Tiling over your existing tiles can save you money and time, but not all tiled surfaces are suitable for this type of installation. What are the most important factors to consider when completing a successful tile-on-tile application? TAL offers some tips on how to get it right.

Important considerations before you consider tiling over existing tiles
Note that TAL does not recommend tiling over natural stone tiles such as sandstone, slate, etc., as these natural stone products tend to delaminate, and are therefore not considered a stable or suitable background for tiling. The floor level will rise with the extra layer of tiles so carefully check how this floor will match up to the existing floor and consider that doors may need to be trimmed.

Step 1: Prepare the area and tiles
It is important that the existing tiles are in good condition and attached firmly to the background.

The existing tiles should be cleaned thoroughly to remove all traces of dirt, grime, polishes and sealants. Any surface contamination will impair the adhesive bond onto the existing tiles and can cause the new tiles to be hollow-sounding and/or loose.

All existing cracked, damaged, loose or hollow-sounding tiles must be identified and removed before installing the new tiles. Tiling over hollow-sounding tiles can result in this hollow sound being echoed in the new tile installation, even if they are solidly bedded in adhesive, while tiling over cracked tiles can result in reflective (mirrored) cracking in the new tiles.

The surface must to be primed before applying the adhesive to ensure a good bond onto the existing tiles. The adhesive can be applied once the slurry priming coat is touch-dry (i.e. no visible transfer when wiped or rubbed).

Step 2: Buy the right adhesive system
When tiling onto existing tiles, it is important to use only a quick- or rapid-setting adhesive, as the existing tiles will present a dense, impervious surface, which requires a chemical bond.

Step 3: Install movement joints
The lack of movement joints in tile installations is a major cause of tile failure. When tiling over existing tiles, the existing structural and movement joints must be maintained in the new tile installation. The movement joints should be at least 5mm wide and extend through the adhesive and both tile layers.

For more information, contact Tal on Tel: +27 (11) 206 9700 or via www.tal.co.za.