Surface Preparation
First, gently tap the tile with a hammer. If the sound echoes beneath it, this indicates that the tile needs to be repaired. If the foundation requires repair, first scrape off the grout around the tile and remove the tile.
Be careful not to damage the tile while doing this. Then, pour mortar under the tile and reattach it to the desired surface. It’s best to wait for 24 hours after completing this step before proceeding with the remaining tasks.
At this stage, if there are any unusual holes or scratches on the tile, locate and mark them. Be sure to mark the damage based on the depth. For instance, if the damage is deep, use an “H,” and if it’s shallow, use an “L.”
Now, using a grinder, grind down the deep scratches or damaged areas. Continuously check the spot as you work and ensure it’s leveled. After repairing the damaged areas, proceed to sand the entire surface. Use a sanding machine for this step, as it’s important for the surface preparation.
Once sanding is complete, vacuum the surface thoroughly. Next, clean the tiles with warm water and detergent to remove all dirt and stains. Ceramic tile cleaners are suitable for this job.
After cleaning, dry the surface with a towel and wait for two hours to ensure all remaining moisture evaporates.
Tile Installation
What you’ve done up to this point was preparing the surface for installing new tiles. Now, it’s time to prepare for the tile installation itself. Apply a thin layer of mortar over the old tiles.
It’s best not to do this all at once. Instead, divide the surface into smaller sections. Spread a thin layer of mortar in one direction over the old tiles.
If the old tiles are cracked, you’ll need to use a thicker layer of mortar. The thickness of the mortar should be about 6.35 mm. When using mortar, it’s a good idea to opt for powdered types and mix them with liquid latex instead of water.
If the old tile is cracked and you’ve applied mortar over it, for extra strength, you can place mesh tape over the wet mortar. Remember to only apply this tape to the damaged area. At this stage, proceed with installing the new tiles. The rest of the installation steps follow the previously described instructions.
Source: Aseman Magazine