It depends on your state — some require waterproofing of wet areas to be done or certified by a licensed or registered practitioner — and even where DIY is allowed, it is the single costliest defect class to get wrong.
The rules vary — check yours first
Waterproofing sits in a grey zone that differs by state. In some jurisdictions, wet-area waterproofing must be carried out or certified by a licensed waterproofer or registered practitioner, with a compliance certificate issued; in others an owner-builder may do it, but the work must still meet the Australian Standard and pass inspection. Confirm your state’s position before you pick up a trowel.
Why this is the wrong place to save
Even where DIY waterproofing is legal, it’s the most expensive defect class in Australian homes. A membrane failure behind finished tiling isn’t a touch-up — it’s demolishing the tiling, drying out, re-membraning and re-tiling, often with damage to adjoining rooms. The saving on the labour is trivial against the cost of getting it wrong.
If you do engage a waterproofer
Check the licence is current on the public register before work starts — a lapsed licence is worthless when you need to claim, and rectifying uninsured waterproofing after tiling routinely runs into five figures. The full picture — what a compliant membrane job looks like and the checks to make — is in the waterproofing and wet areas guide.