@Róbert Pagáčik - we are about to embark on a similar project. I have a rammed earth house with poured earth floors from the 60s. The bathroom floor has been covered in linoleum and I am planning to tile.
When you mention material between the flooring and the tiles – what are you using? Is it literally just the same plaster you used for the floors and walls?
How has your floor held up? What kind of grout did you choose?
I have been using a plaster mixture of clay, masonry, sand, and cattail (plant) fluff for my walls. My floors have not been touched other than to remove the linoleum.
