If you notice that your tiles are moving, that there is play between two tiles or that the joints are broken or damaged, it is time to change them, otherwise you risk damaging all the tiles. This wear tends to appear on the parts of the floor where you walk the most. But it is easy to repair the joints without having to change all the tiles.
Start by cleaning the intervention area
Before embarking on the total scraping of the joints in place to replace them entirely, it is better to make sure that the tiles around are in good condition. To do this, just listen to the sound that comes out when you tap it: if the sound is muted, it means that the tiles are well fixed to the ground; otherwise, a hollow sound will come out. In this case, you must first glue the tile and then make the joints. If all goes well on that side, you can start removing the remaining pieces of the joint to be repaired. Scraper, screwdriver and hammer, drill with special drill, multiple solutions exist. A priority remains: be careful not to attack the tiles affected by the joint. After removing the large pieces, a vacuum cleaner helps to sanitize the area.
Rebuild the tile joint
After removing the defective joint, it remains to pour mortar between the tiles. The principle is to apply the mixture on a large surface including the joint to be filled and the surrounding tiles and to smooth everything with a squeegee, being careful to fill the junction of the tiles. Once the mortar is dry, pass a damp sponge over the tiles to clean the traces.