Quick answer
Most tiling that fails did not fail as tiling. It failed underneath, at the waterproofing. In a NZ wet area the membrane is the thing that keeps water out of the building; the tiles are the wearing surface over it. Get the fall to the drain, the membrane and the sealing of junctions right, and a bathroom lasts decades. Skip or rush the membrane and no amount of good tiling saves it. So the question to ask about a tiling job is really a question about what is under the tiles.
The order that keeps water in the room, not the wall.
Key points
- The membrane is the waterproofing; the tiles are the wearing surface over it. A tile job is only as good as what is under it.
- Falls to the drain and sealed junctions (wall-to-floor, penetrations) are where wet areas leak, not the open field of tiles.
- Re-grouting freshens a sound floor; it does not fix a failed membrane, and selling it as a fix for a leak is the classic trap.
- Silicone belongs in the movement joints (corners, wall-to-floor); grout belongs in the flat joints. Swapping them cracks the grout.
- In an occupied home a wet area is out of use while it cures, so sequencing and a second bathroom matter as much as the tiling.
Tiling looks like the visible job and waterproofing looks like the hidden one, so that is exactly where corners get cut. Nobody sees the membrane. The client sees the tiles. A year or two later they see the water stain on the ceiling below, and by then the fix is not a re-grout, it is a strip-out. We tile and waterproof wet areas across Auckland alongside our kitchen and bathroom work, and the part we care most about is the part you never see.
Why waterproofing is the whole job
A NZ wet area is built as a system. The substrate has to be sound and set to a fall so water runs to the drain rather than pooling. A waterproofing membrane goes over it, carried up the walls to the required height and sealed at every junction and penetration, the tap, the waste, the wall-to-floor corner. Only then do the tiles go on. The tiles and grout shed most of the water, but the membrane is what protects the timber and the room below when water gets past them, which over years it always does.
This matters most in the junctions and the falls, not the open floor. A leak almost never comes through the middle of a tile. It comes at the corner, the drain or the shower hob, where the membrane was skipped, or where silicone was replaced with grout that then cracked. Get those details right and the field of tiles looks after itself.
Grout, silicone and the joint that keeps cracking
There is a simple rule that prevents a lot of callbacks: grout goes in the flat joints between tiles, and flexible silicone goes in the movement joints, the internal corners and the wall-to-floor junction. Those junctions move slightly as the building does. Fill them with rigid grout and the grout cracks, water gets in, and the failure starts. Fill them with the right silicone and they flex and stay sealed. When a client tells us the grout in the corner keeps cracking, that is nearly always the reason.
| Location | Right material | What happens if it is wrong |
|---|---|---|
| Flat joint between tiles | Grout | Silicone here looks messy and peels |
| Internal corner | Flexible silicone | Grout cracks as the wall moves |
| Wall-to-floor junction | Flexible silicone | Grout cracks, water tracks in |
| Around waste & taps | Sealed membrane + silicone | The classic hidden leak point |
Splashbacks, re-grouts and the smaller wet-area jobs
Not every tiling job is a full wet area. A kitchen splashback, a tidy re-grout, a cracked-tile replacement or a silicone reseal are all common maintenance works, and the honest answer on each is different. A mouldy silicone junction is often a clean-and-reseal, not a re-tile. A tired but sound floor can be re-grouted to freshen it. A leaking shower usually cannot, for the reasons above. Part of the job is telling you which one you actually have rather than selling the biggest version.
Where tiling meets the kitchen, it pairs with the rest of the make-good: a new splashback alongside a benchtop, or tiling as part of a wider refresh. Done under one contract with the joinery, the wet trades and the tiling are sequenced together rather than three contractors blaming each other for the join that does not line up.
Tiling a wet area in an occupied home
A wet area is out of use while it is built and while it cures, so in an occupied home the sequencing is the hard part. If it is the only bathroom, that has to be planned around, the same way we plan a kitchen renewal around a resident staying in the home. Waterproofing membranes need their cure time and it should not be rushed to get the room back a day sooner; a bathroom you cannot hurry is better than one you have to redo.
Frequently asked questions
Why does my newly tiled bathroom leak?
Almost always because the waterproofing membrane under the tiles was skipped, incomplete, or not sealed at the junctions and penetrations. Tiles and grout shed most water but are not the waterproofing; the membrane is. If it failed or was never there, water gets past the tiles into the structure and shows up as a leak below.
Can you just re-grout to stop a leak?
No. Re-grouting freshens the joints on a sound, dry floor, but it does not replace a failed waterproofing membrane. If a wet area is leaking, the water is getting past the tiles, so the fix is to address the membrane, not the grout. Re-grouting to chase a leak only hides it for a while.
Should the corners be grouted or siliconed?
Siliconed. Internal corners and the wall-to-floor junction are movement joints that flex as the building moves, so they need flexible silicone. Grout is rigid and will crack there, letting water in. Grout belongs in the flat joints between tiles; silicone belongs in the corners and junctions.
Do you need to waterproof before tiling every wet area?
Yes, a NZ wet area needs a waterproofing membrane installed and sealed before the tiles go on, carried up the walls to the required height and sealed at every junction and penetration. It is the part of the job that protects the building, so it is never the part to skip to save time or money.
How long is a bathroom out of use when it is re-tiled?
It depends on the scope, but plan for several days: the substrate and falls, the membrane and its cure time, tiling, grouting and sealing each need their turn and some need to cure. In an occupied home with one bathroom, that curing time cannot be rushed, so the job is sequenced around access to another bathroom.
Can you re-tile a splashback without redoing the whole kitchen?
Yes. A splashback is a standalone job and a common refresh, whether tiled, glass or another surface. It is often done as part of a wider make-good or alongside a new benchtop, and under one contract the tiling is sequenced with the joinery so the joins line up rather than being left to separate trades.
If you have a wet area that is leaking, tired, or just needs a fresh splashback, we will tell you honestly whether it is a reseal, a re-grout or a strip-out, and price the job that actually fixes it. Waterproofing first, tiles over the top, sealed where it counts. That is the order that lasts.