Structural · 5 min read
Cracks in ceilings and cornices: when a Brisbane roof is telling you something
Wall cracks get attention; ceiling cracks get painted over. Some are cosmetic seasonal movement, and some are the first visible sign that a roof member is overloaded or a footing is moving. Here is how to tell them apart.
What we look at
The pattern and location tell us more than the width.
- A straight crack along the cornice, opening seasonally — usually truss or roof movement, often cosmetic
- A crack across the middle of a ceiling with sag — deflection of a beam, truss or ceiling joist
- Cracks radiating from a corner or over an opening — load path or footing movement
- Cracks matching a wall crack below — usually footing movement, not a roof problem
- New cracking after a renovation — a wall was removed, or load has been added above
- Water staining with cracking — a leak plus timber movement or decay
The usual causes in Brisbane homes
Roof truss expansion and contraction with heat and humidity causes most cornice cracking, and is largely cosmetic. Real structural causes are load added on the roof, a tiled roof on framing designed for sheet, an internal wall removed without a designed beam, deflection under an air conditioning unit or solar array, and footing movement on reactive clay.
What to do before calling anyone
Photograph the crack with a ruler beside it, note the date, and repeat in a month or after heavy rain. A crack that grows or opens and closes seasonally is a different problem from one that suddenly appeared.
Fix leaks and blocked gutters first — water is a common contributor and the cheapest thing to correct.
What an inspection costs
A crack inspection is $400 and includes measuring, classifying and explaining what the cracking is doing. A full written assessment report — for insurance, a builder, a body corporate or a sale — adds $300.
If remedial design is needed, we design it, whether that is a beam, propping, tie-down or footing work.
Frequently asked questions
- Are ceiling cracks serious?
- Often not — cornice cracking from roof truss movement is common and cosmetic. Cracks with sagging, or matching cracks in the walls below, deserve an inspection.
- How much is a crack inspection in Brisbane?
- $400, with a written assessment report for an extra $300 if you need documentation.
- Can adding solar panels crack my ceiling?
- Added roof load can increase deflection in marginal framing. It is worth checking if cracking or sagging started after installation.
Book a crack inspection from $400.
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