Large-format tile: the preparation decides the result

Large-format tile is the clearest example of a material where the visible work is the easy part. A substrate that would happily take a 150 mm mosaic will show every high spot through a 600 by 1200 mm panel.

Flatness, measured properly

Flatness is not one straightedge reading. It is a survey of the whole plane, taken in several directions, recorded, and corrected. A wall can be perfectly plumb and still be unusable for large format if it undulates.

The tolerance tightens as the format grows. We correct with levelling compound on floors and a render or board correction on walls, and we do it before the tile arrives rather than while it waits on the pallet.

Lippage and why offsets matter

Every tile has a slight curvature along its length. Offset two long tiles by half their length and the high point of one meets the low point of the other, producing a visible edge. That is why plank and large-format layouts are limited to a one-third offset or a stacked pattern.

Full coverage, not five dabs

Large panels need mortar coverage across essentially the whole back of the tile. That means the right notch trowel, troweling in one direction, and back-buttering the tile as well as the substrate.

Voids behind a large panel become cracks later, usually starting at a corner where somebody stood on it.

Handling and cutting

Slab formats need a frame to move and two people to set. Cutting is done with a rail system and a wet saw for the shapes it cannot handle. None of this is exotic, but a crew that does not own the equipment will avoid the format or damage the material.

From the shopLarge-format tile mortarThe medium-bed mortar we use for these formats.From $38 per bag