Balcony Waterproofing for Sydney Apartment Buildings
We carry out balcony waterproofing for Sydney apartment buildings, starting with finding where the water gets in.
A leak in a strata building almost never announces itself where the water gets in. It turns up as a stain on the ceiling of the unit below, or as efflorescence on a soffit two floors down, and by then the membrane above it has been failing for a long time.
Balconies are the most common source. They sit outside, they are tiled, they take foot traffic and furniture, and they rely on a membrane that was installed once and has not been looked at since.
Why balconies fail
Five things cause most of what we see:
01
Falls that do not run to the drain, so water sits on the membrane instead of leaving the slab.
02
Terminations that stop too low at the door threshold or the balustrade fixing, so water tracks behind them.
03
Drainage that takes water off the tile surface only, leaving the bedding wet with nowhere to drain.
04
Saturated bedding that stays wet and moves through wetting and drying.
05
Movement cracks straight through the membrane, where no bond breaker was installed at the joint.
A leaking balcony is rarely one of these on its own. It is usually the first one on the list quietly making the rest inevitable.
Can it be done without removing the tiles
Sometimes, and it is worth asking, because it is the difference between a balcony out of use for a week and one out of use for a month.
When an overlay works
An overlay system, a liquid applied membrane installed over the existing tiles, works where the substrate is sound, the falls already run to the drain, and water is getting through the tile bed and grout rather than through a failed membrane underneath. Where those conditions hold, an overlay is a legitimate repair rather than a shortcut.
When the tiles come up
Where they do not hold, it buys a year or two, and then the same leak returns with a new membrane sitting on top of the problem. If the falls are wrong, if the membrane below has debonded, or if the bedding is saturated, the tiles come up. We test for all three before quoting, and we will tell you which case you are in.
Finding where the water is actually getting in
Method 01
Flood testing
To isolate the balcony from the facade and the window above it.
Method 02
Moisture readings
Through the slab and the wall below.
Method 03
Thermal imaging
To map the wet area rather than the visible one.
Method 04
Dye testing
Where there is more than one candidate.
It takes a few hours, and it is the only way to avoid rectifying the wrong element. In a strata building that also means billing the wrong lot.
What a compliant system looks like
External balcony waterproofing is installed in accordance with AS 4654.2, and where the work continues through a door threshold into the apartment, AS 3740 applies to the internal portion.
In practice that means upstands carried high enough at the door and the balustrade, drainage taken at membrane level rather than only at the surface, bond breakers at movement joints, and a membrane suited to the traffic the balcony actually gets. Standards are complied with on a job, not held as a credential, so what matters is the set-out and not a certificate.
Where water has been getting in long enough to reach the reinforcement the repair widens, and our note on balcony rectification covers what that involves.
What moves the price
Four things, in roughly this order. How many balconies, because a program across a whole block is priced differently to a single lot. Whether the tiles come up, which is the largest single variable. Access, because a balcony reachable from a swing stage costs less to reach than one needing a full scaffold. And what the investigation finds behind the membrane, since concrete repair at the slab edge is a separate sequence with its own trades.
We price from the investigation rather than from a square metre rate, and we scope it so a committee can take it to a general meeting with the variables written down instead of discovered later. Where the capital works fund will not cover a full program in one go, the work stages by elevation or by risk, and we will say plainly which balconies can wait and which cannot.
Working around residents
Every balcony belongs to somebody. We stage the work so a building is not fully scaffolded for the entire program, so residents know which week affects them, and so common property is handed back progressively rather than all at the end. How water ingress moves through an apartment block is worth understanding before a committee scopes one balcony in isolation.
Compliance and warranties
Waterproofing is a major defect under the Home Building Act, which carries a six year statutory warranty from completion. Two years applies to everything else. Where the work is structural, or forms part of a wider remediation to a Class 2 building, the Design and Building Practitioners Act applies and we lodge the building compliance declaration at the end of it. How those obligations fall on an owners corporation is set out on our Class 2 compliance page.
6 years
On waterproofing, a major defect under the Home Building Act, from completion.
2 years
On everything else, from completion.
Class 2 Builder Sydney is the trading name of Sydney Building & Construction Group Pty Ltd, Licence No. 283692C.
Start with the investigation
If an owner has reported a stain, the useful first step is finding out which element is leaking, not quoting a membrane. Book a site inspection and we will flood test, report what we find, and price the repair the test points at.
