Ground Subsidence Repair Guide: Professional Resin Injection Solutions

Why Foundations Fail

Most Australian homes and commercial buildings are founded on clay soils. Clay expands when wet and contracts when dry, creating constant movement under foundations. Seasonal variations, leaking plumbing, poor drainage, or tree roots can all cause soils to lose their ability to provide stable support.

This results in foundation instability, where sections of a building settle or lift unevenly.

Signs to look out for include:

• Cracks in walls, brickwork, or concrete slabs.
• Doors or windows that stick, twist, or won’t close.
• Gaps between floors and skirtings or between walls and ceilings.
• Uneven or sloping floors.
• Efflorescence (white salts) or damp patches indicating rising moisture.

If left untreated, small movements grow into major structural problems.

Professional Assessment: What Happens Next

At Rectify Group, we provide a free, no-obligation assessment. One of our specialists will spend approximately one hour on site, carefully inspecting your property.

The assessment includes:

• A review of footing performance.
• Identification of contributing factors such as soil reactivity, drainage, or plumbing issues.
• Discussion of movement indicators and potential risks.

Following the inspection, you will receive a clear scope of works packaged in a no-obligation written quote. Our process ensures you fully understand the nature of the problem and the most effective solution before any work begins.

Why Polyurethane Resin Injection?

Unlike traditional underpinning methods that require excavation and heavy construction, polyurethane resin injection is non-invasive, precise, and highly effective.

How it works:

1. Small injection ports are drilled into the foundation zone.
2. A two-part expanding resin is injected beneath the footing or slab.
3. The resin expands to fill voids, compact soils, and restore the ground’s bearing capacity.
4. Additional resin can be applied to gently lift and realign affected sections.

Key benefits:

• Strengthens soils without adding weight.
• Seals voids and prevents further washout.
• Immediate curing – minimal downtime for occupants.
• Precise and controllable with millimetre accuracy.
• Long-term stability with minimal disruption.

Cost Guide

Resin injection is efficient and cost-effective compared to traditional underpinning.

• Small jobs (e.g. repairing the corner of a garage): $4,500–$8,000.
• Most residential jobs (12–15 metres of footing treatment): around $15,000.
• Yardstick price: approx. $1,200 per lineal metre of footing.
• Slab treatments: more complex due to internal access requirements and whether the slab is a waffle pod or raft design.

This transparency allows property owners to budget with confidence.

Maintenance and Prevention (CSIRO BTF18 Guidance)

The CSIRO BTF18 Foundation Maintenance Guide emphasises that foundation performance is closely linked to moisture management:

• Ensure effective drainage so water flows away from the building.
• Maintain and repair roof plumbing, gutters, and downpipes.
• Avoid garden beds, trees, or irrigation systems close to foundations.
• During dry periods, maintain consistent soil moisture to avoid excessive shrinkage.

Following these practices helps reduce soil reactivity and limits future foundation issues.

Conclusion

Ground subsidence is serious, but it can be managed effectively with early detection and modern repair methods.

Polyurethane resin injection is the most advanced, precise, and non-invasive solution for stabilising soils and restoring foundation performance.

With Rectify Group’s free professional assessment, detailed scope of works, and proven resin technology, you can be confident your home or building is in safe hands — both now and for the future.