Tiling a bathroom wall properly is less about speed and more about preparation. A flawless tiled wall depends on a flat, dry and stable surface, the right waterproof adhesive, and careful sealing around every edge and joint. Get those basics right and your tiles will stay put, your grout will stay clean, and moisture will stay firmly on the bathroom side of the wall. Here is how to approach the job with confidence.

Gather the right tools and materials

Before you lift a tile, gather everything you need. Stopping mid-job to hunt for a missing tool breaks your rhythm and your levels.

• Safety kit: dust mask, safety glasses, gloves and knee pads.
• Surface preparation: scraper, filler, sandpaper, primer, tanking membrane or tile backer board for wet zones.
• Setting out: long spirit level, tape measure, pencil, laser level or chalk line.
• Tiling: notched trowel (6mm for small tiles, 10mm for large format), tile cutter, diamond holesaw, spacers, wedges or levelling clips, rubber mallet.
• Finishing: waterproof cementitious adhesive, flexible grout, grout float, sponges, buckets, mixing paddle, silicone sealant and applicator.

Buy 10 per cent extra tile for cuts and future repairs.

Prepare a sound, level surface

The secret to a professional finish is what sits behind the tile. Strip off old tiles, wallpaper or flaking paint. If the plaster is blown, crumbly or damp, repair it before you go any further.

In wet areas — inside a shower, around a bath or behind a basin — ordinary plasterboard is not enough. Fit tile backer board or apply a waterproof tanking membrane. This continuous barrier stops steam and splashes reaching the wall structure. Tanking is vital in shower enclosures, where water can otherwise creep behind tiles and cause mould, rotten timber or damp patches next door.

Check the wall for level with a long spirit level. Fill small hollows with patching compound; larger dips may need a skim coat or backing board. Once dry, sand smooth and prime according to your adhesive. Priming stops porous surfaces sucking moisture from the adhesive before it cures. Dust down and ensure the wall is completely dry before tiling.

Plan the layout before you mix adhesive

Dry-lay tiles along the floor and up the wall to see how cuts fall. Avoid thin slivers at corners or above the bath. If a full tile at one end leaves a tiny cut at the other, shift your starting line so both ends have similar cuts.

Mark a vertical datum line and a horizontal line one tile up from the bath or tray. Use them to keep courses straight. For brick bond, offset each row by half a tile. Plan around shower valves, pipework and niches. Drill pipe holes with a diamond holesaw before tiling, not after.

Use waterproof adhesive and tile methodically

In a bathroom, avoid ready-mixed adhesive in wet zones. Choose a powdered cementitious adhesive labelled waterproof and suitable for your substrate and tile. Mix precisely, leave to slake, then mix briefly again. Aim for a stiff but spreadable consistency.

Apply adhesive with a notched trowel at a consistent angle. For large or heavy tiles, back-butter with a thin, even coat. Press and twist each tile so adhesive spreads fully behind it. Never rely on corner blobs — hollow spots trap moisture and crack easily.

Insert spacers as you go. A 2mm or 3mm joint is typical; larger tiles may suit 3mm to 5mm. Check level every few tiles, and use wedges or clips to keep neighbours flush. Wipe excess adhesive from joints and faces before it sets. Work in manageable sections so adhesive does not skin over.

Grout and seal carefully to prevent moisture damage

Wait until the adhesive is fully cured — usually 24 hours, but check guidance. Mix flexible, water-resistant grout and work it diagonally into joints with a rubber float. Press firmly so every gap fills, then scrape off excess. Clean tiles with a damp sponge, rinsing often. Avoid flooding joints, which weakens grout as it cures.

Once cured, seal cementitious grout with an impregnating sealer to repel water and stains, especially in a shower. Epoxy grout needs no sealing but is less forgiving. The most critical step is silicone, not grout, at internal corners, along the bath or tray, and around pipe collars. Use mould-resistant sanitary silicone, smoothed with a tool or soapy finger. With an acrylic bath, fill it with water before applying silicone, then drain after curing, so the seal moves with the bath.

Finally, leave everything undisturbed for the full curing time before showering. Patience now protects all your work — and keeps moisture in the water, not in your walls.