How Do You Plan and Set Out a Bathroom Tile Layout? Working from Centre and Handling Cuts

Summary

Tile layout planning is the most important phase of any tiling project. A poorly set-out job — with thin slivers of tile at eye level, uneven cuts at doorways, or grout lines that do not align between floor and wall — will be immediately obvious to any experienced eye and may result in callbacks, remedial work, and reputational damage.

The principle of setting out from the centre is fundamental: by starting your tile layout from the visual centre of the space and working outward, you ensure that cuts at opposite ends are equal. You also place full tiles in the most prominent positions. In bathrooms, the visual centre is not always the geometric centre of the room — it is the centre of the focal wall (typically the wall the bather or shower user faces) or the centre of the bath or shower enclosure.

British Standard BS 5385 (Wall and Floor Tiling) is the UK's definitive standard for professional tiling. It covers substrate preparation, adhesive selection, joint widths, movement joints, and waterproofing. Professional tilers should be familiar with the relevant parts.

Key Facts

• Centre-line setting out — always set out from the visual centre of the space; ensures equal cuts at both ends of each wall
• Minimum cut tile size — as a rule of thumb, avoid cuts smaller than half a tile; slivers less than 50mm are very difficult to cut cleanly and look unprofessional
• Datum line — a spirit-level horizontal line (batten line) set at the height of the first full course; gives a true horizontal reference for the entire job
• Avoid slivers — if the layout would produce a sliver below 50mm at any edge, shift the centre line by half a tile to increase the minimum cut
• Internal corners — silicone only — never grout internal corners (wall-to-wall, wall-to-floor); use a flexible silicone sealant matched to the grout colour; grout at corners will always crack due to differential movement
• BS 5385-3 — the section covering floor tiling; specifies movement joint positions and maximum panel sizes
• BS 5385-1 — wall tiling on internal surfaces
• Movement joints in floors — required at every 4.5m in each direction; also at all structural movement joints in the substrate; at changes of substrate type; and at the perimeter of each floor area
• Movement joints in walls — required at every 3m in each direction and at all changes of substrate
• Joint width — minimum 2mm for floor tiles under 100mm; 3mm for tiles 100–300mm; 5mm for larger format tiles; see BS 5385 for full table
• Herringbone setting out — start from the centre line of the wall; a separate 45° grid is marked; typically more waste (up to 15%) must be allowed
• Offset (brick) pattern — standard stretcher bond offset of 1/3 or 1/2; for large format tiles, BS 5385 recommends 1/3 offset maximum to minimise lippage risk on slightly uneven substrates

Quick Reference Table

Detailed Guidance

Establishing the Datum Line

Before any tile is fixed, the datum line must be established. This is a perfectly level horizontal line on the wall, typically set one tile height above the lowest point of the floor (or above the bath rim, shower tray, or skirting). The datum line is your reference for all horizontal courses throughout the room.

Use a long spirit level (1.2m minimum) or a laser level to mark the datum line. Mark it lightly in pencil or chalk, then fix a temporary wooden batten (50×25mm PAR) to the wall with masonry screws, with the top of the batten on the datum line. This batten supports the first full tile course while the adhesive cures.

Why not start from the floor? Floors are almost never truly level. Starting from a floor reference would make any floor variation visible in the first course of wall tiles — by the time you reach eye level, the discrepancy would be very apparent. Starting from a datum line ensures horizontal courses throughout.

The datum line height should be planned to avoid thin cuts at the top of the wall. If the distance from the datum line to the ceiling leaves a thin sliver, lower the datum line by half a tile to create a larger cut at top.

Setting Out the Horizontal (Centre Line)

On each wall, find the geometric centre and mark a vertical line. From this centre line, dry-lay tiles on the floor or on the batten to check the layout. Count out from the centre to each edge of the wall to calculate the cut tile size.

If the wall width is 2,400mm and the tile is 300mm wide (with 3mm joints = 303mm per tile position), the layout would be:

• 2,400 ÷ 303 = 7.92 tiles
• To make the cuts equal: 0.92 ÷ 2 = 0.46 tiles at each side = approximately 138mm cut

138mm is close to half a 300mm tile (150mm), so this is a good layout. If the result was 0.2 tiles (approximately 60mm sliver), you would shift the centre line by half a tile so the sliver becomes 150mm + 60mm = 210mm — a much larger, cleaner cut.

Always do this calculation for every wall and the floor before buying tiles — it determines the exact quantity required and may influence which tile size gives the best layout.

Setting Out the Floor

Floor setting out must consider the view from the doorway. Tiles that are cut and truncated right at the entrance look poor — the ideal is a full or near-full tile at the doorway threshold.

Work backwards: measure from the doorway into the room and calculate how the floor grid falls. If a straight-set grid works from the doorway, use it. If a diagonal (45°) layout is used, the starting point shifts to the centre of the room and the tiles are set at 45° to the walls.

For floor-to-wall alignment: ideally, the floor grout lines should align with the wall grout lines at the floor-wall junction. This requires coordinating the floor and wall setting-out before any tile is laid.

