Concrete Cancer Repair FAQ — Port Macquarie

It depends on how far the rust has spread. A small, early patch on a balcony edge or carport beam is usually a relatively minor job. Remediation across a whole apartment block is a structural project, priced on how much concrete has to be cut out, how much steel needs treating and what scaffolding or other access the building needs. It cannot be priced accurately from a photo; it needs to be seen before it can be quoted. Where the ground may have moved, an engineer's report can be needed first, and that adds to the cost.

Near the coast the main trigger is chloride from salt. Sea spray carries it into the concrete, where it breaks down the protection around the reinforcing steel and lets the steel rust. Salt can also arrive by water. Port Macquarie-Hastings Council's tidal inundation fact sheet says some estuary-foreshore residents get nuisance flooding from tides, and gives the North Shore as an example. It warns that saltwater will move further inland through waterways and groundwater as sea levels rise, with corrosion of below-ground infrastructure among the listed impacts. Away from salt, carbonation, a slow loss of alkalinity as concrete ages, can start the same rusting. Older buildings with thin concrete cover over the steel tend to show it first.

Not always. Concrete cancer usually shows as rust stains, cracks running along the line of the steel, and concrete lifting or falling away. Cracks can also come from the ground moving. A 2022 report for Port Macquarie-Hastings Council cites a 2010 assessment placing 16 dwellings, mainly along Illaroo Road at Lake Cathie, in a zone of reduced foundation capacity. The council's coastal hazards fact sheet also records landslips after heavy rain in March 2021 behind the Town Beach car park and at South Oxley Beach. Building inspectors flag the defect but usually do not scope the repair, so have a concrete repairer look at it, and an engineer if movement is suspected.

Sometimes, but not automatically. Cover usually turns on the cause. Sudden, accidental damage is more likely to be covered than gradual deterioration, which many policies exclude. A written report from the repairer setting out the cause and extent can support a claim or a special levy, but only the policy wording and the insurer can settle it for your building. Raise it with the owners corporation or strata manager early, before the damage spreads further.

We would not. Render or filler over live concrete cancer traps salt and moisture against the steel, and the rust keeps swelling underneath where you cannot see it. The proper fix cuts the damaged concrete back until clean steel is exposed, treats or replaces the rusted bars, rebuilds with a structural repair mortar and usually finishes with a protective coating. Salt here is not just spray. It is in the Hastings, the Camden Haven and Lake Cathie-Lake Innes, and some North Shore foreshore homes already get nuisance flooding from tides, so a slab there can be wet from underneath and a patch on top changes nothing. Check the crack first. Concrete cancer leaves rust stains, sounds hollow when you tap it and cracks in a line along the steel. A movement crack runs on an angle, often from a corner, tapers out and shows no rust stain. Ground moves here: slopes slipped in the March 2021 rain behind the Town Beach car park and at South Oxley Beach, and a 2010 assessment put 16 Lake Cathie dwellings, mainly along Illaroo Road, in a zone of reduced foundation capacity. Render will not hold moving ground. On a balcony or soffit it is a safety question too. Send us a photo before you buy the filler.

A single balcony or small patch often takes a few days, allowing for the repair mortar and coatings to cure. Larger strata jobs across several balconies or a facade can run for weeks. Outdoor work depends on the weather, because mortars, coatings and membranes need dry conditions. Bureau of Meteorology averages for Port Macquarie's Hill Street station (1840 to 2010) put the wettest months at February (178.1 mm) and March (175.2 mm) and the driest at August and September (about 81 mm each). Ask the repairer how they plan around the wet months.