Balcony & Deck Waterproofing
Balconies leak more than anything else, because they live outside and rely on a fall to drain that is easy to get wrong. We waterproof balconies and decks to AS 4654, with the fall corrected, the upturns and the drainage detailed, and a membrane rated for the exposure. Where the leak is through the grout on a sound deck we can often membrane over the tiles, and where the falls or the membrane have failed we will tell you it needs the tiles up.
What this job includes.
- ✓Balconies and decks to AS 4654, exposed and under-tile membranes
- ✓Fall to drain checked and corrected, upturns and drainage detailed
- ✓Liquid membrane over sound tiles where the leak is grout and joints
- ✓Full strip-out and re-membrane where the falls or membrane have failed
- ✓Diagnosed honestly first, then quoted by the m²
Why balconies leak more than anything else
A balcony lives outside. It takes the sun, the rain, the movement of the building, the seasonal expansion of the tile bed, and it relies on a fall to drain that is the single most common thing a cheap operator gets wrong. AS 4654 sets the fall, the upturns at the door threshold and the wall junctions, the detailing around the drains and the penetrations, and the membrane that has to be rated for the exposure.
When a balcony leaks into the room below, the staining is almost never directly under the source. Water tracks along the substrate, finds the slope or the wall cavity, and shows up two metres away. The diagnosis is the job before any fix is quoted.
What we do on an AS 4654 balcony
- Diagnose the source first. We trace where the water is actually getting in, often at the cove, the drain or the door threshold, before we quote a thing. Sealing the spot under the stain wastes your money and the leak keeps going.
- Check the fall, correct it if it ponds. A perfect membrane over a deck with a back-fall will still hold water against the building. Where the fall is wrong, we lay a screed correction so the water leaves the surface the way the Standard requires.
- Detail the junctions and the drains. Upturns at the door threshold and the wall junctions taken to height, bond breakers in the cove, the drain re-set if it sits proud or low, every penetration sealed in.
- Apply a membrane rated for the exposure. Liquid-applied polyurethane or acrylic for most balconies, a sheet system for some decks, in the system the substrate and the exposure call for. Each coat cured to hold-down before the next.
- Flood test and certify. The balcony flooded for the period the Standard sets, the membrane proven to hold water, then the AS 4654 compliance certificate issued for the building file.
When tiles can stay, and when they have to come up
Where the leak is through the grout and the joints on an otherwise sound deck, a liquid membrane over the existing tiles can be an honest fix and saves a strip-out. Where the falls are wrong or the original membrane under the tiles has failed, lifting the tiles and re-doing the membrane to AS 4654 is the only answer that holds. We diagnose first, then quote the option that actually fixes the cause rather than the symptom.
Priced by the m², itemised line by line.
The area by the m², the Standard it meets, AS 3740 inside or AS 4654 outside, the membrane system and the product, the number of coats, the prep and any strip-out, the flood test and the certificate. Not one round number for the waterproofing.
- 1 The area, by the square metre. The price broken down by the m² and the area, not one round number for "the waterproofing". A shower recess, a bathroom and a balcony are different jobs, and the quote should show it.
- 2 The Standard it has to meet. AS 3740 inside a wet area, or AS 4654 outside on a balcony, deck or roof, named on the page. The Standard is what sets the coats and the detailing, so naming it is the honest part of the quote.
- 3 The membrane system and product. Cementitious, liquid-applied or sheet, and the actual product named, not "we will seal it". The system is chosen for the exposure and the substrate, and you should see which one you are paying for.
- 4 The number of coats. How many coats, because the most common cheap shortcut is one coat where the Standard needs two. It is invisible the moment the tiles go down, so it belongs on the quote.
- 5 Prep and any strip-out. The substrate prep, and the strip-out of failed tiles or membrane where it is needed, as their own line. Prep is a real cost before any membrane goes down, never folded into a round number.
- 6 The flood test and certificate. The flood test that proves the membrane holds water, and the compliance certificate a licensed waterproofer issues. The test is the difference between it looks done and it is proven.
- 7 The membrane warranty. The 10-year membrane workmanship warranty in writing, alongside the manufacturer system warranty. The cover a cheap operator will not put on paper, because they cannot stand behind a rushed job.
What happens, step by step.
Inspect and diagnose
We look at the job and, for a leak, trace where the water is actually getting in, because the stain is rarely under the source. We check the falls, the substrate and the detailing before we quote anything.
Strip out and prepare
Where the old membrane or tiles have failed, we strip them back. Then we grind, repair cracks, and prime the substrate, because a membrane is only as good as what it is stuck to.
Detail the junctions
Bond breakers at the wall-to-floor corners, the upturns to height, the penetrations and wastes sealed in, and the fall to the drain set right. The junctions are where a wet area moves and where it leaks.
Apply the coats
The membrane system to AS 3740 or AS 4654, the number of coats the Standard needs, each cured before the next. We name the system and the coats on the quote, and apply exactly that.
Flood test
We plug the wastes, flood the area, and leave it to confirm the membrane holds water before anything goes on top. The test is the proof, and it is a real step, not an optional extra.
Certify and hand over
We issue the compliance certificate for the work and hand over the membrane warranty in writing, so your builder, certifier and insurer have the paperwork the job needs.
The paperwork behind the price.
Public liability to $20M, and a 10-year membrane workmanship, all in writing, all on request.
We hold a QBCC licence for waterproofing in Queensland, the licence that lets us flood-test and issue the compliance certificate, and we carry public liability insurance, so you are covered on site. The guarantee is a 10-year written warranty on the membrane workmanship, the part that fails first when a job is rushed, alongside the manufacturer system warranty on the accredited membrane we install to AS 3740 or AS 4654. All in writing, with exclusions named.
Balcony & Deck Waterproofing jobs we’ve done.
Before 
After Balcony & Deck Waterproofing: common questions.
Why do balconies leak so often?
Can you membrane over the tiles, or do they have to come up?
What membrane system do you use on a balcony?
Do you handle the drainage and the falls, not just the coating?
Get a free, itemised quote you can actually read.
Tell us what you need. We’ll book a walkthrough and send a quote with the work itemised, not just a number.