Porcelain bathroom tiles: the complete guide to choosing

At the start of the search, bathroom tiles seem to offer endless possibilities. The opposite is true: no other room in the house is so tightly constrained. Permanent humidity, water sitting on the floor for minutes at a time, harsh cleaning products used frequently, surfaces walked on barefoot. The bathroom sets conditions before it offers choices, and knowing them narrows the field far faster than any aesthetic criterion.

One clarification before going further. Floor and wall are not subject to the same constraints: the floor has to meet precise technical requirements, the wall covering almost none. This guide deals with what makes a tile suitable for this room. How the two surfaces relate to one another — continuity or contrast, how high to tile, grout colour — is a separate subject, covered in the guide on matching bathroom floor and wall tiles.

What the bathroom demands of a surface

Before starting to choose, it helps to know what you are looking for. Four stresses act on this room, and each one translates into a requirement you can verify on a technical datasheet.

The first is permanent humidity. This is not about shower water, but about the steam that saturates the air after every use and settles everywhere, including on walls far from the wet area. A porous surface absorbs it, and that absorption is the starting point for deep staining, persistent hazing and mould in the grout lines. The figure that measures it is water absorption, expressed as a percentage of weight: porcelain stoneware stays below 0.5%, a threshold that makes it near-waterproof — enough to behave as such in domestic use, for the whole life of the bathroom.

The second is chemical attack. The bathroom is where the harshest products in the house end up: acidic limescale removers, chlorine-based disinfectants, tap cleaners that inevitably run down onto the surface below. A material that cannot cope does not crack — it does something more insidious: it gradually loses its evenness, and the damage is irreversible because it happens in the layer you actually see.

The third is barefoot traffic on a wet surface, the typical bathroom condition and one that occurs in no other domestic room with the same frequency. It shapes the choice of floor tiles more than anything else, and it deserves the section that follows.

The fourth is cleaning frequency. No room is cleaned as often as the bathroom, and usually in a hurry. A surface that calls for special attention, periodic treatments or dedicated products is not a technical detail: it is a daily burden.

Porcelain answers all four at once, which is why it has become the de facto standard for this room: not because it is always the best-looking option, but because it is the only material that asks for no compromise on any of the four fronts. To see how it sits alongside traditional ceramic, from which it derives and from which it differs precisely in density and absorption, the comparison is set out in the article on the differences between porcelain and ceramic tiles.

Anti-slip bathroom tiles: which rating is needed

For the floor of a domestic bathroom, the practical benchmark is R10. It covers the real situation — spread humidity, splashes, water sitting for a few minutes — without the pronounced texture of more heavily slip-resistant surfaces, which is noticeable underfoot in a room walked on barefoot and lengthens cleaning.

There is a second value to read, however, and in this room it counts just as much. The R scale comes from a test carried out wearing shoes, whereas here you walk barefoot on a wet surface: for that condition a separate classification exists, expressed with the letters A, B and C. In the shower area, the only spot where you stand still on a wet surface, class B is the commonly accepted benchmark. Both scales, their thresholds and how they appear on a datasheet are explained in the guide to R9, R10 and R11 anti-slip finishes. Here the principle is enough: on the floor you read the R rating, in the shower you also read the barefoot classification.

Finish and colour: what you see every day

Technical requirements tell you whether a tile will hold up. The finish tells you what living with that bathroom will be like day to day, and it is the part almost nobody assesses when choosing, because it does not show on a dry sample under screen light.

In a room where water evaporates continuously, the daily adversary is limescale. It settles as pale, dull hazing, the cleaner removes it and it comes back: this is not a problem you solve once, it is a permanent condition you live with. Matt and natural surfaces mask it far better, because they lack the even reflection that makes every deposit visible in raking light. In a bathroom, a matt finish is therefore not only a contemporary aesthetic choice: it is what narrows the gap between the freshly cleaned room and the same room three days later.

