The common misunderstanding

Tile and grout shed water, they don't stop it. Grout is cementitious and porous. Water passes through the tile assembly and reaches whatever is behind it. If that's ordinary drywall, it will eventually fail: the substrate softens, the tile loses its bond, and moisture moves into framing.

So the real question for a shower is not which tile, it's what's behind it and how the transitions are treated.

What proper wet area construction includes

  • An appropriate substrate. Cement board or a foam tile backer board rather than standard drywall in the wet area.
  • A continuous waterproofing layer, either a sheet membrane or a liquid-applied membrane, covering the whole wet zone.
  • Reinforced corners and changes of plane, since corners and floor-to-wall junctions move and are where failures start.
  • A correctly built shower pan, sloped to the drain, with the membrane properly integrated into the drain assembly. Slope is built in, not created by grout.
  • Sealant, not grout, at movement joints, meaning inside corners and the wall-to-floor junction. These joints move; grout cracks when it moves.
  • Ventilation. An exhaust fan ducted outside, sized for the room, and ideally on a timer. Ducting a fan into an attic just relocates the moisture problem.

Where you can see quality: ask a contractor what membrane they use and how they treat inside corners and the drain. A clear specific answer is a good sign. A vague one about "waterproof grout" is not.

Signs of an existing problem

  • Loose, hollow-sounding, or cracked tiles, especially at the base of a shower
  • Grout that keeps cracking or falling out in the same spot
  • A musty smell that doesn't clear with ventilation
  • Staining or soft spots on the ceiling below a bathroom
  • Peeling paint or lifting flooring just outside the shower

Repeated grout repair in one location is usually not a grout problem, it's movement or water getting behind the assembly.

Why "just re-tile it" often isn't the answer

If water has been getting behind tile for years, new tile over a compromised substrate will fail the same way. Once the wall is opened, the substrate and framing can be assessed, and that assessment decides the real scope. A quote given without opening the wall is an estimate with an assumption inside it, and that assumption is worth asking about directly.

Permits

A like-for-like refresh that doesn't move plumbing often doesn't require a permit. Relocating fixtures, adding a fixture, or electrical work beyond simple repairs generally does. Requirements vary by municipality, so confirm before demolition.

Common questions

Is tile waterproof?

No. Tile and grout shed water but do not stop it, and grout is porous. Waterproofing comes from the layer behind the tile, either a sheet or liquid-applied membrane over a suitable substrate such as cement board, with reinforced corners and a properly integrated drain.

Why does my shower grout keep cracking in the same spot?

Repeated cracking in one location usually indicates movement at that joint or water getting behind the tile assembly, rather than a grout defect. Inside corners and wall-to-floor junctions move and should be sealed with a flexible sealant rather than grout.

Can I just re-tile over an existing shower?

If water has been reaching the substrate, new tile over a compromised base will fail the same way. The substrate and framing need to be assessed once the wall is opened, and that assessment determines the actual scope of work.

This guide is general information for Metro Vancouver and the Fraser Valley, not legal advice or a substitute for your municipality's building department. Requirements vary by city and by project.