Now that you've read part 4 and have your level lines and wall molding in place, you are ready to lay out chalklines, popped across the bottom of the ceiling joists (or existing ceiling), to mark where the runners will be. You need to do some figuring beforehand.
The object of this runner layout is to be certain that no border tile (the tiles that meet the wall) is ever less than half the length of the other tiles (24 inches with 4-foot tiles). To explain this process, an example: Imagine a room that is 10 feet, 2 inches wide. You would first need to convert this measurement in order to be sure the border courses are at least half a tile, and that each border row on the opposing walls is equal.
10 feet, 2 inches converts to 122 inches. This allows you one full 4-foot tile and two border rows of 37 inches each (37 + 48 + 37 = 122). Using your tape measure, snap two chalklines, one 37 inches from each wall, running perpendicular to the joists. These lines will leave a 48-inch space in the middle.
Tip: Locate wall studs by gently tapping on the wall with your hammer and listening for a solid sound (or use a stud locator, which uses a magnet to find nails in the studs).