Movement Joints

Movement joints are compressory joints — gaps filled with flexible sealant rather than rigid grout — that accommodate thermal and structural movement in the tiled surface. They are required:

In floor tiling (BS 5385-3):

• At the perimeter of each floor area (between floor tiles and wall, skirting, or bath/shower enclosure)
• At any structural movement joint in the substrate
• At changes of substrate (e.g. where screed meets structural concrete)
• At every 4.5m in each direction across the floor

In wall tiling (BS 5385-1):

• At all internal corners (wall-to-wall, wall-to-bath, wall-to-shower tray)
• At every 3m in each direction across the wall
• At any background joint or change of substrate

Movement joints in floors must be filled with a flexible polyurethane or polysulphide sealant (colour-matched to grout). Movement joints at internal corners and the floor-wall perimeter are typically filled with silicone sealant, colour-matched to the grout.

Do not grout movement joints. Grout is rigid and will crack within months at any movement joint location — the thermal expansion and slight building movement that occurs in all structures will crack a grouted corner.

Handling Cuts

Tile cutting in bathrooms requires care because:

• Many cuts are in visible positions at eye level
• Ceramic and porcelain tiles must be scored and snapped (for straight cuts) or cut with a wet saw (for curves, L-shapes, and holes)
• Natural stone tiles may need diamond blade cutting only (no score-and-snap)

Straight cuts: Use a manual tile cutter with a tungsten carbide scoring wheel for wall tiles up to 400mm. Score firmly in one pass along the cut line, then press down on the breaker bar. For porcelain tiles over 10mm thick, a wet diamond-blade tile saw is more reliable.

Cuts around pipes: Mark the pipe centre on the tile, drill a hole slightly larger than the pipe diameter using a diamond core drill, then cut the tile in two to place each half either side of the pipe. Cover the cut with an escutcheon plate.

Awkward shapes: Use an angle grinder with a diamond disc for one-off complex cuts. Always wear eye protection and a dust mask — tile cutting dust contains crystalline silica, which is a respirable carcinogen.

Herringbone and Offset Patterns

Herringbone setting out: establish the centre line of the wall, then draw a 45° grid from this centre. One set of tiles runs at +45° and the other at -45°. Starting from the centre ensures the pattern is symmetrical around the focal point. Allow 15% extra for waste in herringbone layouts.

Staggered (brick/offset) pattern: for floor tiles over 300mm in a staggered pattern, BS 5385-3 recommends a maximum offset of one-third rather than one-half (half-bond). This is because large format tiles on slightly uneven substrates can exhibit lippage — one tile edge raised above the adjacent tile — and the one-third offset makes lippage less visually apparent than half-bond.

Frequently Asked Questions

Should I use grout or silicone in the corners of my shower?

Always silicone. Internal corners — wall-to-wall, wall-to-shower tray, wall-to-bath — are movement joints. Building movement, thermal expansion, and the weight of users mean that these junctions flex slightly. Rigid grout at internal corners will crack, allowing water to penetrate behind the tiles. Use a sanitary silicone sealant matched to your grout colour, and rake out any grout at these positions before sealing.

How do I decide where to start on a diagonal floor?

For a diagonal (45°) floor layout, the key reference is the centre of the floor. Find the geometric centre of the floor area, snap chalk lines from corner to corner, and where they cross is your starting point. Lay the first tile centred on this point, at 45° to the walls. Work outward in all four directions from this tile.

What is the maximum size of tile I can use on a plasterboard wall?

BS 5385-1 limits tile weight on plasterboard to a maximum of 32 kg/m² (including tile, adhesive, and grout). A typical 300×300×8mm ceramic tile weighs approximately 5–6 kg/m², well within this limit. However, large format porcelain tiles (600×600mm or larger at 10–12mm thick) can weigh 20–25 kg/m², approaching the limit. Always check the tile weight per m² and ensure the adhesive fixing is appropriate for the substrate.

Do I need to leave a gap between tiles?

Yes. A minimum grout joint of 2mm (small tiles) to 5mm (large format) is required by BS 5385. Tiles nominally installed "butt joint" (touching) will almost certainly crack — the slight variation in tile dimensions means they cannot be perfectly butted, and there is no room for thermal movement. Joint width also helps disguise minor inconsistencies in tile size.

Regulations & Standards

• BS 5385-1:2018 — Wall and floor tiling; design and installation of ceramic, stone, and mosaic wall tiling in normal conditions (internal)

• BS 5385-3:2014 — Wall and floor tiling; design and installation of internal and external ceramic and mosaic floor tiling in normal conditions

• BS 5385-5 — design and installation of terrazzo tile and slab, natural stone and reconstruction stone flooring

• TTSA (Tile Association) — technical guidance documents

• The Tile Association (TTA) — UK trade association; technical guidance on BS 5385

• RIBA Product Selector — Tiling — specification guidance

• British Ceramic Tile — Installation Guidance — manufacturer guidance on layout and fixing

• Mapei Technical Support — adhesive and grout selection guidance

• waterproofing — tanking before tiling in wet areas

• electric ufh thermostats — underfloor heating beneath tiles

• large format tiles — special considerations for tiles over 600mm

• grout repair — maintaining and repairing grout joints