Bathroom Tile Setout Explained

What setout is

Tile setout is the planning step that decides where the tile grid starts, which direction tiles run, and where cuts fall at every edge and obstacle in the room. It happens before a single tile is fixed.

The setout module is straightforward: tile face width plus one grout joint. A 600mm tile with a 3mm joint has a 603mm module. Every grout line across the floor or wall follows that grid. Fix the joint width first, because changing it shifts every cut dimension across the whole installation.

The setout drawing records the datum point (the grid origin, typically marked with a cross), the grid lines radiating from it, and the cut dimension at every edge, fixture, and opening.

Why it matters before work starts

Setout affects more than appearance. Where the tile grid lands determines three things that are hard to change once framing or plumbing is set.

Niche placement. A shower niche sized to a tile multiple (for example, two tiles wide by two tiles tall) sits cleanly in the grid. Ignore the module and you get awkward slivers on all four sides that no amount of careful tiling can fix.

Shower screen channel position. The channel should land on a tile face or a grout joint, not bisect a tile arbitrarily. That decision needs to be made before the screen is ordered and before the frame is fixed to the substrate.

Plumbing rough-ins. A wall tap centred on a tile face looks intentional. One positioned 80mm off a grout line looks like it was placed without a drawing. Rough-in positions can often be shifted 50 to 100mm before the slab is poured or the frame is lined, at no cost. After that, they cannot.

Industry practice is clear on the core rule: cuts smaller than half a tile should be avoided, and the target for any tiled space is equal-sized cuts on opposing sides. Poor setout in a bathroom is visible for the life of the building.

Planning the grid

Shower floor. Start from the floor waste and work outward. The NCC Housing Provisions require a continuous floor fall of at least 1:80 to the waste (maximum 1:50). That fall requirement, combined with the waste position, drives the floor grid. Standard circular or square wastes limit floor tile size to 300x300mm; larger tiles cannot achieve the required fall without lippage at the corners. A lineal (strip) drain removes that constraint, because the fall runs in one direction only, and large-format floor tiles work.

Shower and feature walls. Set out from the centre of the most visible wall first, typically the shower's back wall. Dry-lay a row of tiles with spacers to simulate grout joints and check where cuts land at both ends. If the unshifted grid would produce a cut smaller than half a tile at either side, shift the starting point by half a module. Wall tiles run from a horizontal datum line (one tile height above the floor), with the bottom row cut to the actual floor level installed last.

Large-format tiles. A 600x1200mm tile works cleanly in a standard 2.4m-ceiling room: two tiles stack full-height with no horizontal grout line mid-wall. But larger tiles amplify any setout error, so the documentation needs to be precise before anything is ordered or fixed.

What AS 3958:2023 says about joint widths

Australian Standard AS 3958:2023 (Installation of ceramic and stone tiles) specifies grout joint widths by tile type. For floors: 3mm joints for dust-pressed tiles, 6mm for extruded tiles. For walls: 1.5mm joints for dust-pressed tiles, 6mm for extruded tiles. These are not design choices; they follow the tile type and its manufacturing tolerances.

The joint width is also the number that determines the full setout module. It needs to be agreed on before any grid calculations are done, not decided on site.

What a setout drawing includes

A complete tiling setout drawing covers:

• The datum point and grid lines at the correct module (tile face dimension plus joint width)
• Cut dimensions at all walls, around niches, and at the floor waste
• Perimeter movement joints, which isolate tiles from walls and fixed fittings per AS 3958:2023
• Confirmed grout joint width, which flows through to every cut dimension in the room

Where Form & Fixture fits

The floor plan and internal elevations in a Form & Fixture package show room dimensions, fixture positions, and tile extents on every wall. A tiler can use them directly as a setout reference: the grid, the fixture positions, and the cut locations are already drawn.

That means the builder, tiler, and client are aligned on the grid before the first trade arrives. Builders on a membership get white-label drawings they can hand straight to their tiler and client under their own name.

Decisions made at drawing stage are free. Decisions made during tiling are not.