Foundation Movement & Settlement
Cracks appearing in walls, doors that stick, floors that slope — your house may be on the move.
Foundation movement happens when soil under a house expands, contracts or sinks unevenly — reactive clay soils in Sydney are a major cause. Signs include stair-step wall cracks, doors that stick, sloping floors, and gaps opening up between walls and skirtings. Active movement needs underpinning to extend footings deeper to stable ground. Minor finished movement can usually be repaired with crack stitching alone. Monitoring cracks over a few months is the cheapest way to work out which you have. Romans Building Services assesses foundation movement & settlement across Sydney before recommending repair, so the visible damage and the cause are both dealt with.
Last updated: 2026-05-29
What is foundation movement & settlement?
Foundation movement happens when the soil under a house expands, contracts or sinks unevenly. The footings — and the walls sitting on them — move with it. Sydney has a lot of reactive clay soils, especially in parts of the Inner West, Parramatta, Blacktown and out west. Reactive clay swells when wet and shrinks when dry, and that cycle over years moves houses.
The classic signs are stair-step cracks in brickwork, doors that stop closing, gaps between floors and skirtings, and floors that have developed a noticeable slope. Not every house with a crack is moving — thermal movement and minor settlement happen to every house. The question is whether the movement is ongoing.
Severe or ongoing movement needs structural intervention: usually underpinning, where the footings are extended deeper to reach stable ground. Minor or finished movement can usually be repaired with crack stitching and cosmetic work. Working out which is which is half the job.
Signs to look for
- Stair-step cracks running diagonally through brickwork
- Cracks wider than 5mm that continue to grow
- Doors or windows sticking or no longer closing
- Floors sloping — marble test confirms (ball rolls to one side)
- Gaps opening between walls and skirtings or ceilings
- Brick walls tilting out of vertical
- Cracks reappearing after previous repairs
Why it happens
- Reactive clay soils expanding and contracting with moisture changes
- Leaking pipes or drains washing out soil under footings
- Trees drawing water out of clay soil (causes shrinkage)
- Poorly compacted fill from original construction
- Undersized or shallow original footings
- Drainage issues causing soil softening near foundations
- Adjacent excavation (new neighbouring construction)
How urgent is this?
Ongoing foundation movement does not stop on its own and usually accelerates. If cracks are growing, doors have started sticking recently, or the house feels noticeably different, get it assessed soon. Catching it early means a smaller underpinning scope and less collateral damage to walls, floors and services.
How we fix it properly
Investigate
Crack monitoring gauges on suspect cracks to measure ongoing movement. Sometimes a drain inspection to rule out leaking services. We usually bring in a structural engineer for anything suspected to be active movement.
Fix the cause
Leaking pipes get fixed. Tree roots drawing moisture from under the slab may need addressing. Drainage near footings corrected. Without stopping the cause, any structural repair is temporary.
Underpin if required
For active or severe movement, underpinning extends the footing deeper to reach stable ground. Traditional mass concrete underpinning or modern screw-pile underpinning depending on site. Engineered for the specific situation.
Stitch the cracks
Once movement has stopped, cracks get structural repair — helical bar stitching tied into the brickwork across the crack. Holds the wall together without needing major demolition.
Repoint and repair
Damaged bricks replaced, joints repointed to match, interior finishes made good. The work should be invisible when finished.
Typical cost range
Underpinning typically $2,500 – $7,000 per pier, with houses needing 4 to 20 piers depending on severity. Total jobs often $15,000 – $100,000+. Engineering fees extra.
Every job is different. We give a firm quote after inspection.
Common questions
How do I know if my house is actively moving?
Fit crack monitors across suspect cracks. If the gauge reading changes over 3–6 months, the house is moving. If it stays stable, movement has probably finished and you can do a repair without underpinning. Movement monitoring is cheap and saves expensive guessing.
Do I need a structural engineer?
For suspected active movement, yes. The engineer designs the underpinning, certifies the work, and provides documentation for insurance or resale. We work with engineers regularly and can bring one in or work with one you have engaged.
Will my house insurance cover it?
Depends on the policy and the cause. Movement from a leaking pipe is often covered. Movement from reactive clay alone is usually not. Check your PDS or ask your insurer. We can provide documentation for claims where relevant.
How long does underpinning take?
Depends on scope. A 6-pier traditional underpin typically 2–4 weeks. Screw pile underpinning is faster, often 1–2 weeks. Crack repair and finishing after underpinning adds another week or two.
Services that fix this
Foundation Movement & Settlement in your area
The causes and right fix for foundation movement & settlement vary with local housing stock and exposure. Read the version closest to where you are:
Where we see foundation movement & settlement most often
Some suburbs have more of this problem than others — the local housing stock, age, and coastal exposure all play a part. Click through for the local context.
Think you might have foundation movement & settlement?
Send a photo or call Minas directly. We will tell you straight whether it needs doing now, or whether it can wait.