Surface Preparation for Tiling
Thorough surface preparation is essential for successful tiling. It must be clean, flat, dry and firm.
Listed below are the main surfaces that you are likely to find and the preparation necessary for each one.
A newly plastered surface must be left to dry out for at least one month before tiles are laid on to it. With old plaster, make sure that it is perfectly sound, hacking away and making good any loose areas and removing all loose particles with a dusting brush. Treat porous or dusty plaster with a solvent-based primer such as Bal-Primer, to prevent liquid from thefrom being absorbed too quickly.
If the paint film is sound, tiles can be laid straight on top of it, but if you are in any doubt about the strength of the paint film, then it is best to strip it off. Use a sanding disc, not chemical strippers. Avoid using solvent-based.
Old ceramic tiles provide a good surface when they are perfectly flat. Repair any chipped or broken tiles with sand and cement or, and test the remainder to see that they are sticking to the wall properly — any loose tiles must be removed and stuck back on. Wash them down to remove any dirt or grease.
Building boards (, , , plasterboard, etc.)
These materials provide an ideal surface for tiling, but they must be properly braced so that no movement or warping can take place.
Screw the sheets to 75 x 50 mm (3 x 2 in) timbers spaced at 300 mm (12 in) centres horizontally and vertically. If the board has a rough and a smooth side, use the former for the working surface as it will provide better adhesion. Seal the back and sides of the board with an ordinary undercoat against moisture penetration.
Brush the surface down thoroughly to remove any dust or loose material, and rub or wash off any grease.
Only attempt to lay ceramic tiles on to concrete if the surface is perfectly flat and dry.
Leave new concrete for at least 28 days before laying tiles on to it. Brush dry concrete thoroughly to remove any dust and loose material.
Rough and uneven concrete should be cement screeded before tiles are laid on to it. On slightly uneven concrete use a thick bed. Rendering a vertical surface such as a wall is a difficult job which is best left to the professional.
Use a water-resistant grade of adhesive for fixing tiles in a shower area.
The surface must be perfectly clean and dry. Apply the adhesive in an even layer about 3 mm (1/8 in) thick — do not get ridges in it by using a notched trowel.
Allow the tiles to dry for at least 14 days after grouting before using the shower.