Insights: Building and Timber Pest Inspections

Signs You Need a Retaining Wall Inspection on Leaning Walls

When you are sizing up a property with visible soil cut-and-fill work, knowing whether a retaining wall inspection is wrapped into your pre-purchase building inspection matters a great deal. According to the Bureau of Meteorology, Perth’s climate dishes out hot, dry summers followed by winter fronts that can drop 140 mm or more in winter months, putting huge sideways pressure on masonry. A wall that looks solid in February can lean dangerously by August, so clarity on inspection scope is critical before you sign a contract.

The Core Difference Between Structural-Only and Comprehensive Inspections

Across Western Australia, a Structural-only inspection focuses on the roof frame, slab and load-bearing walls of the main dwelling. The inspector notes a retaining wall only if its movement directly threatens the house foundation. That means no tilt measurements, no drainage checks and no footing depth verification of the wall itself.

Broad Building Inspection’s Comprehensive inspection, on the other hand, expands the checklist to include “additional structures like sheds, outbuildings and boundary walls up to 30 m from the main home.” You will find that wording in the scope of our Comprehensive pre-purchase inspection package.

What the Inspector Checks During a Retaining Wall Inspection

Under AS 4349.1 during a comprehensive pre purchase building inspection, inspectors check accessible parts of the building , together with features of the property within 30 m of the building and within the boundaries of the site. Because most retaining walls sit on or near the boundary, they usually fall inside that allowance, so an assessment is carried out as part of the comprehensive pre purchase inspection. Inspectors carry out a visual inspection of the following types of retaining walls:

Supporting retaining Walls: Retaining Walls supporting other structures on the site
Landscape Retaining: Inspectors only check landscaping retaining walls more than 700m high

The types of things inspectors may check for include the following:

Verticality – laser plumb readings log any lean in millimetres per metre of height.
Cracking – width, pattern and length of fissures are recorded for future reference.
Footings – visible footings are examined for scouring, erosion or undermining.
Drainage performance – Ponding of water against retaining walls.

Common Types of Retaining Wall Problems

Retaining wall inspections often uncover common failures such as sliding, overturning, bearing capacity failure and excessive deflection.

Sliding occurs when soil pressure pushes the wall forward, while overturning happens if the base rotates, causing the wall to lean or bulge.

Bearing capacity failure develops when the foundation cannot support the soil load, leading to sinking, cracking or collapsing.

Excessive deflection is seen when poor materials or construction cause the wall to bend or droop, leaving visible cracks or deformation.

There are many underlying causes of retaining wall problems including poor design or construction, faulty drainage is another major cause, with waterlogged soil adding weight and pressure that can push walls and soil movement, including erosion or settlement, can also weaken stability and lead to collapse. Ensuring a retaining wall inspection is included in your pre purchase building gives you leverage for price adjustments or repair conditions during negotiation.

Why Retaining Walls Require Special Attention in Perth

Most local councils require a building permit for any wall higher than 500 mm or any tiered wall whose combined rise exceeds that height. The permit ties construction to the National Construction Code, which in turn references AS 4678 for design. Once the wall stands, the onus for safety shifts squarely to the owner. Councils can issue a Building Order if they believe a wall is unsafe, at which point you will have to engage an engineer at your own expense. Adding a pre purchase retaining wall inspection to your due-diligence bundle is therefore a low-cost safeguard against future legal and repair bills.

Common Buyer Questions

“Will the inspection report satisfy my lender or insurer?”

For most banks and insurers our Comprehensive pre purchase inspection package is satisfactory evidence that the retaining wall was inspected by a competent professional. If the inspector flags a serious defect, the institution may require further engineering certification.

“Do I need council approval to repair a leaning retaining wall?”

Like-for-like repairs under 500 mm high usually count as maintenance, but raising the height, altering drainage or rebuilding footings triggers the need for a permit. Using the inspection report to scope the repair keeps your application paperwork simple.

“How often should I re-inspect after purchase?”

In Perth’s climate, walls over one metre or those retaining clay should be checked every two to three years, and always after significant earthworks next door or severe winter storms.

Final Thoughts

If your prospective purchase features a retaining wall that props up a patio, driveway or neighbour’s fence, give it the same scrutiny you give the roof and slab. Call us now for our Comprehensive pre purchase inspection package, gain a clear retaining wall inspection, and protect your position at the negotiating table.