Wet Areas & Waterproofing
Bathrooms, ensuites, laundries — the highest-risk area for defects. Substrate, falls, membrane and finishes all have to be right.
Overview
Part 10.2 of the Housing Provisions defers most of the technical detail to AS 3740. The NCC defines what counts as a wet area, where waterproofing membranes are required (full vs partial), minimum falls, and required substrate types. Defects here are the single most common cause of insurance claims on residential builds.
Key Clauses to expand
- 10.2.1 — Application
- 10.2.2 — Wet area defined (shower, bath, laundry, WC)
- 10.2.3 — Waterproofing of wet areas (AS 3740)
- Membrane required to floor and 150 mm up walls in most cases
- Full waterproofing of shower enclosure (floor + walls + hob)
On-site Checklist to expand
- Substrate is approved (compressed FC sheet, concrete, masonry)
- Falls to waste: min 1:80 floor, 1:60 shower enclosure
- Hob or step-down to shower
- Membrane laps onto floor waste and turns up walls
- Tile adhesive compatible with membrane (AS 3958)
- Installer is licensed waterproofer (state-dependent)
Common Gotchas to expand
- Insufficient floor fall — water pools at waste
- Membrane not lapped over shower hob
- Plumbing penetrations sealed after tiling instead of before membrane
- Wrong substrate (e.g. standard plasterboard behind shower)
- Missing certificate of compliance from waterproofer
Notes & Examples to fill in
Add worked examples, diagrams, photos and project-specific notes here as you accumulate them.