A second, more technical figure is abrasion resistance, measured by the PEI rating. In a bathroom it is not a tight constraint: the room is small, walked on barefoot or in slippers, without the abrasive grit carried in from outside in an entrance hall. PEI 3 is more than adequate, and insisting on higher values means applying to this room a criterion designed for circulation areas.

Colour works on the same ground, in a less obvious way than people assume. Very dark, saturated shades show limescale clearly, because the deposit is pale and the contrast highlights it; very light shades show organic soiling better. Mid tones, and surfaces with slight shade variation within them, are the most forgiving: neither type of residue finds an even background to stand out against. Then there is light, often artificial and directional in this room: the same tile changes character under cool or warm lighting, and deserves to be judged in the conditions in which it will actually be seen. None of this replaces personal taste, but it is worth weighing before deciding; on colour direction itself, the article on colours for a modern bathroom goes into detail.

Tile sizes: start from the real dimensions of the room

Where size is concerned, the discussion almost always centres on visual effect. But in a bathroom there is a constraint that comes first, and no product datasheet can tell you about it: this is the room with the highest density of obstacles per square metre in the whole house. Floor-standing or wall-hung sanitaryware, shower tray, soil pipes, inspection hatches, niches, fitted units, thresholds. Every obstacle is a cut, and every cut is where the chosen size proves either well judged or awkward.

The working rule is simple: a larger tile reduces the number of grout lines but raises the cost of every single mistake. In a bathroom of a few square metres, a 120x120 cm tile cut wrongly cannot be used up elsewhere, because there is nowhere free. The ratio between whole and cut tiles can shift to the point where the advantage of large format tiles is lost during installation. The sizes that work best in this room are the intermediate ones — 60x60, 60x120 — which give continuous surfaces while staying manageable around obstacles.

Then comes a choice that affects the result more than its technical name suggests. A rectified tile has edges mechanically trimmed to exactly 90 degrees after firing, with a dimensional precision that allows 2 mm grout lines. In a bathroom the consequence is twofold: less grout surface means fewer places where limescale and soap residue collect, and visually the eye stops reading a grid and reads a surface instead. In a small room, where every wall is half a metre from your gaze, that difference registers every day.

One last check if there is underfloor heating below, a common arrangement in this room in particular: porcelain is among the coverings that transmit heat best, and there is no contraindication. Thickness does matter, though, because a thinner tile reduces thermal inertia and shortens the time the system takes to reach temperature.

If the bathroom is tight on space and size is the central question, the article on choosing size and colour in a small bathroom addresses that situation specifically.

The zones of the room ask for different things

So far the reasoning has been about the room as a whole. But a bathroom is not one single surface: four zones coexist within a few square metres, with distinct requirements, and each develops a different recurring problem that the choice of surface can either ease or aggravate.

The shower area deserves a note, because it is the only zone where the choice of tile depends on a decision taken earlier: whether the floor will be tiled or resolved with a shower tray. In the first case the surface continues without a break, a finish with the grip described above is needed, and the tile has to be able to follow the fall towards the drain, which generally rules out the largest sizes. In the second, tiling stops at the walls, the floor is a separate element with its own properties, and no constraint applies to size at all.

One misunderstanding worth clearing up, because it is the most expensive one: the watertightness of a shower does not come from the tile, it comes from the waterproofing membrane laid underneath. Porcelain is near-waterproof, but it is the build-up below that stops water getting through. No choice of tile compensates for poorly executed waterproofing.

What remains to be decided is how high to take the wall covering: a question that combines aesthetics, budget and the proportions of the room, and one covered in the matching guide referred to at the start.

Effects: what really changes, and what does not

A useful clarification before choosing the look: the effect does not change technical behaviour. The body is the same, absorption is the same, grip depends on the finish and not on the pattern. A wood-effect tile and a marble-effect tile with the same finish behave identically in this room. Choosing the effect is therefore genuinely free, once the requirements described above are met.

