Concrete Cancer & Spalling Repair in Sydney — questions and answers
The questions below come up on nearly every call. Every rule and dollar figure quoted here comes from a government source, listed at the foot of the page.
Call (02) 9072 0776Cost
How much does concrete cancer repair cost in Sydney?
There is no honest per-square-metre figure before someone has looked at the building, because the price follows the area that sounds hollow and how the work is reached. Where the scaffold stands on the footpath the council charges for the land it occupies: Inner West Council, for one, charges a non-refundable $575.20 application fee and $61.70 per square metre per month for a hoarding lease. The pricing page sets out what government publishes around the job, and none of it is a quote for your building. The costs page's Concrete cancer repair costs and rules check shows which NSW contract, deposit and cooling-off rules apply at your job's value.
Who pays in a strata building — the owner or the owners corporation?
It depends on whether the affected element is common property or part of the lot, and that boundary is the thing to establish before anyone quotes. In a Class 2 building the structural slab is generally common property even where a balcony is used exclusively by one lot, which usually puts the repair with the owners corporation rather than the owner — but the answer is set by the strata plan and the by-laws for that building. NSW Fair Trading publishes guidance on the common property boundary, and your strata manager will have the plan.
Concrete cancer repair in Sydney
What an owners corporation settles before the repair
A cracked slab or balcony in a unit block is usually common property. These are the rules that shape the decision, each with its source.
Check the building's age first
6 years
from completion, to act on a major defect
A major defect includes load-bearing floors, columns and beams. On common property, the owners corporation makes the complaint.
Source: Building Commission NSW, building defect complaints · read
Read the capital works plan
10-year plan
of expected major work, paid from the capital works fund
Ask the secretary or strata manager for a copy. The plan must be considered at each annual general meeting.
Source: NSW Government, strata levies and finances · read
Apartment buildings need a regulated design
Class 2
remedial work on these buildings is regulated
A registered design practitioner prepares the design, and a building practitioner lodges it on the NSW Planning Portal.
Source: Building Commission NSW, remedial building work · read
Get two independent quotes
$30,000
work valued at this or above needs at least two
Emergency repairs are exempt. Check that each supplier is licensed for the work and carries the right insurance.
Source: NSW Government, strata repairs and maintenance · read
Expect the levy notice
30 days · 14 days
notice to pay a special levy · an emergency repair levy
The shorter notice is for emergency repairs to a serious and imminent threat to occupants' health or safety.
Source: NSW Government, strata levies and finances · read
Each section names its source and the date it was read. NSW is changing its strata laws, so check the current rules with your strata manager.
Process
Does patching or painting over it work?
No, and it usually makes the next repair bigger. Painting over a stain leaves the reinforcement corroding behind it, and the corrosion continues along the bar past the patch. The tell is a repair that fails at its own edges within a year or two, taking the sound concrete beside it.
Will it come back?
Not in the repaired area if the reinforcement was properly cleaned, treated and re-covered and the water that started it was dealt with. It can appear elsewhere on the same building, because the rest of the structure is the same age and has had the same exposure. That is why a scope on an older block often covers an elevation rather than a single balcony.
Timing
How quickly can someone get to me?
Form and phone enquiries are passed to a local provider, who contacts you directly. Whoever calls you back works the corridor your building sits in, because the Eastern Suburbs, the Shire and the North Shore are three different jobs.
Is concrete cancer structural, and how urgent is it?
It is corrosion of the structural reinforcement, so it is structural by definition — but the urgency depends on where it is and how far it has gone. The case to act on immediately is spalling on an overhead surface: a soffit shedding concrete drops it on whatever is below. Keep people out from under it and get it inspected rather than waiting to see whether more comes away.
Permits and approvals
Do I need an engineer?
Sometimes, and it is a scope question rather than a formality. Where reinforcement has lost enough section to matter, or where the repair is to a structural element such as a beam or column rather than a slab edge, a design is needed rather than a method. On Class 2 buildings the NSW Design and Building Practitioners scheme requires a regulated design produced by a registered design practitioner and lodged on the NSW Planning Portal, which puts an engineer in the process by law rather than by choice.
Source: NSW Government guidance on remedial building work in regulated buildings
Service area
Which suburbs do you cover?
Sydney's Eastern Suburbs, Sutherland Shire, Lower North Shore and Inner West — Bondi through Maroubra, Cronulla, and Mosman through Marrickville.
What is magnesite, and why does it come up?
Magnesite is a floor topping laid over concrete slabs in a lot of older Sydney unit blocks — you may see it as a hard, sandy-grey layer under the floor covering, often on balconies and landings. Where it is present and has been getting wet, it is associated with corrosion of the slab reinforcement underneath it, and an inspection of an older block will usually check for it. Whether it is the cause in a particular building is something the inspection establishes, not something to assume from the era.
Thanks — we have your enquiry. Someone will be in touch shortly. Prefer to talk now? Call (02) 9072 0776.
Last reviewed · Updated · First published