The short answer
There isn't a per-square-metre price that's honest, because two balconies the same size can be a half-day job or a week's work depending on what's under the tiles. What we can tell you is what actually moves the number, and what a quote should include so you can compare like with like.
What drives the cost of a waterproofing job
- Area and shape. Square metres matter less than edges. A big, open flat roof is faster per metre than a small balcony with a door, three posts, a drain and a hob, because every one of those is a hand-detailed junction.
- What has to come up. Waterproofing a bare slab is one job. Removing tiles, screed and a failed membrane first, then rebuilding it all afterwards, is three. On balconies and terraces the strip-back and reinstatement are usually the biggest lines on the quote, not the membrane.
- The state of the substrate. Crumbling screed, incorrect falls, drummy render or concrete cancer all have to be fixed before a membrane goes down, or it's going down onto a problem.
- The system. A two-layer torch-on membrane costs more in materials and labour than a single liquid coat. It also lasts two to three times longer and carries a warranty of 20+ years, which is why the whole-of-life cost is lower. See our torch-on vs liquid membrane comparison.
- Access. A ground-floor terrace is easy. A rooftop above eight storeys with no lift access means hoists, crane windows or carrying every roll up the fire stairs.
- Compliance. Commercial and strata jobs need SWMS, hot-works permits, fire watch and staging around occupants. That's time, and it's built into an honest quote.
How the common jobs compare
Because people ask, here's how the jobs we quote most often relate to each other, without pretending a number fits every building.
- Localised balcony leak repair (threshold, post or outlet, membrane still sound): the smallest job we do, typically a day on site including reinstating the tiles.
- Full residential balcony re-waterproof (strip, membrane, flood test, retile): most of the cost is the strip-out and the retiling, not the membrane itself.
- Flat roof re-membrane: priced by area, detailing and access; a clean open roof is faster per metre than a small one crowded with penetrations.
- Planter boxes: small in area but dense in detail (outlets, overflows, root barrier, drainage), so per-metre cost runs higher than a roof.
- Basement and retaining wall tanking: quoted per project, because excavation, drainage and sequencing with the builder matter more than the membrane itself.
If a number is what you need to plan a budget, call 0427 207 670, send photos, and we'll give you a realistic range before anyone comes out.
Why the cheapest quote usually costs the most
The waterproofing industry runs on two prices: the price to do it, and the price to do it again. A thin liquid membrane applied by a subcontractor on a day rate is cheap to install and fails in three to seven years, at which point you pay for strip-out, disposal, a new system and the water damage in between. A two-layer torch-on membrane installed to manufacturer spec costs more on day one and then costs nothing for twenty-plus years.
Ask every quote the same questions: What membrane, exactly? How many layers? Is it flood tested? Who is on the tools, the person quoting or a sub? What's the warranty, and who backs it? Our guide to choosing a waterproofing contractor goes through this in detail.
What a Top Torch quote includes
A site inspection with photos of what we find. A fixed, itemised price covering strip-out, preparation, the membrane system by name, detailing, testing and reinstatement. The warranty term in writing. And the two names on the quote are the two people who'll be on the torch. No variations invented halfway through, no subcontractors, no surprise second invoice.