Stone-effect comes closest to the contemporary idea of the bathroom as a place to decompress, with tactile surfaces and natural tones: the possible variations are gathered in the ideas for a stone-effect bathroom. Wood-effect brings warmth into a room that tends towards coolness, and today it is a widely used solution here too: the full picture is set out in the article on the pros and cons of wood-effect tiles in the bathroom; for species and sizes there is the complete guide to wood-look tiles. Concrete-effect remains the most coherent choice for a minimal, continuous bathroom, explored in the guide to concrete-effect porcelain tiles. Marble-effect, finally, is the reference point when a more classic or brighter register is wanted.

Why the choice weighs on cost more here than elsewhere

Something you only discover when doing the sums: the bathroom is the room in the house with the highest ratio of tiled wall surface to floor surface. In a living room you tile the floor and nothing else. In a bathroom you tile the floor and three or four walls, and the vertical square metres often exceed the horizontal ones by two or three times.

The consequence is that every unit decision gets multiplied by a far larger area than you have in mind. A price difference between two products that looks negligible at a glance becomes significant across the total. And the reverse holds too: giving up a useful property to keep the unit price down produces a proportionally larger saving, but across a surface you will have in front of you every day, half a metre from your eyes.

Two factors weigh more than the rest. The first is size, which affects installation cost: larger tiles demand more care per piece but cover ground faster, and the balance shifts depending on how regular the room is. The second is wastage, the material lost in cutting: in a bathroom, because of the density of obstacles already discussed, the percentage to allow for when ordering is higher than in an unobstructed room, and large sizes push it higher still. These are assessments to make before choosing the size, not after.

How to proceed, in practice

The order of decisions matters more than the decisions themselves. Start with the floor and the shower, because they are the only surfaces with non-negotiable constraints: grip suited to barefoot use, a finish that stands up to limescale, a size compatible with the real obstacles in the room. Once that perimeter is settled, the walls are free — no technical requirement conditions them — and every choice becomes a matter of taste again. This is the opposite of the usual approach, first what appeals and then a check that it works, and it is why so many bathrooms turn out to be impractical only once the work is finished.

Frequently asked questions

Are porcelain bathroom tiles really waterproof?

Water absorption is below 0.5%, so it is fair to describe them as near-waterproof. Be careful not to confuse the material with the system, though: the watertightness of a shower area depends on the membrane laid beneath the tiles, not on the tiles themselves.

Do bathroom tiles have to be rectified?

No, there is no technical obligation. Rectified tiles allow narrower grout lines and therefore less residue build-up, but they need a perfectly level substrate to show at their best.

Can porcelain be used on walls as well?

Yes, and it is now the most common solution in contemporary bathrooms. The only point to check is weight: with large sizes and greater thicknesses, an adhesive suited to vertical installation and a substrate able to carry the load are both needed.

How many extra tiles should be ordered?

More than the theoretical calculation, because cuts around sanitaryware and drains generate wastage, and the allowance to plan for is higher here than in a regular room. It is best to order everything at once and from the same batch: different production batches of the same product can show slight shade variations that are hard to correct later.

Can porcelain be laid over existing bathroom tiles?

It is possible if the existing substrate is soundly bonded, level and free of loose areas, using an adhesive suited to tiling over tiles. The rise in floor level does need to be taken into account, though, as in a bathroom it interferes with thresholds, doors, floor-standing sanitaryware and drains.

Can the bathroom floor be the same as the rest of the house?

Yes, provided the product chosen offers grip suited to use in a damp room. Continuous flooring between the bathroom and the sleeping area is an increasingly common choice, and it is the bathroom that sets the technical constraint: it is the most demanding room, so it is the starting point.

Should bathroom grout be a particular colour?

From a maintenance point of view, the type of grout matters more than the colour: in areas in direct contact with water, epoxy grout resists staining and mould better than cement-based grout. The choice of colour, by contrast, answers to aesthetic criteria and to how the surfaces are matched.