If you don’t prep it right, you may as well have the 8 year old neighbor kid put in the tile.

On concrete; occasionally the floor is so out of flat, (picture on the left) , that a jackhammer and bush head needs to be used to flatten it out prior to tile. (picture on the right)

For very large tiles, or slate or on uneven floors LASH clips can be used-these  are clips that fit under the tile, then a wedge is inserted above the tile to pull he tiles up to perfectly align the top face.  It makes for a  wonderfully flat floor.

 Tile on a wood floor-a wood floor will flex and over time the grout will flake out.. First a cement board or fiberboard  underlayment needs to be installed.  A layer of mortar is troweled on first, then it gets screwed  6” in each direction.  This will form a solid base to install the tile.

Preparation is critical!