Insights
When the leak comes back: a strata committee's guide to apartment waterproofing remediation in NSW
What goes wrong, why the system rarely helps, and what to do about it.
A story we hear every week
Imagine you have bought an apartment. It might be your first step onto the housing market, your first home, or an investment property you saved years to put a deposit on.
Within months of moving in, water is coming through the windows and the walls. The defect list is long. The builder's company is wound up. Your application to the Building Commission goes nowhere because the developer is no longer trading. You spend tens of thousands of dollars on lawyers and the case goes nowhere because the company that built your building does not exist any more, even though the people who built it are still building.
So you pay to fix it yourself. At a loss. Just so you can sell the apartment and walk away.
This is a composite of stories we hear from owners across NSW. The pattern is so common it is almost predictable. The reforms of the last five years have made things better for new buildings. They have done very little for the buildings already standing.
This article is for the strata committees, strata managers, and owners of those buildings. It is what we wish someone had told us when we started doing this work.
Why waterproofing fails
In apartment buildings, waterproofing almost never fails because the membrane was wrong. It fails at the junctions. Where the membrane meets a drainage flange. Where it terminates against a balustrade fixing. Where it turns up under a door threshold. Where the screed cracks above it and water travels sideways for three metres before it shows up two apartments away.
This matters because most leak investigations and most quotes focus on what is visible. The render. The tile. The sealant bead. These are symptoms. The cause is usually a few millimetres of misalignment between two trades who never met each other, sealed up under five layers of finish, and signed off by a certifier who never saw it.
A patch repair on the symptom buys you six to twelve months. Then the water is back, often in a different unit, and the strata committee is having the same conversation again with a different contractor.
Why the system rarely helps once the building is occupied
NSW has several mechanisms in theory.
The Design and Building Practitioners Act 2020 creates a statutory duty of care owed to owners, including the owners corporation, and to later owners. Claims are subject to limitation periods, and in any case a building claim must be brought within ten years of the work being completed. It is a powerful tool, but it requires evidence, expert reports, and usually litigation. Strata committees who try to use it without proper documentation are at a serious disadvantage.
The Residential Apartment Buildings Act 2020 gives Building Commission NSW powers to compel developers to remediate. The flagship program under it, Project Intervene, accepted 227 matters before registrations closed on 30 November 2023. It is now closed to new registrations. Buildings that did not get in face the standard complaint pathway, which is slower and which still generally requires the developer to be trading.
Statutory warranties under the Home Building Act apply for six years on major defects and two years on others, both running from completion. By the time most apartment owners realise they have a problem, one or both clocks have often run out.
Insurance. Most building insurance excludes defective workmanship. Once mould is established, premiums escalate quickly, and some insurers will decline to renew at all.
None of these mechanisms help you while water is still coming through the wall. None of them produce the one thing your building actually needs, which is a properly designed, properly documented, properly executed repair.
What good remediation actually looks like
There are five steps, in this order. Skipping any of them is how strata committees end up paying twice.
1. Diagnose the cause, not the symptom. This means non-destructive investigation first. Thermal imaging. Moisture mapping. Trace dye testing where appropriate. Selective opening up only where the evidence points. The output is a written report that says where the water is entering, where it is travelling, and where it is appearing. These are three different places. If your investigator does not distinguish between them, find a different investigator.
2. Design the remediation. This is the step most owners do not realise exists. A scope of works is not a design. A quote is not a design. The remediation needs detail drawings showing how the new waterproofing system will integrate with the existing building, how each junction will be detailed, what materials will be used, in what sequence, and how the work will be tested before being closed up. Under the Design and Building Practitioners Act, much of this waterproofing work is regulated and requires regulated designs prepared by registered design practitioners.
3. Tender the work properly. A properly designed scope can be priced by multiple contractors on a like-for-like basis. This is the only way a strata committee can compare quotes meaningfully. Without it, you are comparing apples to a different builder's marketing brochure.
4. Inspect during construction. This is the step that protects everything that came before it. Waterproofing fails when the trades do not follow the design. The only way to know they did is to be there at the critical inspection points. Membrane lap testing before screeding. Flood testing before tiling. Junction inspection before finishes.
5. Document the completion. Photographs, test results, as-built drawings, product warranties, and a final certification. This is what supports an insurance claim, a Design and Building Practitioners Act action, a future buyer's due diligence, or a strata renewal valuation. Without it, the work is invisible the day the scaffolding comes down.
Why an architect, not just a builder or building consultant
A building consultant can tell you there is a problem. A builder can quote on a fix. Neither of those is the same as having someone who can issue regulated designs under their NSW registration, who has a Code of Conduct obligation to act in your interests rather than a contractor's, and who is trained to coordinate the design, sequence, and detail of the work across all the trades that touch it.
Most waterproofing failures are not material failures. They are coordination failures. The fix has to be led by someone whose job it is to coordinate, working alongside builders who specialise in carrying the work out.
What it costs
An initial Class 2 waterproofing consultation is a fixed fee of $660 and includes a diagnostic site visit. Detailed investigation and remediation design are quoted once the scope is clear, and we tell you the cost of each stage before you commit. We do not build the repair ourselves. Once it is designed, we bring in builders who specialise in waterproofing remediation and oversee their work against the design, so the building is fixed for good. Keeping the design and the construction in separate hands is how you avoid paying for the same leak twice.
How to start
If you are on a strata committee or you manage one, and your building has a recurring leak, send us the address and a few photos. We will tell you whether what you are describing sounds like a quick win or a bigger problem, and what an independent investigation would cost.
Further reading
Book a Class 2 waterproofing consultation
Send the building address and a few photos. We will tell you whether it sounds like a quick win or a bigger problem, and what an independent investigation would cost.
Or call 0405 837 228