Wall Crack Types in Adelaide Homes

Common Types of Cracks

Here are some common types of wall cracks:

Hairline

Hairline cracks are usually less than 1 mm in diameter, thin, and superficial. They are generally cosmetic, resulting from minor house settlement or plaster shrinkage, and are commonly found in paint or plaster. These cracks are usually not a serious problem, but keep an eye on them to ensure they don’t grow larger.

Vertical

Vertical cracks run straight on walls, either upward or downward. They appear near doors, windows, or in the middle of walls. In Adelaide, these cracks aren’t usually serious unless they widen beyond 3mm. If they do, get a pro to check them.

Horizontal

Horizontal cracks are more concerning because they can indicate foundation movement or soil pressure, especially with Adelaide’s clay soils that shift with moisture. Don’t ignore them, as they can weaken walls.

Diagonal

Diagonal cracks indicate uneven settling and are commonly seen around windows or doors. This can be due to tree roots, poor drainage, or changing soil, which leads to foundation movement.

Stair-Step

Stair-step cracks appear along mortar joints in brickwork, forming a step-like pattern. They typically result from foundation settlement or movement. In Adelaide, stair-step cracks in external brickwork are a clear warning sign of structural stress and require professional evaluation.

Spider Web

Spider web cracks look like fine lines on plaster or paint, usually caused by surface shrinkage or poor plastering. They are unsightly but not structural, so fix them to prevent them from worsening.

Thermal

Thermal cracks occur due to temperature changes. The hot summers and cold winters in Adelaide can stress walls, leading to external cracks. Flexible finishes and using expansion joints can help prevent them.

Local and Climate Factors

Adelaide’s weather and terrain have a significant impact on walls, causing cracks. The clay soil swells when wet and shrinks when dry, putting pressure on building foundations. Summer heat causes materials to expand, while winter rains can saturate the ground. These factors can accelerate the appearance of cracks, particularly in older or poorly constructed buildings.

Tracking and Monitoring Crack Progression

You don’t always need to fix every crack right away. What’s important is to monitor how they change:

• Measure their width with a gauge or ruler.
• Take pictures to record their location and length.
• Check seasonally to see if cracks widen or remain stable.

If cracks grow rapidly or exceed 5mm in width, seek professional help as soon as possible.

DIY Repairs vs. Hiring a Pro

You can fix small hairline cracks yourself. However, for bigger, structural cracks (horizontal, diagonal, or stair-step), you should hire a professional. Trying to fix these yourself can hide bigger issues and cost you more later.

Interior vs. Exterior Cracks

Interior cracks are mostly surface-level but still should be checked. Exterior cracks, especially in brick or concrete walls, need more attention. Cracks in external render, mortar, or brickwork can allow water intrusion, worsening the problem over time. Always inspect both interior and exterior walls to determine the full extent of the damage.

Crack Repair Options

• Cosmetic filling for spider web and hairline cracks.
• Repointing for stair-step cracks in brickwork.
• Epoxy injection for structural cracks in concrete.
• Underpinning for foundation movement, causing diagonal or horizontal cracks.
• Waterproofing for cracks linked to moisture infiltration.

Repair options vary depending on severity, but early intervention is always more cost-effective than full structural remediation.

How to Prevent Future Cracks

Prevention is just as important as repair. To keep your Adelaide home’s walls in good shape:

• Install good drainage to keep soil moisture steady.
• Water the foundations evenly when it’s dry to stabilize the soil.
• Do not plant large trees too close to your home.
• Use flexible render to accommodate thermal changes.

Warning Signs of Serious Structural Damage

• Cracks wider than 5mm.
• Multiple cracks appear at once.
• Cracks near doors and windows
• Walls that are bulging or leaning.
• Gaps between walls, ceilings, or floors.

If you notice any of these signs, call a professional to inspect your home as soon as possible to prevent the problem from getting worse.

Why Hire a Professional

A professional inspection gives you confidence that problems are properly diagnosed. A structural engineer or repair specialist can figure out what’s causing the damage, suggest the right fixes, and make sure everything meets Australian building codes.

Here’s how much you can expect to pay