How to Tile Diagonal Patterns for a Backsplash

Use your square and pencil to mark out the border you want for your backsplash, making it level and square.

Spread thin-set mortar on the back of your first trim tile, using a notched trowel. Press the trim tile to the wall on the inside of the first vertical pencil line, just above the counter.

Repeat the process to hang the rest of the trim tiles around the perimeter. Put spacers between them as you hang them. Cut the end tiles as needed to get them to fit.

Use your tape measure, tri-square and pencil to make an X that goes through the center of the backsplash area, with the intersection of the X at dead center. The two lines should be 90 degrees square off each other, even if the backsplash area is rectangular.

Spread mortar over the whole area inside the trim tiles with your notched trowel. The notches will create a combed pattern in the mortar that should still allow you to see the X that you marked across the area.

Set the first standard tile in one of the four corners formed at the intersection of the two lines at the middle of the area (off the center of the X). Set additional tiles off the first one, building your way outward from the center toward the edges. Put spacers between the tiles as you hang them. Hang all the full tiles that will fit.

Measure the spaces between the last full standard tiles around the edges and the inside borders of the trim tiles. The spaces there will be triangular. Cut square tiles to fit, using your tile cutter to cut from the tile corners as needed to get the triangular cuts.

Let the tiles set 12 hours. Remove the spacers.

Grout the backsplash, spreading grout over all the tiles with a grout float, forcing it into the spaces between the tiles while scraping it off the surface. Wipe up the excess grout with a damp sponge.

Let the grout set 24 hours. Run a caulk line along the bottom of the backsplash area where it meets the countertop.