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Should You Buy a House with Cracks? A South Australian Guide

Finding cracks in the walls of a home you are about to buy can stop you in your tracks. The first question is usually the same: does this mean the house has structural problems? The honest answer is not necessarily. Plenty of South Australian homes have cracks, and many are nothing to lose sleep over. The trick is knowing which cracks are cosmetic and which are telling you something serious.

Why South Australian homes crack

Almost every house moves over its life. Building materials expand and contract with heat and moisture, and footings shift as the ground beneath them changes. In South Australia that ground is often the issue. Large parts of the state sit on reactive clay soil that swells in wet winters and shrinks through dry summers. That seasonal movement lifts and drops footings year after year, and cracking is one of the ways it shows. Add poor drainage, thirsty trees drawing moisture from the soil, or older footings never designed for modern loads, and movement becomes more likely. Homes in the Hills and on the Fleurieu, where stone and older masonry construction is common, are worth particular attention.

Cosmetic cracks

Cosmetic cracks affect the surface finishes rather than the structure. You find them in plaster, cornices, paintwork and ceiling joints, and they usually come from normal settlement, minor seasonal movement or the plain ageing of materials. They tend to be fine hairline cracks, under about 2mm wide, short and stable over time, and they are not usually joined by doors that stick or floors that slope. They can be a bit ugly, but they rarely point to a real problem.

Structural cracks

Structural cracks are a different matter. These involve the load-bearing parts of the home and suggest the building has moved, or is still moving. Warning signs worth noticing include:

  • Cracks wider than about 5mm.
  • Stepped cracking through brickwork or masonry.
  • Diagonal cracks running from the corners of doors and windows.
  • Cracks that pass through both inside and outside walls.
  • Cracks that appear to be getting wider.
  • Bulging or leaning walls, or sloping floors.
  • Doors and windows that no longer close properly.

One sign on its own may mean little. Several together are a reason to look closer.

Can you tell just by looking?

Not reliably. The width, direction and pattern of a crack are clues, but they do not tell the whole story. An experienced inspector reads cracking in the context of the whole property: the age and type of construction, the state of the footings and drainage, the roof load, and any signs of ongoing movement or past repairs. Where cracking looks significant, or sits beyond what a visual inspection can determine, the report may recommend a structural engineer take a look.

A crack does not always mean walk away

This is the part buyers most often get wrong. A serious-looking crack is not an automatic reason to pull out. Some homes moved years ago and have long since settled. Others need nothing more than better drainage to stop the movement getting worse. What matters is understanding the cause, whether the movement is still active, and the likely cost to fix. Plenty of people buy homes with known cracking after negotiating the price or arranging repairs. The important thing is knowing all of this before your contract goes unconditional.

How a pre-purchase inspection helps

During a pre-purchase building inspection we check the accessible areas for visible signs of movement: internal and external walls, brickwork and masonry, floors, ceilings, the roof structure where we can reach it, retaining walls, drainage and evidence of moisture. The inspection is carried out to Australian Standard AS 4349.1, and the report explains what we found, what it likely means, and what to do next.

At Great Southern Building Inspections, Phil Sargent brings more than 35 years of building experience to every job. He understands how South Australian homes behave on our soils and in our climate, and he knows the difference between a crack that is just age and one that is a warning. That experience is what turns an alarming crack into a clear decision.

If you are buying across the Fleurieu Peninsula, Adelaide Hills or surrounding regions, call 0493 899 262 or email inspect@gsbi.com.au to arrange your inspection. Not every crack is a problem, but every crack deserves a proper look.

