do everything and what thickness of mortar between the tiles and the floor should be observed
If the bathroom has timber floor boards with a covering on top remove any plastic tiles or old carpets and lay thin plywood on top screwed down to the floorboards as a solid base for the new tiles (you omit this if the bathroom has a concrete floor) then either buy some floor tiles adhesive (for plastic tiles) or mix some tile cement (for ceramic tiles) spread the adhesive /tile cement on the floor base using a slotted trowel that applies the adhesive/cement in rows, then follow the adhesive/cement makers instructions to leave for a period - then lay the plastic tiles edges butting or ceramic tiles with plastic spacers to allow for the grout to be added between the tiles, start from the back working obviously towards the door. You can unscrew the toilet pan and slide tiles underneath likewise the bathtub panels remove to fit the tiles underneath (note you will have to trim the bathtub panel so it can be re fitted over the tiles, you may wish to tile up to baseboards (skirting UK) or remove them and tile underneath. As you can see this job is quite involved -do you have good diy skills? Otherwise leave to a pro to tile it for you maybe you can buy the tiles and he lays them?
Depends what kind of tile, large? small inch tiles? Either way, a cement board floor should be installed first.Most grout gaps are 1/8th inch or less.
