Bathrooms · Waterproofing

The membrane is the bathroom

Tiles are not waterproofing. A membrane, correctly detailed falls, and sealed penetrations are — and they are why inspections exist.

NCC / ABCB

Read official rules at

AS 3740

Industry standard often cited

Falls + upturns

Common fail

Tiles waterproof?

Independent guide — not a contractor. Planning information only. Confirm licences, waterproofing, and quotes with qualified trades and the relevant state authority.

Waterproofing briefing checklist (not a method)

Watch	Homeowner question	Why it matters
Falls	Does water want to go to the waste before the membrane?	Ponding finds silicone and then the building
Upturns	Does the membrane climb walls, hobs, and baths?	A rectangle on the floor is not a tray
Penetrations	How are mixers, wastes, and pipes detailed?	Each hole is a designed detail or a leak
Record	Photos, product name, inspection or flood test?	The folder you need in five years

Official performance lives at the NCC / ABCB. Industry practice in houses often cites AS 3740. We do not invent clause numbers.

What visitors always ask

What is bathroom waterproofing and why does it matter?+

Waterproofing is a continuous barrier — usually a liquid or sheet membrane — that stops water reaching timber, plaster, and the dwelling below. Tiles and grout are not that barrier; they are a wearing surface. In Australia, wet-area work is framed by the National Construction Code and referenced standards (industry practice often cites AS 3740 for domestic wet areas). Failures show up as rotten floors, mould, and downstairs ceilings. That is why membranes are inspected.

How do I avoid waterproofing failures?+

Hire a waterproofer who will document the system, form falls to the waste before the membrane, take upturns to the height required for that location, seal every penetration, and allow a flood test or inspection if your certifier requires it. Do not tile over a membrane that has not been accepted. Do not let silicone be the only upstand behind a bath. Read ABCB / NCC guidance and your state building authority rather than a product advertisement.

Keep reading

Bathroom hub

Where this sits in the job.

Showers

Trays, screens, wet-rooms.

Ensuites

Small wet areas, same membrane.

Heating & ventilation

Fans are not membranes.

Australia · kitchens & bathrooms

Make a renovation day of it

Whether you have a weekend cosmetic refresh or a full wet-area rebuild, start with the checklist, then read the cost bands with their assumptions still attached.

Open the checklist →Read cost guides