Marking Up for Laying Floor Tiles
Lay ceramic tiles so that they are square in relation to the doorway — when you enter the room the line of tiles must run away squarely from you towards the back of the room. This is particularly important with odd-shaped rooms that are neither square nor rectangular.
Mark a line on the floor, at right angles to the doorway, running from the centre of the door to the back of the room.
Take a spare length of wood and divide it into tile lengths, as previously described in Guide to Wall Tiling. As floor tiles do not have any spacer lugs, you must allow a 3 mm (1/8 in) gap between the tiles.
Use this wood as a measuring staff.
Starting from the door jamb with your first full tile, use your measuring staff to divide the centre line off into tile widths. It is very unlikely that a number of full tiles will fit exactly into the length of the room, and you will have to cut tiles to fit right up to the wall. Mark the point near the far wall where the last full tile will finish.
Nail a wooden batten across the width of the room at the point where the last full tile finishes. The batten must be at right angles to the centre line, no matter what angle the back wall makes.
Nail another batten at the left-hand end of the first batten to give you a perfectly square corner. This corner is where tiling will start.
The angle between these battens must be accurate since the slightest error at the beginning of the work will be greatly magnified by the time you reach the opposite corner of the room.
You can adjust the position of the second batten if it is important that the cut tiles at either side of the room should be the same size. This is not really important if the tiles are all of the same design and do not have to form a pattern.