When i tile diagonally on a wall i always use a straightedge in the middle of the wall.
How to lay tile diagonally wall.
This is a fold.
Diagonal tile installations draw the eye out to the sides of the installation visually widening and enlarging the space.
Then every subsequent row is a process of draping over the pyramid back and forth.
If the wall is really large i use a square to keep the corners lined up.
Install tiles one through four as directed.
If you are laying the diagonal tiles over the entire backsplas simply drawing a chalk line from one corner to the opposite will not work.
Instead you need to find the 45 degree angles on the wall.
The best way is to arrange your wall tile in a pyramid shape.
Because tile laid on a diagonal has half tiles or pieces of cut tile along each edge of the installation a lot more tile is required to complete the job.
There are only two ways to handle an inside corner with diagonal tiles.
Using a wet saw cut one tile into a triangle diagonally from opposite tip to opposite tip.
If it seems complicated try this.
Homeowners often shy away from diagonal tile layouts also called bias layouts in a bathroom.
Lay half of first tile with cut side facing 90 degree corner and tips almost touching walls at a 45 degree angle.
Dry fit a row of tiles along each diagonal line.
For the tiles near the center line up the two sides of the tiles with the diagonal lines and the opposing corners of the tile with the straight.