The cheapest leak to prevent and one of the costliest to ignore. Here's how wet-area waterproofing works, what it costs, and how to spot failure early.
Here's the thing most people don't realise: tiles and grout are not waterproof. They shed most water, but moisture passes through grout lines over time. What actually keeps water out of your floor and walls is the waterproof membrane underneath — and if that's missing or has failed, water quietly soaks into the structure for years.
Under the New Zealand Building Code, wet areas must be waterproofed before they're tiled or lined. A correctly tanked shower protects the timber framing, subfloor and the rooms below. Skipping or botching it is a leading cause of rot, mould and — in multi-level homes — ceiling damage downstairs.
Wet-area waterproofing is typically $60–$100/m², or roughly $800–$2,500 for a standard shower or bathroom — done as part of a renovation before tiling. Compare that to the thousands it costs to repair rotten framing and a damaged ceiling below, and it's the best-value waterproofing you can buy. See our full NZ waterproofing cost guide for other job types.
DIY membranes exist, but wet-area waterproofing is unforgiving — corners, drains, junctions and the right number of coats are where it fails. For anything you're tiling over (and especially upper-level bathrooms), a professional membrane with documentation is worth it. It also matters for resale, LIM and building reports.
A DryGuard-matched specialist tanks your wet area to Code, documents it, and backs it with a 15-year guarantee — so it's protected before the first tile goes on. We cover Auckland, Tauranga, Wellington, Christchurch and more.
Get my wet-area quote →Sometimes a surface-applied system works for minor cases, but if the membrane has failed the reliable fix is to strip, re-waterproof and re-tile. An inspection confirms which is appropriate.
The membrane itself is usually 1–2 days plus curing time before tiling. Full bathroom timelines depend on the wider renovation.
Yes — work is completed to Code and backed by a 15-year workmanship guarantee.