Concrete Cancer Repair FAQ — Port Stephens

It depends on how far the rust has spread, the structure and how we get to it. A small job is one patch on a carport beam or balcony edge: a short run of steel, a little concrete off, done from a ladder. A medium job is a balcony slab or pool surround: rust along the bars, more concrete out, some steel replaced. On a retaining wall or seawall a large job is length: long runs of bar cut back or replaced, propping while sections are open, working around the water. On a unit block it is damage on more than one level, with scaffold and strata sign-off. Good photos tell us the structure, how big the visible patch is, whether steel is showing and how we would reach it. They can't show how far rust runs under sound-looking concrete; we find that on site by tapping for drummy areas. That is why a building report may flag concrete cancer but won't price the repair. For a seawall, jetty or boat ramp, check whether a marine park permit applies.

No. Concrete cancer is corrosion of the steel inside reinforced concrete. Chlorides from salt, or carbonation over time, break down the protection the concrete gives the steel. The steel rusts and swells, and the concrete cracks and breaks away. Any reinforced concrete can be affected, whether it belongs to a house or a unit block: slabs, beams, balconies, pools, retaining walls and seawalls. That is worth knowing in Port Stephens. In the ABS 2021 Census, separate houses made up 80.9% of occupied private dwellings in the council area, and flats or apartments 3.6%.

Possibly, so find out before work is booked. The Port Stephens–Great Lakes Marine Park, one of six marine parks in NSW, covers about 980 square kilometres and takes in the whole Port Stephens waterway, plus the Karuah and Myall rivers to their tidal limit. NSW DPI lists driving posts or piles and building seawalls, jetties, pontoons and boat ramps among works in the park that need a marine parks permit. It also says development in or next to the park is assessed under marine estate and planning law. Ask the tradesperson how this affects the scope and timing of your job.

Sometimes, but don't count on it. Policies usually cover sudden accidental damage, something that happens all at once. They usually leave out slow damage from age, salt and weather, which is what concrete cancer mostly is. So the cause decides it. If you own a house, it is a question for your home insurer. If you own a unit, the building is covered by the owners corporation's policy, so the claim goes through them. Before you ring the insurer, read what your policy says about wear and tear or gradual deterioration, and note when you first saw the stains or cracks. What we can give you is a written description of what we found: where the damage is, what caused it and how far it has spread. That helps when you talk to the insurer, but the policy wording still decides whether it pays.

It's not recommended. Filler or render over active concrete cancer traps moisture against the corroding steel, and the damage keeps spreading underneath where you can't see it. A proper repair cuts back the damaged concrete, cleans and treats the exposed steel, or replaces it if too much has been lost, then rebuilds with structural repair mortar and a protective coating where needed. Skipping those steps usually just delays a bigger job.

A single balcony or small patch usually takes 2–4 days, including curing time for the repair mortar and any coating. A retaining wall, seawall or unit block can take several weeks. The biggest factor is how far the rust has spread: a patch we can cut back in a morning, or rust running the length of a beam, where the concrete comes off in stages so the beam keeps its support. Access adds time when we need scaffold or a platform, and on a unit block strata sign-off comes before we start. Curing and coating set the rest of the pace: mortar has to cure before it is coated, and each coat needs a dry base before the next goes on. Rain holds up outdoor work for the same reason. Bureau of Meteorology records from the Nelson Head station at Nelson Bay, kept from 1881 to 2023, show June as the wettest month on average, at 157.2 mm, and October as the driest, at 78.4 mm. If you can pick your timing, aim for the drier months.