NZ Waterproofing Requirements
Waterproofing is mandated under NZ Building Code Clause E3 (Internal Moisture). Failing to waterproof correctly is one of the most common causes of leaky building claims in NZ.
What Must Be Waterproofed
- Shower floors and walls (min 1.8m up walls in shower area)
- Bathroom floors (all floor area)
- Balconies and decks (trafficable or non-trafficable membranes)
- Wet areas in commercial buildings
Approved Membrane Systems (NZ)
- Liquid applied membranes (Ardex, Mapei, Laticrete) — most common in bathrooms
- Sheet membranes (Wedi, Schluter Kerdi) — faster install in showers
- GRP/fibreglass — standard for trafficable decks
- TPO/single-ply — commercial flat roofs and large decks
Why DIY Waterproofing Fails
NZ has strict requirements for membrane coverage, lap joints, and curing times. Defective waterproofing voids your building consent and can result in costly remediation. Always use a licensed waterproofer or qualified tiler for wet area waterproofing.