What Actually Goes Into a Properly Tiled Bathroom Wall?

Existing plaster in dry areas can often be tiled onto directly if it is sound, dry and free of flaking paint, checked by tapping across the surface for hollow patches. Anything hollow or soft gets cut back to solid material.

In wet areas, particularly around a shower or bath, plaster is not enough on its own. We use tile backer board, either cement-based or foam-cored, fixed to studwork or over existing plasterboard, because it gives a stable, water-tolerant base that will not swell or delaminate.

Stud walls being rebuilt as part of a refurbishment are boarded with backer board from the outset rather than standard plasterboard behind any tiled area.

Backer board joints are taped and filled with a proprietary jointing compound so the board reads as one continuous flat surface. Highly absorbent or dusty substrates, including some plasters and old render, get a coat of primer to control suction so the adhesive cures evenly rather than drying too fast at the surface and too slow underneath.

Any existing tiles being tiled over, which is sometimes viable on a sound, flat wall, are keyed and primed with a specialist bonding primer rather than tiled onto directly.

Adhesive is not a single product. Classes under the EN 12004 standard tell you what it can be trusted to do, and using the wrong one is a common cause of tiles coming loose.

We measure the wall and dry-lay or mark out the tile positions before mixing any adhesive, working out from a level datum line rather than starting in a corner. The aim is to avoid slivers of cut tile at an eye-level edge and to keep cuts balanced on both sides of a feature such as a niche or window.

Tile spacers keep joint widths consistent, typically 2-3mm for rectified large-format porcelain and slightly wider for pressed ceramic with a more irregular edge. A laser level or spirit level checks both the horizontal course lines and that the first row is genuinely level, since an out-of-level starting row throws every tile above it out gradually.

Adhesive is combed onto the wall and, for large-format tiles, back-buttered onto the tile itself to achieve full coverage and avoid voids that later crack under pressure or let water track behind the tile. Tiles are tapped in and checked for lippage as they go rather than corrected after the adhesive sets.

Once cured, typically around 24 hours, joints are grouted with a CG2 waterproof grout in wet areas. Internal corners and the junction between wall and bath or tray are left ungrouted and finished with silicone sealant instead, because these are movement joints that rigid grout would eventually crack.