Who is responsible for a leaking balcony in a NSW apartment?

Usually the owners corporation. The original balcony tiles and waterproofing, installed when the strata plan was registered, are common property under the Registrar General's Common Property Memorandum, and section 106 of the Strata Schemes Management Act 2015 places a strict repair duty on the owners corporation. If a later renovation replaced the balcony surface, responsibility may sit with the lot owner who did it.

What should I do first about a leaking balcony?

Document it (photos, dates, weather), report it to the strata manager or secretary in writing so the owners corporation is formally on notice, and keep copies. If the building is under about 10 years old, put the builder and developer on written notice too, because statutory warranty and defect bond clocks are running.

Why does my balcony keep leaking after repairs?

Because the visible symptom keeps being patched while the cause is somewhere else. Water can enter at a door threshold, a hob, a drainage outlet or cracked tiling and travel before it appears. Resealing grout or repainting a membrane over the top rarely fixes the entry path, which is why independent diagnosis before repair matters.

Balcony Leaking in My Apartment (NSW): What to Do

Shea CullenNSW Registered Architect 9748 · Updated 10 July 2026

Water coming through a balcony is the single most common way apartment owners meet the world of strata defects. Maybe it is a stain spreading on the ceiling below, drummy tiles, a musty smell in the bedroom, or your downstairs neighbour knocking on the door. Whatever the symptom, the sequence of what to do next matters more than people realise, because the wrong first moves cost months and sometimes claims. Here is the path I recommend, as an independent remediation architect who deals with exactly this.

Step 1: Document everything, from today

Photos with dates. Videos during rain. Notes of when it appears and what the weather was doing. If the leak stains the unit below, ask the neighbour for their photos too. This costs nothing and it is the foundation of every later step, whether that is an owners corporation repair, a warranty claim or an insurance conversation.

Step 2: Put the owners corporation on notice, in writing

For most buildings the balcony's original tiles and membrane are common property, which makes the leak the owners corporation's problem to fix under the strict repair duty in section 106 of the Strata Schemes Management Act 2015. The full legal picture, including where lot owners are responsible instead, is in waterproofing defects in strata: who pays.

So write to your strata manager or secretary, describe the problem, attach the photos, and ask for it to be tabled. Email is fine. The point is a dated record that the owners corporation knew. If your loss grows later (lost rent, ruined finishes), that record is what your damages claim under section 106(5) stands on.

Step 3: Check how old the building is, because clocks are running

If the building is under about 10 years old, urgency changes:

Statutory warranties under the Home Building Act 1989 give 6 years from completion for major defects, and waterproofing is expressly a major element. Notice matters: put the builder and developer on written notice of the defect promptly, because the Act expects notice within 6 months of a defect becoming apparent.
The strata building bond for buildings over three storeys is claimable only through a fixed inspection timetable in the first two to three years. If your building is in that window, the committee needs to move now, not next AGM. Details in the 2% defect bond and waterproofing claims.
The DBP duty of care reaches back up to 10 years for economic loss from defects. See the DBP Act and waterproofing designs.
Building Commission NSW can inspect serious defects (waterproofing qualifies) in buildings under 10 years and order rectification. Lodging a complaint is free.

None of these run themselves, and one honest note: pursuing the people who built it is slow and uncertain, so run it in parallel with fixing the building, never instead of.

Step 4: Diagnose before anyone quotes

Here is where most balconies go wrong the second time. The committee asks a contractor for a quote, the contractor quotes what they sell (reseal the grout, recoat the surface, new sealant at the door), the work is done, and the leak returns the next east coast low, because the water was never entering where it appeared.

Balconies fail at junctions and details: the door threshold, the hob, the balustrade fixings, the drainage outlet, the membrane termination at the edge. Water enters at one, travels under tiles or through the slab, and appears somewhere else entirely. Finding the actual path needs investigation (moisture mapping, sometimes dye or flood testing), done by someone with no financial interest in which repair gets specified. That is the entire argument of engaging a remedial consultant versus a builder quote.

Step 5: Fix it once, with a designed repair

A proper balcony remediation is designed, not improvised: detail drawings for every junction, specified materials, a testing regime before the tiles go back on. For class 2 buildings this is not just good practice, remedial waterproofing is regulated design work under the Design and Building Practitioners Act, which means a registered practitioner must document and declare it. Then specialist remediation builders price the same documented scope, and the work gets inspected at the hold points that matter (membrane testing before screed, flood test before tiling).

That is the five step method on our waterproofing remediation service page: diagnose, design, tender, inspect, document. It exists because the patch-and-hope cycle is how buildings end up paying for the same balcony three times.

What it costs to start

A Class 2 waterproofing consultation is a fixed $660 including a diagnostic site visit, and it ends with an honest read: sometimes the answer genuinely is a small repair, and I will say so. If it is bigger, you will know what the investigation and design stages cost before committing to anything. Either way, your committee stops arguing about a stain and starts working from evidence.