Some manufacturers will say the grout joint can be as slender as 2 mm (1⁄16 in.), but this author by no means recommends lower than 4 mm (1⁄8 in.). Whether making use of thinset to the mortar or substrate, apply a minimal of 1/four-inch-thick mortar mattress, often achieved with 1/4-inch notches in the thinset trowel. Use a wet toothbrush to clean thinset from the grout joints between tiles as you put in. This will provide a deeper base for the grout to anchor the tile. Continue this process, working forwards and backwards throughout the room and overlaying 2-foot square areas at a time.
If you ask, they may probably allow you to mix slightly Thinset, apply it to the check surface, and install a few tiles. By doing this, you get the feel of thickness of the Thinset and the way to trowel the Thinset to the floor. Remove all …
