Adelaide clay soils
Adelaide clay soils can move as they dry out and get wet again, especially in older inner, eastern and north-eastern suburbs.
In the eastern suburbs it is known locally as Bay of Biscay soil. It shrinks a lot in dry spells and swells after heavy rain.
How local ground movement affects older homes
Many Adelaide homes are solid masonry, meaning stone or brick, on dwarf wall footings or raft slabs.
As the clay shrinks and swells, footings can move with it. Older homes are more affected.
What the September 2026 soil study found
University research reported on 9 September 2026 measured shrinkage cracks at an Adelaide clay site from 5 mm to 40 mm wide and up to one metre deep.
The deepest cracks appeared in March and April. The study found that footings designed for uncracked ground may not perform as well where significant shrinkage cracks open up.
These are cracks in soil, not a size guide for judging wall cracks. The finding is a reason to understand the ground before choosing a footing repair.
The university news article also cites earlier research finding about $1.5 billion in shrinkage-crack damage across almost 480,000 South Australian houses built before 1981. That is an earlier study, not a new count of damaged homes in 2026.
Sources: University news, 9 September 2026: clay cracking study
Why the inner ring and eastern clay matter
In an August 2022 InDaily report, the Master Builders Association said reactive clay soils predominate in the inner ring, city and north-eastern suburbs.
The report describes eastern Adelaide’s highly reactive Bay of Biscay soil. It can shrink a lot through dry spells and swell after heavy rain.
Sources: InDaily, August 2022: Adelaide soils and ABS figures
Fault lines under parts of Adelaide
Industry reports note fault lines under parts of Adelaide, including around Burnside, Hope Valley, Clarendon and Crafers.
A suburb name is not a diagnosis. An engineer checks the structure of your home.
South Australia and cracking
ABS data reported in 2022 that South Australia had the highest share of houses with major cracks in ceilings or floors in Australia.
That share was 6.5%.
Sources: InDaily, August 2022: Adelaide soils and ABS figures
Trees and dry soil
Trees can dry the soil out near a home.
The engineer will check whether they play a part at yours.
The ways a footing can be underpinned
Common methods are mini bored piers, screw piles and mass concrete pads.
Which one suits depends on your soil, your house, access and the engineer design.
More help with your next step
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Questions homeowners ask
Why do so many Adelaide homes crack?
Adelaide's older inner, eastern and north-eastern suburbs sit on highly reactive clay.
In the eastern suburbs, it is known locally as Bay of Biscay soil. It shrinks a lot in dry spells and swells after heavy rain.
Many Adelaide homes are solid stone or brick on dwarf wall footings or raft slabs. Older homes are more affected.
Can trees cause cracks?
Trees can dry the soil out near a home.
The engineer will check whether trees are playing a part at your place.
Is my crack serious?
Some cracks are cosmetic. Not every crack needs underpinning.
Start with the form. When we reply, we'll explain how to share photos. We'll tell you if it looks cosmetic or needs an engineer to take a look.
Photos can't tell us what the footings are doing. An engineer checks the structure.
Do I need an engineer?
If the cracks point to footing movement, yes. An engineer checks the structure and designs the fix.
Industry reports note fault lines under parts of Adelaide, including around Burnside, Hope Valley, Clarendon and Crafers.
We look at your home rather than guessing the cause from its suburb.
We look after that as part of the job, so you deal with one team the whole way.
Which underpinning method will I get?
Common methods are mini bored piers, screw piles and mass concrete pads.
Many Adelaide homes are solid masonry on dwarf wall footings or raft slabs. That is part of what the engineer checks.
For example, a stone home in Norwood and a brick home in Prospect each need a design for that house.
The choice depends on your soil, your house, access and the engineer design.
Get a fast quote
Tell us what you're seeing. We'll be in touch within 30 minutes.
When we reply, we'll explain how to share photos of the cracks.