iF you need to save money on demolition and to avoid the great part of the renovation mess, tiling over tiles is a great option but the job has to be assest and a few key points have to be considered before the start: The height will be increased for  the floor and walls then you have to adjusts the trims, doors and outlets. Also weight has to be taken into account, make sure that it can handle the substrate.

Lets have a look at this guide.

Stage number 1

 Check the state of the tiles on the wall for:

1. Crack, moisture damage or mold- if you have any of this the tiles have to come off.
2. Check the adherence of the tiles to the wall ( No loose or hollow spots)
3. The surface has to level. If there is any uneven tile it has to be removed.

Stage number 2

The cleaning and preparation of the space:

1. The surface has to be degreased to remove soap scum and wax with a degreaser or TSP(trisodium phosphate).
2.  The surface has to be rough so you have to sand the tiles with 60-80 grit  to make them ready for the bond.
3. The surface has to be wiped clean and dry.

 Stage number 3

The application of the bonding primer:

Apply the primer thoroughly all over the surface.

Use a high-quality primer and then let it dry. ( UltraTile ProPrimer Floor/Wall Primer)

Stage number 4

Choosing the suitable mortar:

Use a thin-set adhesive like RAPID SET FLEXIBLE S1 SP, which is suitable to tile over tiles.

It is important to avoid ready mixed adhesives as these are not suitable and dry out very slow.

Stage number 5

Installation of the new tiles:

You have to apply thin-set with a notched trowel.

Put the tiles firmly applying pressure and use spacers for even grout lines.

Use a levelling system like Genesis to make sure that the surface is levelled.

Stage number 6

Grouting and finishing the job:

Grout has to be applied in 24 hours, for better results use a polymer-modified grout.

In the end you have to seal the grout and  the tiles if required.