AS 3740 Requirements
The Australian Standard for waterproofing wet areas specifies:
Shower Areas
- Floor: Entire shower floor plus 50mm up walls
- Walls: Full height on all shower walls
- Hob-less showers: Extended floor waterproofing
Bathroom Floor
- Minimum 100mm up walls around entire floor
- Step-down from adjacent areas or
- Continuous waterproofing under threshold
Bath Areas
- Floor under bath
- Wall behind bath to 1.8m height
- 150mm beyond bath edges
Membrane Types
- Sheet membranes: Torch-on or self-adhesive
- Liquid membranes: Paint-on (most common residential)
- Combined systems: Liquid with fabric reinforcement
Critical Details
- Bond breaker at wall-floor junction
- Membrane under all fixtures
- Falls to waste (1:80 minimum)
- 24-48 hour drying before tiling
Certification Required
- Licensed waterproofer in most states
- Certificate of waterproofing
- Photos of membrane installation
- Product details and warranty
Common Failures
- Poor preparation
- Insufficient membrane thickness
- Inadequate corner treatment
- Tiles installed too soon
- No bond breaker