- 1). Divide the floor into four squares by laying two intersecting lines with your chalk snap line. Lay a carpenter's square at the intersection and adjust the lines as needed to make sure they're exactly perpendicular to each other.
- 2). Cover a few square feet of the middle of the floor with thinset mortar, spreading it down with a notched trowel in one of the four corners formed by the intersection of the lines.
- 3). Press one granite tile in the mortar at the intersection. Put two spacers alongside one edge of the tile, and set a second tile next to it. Set a third and fourth tile in place in the same manner.
- 4). Lay your 3-foot 2-by-4 flat over the tiles you've laid and gently tap the board with your mallet to get the surfaces even with each other.
- 5). Repeat and continue, spreading more mortar laying more tiles. Build out toward the walls in a grid pattern, stopping after every three or four tiles to even out the surface with your board and mallet. Cut tiles at the perimeter of the room on a wet saw as needed to fit.
- 6). Let the mortar set for 10 hours. Remove the spacers.
- 7). Grout the floor with unsanded grout, spreading it over the tiles with a grout float and pressing it into the spaces between the tiles while pulling it off the surface. Wipe up the excess grout with a damp sponge.
Source...