Structural · 6 min read
Cracks in your walls: what a Brisbane crack inspection tells you
Brisbane's reactive clay soils swell and shrink with every wet and dry cycle, so some cracking is normal. The question an engineer answers is whether your cracks are cosmetic movement or a sign the footing system is failing.
How cracks are classified
AS 2870 grades damage from Category 0 to Category 4 based on crack width and what it means structurally.
- Category 0 — hairline, under 0.1 mm: no action
- Category 1 — up to 1 mm: fine, easily filled
- Category 2 — up to 5 mm: noticeable, may need repointing and door adjustment
- Category 3 — 5 to 15 mm: repairs involving cutting out brickwork, likely footing movement
- Category 4 — 15 to 25 mm and beyond: major repair, structural involvement
What causes cracking in Brisbane houses
Reactive clay movement, poor site drainage and downpipes discharging next to footings, large trees drawing moisture from under the slab, leaking plumbing, uncontrolled fill, sloping sites, and footings that were never designed for the soil class.
The crack pattern tells the story: diagonal cracks at openings, stepped cracks in brickwork, horizontal cracks in a retaining wall and separation at the cornice each point to different mechanisms.
What our inspection includes
An RPEQ engineer attends site, maps and measures the cracks, takes floor levels where settlement is suspected, reviews drainage, trees, fill and footing type, and explains the likely cause in plain language on the day.
A crack inspection is $400. If you need a full written engineering assessment report — for insurance, a builder dispute, a body corporate or a sale — add $300. Crack control and remedial design is quoted separately.
When to call an engineer now
Cracks wider than 5 mm, cracks growing week to week, doors or windows jamming, floors that have visibly dropped, a wall that has bowed or leaned, or cracks in a retaining wall or a suspended slab. Those are not cosmetic.
Frequently asked questions
- How much is a crack inspection in Brisbane?
- $400 for the site inspection and verbal findings. A full written assessment report is an extra $300.
- Will you tell me how to fix it?
- Yes. The report sets out the cause and the recommended remedial approach, whether that is drainage, crack control, underpinning or structural repair. We can then design the repair.
- Can I use the report for insurance?
- Yes — the written assessment report is prepared and certified by an RPEQ engineer and is suitable for insurers, certifiers and dispute resolution.
Book a $400 crack inspection with an RPEQ engineer.
Request a quote