Uneven edges on large tiles: what lipping is and how to avoid it

Why big tiles are less forgiving

Most porcelain tiles have a very slight bow from the manufacturing process. On a small tile it is invisible. On a large tile the same curve spans a much wider face, so two neighbouring tiles can meet at slightly different heights. Any unevenness in the wall or floor behind makes it worse.

Low, raking light from a window or downlighter then picks out every raised edge, which is why lipping often looks worse in the evening.

Start with a flat surface

Adhesive cannot fully make up for a wavy wall or a humped floor. Substrate preparation comes first, with backer boarding on walls where needed and levelling on floors, so the tiles have a true surface to sit on.

Using the right adhesive for the substrate, rather than whatever is in the van, also matters. Floors over heating and areas prone to movement need a flexible adhesive.

Back buttering for full coverage

Large tiles are back buttered, meaning adhesive is spread on the back of the tile as well as on the wall or floor. This gives solid contact across the whole tile with no hollow spots, which stops tiles rocking, cracking under load or settling unevenly as the adhesive cures.

Levelling clips hold everything flush

A tile levelling system uses clips under the edges of neighbouring tiles and wedges or caps on top. As they are tightened, they pull adjoining edges into the same plane and hold them there while the adhesive sets. We level large tiles with clips so there is no lipping across a wall or floor.

• Clips sit in the joint under both tile edges
• Wedges or caps pull the edges flush
• Everything stays in place while the adhesive cures
• Clips are snapped off before grouting

Setting out so cuts look intentional

Lipping is not the only thing that spoils large tiles. Awkward thin slivers at the edges draw the eye just as much. We set out every room from the centre line and dry lay before fixing, so cuts land in sensible places and the pattern sits balanced in the room.

Edges are finished with trim or mitres rather than a thick line of silicone, which keeps corners crisp with big porcelain.

Can existing lipping be fixed?

Once the adhesive has set, a proud tile cannot be pushed back down. Minor lipping has to be lived with, and anything worse means lifting and relaying the affected tiles, which risks damaging neighbours. That is why getting it right first time is so important.