Services
Concrete Cancer Repair Sydney
Spalling concrete never repairs itself. Early diagnosis is the difference between a patch and a structural rebuild.
Overview
Stop the corrosion, not just the symptoms.
Concrete cancer, also called concrete spalling, happens when the steel reinforcement inside concrete corrodes. As the steel rusts it expands, cracking the surrounding concrete and letting in more moisture, which speeds the corrosion further. Left alone, the cycle only accelerates.
We repair concrete cancer across greater Sydney for strata, commercial and residential buildings. Every repair starts with diagnosis: establishing why the reinforcement is corroding (carbonation, chloride attack, cracked cover concrete or a failed membrane) so the repair treats the cause, not just the visible damage.
Sydney’s harbour and coastal suburbs are especially exposed: salt-laden air accelerates corrosion in balconies, awnings and facades from the Eastern Suburbs to the Northern Beaches. The earlier spalling is treated, the smaller and cheaper the repair.
Signs to look for
How concrete cancer shows itself.
Cracked or drummy concrete
Concrete that cracks along lines or sounds hollow when tapped has separated from the reinforcement behind it, a classic early sign of spalling.
Rust stains
Brown staining bleeding from cracks, joints or slab edges usually means the reinforcement behind the surface is already corroding.
Exposed reinforcement
Steel visible through broken concrete has lost its protective cover and corrodes on contact with air and moisture. It needs prompt attention.
Bubbling render or paint
Coatings that bubble, blister or delaminate often signal moisture and corrosion working away behind the surface.
Leaks after rain
Water ingress through slabs, planter boxes and balconies both causes and accelerates concrete cancer; the two almost always go together.
Cracking balcony edges
Persistent cracking or movement in balcony edges and soffits can indicate corroding reinforcement inside the slab.
Our process
Repairs that treat the cause.
Inspect & diagnose
We identify the extent of the spalling and the cause of the corrosion (carbonation, chloride attack from salt air, or a failed membrane) before pricing the repair.
Break out & treat
Damaged concrete is broken out to sound material, corroded steel is cleaned or replaced, and the reinforcement is treated with corrosion inhibitors.
Reinstate
The section is rebuilt with purpose-designed repair mortars matched to the structure, restoring full protective cover to the reinforcement.
Protect
Membranes and protective coatings address the moisture path that caused the corrosion in the first place, so the repair lasts.
Sign off & prevent
We document the completed works and recommend an inspection cycle to catch any future deterioration while it's still minor.
FAQ
Concrete cancer questions, answered.
- What is concrete cancer?
- Concrete cancer (concrete spalling) happens when the steel reinforcement inside concrete corrodes. Rusting steel expands to several times its original volume, cracking the concrete around it and letting in more moisture, which accelerates the corrosion. Left untreated, the cycle compounds.
- Is concrete cancer dangerous?
- Early on it can look cosmetic, but corroding reinforcement progressively weakens the structure, and falling concrete from balconies, awnings and facades is a genuine safety risk. The earlier it's treated, the smaller, safer and cheaper the repair.
- How much does concrete cancer repair cost?
- It depends on how far the corrosion has progressed and how accessible the affected areas are. An early-stage patch repair is a fraction of the cost of rebuilding a structural element. We inspect and diagnose first, then provide a clear itemised quote.
- Who is responsible for concrete cancer in a strata building?
- Spalling in the building structure (slabs, columns, balcony soffits and external walls) is generally common property in NSW, making it the owners corporation's responsibility. We work with strata managers and committees on inspection reports, quotes and staged repairs.
- How long do concrete cancer repairs take?
- Small repairs are typically completed in days. Larger programs across multiple balconies or facade elements are staged over weeks, planned around residents and tenants on occupied buildings.
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Seeing cracks, rust stains or drummy concrete?
Send us a photo of what you’re seeing and we’ll come back with straight answers and a clear next step.