Concrete Repair Perth: Cracks, Spalling & Sunken Slabs

Perth's reactive clay soils and temperature extremes cause concrete movement and cracking more than most Australian cities. Here's how to assess concrete damage and make the right repair decision.

Types of Concrete Damage

Hairline cracks: Surface-level cracks up to 1mm wide. Often cosmetic, caused by shrinkage during curing or minor movement. Can be sealed with concrete crack filler to prevent water ingress. Structural cracks: Wider than 3mm, or cracks that run through the full depth of the slab. Indicate movement in the substrate — need professional assessment. Spalling: The surface layer flaking or scaling off, exposing aggregate. Caused by poor finishing, freeze-thaw cycles (rare in Perth), or chemical attack. Repair with resurfacing compounds. Sunken or heaved slabs: Caused by soil movement, tree roots, or erosion. Slab lifting (mudjacking or polyurethane foam injection) can raise sunken sections without full replacement.

Repair vs. Replace

Repair is cost-effective when damage is localised and the substrate is stable. Replace when: structural damage is widespread, the slab is badly cracked throughout, or repair costs exceed 50–60% of replacement. For driveways and paths, sometimes a resurfacing overlay is the middle ground.

Concrete Repair Costs in Perth

Crack repair (per linear metre): $30–$80. Surface resurfacing (per m²): $40–$70. Slab lifting (polyurethane foam): $100–$200 per m². Full driveway replacement: $100–$180 per m².