not structural.
• Cracks wider than 2–3mm: Always warrant engineering assessment.

3. Check Drainage

• Can you see weep holes (small pipes through the wall face)? If not, drainage may be inadequate.
• Is water pooling at the base of the wall? Drainage not functioning.
• Is there staining or efflorescence (white salt deposits) on the wall face? Moisture coming through the wall.
• After rain, is there a wet or boggy zone behind the wall crest? Water not draining.

4. Check for Gaps and Movement

• Gap between soil and wall top: The wall has moved forward, soil has slumped behind. Red flag.
• Sunken ground behind the wall: Backfill has settled — drainage may be compromised.
• Displaced sleepers or panels: Individual elements pushed out of alignment by pressure.
• Gaps between sleepers: Wall expanding or posts bending.

5. Check the Material Condition

• Timber: Tap with a screwdriver. Soft, spongy, or hollow-sounding timber is rotting. Check below ground level where rot is worst.
• Steel posts: Look for rust staining, flaking, or reduced cross-section. Severely corroded posts lose structural capacity.
• Concrete: Check for spalling (surface breaking off), exposed reinforcement, or crumbling.
• Gabion wire: Check for broken or corroded mesh. Bulging sections where wire has failed.

6. Check for Permits

• Ask the vendor: was a building permit obtained?
• Request copies of engineering drawings and permit
• Check with council for permit records for the property
• An unpermitted wall over the permit threshold is a compliance issue you may inherit

When to Get an Engineering Assessment

Get a professional engineering assessment before purchase if:

• Any wall shows visible lean, significant cracking, or gaps
• Walls are tall (over 1.5m) or support driveways/structures
• There are no permit records for walls that should have been permitted
• Timber walls are more than 10 years old
• Multiple retaining walls on the property (compounding risk)
• The property is on a steep slope with walls integral to the usability

Using Findings in Negotiation

If the inspection reveals issues, you have several options:

• Request the vendor fix the wall before settlement (with proper engineering)
• Negotiate a price reduction equivalent to the estimated remediation/rebuild cost
• Obtain a engineering report documenting the condition and estimated costs — this is powerful evidence for negotiation
• Walk away if the wall issues are severe and the vendor won't negotiate — sometimes the best deal is the one you don't make

Frequently Asked Questions