 From the midpoint of adjacent walls run a string across the floor. Using a pencil or chalk mark the intersecting guidelines on the floor and remove the strings.
 From the where the guidelines form a right angle in the centre of the room dry lay a single row of tiles  with tile spacers between  towards one wall.
 From the centre of the room dry lay a second row of tiles at right angles to the first. Once again place tile spacers between the tiles so the gap between the tiles is uniform.
 Where there is a gap between the tiles and the wall, draw a line to mark the border edge. If you are left with a narrow gap (less than half a tile width) or the gap is only a little smaller than a whole tile that requires only a narrow strip of tile to be cut away, you will need to move the guidelines by half a tile's width and reposition the first tile to achieve a wider gap around the perimeter of the room. This is important because it is difficult to cut narrow strips from ceramic tiles.
 When you are satisfied with the gap around the room's perimeter, nail a temporary batten around the floor marking out the area where whole tiles can be laid.
 In one corner of the battened area drylay a square of nine tiles. If the tile edges don't meet flush against the batten on both sides, then the battens are not square and will need to be repositioned.

You will need to move the guidelines if the width of the border edge is less than half a tile.
Nail a temporary batten around the floor marking out the area where whole tiles can be laid.
Drylay a square of nine tiles, if the tile edges don't meet flush against the batten on both sides, then the battens are not square.
