The 5 Most Common Defects We Find in WA Homes

After thousands of building inspections across the Perth metropolitan area, from the coastal northern suburbs through the inner north-east corridor to the southern growth areas, the pattern of what we find is remarkably consistent.

Our DefectIndex records 212,641 defect observations across 8,245 inspections. Across the WA properties in that dataset, five defect categories dominate. Here is what they are, why they occur, and what they mean for buyers.

1. External Wall Cracking Due to Settlement

External wall cracking due to settlement is the most frequently recorded defect observation in our WA inspection data by a significant margin. It appears across suburbs and property ages, though it is particularly prevalent in homes between 10 and 30 years old built on clay-bearing soils.

The cause is reactive soil movement, Perth’s clay-rich subsoils expanding when wet and contracting when dry, placing cyclical stress on the slab and the masonry above it. The result is stepped diagonal cracking through mortar joints, cracking at window and door corners, and in more significant cases, displacement between the two sides of a crack.

Not all wall cracking indicates structural failure. Many instances are classified as moderate, a genuine ongoing risk from the site conditions, documented for monitoring. Where cracking is widespread, shows displacement, or involves structural elements, a specialist structural assessment is the appropriate next step.

2. Termite Risk Indicators

Termite-related findings, collectively, are among the most consistent observations across Perth inspections. The dominant findings are not active termite infestations but risk indicators: concealed slab edges (where garden beds, paving, or soil build-up obscure the inspection point at the slab perimeter), mulch and garden beds placed against the house, timber in contact with the ground, and outdated chemical treatment barriers.

These findings reflect Perth’s genuine and sustained termite pressure. The warm climate, sandy soils with clay pockets, and the prevalence of established gardens create conditions that support subterranean termite colonies across the metropolitan area.

A concealed slab edge is both a termite risk (it prevents inspection and detection of mud leads) and a compounding issue (it traps moisture against the wall base, which is itself a termite attractant). The remedy is typically straightforward, lower garden beds, reset paving with a gap, and restore the inspectable slab perimeter.

3. Tree and Vegetation Proximity

Trees and dense vegetation in close proximity to the dwelling appear consistently across Perth inspection records. The concern is dual: root systems that extract moisture from the soil directly beneath footings (driving differential slab movement), and root intrusion into soakwells, stormwater pipes, and sub-floor areas.

Perth’s established suburbs, particularly the inner northern and north-eastern corridors, have mature street and garden trees that are increasingly close to buildings as properties age. The risk is not from small ornamental plantings but from established trees with significant root systems.

Inspectors note proximity of trees to the building as a finding where the tree is within a radius that could affect the slab and document it for ongoing management. The appropriate response depends on the species, the distance, and the observed cracking pattern.

4. Drainage Deficiencies

Poor drainage is a root cause defect in Perth. It drives or worsens several of the other findings above. Inadequate soakwells, disconnected or undersized downpipes, and surface grading that directs water toward the building rather than away are consistently found across established Perth properties.

Perth’s sandy soils have good intrinsic drainage in many areas, but soakwells fail over time (filling with silt), paved surfaces prevent infiltration, and additions or landscaping changes alter the original drainage design. The consequence is moisture accumulation at the building perimeter, which drives reactive soil movement, creates conditions for termite activity, and can cause sub-floor moisture issues in properties with raised timber floors.

5. Roofing Defects

Roof-related findings are consistent across Perth’s inspection data, particularly in homes from the 1980s-2000s era. Cracked ridge mortar (pointing) is particularly common, the mortar that seals the ridge capping tiles cracks and shrinks over time, allowing water entry into the roof cavity. Cracked or displaced concrete roof tiles, corroded valley flashings, and deteriorated pointing at hip junctions are also regularly recorded.

Perth’s UV exposure and temperature extremes accelerate the deterioration of roofing materials compared to milder climates. A roof that is 15-20 years old without maintenance is likely to have some level of these findings. Left unaddressed, the consequences are water entry into the roof cavity, damage to insulation and framing, and eventually ceiling damage.

Using This Information as a Buyer

Understanding these common findings helps Perth buyers set realistic expectations. A building report that records wall cracking, some termite risk indicators, and minor roof maintenance in a 20-year-old property in a clay-soil suburb is not necessarily an alarming report, it may be a typical one for that property type.

What matters is severity classification and specialist follow-up where recommended. An inspection that finds wall cracking, classifies it as significant, and recommends a structural engineer assessment is telling you something important. An inspection that finds hairline cracking in render, classifies it as a maintenance item, and notes it for monitoring is telling you something quite different.

Book a Perth building inspection and get a same-day report with full defect classification, photographs, and clear recommendations.