Almost every Melbourne home has cracks somewhere. Most are harmless. A few are telling you something important. Knowing which is which saves you money and stops you repeatedly patching something that keeps coming back.
Why Melbourne homes crack
Much of Melbourne sits on reactive clay soil. It swells when wet and shrinks when dry, so the ground under your house moves through the seasons. That movement transfers into the building, and plaster, being brittle, cracks first.
This is why cracks often appear or widen after a very dry summer or a long wet spell, then partially close again.
Cracks that are usually cosmetic
- Fine hairline cracks, under about 1mm
- Cracks along plasterboard joins, appearing as straight vertical or horizontal lines
- Cracks where the cornice meets the ceiling or wall
- Small cracks around a single window or door that have not changed in years
- Shrinkage cracks in a new build during the first year or two
These are repairable with filling, taping where needed, sanding and repainting.
Cracks worth investigating
| Warning sign | Why it matters |
|---|---|
| Wider than about 5mm | Suggests significant movement |
| Tapered, wider at one end | Indicates one section is moving relative to another |
| Diagonal from window or door corners | Classic movement or settlement pattern |
| Doors and windows now sticking | The frame itself has moved |
| Matching crack visible in external brickwork | Movement is structural, not surface |
| Reopens within months of repair | The cause has not been addressed |
| Stair-step cracking through brick mortar | Foundation movement |
If you see these, the right call is a structural engineer or building inspector before any cosmetic repair. Filling a structural crack just hides it until it returns.
The proper repair process
- Open the crack slightly so filler has something to key into
- Tape where the crack crosses a plasterboard join, or it will reappear
- Fill in layers, allowing each to dry rather than one thick application
- Sand flush with the surrounding surface
- Seal the repair, because bare filler absorbs paint differently
- Repaint the full wall or ceiling, corner to corner
That last point catches people out. Spot-painting a repair almost always leaves a visible patch, because existing paint has aged and the sheen no longer matches.
Why cracks come back
If a repaired crack reopens, one of three things is happening: the movement is ongoing and the repair was rigid, the crack was filled without taping across a join, or there is a moisture problem behind the plaster. Repeated patching will not fix any of those; identifying the cause will.
For homes with ongoing seasonal movement, flexible fillers and proper taping give a much better result than rigid filler.
Cornices and ceilings
Cracking where the cornice meets the wall is extremely common and usually cosmetic, caused by slight differential movement. It is repaired with a flexible filler rather than rigid compound, which is why it sometimes reappears when a standard filler was used.
Ceiling cracks accompanied by sagging are a different matter and should be looked at promptly.
Talk to your local team
Expert Painting and Renovation is a family-run, Aussie-local company based in Richmond, with more than 9 years of experience. We will tell you honestly if a crack looks structural rather than simply patching it.
See our plastering services, our interior painting service, or read our guide to plastering near me.
FAQ
Are cracks in my walls serious?
Most are cosmetic movement cracks. Width, direction and whether doors stick are the things that distinguish serious ones.
Why does the same crack keep coming back?
Usually ongoing movement, a missing tape over a join, or moisture. The cause needs addressing, not just the crack.
Can I just fill it myself?
Small hairline cracks, yes. Anything wide, tapered or recurring is worth having assessed.
Do I have to repaint the whole wall?
Generally yes. Spot repairs show as patches because surrounding paint has aged.
Related guides
Worried about a crack? Contact Expert Painting and Renovation and we will take a look.
About Expert Painting & Renovation
Expert Painting and Renovation is an Aussie-local, family-run company based in Richmond, Melbourne, with more than 9 years of experience in residential and commercial painting and renovation. Our specialists deliver premium workmanship, timely service and durable finishes designed for Melbourne homes.
- Ceiling crack repairs
- Sagging ceiling restoration
- Water‑damaged ceiling repairs
- Cornice replacement
- Full plastering services
- Interior & exterior painting
- Weatherboard restoration
- Deck & timber maintenance
- Roof painting
- Rendering & texture coating
- Commercial Painting
- Plastering Services
- House Painting
Whether you need maintenance advice, a single-room refresh or a full home makeover, our team is just a call away.
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