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FAQs
Subsidence
Subsidence occurs when the ground beneath a property sinks or shifts, causing the building’s foundations to move. This movement can lead to structural damage including cracks, uneven floors, and unstable foundations. While the earth’s crust is naturally always on the move, subsidence can be accelerated by factors like soil compaction, moisture loss, over-excavation, or erosion.
Several factors contribute to subsidence in Australian properties:
Clay soil: Australia has extensive clay-rich soils that shrink during dry periods and swell when wet, causing ground movement
Tree roots: Large trees near buildings extract moisture from soil, causing it to dry out and contract
Leaking pipes: Damaged water or drainage pipes can wash away soil or cause it to soften and shift
Drought: Extended dry periods cause soil to shrink significantly, especially in clay-rich areas
Mining activity: Old mine shafts or tunnels can collapse, leading to ground instability
Poor drainage: Water pooling around foundations can soften soil and cause movement
Look for these common warning signs:
Cracks in walls, particularly those that are wider at the top or diagonal in shape
Gaps appearing between walls and skirting boards or door frames
Doors and windows that stick or won’t close properly
Sloping or uneven floors
Wallpaper rippling or tearing without obvious cause
Cracks in external brickwork, especially around windows and doors
If you notice any of these signs, it’s important to get a professional assessment as soon as possible.
Many Australian home insurance policies do cover subsidence damage, but coverage varies significantly between insurers. Some policies exclude certain causes (like tree root damage or insufficient soil compaction). It’s essential to check your specific policy and contact your insurer if you suspect subsidence. We can provide detailed reports and documentation to support insurance claims.
Yes. When properly addressed, subsidence repairs provide long-lasting stability. Traditional concrete underpinning, if well-constructed, can last 50+ years. Resin injection provides decades of reliable ground stabilisation. The key is identifying the root cause and using the appropriate repair method for your specific situation.
Repair methods
Traditional underpinning extends your building’s foundation to a deeper, more stable layer of soil. This involves excavating holes beneath existing footings and filling them with concrete, essentially creating deeper foundations.
Resin injection strengthens and stabilises the existing soil beneath your footings. Expanding polyurethane resin is injected into the ground, where it fills voids, compacts loose soil, and can lift settled structures. It’s a modern alternative that’s faster and less disruptive.
Small holes (typically 16mm diameter) are drilled through the foundation into the affected soil below. A two-part polyurethane resin is injected under pressure. When the components mix, the resin expands within minutes, filling voids, compacting loose soil, and exerting lifting force. The resin cures in approximately 30 minutes and provides immediate stabilisation and support.
Costs and pricing
No. We provide comprehensive, upfront quotes that include all labour, materials, site protection, and clean-up. We explain exactly what’s included and stick to our quoted price unless you request additional work. There are no hidden fees or surprise charges.
Generally, yes. Resin injection is often more cost-effective because it:
- Requires less labour
- Completes much faster (usually one day vs several days or weeks)
- Needs minimal excavation and site cleanup
- Causes less damage to gardens, driveways, and paths that would need restoration
However, the best method depends on your specific situation, not just cost.
Process and timeline
Resin injection: Most residential properties are completed in a single day. The resin cures in approximately 30 minutes, providing immediate stabilisation.
Traditional underpinning: Timelines vary from a few days for a single underpin to several weeks for extensive work. Concrete requires several days to cure before achieving full strength.
Project duration also depends on weather, site access, and the extent of subsidence damage.
Usually not. Most resin injection projects are completed in a single day with minimal disruption, and you can remain in your home. For extensive traditional underpinning projects, there may be some inconvenience, but most homeowners stay in residence. We’ll discuss any specific concerns during your site inspection.
Technical questions
When properly applied, resin injection provides decades of reliable ground stabilisation. The cured polyurethane resin is extremely durable, resistant to water and chemicals, and maintains its strength indefinitely in normal soil conditions. Many resin injection repairs performed 30+ years ago are still performing perfectly today.
Concrete underpins, if well-constructed using quality concrete, should last 50+ years. Properly designed and installed underpinning effectively becomes a permanent part of your building’s foundation system.
Repairs stabilise your foundation and stop ongoing movement, which prevents new cracks from forming. However, existing cosmetic cracks in walls and plasterwork will still be visible and may need separate cosmetic repairs by a builder or plasterer. Our work focuses on fixing the structural cause, not cosmetic finishing.
Yes. We work on all types of structures including: Residential homes (single-storey and multi-storey), partments and townhouses, commercial buildings and warehouses, industrial facilities, heritage buildings, and retaining walls and boundary fences.
When we identify and address the root cause properly, subsidence shouldn’t return. However, if new issues arise (such as new leaking pipes or additional tree root interference), additional ground movement could occur. This is why we thoroughly investigate the cause during our initial assessment.
Yes. Large trees, especially species like eucalyptus, can extract significant moisture from clay soils, causing them to shrink and leading to subsidence. Trees within a distance equal to their mature height from your property can potentially affect foundations. We assess tree-related subsidence risks during our inspections and can advise on appropriate management.