Bathroom Tile Work: Waterproofing, Slope and Joints Done Right

A bathroom can have the most expensive tiles in the house and still be a constant headache. Water standing near the door, damp patches on the bedroom wall behind the shower, black grout lines that never come clean: these are all signs of bathroom tile work that went wrong, usually at a stage that is now hidden under the tiles.

Good bathroom tile work is a sequence. Waterproofing, slope, tile fitting and grouting each depend on the one before. Here is how we approach a bathroom so it stays dry, drains properly and looks neat for years.

Before tiles: plumbing and preparation

All concealed plumbing should be complete and pressure tested before waterproofing begins. Once tiles are fitted, finding a leaking joint inside the wall means breaking tiles. We also confirm with the client and plumber:

• Exact positions of the floor trap, shower drain or linear drain.
• Heights of mixers, shower arms, health faucet and geyser points.
• Position of the WC outlet and washbasin, and whether the basin sits on a counter.
• Any niche in the shower wall and its size, so it can align with tile joints.

The sunken portion, if there is one, should be filled with lightweight filling material and finished level, not with loose debris that can hold water.

Waterproofing: the layer you never see

Waterproofing is the most important step in any bathroom. Typically we apply a cementitious or polymer-based waterproof coating in two coats over the floor and up the walls. Common practice is to take it at least 300 mm up the walls all around, and higher in the shower zone, often up to around 1800 to 2100 mm.

Details that make waterproofing work

• Corners. The junction of floor and wall is the weakest point. A fillet or a reinforcing tape at the corner helps the coating bridge it.
• Pipe penetrations. Every pipe and the floor trap must be sealed properly around its edges.
• Curing and drying. Each coat should dry as the manufacturer advises before the next coat or before tiling.
• Pond test. Where possible, filling the floor with a little water for a day and checking the ceiling below confirms the work before tiles go on.

Getting the floor slope right

Water should run to the drain without the user noticing a slope. A common target is a fall of roughly 1 in 100 towards the trap, a little steeper inside the shower zone. Too little and water stands; too much and the floor feels tilted and tiles show obvious cuts.

The slope is made in the screed or bed, not by tilting individual tiles. With larger tiles, we often cut the floor into sections so each piece slopes evenly towards the drain. Another neat option is a linear drain along one wall, which allows the floor to slope in one direction and suits large-format tiles well.

We also keep the bathroom floor slightly lower than the bedroom floor, usually a few centimetres, with a granite or marble threshold at the door. This stops water from crossing into the room.

Wall tile fitting

Wall tiles are fitted with adhesive, not thick mortar. The first row is set against a true horizontal line, often fixed with a batten, rather than relying on the floor which slopes. Key points:

• Plan joints so that full tiles land at eye level and in the shower zone, with cuts at less visible places.
• Align wall joints with floor joints where tile sizes allow.
• Cut holes for mixers and points neatly with a hole saw rather than breaking corners.
• Keep walls plumb; check with a level every few rows.

Finishing corners and edges

External corners can be finished with aluminium or PVC trims, or with mitred tile edges for a cleaner look. Mitre cutting needs care, since a sharp vitrified mitre can chip easily. Niches should be lined with tiles that have their cut faces hidden.

Tile choice for bathroom floors

Bathroom floors should be slip resistant. Matt or textured vitrified tiles, or tiles with an anti-skid finish, are safer than high-gloss options. Ceramic tiles are fine for walls, but vitrified or porcelain tiles are better for floors because they absorb less water. You can read more in our comparison of ceramic, vitrified and porcelain tiles.

Joints and grout: where most bathrooms fail

Cement grout is porous. In a bathroom it absorbs water, soap and dirt, slowly turns dark and allows moisture to reach the bed. Epoxy grout is non-absorbent, resists stains and fungus, and keeps its colour. We generally recommend epoxy grout for bathroom floors and the shower area at the least.

Movement joints are also important. Where the floor meets the wall, and in large bathrooms at intervals, a flexible sealant joint is better than rigid grout because it allows small movements without cracking.

Bathroom tile work checklist

1. Plumbing complete and pressure tested.
2. Waterproofing applied in two coats with corners and pipes detailed.
3. Pond test done where possible.
4. Slope formed in the bed towards the drain.
5. Bathroom floor kept lower than the adjoining room, with a threshold.
6. Wall tiles set from a true level line, joints aligned.
7. Anti-skid tiles on the floor.
8. Epoxy grout on floor and shower walls, sealant at corners.

A bathroom is a small room, but it needs more planning per square foot than any other. If you are building or renovating, send us your bathroom layout and tile choice on WhatsApp at 9468916422. Our tile fitting and flooring service covers bathroom tile work from waterproofing coordination to final grouting, and we can also fit granite thresholds and vanity tops as part of the same job.