Waterproofing

New Zealand wet areas are governed by Building Code Clause E3 (Internal Moisture) and the referenced standard AS/NZS 3740, which sets out where a membrane is required and how it needs to perform. In practice, that means anywhere water regularly hits a floor or wall (the shower, and often the floor around the bath and vanity) needs a continuous, tested membrane underneath the tiles, properly turned up at the walls and sealed at every penetration, like waste outlets and pipe fittings.

The failure points are fairly predictable: the shower hob or threshold, the junction where the floor meets the wall, and anywhere a pipe passes through the membrane. When one of these fails, the signs show up slowly, a soft or springy floor near the shower, discoloured or peeling paint on a ceiling below, a musty smell that doesn't have an obvious source, or grout that keeps cracking no matter how often it's redone. By the time it's visible, there's usually been water getting through for a while.

Homes built before the mid-2000s sometimes used different membrane materials and methods than what's standard now, and older linings in some pre-2000 properties can contain asbestos, which changes how removal needs to be handled. If your bathroom hasn't been touched since it was built, it's worth mentioning the property's age in your enquiry so your matched specialist comes prepared rather than finding out on site.