Tile is not waterproof. Grout is not waterproof. Both are porous, and both are designed to let a certain amount of moisture through to a layer behind that is meant to stop it. When a tiled shower fails, it almost never fails at the tile — it fails at a corner, a change of plane, a drain flange or a pipe penetration in the layer nobody can see anymore. That is why the waterproofing is the part of this trade worth talking about, and the tile is the part that gets photographed.
Why the coast is different. A bathroom in Nanaimo, Ladysmith or Qualicum Beach dries more slowly than the same bathroom in a dry interior climate. Ambient humidity stays high for much of the year, older wall assemblies were built with vapour strategies that predate modern shower use, and a room that never fully dries puts a continuous rather than intermittent load on every joint. Slow, low-grade moisture movement into a stud bay is more destructive over time than an obvious leak, because an obvious leak gets fixed.
What a waterproofed shower actually requires. The substrate first: standard drywall does not belong in a shower enclosure, and moisture-resistant board is not the same thing as a tile backer suited to continuous wetting. Over that, a continuous waterproofing membrane — sheet or liquid applied — taken from the shower floor, over the curb on all three faces, into every internal corner, up the walls to above the shower head, and lapped correctly at every change of plane. Internal corners and changes of plane get a reinforcing band because that is where movement concentrates. Pipe and valve penetrations get purpose-made seals rather than a smear of sealant. The membrane is bonded to the drain flange itself, not merely dressed near it, because the drain connection is the single most common failure point in a tiled shower floor. Where the assembly allows, a flood test is worth the day it costs.
Slope and drainage. A shower floor is sloped a consistent quarter inch per foot to the drain. With a centre drain that means four planes meeting at the outlet and four hips running to the corners, and the tile has to be small enough to follow that geometry — mosaic or small format there is a requirement, not a style choice. A linear drain at one wall allows a single sloping plane, which permits large format tile and makes a curbless entry far easier to detail. Under either approach the pre-slope beneath the membrane matters as much as the finished slope above it, because water reaching the membrane needs somewhere to run.
Setting out is decided before the first tile. Where the cuts land is the difference between tiling that looks resolved and tiling that looks like it happened. Setting out starts from the most visible plane and works outward: full tiles at the entry and at eye level, cuts pushed to the least visible corner, courses aligned so the niche sits within full tiles, and the top row not left as a 20mm sliver at the ceiling. Where floor and wall tile meet, the joints either align deliberately or offset deliberately — the thing to avoid is nearly aligning. Large format tile adds its own demand: the substrate has to be flat to a much tighter tolerance, because a 600 x 1,200mm tile telegraphs any hollow beneath it and lippage shows under raking light.
Movement joints are not optional. Tile assemblies expand and contract, and the substrate behind them moves at a different rate. Every internal corner, wall-to-floor junction and change of plane gets a flexible sealant joint rather than grout. Grout in a corner cracks — reliably, within a year or two — and then reads as a workmanship problem. Perimeter joints do the same work for the floor.
Feature and accent tile. A herringbone panel, a mosaic niche back, a run of handmade zellige, a contrasting shower floor — these carry a room, and each has a technical consequence. Handmade tile has variable thickness and needs a thicker bed and wider joints. Mosaic sheets need their seams disguised or they read as a grid. Metallic and glass tiles need a white setting bed or the adhesive colour shows through. Polished porcelain on a shower floor is slippery and generally the wrong choice regardless of how it looks in a showroom.
Tile replacement and repair. Matching into existing tile is often harder than replacing a whole surface, because production runs change and an older shade is unlikely to still be available. Where a section of shower tile has failed, the real question is usually whether the waterproofing behind it has failed too, and re-tiling over a compromised membrane simply defers the same job.