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What's not included: full exclusion

Inaccessible, unsafe or obstructed areas. Concealed defects behind walls, ceilings, floors, insulation, stored goods or fixed furnishings. Furniture and stored materials are not moved. Underground services and concealed pipework. Underground drainage, sewer and stormwater. Septic tanks, soakage trenches and treatment systems. Swimming pools, spas and equipment. Irrigation systems. Water tanks and pumps. Water quality or pressure testing. Gas installations and appliances. Electrical wiring, switchboards, circuits or appliances (beyond noting obvious visible defects and readily visible safety devices). Solar power, battery and solar hot water systems. Air conditioning, heating, ventilation and refrigeration. Home automation. Security systems, alarms, CCTV and intercoms. Telecommunications and data cabling. Fire detection beyond noting smoke alarm presence. Lifts and mechanical equipment. Household appliances. Built-in entertainment systems.

No engineering assessments, structural calculations, foundation design, geotechnical investigation, soil testing, load testing, or destructive or invasive investigation. No removal of floor coverings, wall linings, ceiling finishes or roof sheeting.

This inspection does not include a timber pest inspection. Unless specifically commissioned, no assessment is made of termites, borers, fungal decay, timber pest damage, or conditions conducive to timber pest attack. A separate timber pest inspection should be undertaken in accordance with AS 4349.3.

Moisture readings may be taken where appropriate, but the inspection is not a specialist leak detection investigation. It does not determine the exact source of moisture, the duration of water penetration, whether moisture is active or historical, or waterproofing compliance.

Inspected only where safe access is available. May be excluded where access openings are too small, insulation prevents safe inspection, stored items obstruct access, unsafe conditions exist, or clearance heights don’t comply with Australian Standard access requirements.

Inspected only where specifically included in the inspection agreement and readily accessible.

No assessment of asbestos, lead paint, mould or air quality, methamphetamine contamination, hazardous chemicals, radiation, noise, environmental contamination or electromagnetic fields.

The inspection does not predict remaining service life of components, future structural movement, future water penetration, future maintenance costs or future material performance.

No responsibility for defects that were concealed at the time of inspection, could not reasonably be detected during a visual inspection, develop after the inspection date, or become apparent due to future weather events or changes in occupancy.

The Full Building Inspection Checklist

Foundation movement, structural cracking, settlement, distortion, deflection, sagging, bulging, stability concerns, undulating floors, uneven surfaces, separation of building elements.

Roof leaks, water penetration, rising damp, moisture intrusion, drainage issues, surface water management, ventilation deficiencies, signs of previous water damage, timber decay (rot).

External walls, brickwork, render, cladding, mortar deterioration, brick fretting, flashings, windows, doors, fascias, barges, eaves, gutters, downpipes, roof coverings, skylights, roof penetrations, valley gutters.

Ceilings, walls, floors, doors, windows, internal linings, plasterwork, paint finishes, cabinetry, bench tops, tiling, wet areas, stairs, balustrades, handrails.

Bathrooms, ensuites, toilets, laundry, kitchen, shower recesses, baths, basins, plumbing fixtures, taps, moisture detection, waterproofing performance (visual indicators only).

Where it is safe and accessible, we inspect roof framing, roof trusses, rafters, ceiling framing, sarking, insulation, ventilation, downlight clearances, evidence of leaks, timber deterioration.

Where it is safe and accessible, we inspect timber framing, bearers, joists, stumps and piers, moisture, ventilation, drainage, timber condition, structural movement.

Smoke alarms (presence only), safety switch / RCD (presence only), obvious electrical safety concerns, trip hazards, unsafe balustrades, general safety hazards. Functional testing of electrical, plumbing or gas systems is outside the scope of a standard building inspection.

We inspect structures within about 30 metres of the dwelling and inside the boundaries. Garages, carports, sheds, detached laundries, pergolas, verandahs, patios, decks, balconies, retaining walls, fencing, paths, driveways, surface drainage.

Structural cracking, movement, settlement, water penetration, roof leaks, timber decay, corrosion, dampness, rising damp, inadequate ventilation, poor drainage, deteriorated mortar joints, brick fretting, delaminating materials, defective render, drummy wall and floor tiles, bulging walls, sagging roof framing, defective internal linings, swollen building materials, moisture damage, maintenance issues, safety hazards.