1800 18 20 20Restore support, arrest movement, and return assets to service, safely and with minimal disruption.
Undermining occurs when soil beneath a slab or footing is removed, weakened, or displaced. The result is loss of bearing, slab deflection, cracking, binding doors/gates, trip steps and service misalignment. Our ground remediation approach targets the cause (voids, washout, loss of density) and rebuilds support beneath the structure using established injection and consolidation methods delivered by a highly experienced team.
Why Undermining Happens
Material mobilisation by water (scouring/flooding)
Roof/downpipe discharge, broken stormwater, surface runoff or flood events erode fines and create voids under slabs and footings.
Animal burrowing
Rabbits, wombats and other burrowers create tunnels leading to localised collapse under pavements, foundations and garden walls.
Service leaks & poor drainage
Leaking water lines and ponding areas soften subgrades and pump fines.
Slope instability & lateral migration
Gravity-driven soil movement on grades transfers support away from slabs/footings, opening joints and creating tilt.
Uncontrolled fill / poor compaction
Long-term consolidation leaves gaps under slabs and footings.
Traffic/vibration
Repetitive loads expose weakened zones, accelerating pumping and void growth.
Symptoms to look for
- Hollow-sounding ("drumming") concrete, rocking slabs, or visible voids at edges.
- Differential transitions over drains, trip hazards, or loss of falls to drains.
- Cracking/rotation of masonry (step cracks, wall opening separation).
- Binding gates/doors, misaligned thresholds or settled crossovers.
- Repeated patch failures where the base keeps moving.
How We Treat Undermining (Process)
Investigate & Map
Level survey to quantify severity of movement and vertical change; locate voids/soft spots; check drainage/services. Where relevant, we may propose CCTV, dye tests or moisture checks.
Design the Remediation
Select treatment based on ground conditions and access.
Void fill & re-support
Targeted resin injection to fill voids, bond loose material and re-establish contact beneath slabs.
Permeation/compaction grouting
Strengthen granular or fill soils and reduce permeability where washout is active.
Local underpinning/stiffening zones
Where footings need deeper improvement.
Water management measures
Sealing joints, redirecting downpipes, drainage tweaks to prevent recurrence.
Controlled Lift (Where Required)
Apply micro-increment lift to remove steps, restore falls and relieve binding, monitored in real time for accuracy.
Verify & Make Good
Plug injection points, seal joints if needed, and document outcomes (levels, volumes, injection map). Provide maintenance recommendations to keep the base stable.
Benefits for Hospitals
Treats the cause
Rebuilds support at depth and fills hidden voids.
Minimal disruption
Small injection points; many areas remain usable during works.
Precise Outcomes
Controlled lift to restore function (falls, alignments, door clearances).
Clean Installation
Fast-curing materials and tidy reinstatement.
Limitations & Suitability
Concrete is too fractured to act as a single element (multiple broken fragments/delamination). Treatment panel width is too narrow to correct side-to-side levels differentially.
Active slope instability is ongoing—global stability must be addressed, not just local support. Ongoing severe scouring persists (e.g., uncontrolled discharge) without feasible water management.
We use a level survey and condition assessment to determine if remediation will realistically restore support, alignment and performance.
Cost & Decision Factors
Small, isolated sections are often cheaper to replace than remediate due to fixed entry costs for injection works. Larger areas or multiple panels typically favour remediation, especially where demolition/reinstatement is disruptive.
Finish Matters
Exposed aggregate or stencilled concrete are difficult to colour/texture match—remediation preserves the existing finish.
Tiled/paved overlays may be hard to source or re-lay—keeping the slab often retains these finishes intact.
Typical Areas We Treat
- Driveways
- Pavements
- Patios and pool surrounds with edge washout or burrows
- Road pavements
- Hardstands
- Garage thresholds that have dropped or "pumped"
- Building strip
- Slab foundations undermined by leaks or runoff
- Structure and slabs adjacent to stormwater discharge systems, or on slopes with lateral soil movement
Why Choose Rectify
Engineering-Led Solutions
Every project begins with understanding the cause of the problem, ensuring the right solution is delivered—not just a temporary fix.
Proven Structural Expertise
Trusted to deliver engineered solutions across residential, commercial and infrastructure projects.
Non-Invasive Technology
Our advanced, non-invasive technologies restore structural stability with less excavation, less mess, and minimal interruption.
Long-Term Confidence
We don't just repair today's problem—we strengthen your asset for long-term performance and lasting value.
Ready to Stop Undermining at the Source?
We'll inspect, map levels and ground conditions, and advise whether remediation or replacement offers the best result for your asset and finish.
1800 18 20 20
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