TILING

Tile over existing tiles

Prepare, key, and stick new tiles straight over sound old ones, then grout, seal and refit fittings safely.

TOT-01Clear the room and check the existing tiles are soundTake down blinds, mirrors and anything hanging on the wall, and lay dust sheets to catch dust and scrapings. Tap every existing tile with a knuckle - a dull, hollow sound or any movement means it isn't bonded and needs fixing or replacing before you start. Press each tile corner and check grout lines for cracks. If more than a handful move, tiling over the top isn't safe - strip back to a sound surface instead.
1 each · Dust sheet
1 each · Masking tape
TOT-02Work out your wall type before you commitTiling over tiles roughly doubles the weight on the wall, so find out what's behind it first. Use a stud detector, or drag a strong magnet slowly over the wall to pick up the screws fixing the plasterboard - a regular line of screws means a stud behind it. Tap along the wall: a solid, dead sound means brick, block or a stud; a hollow, drum-like sound means you're between studs or over a dot-and-dab void. A 3mm pilot hole in an inconspicuous spot giving pale timber dust means a timber stud; fine grey swarf means metal.
1 each · Stud detector
TOT-03Remove old fixtures and old sealantUnscrew any soap dishes, grab rails or toilet roll holders fixed through the old tiles. Cut out old silicone along the bath or basin edge with a sealant removal tool or a sharp blade. If a screw is painted over or won't shift, don't force it - drilling or levering it out is still work on the wall. Check with a detector first, and know where your stopcock is (usually under the kitchen sink) so you can shut off the water fast if you nick a pipe.
1 each · Sealant removal tool
1 each · Flat-head screwdriver
TOT-04Clean and degrease the surfaceWash the whole area with sugar soap and a cloth to strip off soap scum and general grime. Rinse with clean water and let the wall dry fully - adhesive won't bond to a damp or greasy surface. Wipe down any skirting or edges that will be covered by new tile too.
1 each · Sugar soap
2 each · Cloth
TOT-05Key the glazed surfaceGlazed tiles are too smooth for adhesive to grip properly. Rub every tile with a fine abrasive pad or 120 grit sandpaper to dull the shine, or brush on a specialist tile bonding primer instead and let it dry as the tin says. Skip this and the new tiles can slide or fall off later, even if they look stuck at first.
1 each · Fine abrasive sanding pad
1 each · Tile bonding primer
TOT-06Plan your layout and mark a level lineDry-lay a row of new tiles along the bottom of the wall to check spacing and avoid thin slivers at the ends. Use a spirit level to mark a horizontal line about one tile height up from the bottom - this is your starting line, not the floor or bath edge, which are rarely level. Mark vertical guide lines too if the wall is wide.
1 each · Spirit level
1 each · Pencil
1 pack · Tile spacers (2mm)
TOT-07Mix the adhesiveUse a flexible, tile-on-tile rated adhesive - ordinary adhesive isn't designed to grip an existing glazed surface and can fail. Mix small batches in a bucket with a paddle mixer, following the bag's water ratio exactly. Only mix what you can use in 20-30 minutes before it starts to go off.
1 20kg bag · Flexible tile adhesive (tile-on-tile rated)
1 each · Mixing bucket
1 each · Paddle mixer attachment
TOT-08Apply adhesive and fix the new tilesSpread adhesive with a notched trowel, combing it into ridges so air can escape and tiles bed in flat. Work in sections of about 1m² at a time, starting from your marked line. Press each tile in with a slight twist, check it's level, and insert spacers as you go.
1 each · Notched trowel (6mm)
1 m2 · Wall tiles
1 pack · Tile spacers (2mm)
TOT-09Cut and fit edge tilesMeasure each gap at the ends, top and around fittings, and mark the tile face-side up. Score and snap with a manual tile cutter for straight cuts, or use a tile saw for notches around pipes. Fit these last, once the main field of tiles is set.
1 each · Manual tile cutter
1 day · Tile saw hire
TOT-10Leave the adhesive to cureRemove spacers once tiles are firm, usually after a few hours, but leave the wall undisturbed and don't grout for at least 12-24 hours, longer in a cold or damp room. Check the adhesive tub for the exact time - rushing this is the most common cause of tiles slipping.
TOT-11Grout the tilesMix a flexible grout suited to tile-on-tile, and push it into the joints with a rubber grout float held at an angle, working diagonally across the joints. Wipe off excess with a damp sponge before it dries hard, and buff off the haze with a dry cloth once fully cured.
1 5kg bag · Flexible grout
1 each · Grout float
1 each · Sponge
TOT-12Seal the edges with siliconeRun a bead of sanitary-grade silicone along the join between the tiles and the bath, basin or worktop, and along any internal corners. Smooth it with a wet finger or sealant tool for a clean, waterproof line. Leave it to cure fully, per the tube's instructions, before the shower or bath is used.
1 tube · Sanitary silicone sealant
1 each · Sealant gun
TOT-13Drill and refit accessoriesFor anything screwed back into the wall - a soap dish, grab rail or toilet roll holder - drill through the new tile with a tile bit first, then switch to the right bit for the wall behind. Before drilling anywhere, use a cable and pipe detector, but still expect something's there: know your stopcock (usually under the kitchen sink) so you can shut the water off fast, and if there's any doubt, isolate the circuit at the consumer unit first. Into solid brick or block, drill to the plug's stated depth and fit the correct plug and screw. Into a timber stud, drive a wood screw straight into its centre, no plug needed. Into a metal stud, use a self-drilling metal-stud fixing or a toggle-type hollow-wall anchor - a plain plastic plug or a wood screw strips straight through 0.5mm steel. Into plasterboard between studs, or through dot-and-dab into the void, use a toggle or hollow-wall anchor rated for the item's weight, or one long enough to reach the masonry behind the dab. A metal stud alone won't hold a grab rail meant to take a person's weight - fix through to a timber noggin or the masonry behind it instead.
1 each · Tile and glass drill bit
1 each · Masonry drill bit (6mm)
1 pack · Rawlplug (wall plug)
1 pack · Wood screws
1 pack · Metal-stud toggle fixing
1 each · Cable and pipe detector

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