It’s a good idea to make fixings in tiled walls by drilling into grout lines wherever possible, but sometimes drilling through the glaze is unavoidable. Drilling through tiles creates a lot of fine dust, which may stain nearby grouting. To catch the dust, make a simple cardboard tray and stick it to the wall with masking tape or get someone to hold a vacuum-cleaner nozzle near the drill tip as you drill the hole.
Tools: Drill; small masonry bit to make pilot hole and larger one to suit the screw, or sharp spear point bit; chinagraph pencil; screwdriver; possibly steel ruler.
Materials: Masking tape; wallplugs; screws.
Decide where you want to make the screw fixing and mark its position on the surface of the tile with a chinagraph pencil.
Stop the point of the masonry bit from skating over the smooth tile surface by sticking a piece of masking tape over the mark, which should show through it. Re-make the mark on the surface of the tape. If you need to make more than one screw hole, use a strip of tape to cover both hole positions and mark them on the tape.
Make a pilot hole with the small masonry bit. Press the tip firmly against the mark on the tape. Check the drill isn’t on hammer action, and start at a low speed. Drill slowly and carefully through the glazed surface of the tile. Stop drilling when the bit starts to penetrate the plaster. Using a small bit to do this minimises the risk of cracking the glaze. Repeat the process if necessary to drill a second hole through the other mark on the tape.
Switch to the bit that matches the screw size you intend to use. Position its tip in the hole and drill slowly and carefully through the tile and the plaster and well into the masonry.
Alternatively You can buy a special ceramic tile bit with a sharp spear point.
Its shape is designed to break through the glaze immediately. This minimises the risk of skidding across or cracking the tile. The bits are available in a range of sizes.