The quality of any tiling job is largely dependent on the surface to which the tiles are fixed. This should be firm, level, clean and dry with unwanted fixtures such as hooks and screws removed beforehand.
Most surfaces require only a little preparation before they are tiled. A few, though, need more extensive treatment: in such cases, think carefully before you commit I yourself to ceramic tiles.
Plaster: Minor bumps and cracks can be filled with a proprietary plaster filler. The entire surface should then be given a coat of plaster primer, to provide a non-porous base for the adhesive. If the surface is very uneven, it should be replastered and left for a month before being sealed and tiled.
However, rough surfaces can often be relined with plywood, chipboard or plasterboard. To do this, you will need to plug and screw wood battens – 25mm x 25mm will do – to the wall at regular intervals. Make sure that each batten is vertical, using wood chips to pack any gaps between the wood and the old wall surface.
Before screwing your panelling material to the battens, give each strip a thorough coat of wood sealant. As you secure the panels, plan your work so that adjacent ones butt up against each other over the centre of a batten. Wallpaper: On no account should tiles be laid on to wallpaper. Strip the wall back to the bare plaster, then fill and level as described above. Painted walls: Providing these are smooth and firm, tiles may be applied direct. But flaking or rough paint should be partially stripped with medium glasspaper and brushed clean. Timber walls: These must be sanded or planed level and treated with wood primer before the tiles are applied. Existing ceramic tiles: The ideal tiling surface, providing the tiles are clean, firmly fixed and not chipped.
Constructing a baseline
Before you start tiling you will need a horizontal baseline from which to work – floors and skirting boards are not suitable, as they are seldom completely level and can throw the tiling out of true.
To draw a baseline, measure the height of a tile from the floor or skirting board and make a mark. Using the spirit level as a straight edge, check for level and draw a line through this mark.
Finally, pin the top edge of a batten along the line so it forms a level base, right along the length of the surface to be tiled.
Late, when you have tiled above it, you can remove the batten and fill in the space below. The tiles here may have to be cut or trimmed.
Tiling around windows
Arrange the tiles to achieve a good visual balance with cut tiles of equal size on each side of the window. When tiling recessed window sills, fit any cut tiles at the back and in the corners where they are not so obvious. Make sure that patterns are kept continuous, and finished surfaces smooth, by placing the spacer lugs of any cut tile against those of the adjacent tile.
Use round-edged tiles at the front of sills, lapping them over the edges of the wall tiles to form a smooth, rounded edge.
Marking a side line
To keep the tiles exactly square to the baseline, you will also need a vertical line at one side of the surface. Find the centre point of the batten and mark out the tile widths along either end of the wall. Draw your line where the last full tile ends on the lefthand side, using the spirit level – or a plumb line – to give you an accurate vertical line.