Does waterproofing have to meet an Australian Standard?

Waterproofing is not a finish you choose for the look. It is the layer that keeps water out of the building, and it is governed by Australian Standards that say exactly how it has to be done. The trouble is that most quotes treat the Standard as a footer, or leave it off entirely. Here is what it means for your job.

AS 3740 inside, AS 4654 outside

Inside a wet area, the rules are set by AS 3740. It covers where the membrane has to go and how far up: the shower floor and walls to a set height, the upturns at every wall-to-floor junction, bond breakers at the corners, and a fall to the waste. Outside, on a balcony, a deck or a roof, the rules are set by AS 4654. The big extra there is exposure and drainage: the fall to drain, the upturns and a membrane rated to take sun, rain and movement.

Why the Standard is the honest part of the quote

• It names the number of coats. A single coat where the Standard needs two is the most common cheap shortcut, and it is invisible once the tiles are down.
• It names the bond breakers and upturns. The junctions are where a wet area moves and where it leaks. The Standard says how to detail them so it does not.
• It names the fall to drain. A balcony that ponds will leak even under a perfect coat. The Standard says the water has to leave.
• It comes with a flood test. The test is the difference between it looks done and it is proven to hold water.

A quote named to the Standard is one you can check. A vague lump sum is one you have to trust. The Standard is how you tell a licensed specialist from a handyman who also does waterproofing.

The certificate, and who can issue it

A compliant job is flood-tested and certified, and in Queensland a licensed waterproofer is the one able to provide that certificate. It matters for your builder, your insurer and any future sale. We build to AS 3740 or AS 4654, name the system and the coats on the quote, test the work, and hand the certificate over with the warranty.