CONCRETE CANCER – A common house defect that often goes undetected

A defect that we commonly encounter when carrying out building inspections on dwellings that utilise suspended concrete slab construction is something known as “Concrete Cancer” or Concrete Spalling.  This occurs when the steel reinforcement begins to rust due to exposure to moisture – the steel expands causing the surrounding concrete to crack and break away which in turn leads to accelerated corrosion of the steel.  This visible defect not only looks terrible, but is a serious safety hazard and can severely compromise the structural integrity of the concrete slab.

Common causes of Concrete Cancer include inadequate waterproofing to rooftop balconies or cantilevered structures exposed to weather; leaking pipes encased in the concrete; seepage of water through minor cracks in the concrete (particularly in coastal regions); or simply that the reinforcement was not adequately prepared (or too close to surface) at the time of pour.

If spalling is occurring to a concrete slab in a home or apartment building, it is critical that it is identified and repaired in the early stages in order to prevent major structural damage and avoid significant repair costs.  If left unattended for an extended periods catastrophic failure of the structure is a possibility that could lead to permanent injury or even death.

Recently one of our experienced inspectors carried out an inspection in the northern suburbs of Melbourne where the dwelling was approximately 50 years old however was in immaculate condition.  No significant defects were noted throughout the course of the inspection – however the basement level and the garage were locked.  It was fortunate that the inspector requested access to these areas and the keys were located.  Sections of the basement were below a leaking external patio and the garage had garden beds above – both areas has significant concrete cancer (spalling) occurring to the underside of the concrete slabs and were going to require significant repair / replacement works.  The client was able to make an informed decision and opted not to proceed with the purchase of this particular house.

If you are about to purchase a property or simply have some concerns about a house that you own, please give us a call on 1300 729 352.  You will be able to talk directly to one of our experienced inspectors who can answer any questions you have about any aspect of the dwelling.  Alternatively you can find more information or make an on-line enquiry at

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Pre purchase house inspections – Don’t risk not getting one