What Tiles Should You Use in a Bathroom? A Guide to Selecting Wall and Floor Tiles

Quick Answer: For bathroom floors, use porcelain or ceramic tiles with a slip-resistance rating of at least R10 (or PTV 36+) and a minimum 6mm thickness for wet areas. Wall tiles should be impervious (water absorption ≤0.5%) for wet zones. Follow BS 5385-1 for wall tiling and BS 5385-3 for floor tiling throughout.

Summary

Selecting the right tile for a bathroom involves more than aesthetics. The wrong tile in the wrong location can create a slip hazard, fail adhesively within months, or crack under thermal movement. UK tradespeople are frequently asked to advise clients on tile selection — and a tile that looks perfect in a showroom can fail on site due to incorrect substrate, inappropriate adhesive class, or wrong joint width.

British Standard BS 5385 (Parts 1 and 3) sets out the requirements for wall and floor tiling in domestic and commercial settings. While these standards are not mandatory under Building Regulations, they represent the benchmark of good practice, and any installer whose work fails when installed to these standards has a clear defence. Work that deviates from BS 5385 without good reason is difficult to defend.

This guide covers the main tile types available, their appropriate applications, the slip-resistance requirements for floors, and the adhesive and grout selection that follows tile choice.

Key Facts

Quick Reference Table

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Tile Type Water Absorption Typical Application Min Thickness Slip Rating
Vitrified porcelain <0.5% (Group I) All bathroom areas — floors and walls 7–8mm R10–R11 available
Glazed ceramic wall tile 3–6% (Group IIb) Wall areas Zone 2 and dry areas only 6mm N/A (wall use)
Unglazed ceramic 3–6% Feature walls, accent 6mm Variable
Natural marble Variable (1–3%) Walls and floors with sealer 10mm Polished = R9 only
Natural slate <3% Floors — good natural grip 8–10mm R11 natural
Mosaic (porcelain) <0.5% Shower floors, curved surfaces 4–6mm R11+ due to joints
Large-format porcelain <0.5% Feature walls, open-plan wet rooms 10–12mm R10–R11
Encaustic cement tile ~5% (unsealed) Decorative floors — seal required 10mm R10 unsealed
Quarry tile <6% Utility rooms, boot rooms 12mm R11 standard

Detailed Guidance

Slip Resistance: What You Need to Specify

The UK uses the Pendulum Test Value (PTV) as its primary slip-resistance measure, assessed to BS 7976-2. The Ramp Test (R-rating) is a German standard (DIN 51130) commonly quoted by manufacturers but not the primary UK measure. A tile rated R10 does not automatically meet UK low-risk threshold — always request the PTV figure.

For UK domestic bathrooms:

When tiling over electric UFH, the tile will expand and contract thermally. Textured tiles with lower slip resistance when cold may meet requirements when heated — and vice versa. Always test PTV at the intended operating temperature where possible, or specify R11/PTV ≥40 to allow for thermal variation.

Zone Classification and Tile Suitability

BS 7671 (IET Wiring Regulations) defines bathroom zones for electrical purposes, but the same zones inform tile specification for water contact:

The most common tiling failure in bathrooms is using standard ceramic wall tiles (Group IIb) in Zone 0/1 without tanking. These tiles are porous at the edges and reverse face. Over time, water migrates through grout lines and adhesive joints, saturating the substrate. If that substrate is standard plasterboard (not moisture-resistant), the board swells and the tiles delaminate — typically within 3–5 years.

Adhesive Selection by Tile Type

Adhesive selection follows the tile's size, weight, and location — not just aesthetics. The European adhesive classification (EN 12004) divides adhesives into:

Sub-classified by performance:

Practical selection guide:

Situation Minimum Adhesive Class
Ceramic wall tile, standard substrate C1T or D1T
Porcelain floor tile, domestic C2TE S1
Large format tile (>600mm) C2TE S1
Very large format (>900mm) or wet room C2TE S2
Natural stone (marble, limestone) C2TE S1 — white adhesive to avoid colour bleed
Underfloor heating (electric or water) C2TE S1 minimum; S2 for large tiles
Mosaic sheets on mesh C2T (check mesh bond)
Outdoor/balcony C2TE S1 frost-resistant

Ready-mixed (D class) adhesives are not suitable for floors, wet rooms, or external use. Tiles over 300×300mm on walls should use C2T minimum — ready-mixed will not hold the weight reliably.

Grout Joint Width and Type

Grout joint width is determined by tile format and whether tiles are rectified (machine-cut to exact dimensions) or non-rectified (kiln-fired, slight size variation):

Grout type selection:

Movement joints must never be filled with grout. All internal corners, perimeter joints, and mid-floor joints at 4.5m intervals (3m on walls) must be filled with a colour-matched silicone sealant classified S1 or S2 under EN ISO 11600. Grout in these locations will crack within months.

Natural Stone Considerations

Natural stone — marble, granite, limestone, travertine, slate — requires specific attention:

Large Format Tiles: Handling and Installation

Large format tiles (600×600mm and above, up to 1200×2400mm slabs now common) present installation challenges:

Frequently Asked Questions

Can I use wall tiles on the floor?

Not unless specifically rated for floor use. Wall tiles are typically thinner (6mm), lower compressive strength, and have no slip-resistance rating. If a client wants to use a matching floor/wall tile, check the tile's technical datasheet — a floor-rated tile can always go on walls, but a wall-only tile must never go on the floor.

Do I need to tank the walls before tiling a shower?

Yes, for any tiled shower enclosure or wet room. BS 5385-1 recommends a waterproof membrane (tanking system) behind wall tiles in wet areas. Standard moisture-resistant plasterboard alone is not sufficient for a shower — it resists incidental splashing but is not designed for continuous water exposure. Products such as BAL WP1, Mapei Mapelastic, or Schluter Kerdi board provide an appropriate waterproof layer.

What's the difference between porcelain and ceramic?

Porcelain is fired at higher temperatures (1200–1400°C vs 900–1100°C for ceramic), producing a denser, less porous tile. Porcelain has water absorption <0.5% (Group I per ISO 10545-3) and is harder (PEI rating 4–5 vs 2–3 for glazed ceramic). Full-body porcelain (colour throughout the tile) hides chips better than through-colour ceramic. Ceramic is easier to cut with a manual cutter; full-body porcelain requires a wet saw. For bathroom floors, always specify porcelain.

How wide should grout joints be for large-format tiles?

For rectified large-format tiles (600mm+), a 2–3mm grout joint is standard. This narrow joint gives the 'seamless' aesthetic clients often want. However, movement joints (silicone) must still be provided at internal corners, perimeters, and at 4.5m intervals in the floor plane — this is a structural requirement of BS 5385-3, not optional even with narrow grout lines.

Are mosaic tiles good for shower floors?

Yes — mosaic tiles (typically 25×25mm or 48×48mm on mesh sheets) are excellent for shower floors because the frequency of grout joints provides inherent slip resistance. The additional grout lines also mean more flexibility in the tiled surface — important on shower trays where deflection can occur. Use S1 or S2 flexible adhesive and ensure 95% adhesive coverage (voids under shower floor tiles lead to hollow spots and eventual cracking). Clean mosaic mesh with appropriate solvent before tiling if it becomes contaminated.

Regulations & Standards