Can I apply microcement on tiles without demolition?

With old tiles, the main factor is whether they are firmly fixed. Hollow pieces, grease in the joints, or uneven levels will sooner or later show through the new layer. Therefore, the tiles are first checked by tapping, degreased, and covered with a reinforcing layer. It's not just about what material the substrate is made of, but mainly about its condition. Before application, check for strength, flatness, grease, dust, cracks, and possible movement. If the surface is risky, it is better to reinforce it or create a test patch first. A more detailed procedure is also available in the related article: https://www.design-solution.cz/content/17-betonova-stěrka-na-obklad-dlazbu