How to Lay Tiles Diagonally

Michael Straessle

Just as there are a few options available when laying tile perpendicular to the walls of a room, there are also a few options available for laying them diagonally. The key to designing a diagonal tile floor is the planning stage.

Here's one way

Once you know the dimensions of the tile you want to use, grab some graph paper and draw out the desired plan.

  1. Locate the center of the room by measuring and marking the midway point between the four walls, two at a time. It is important that this be as exact as possible. Once you have the center marked, you will need to measure the distance from the wall to the center point from another spot on the wall. For example, if your center point measurement is 78 inches, move the measuring tape a few feet over and make another mark at 78 inches. The objective is to have two marks from which to draw a line.

  2. Measure the distance from one corner diagonally across to the other corner of the tile. Center this measurement on the center mark and the line. For example, if the tile is 12 inches across from corner to corner, measure from the center point of the room six inches in one direction on the line and six inches in the other direction on the line.

  3. Place the corners of the tile on the marks from Step 2. Draw the outline of the tile onto the floor. Next, if the sub floor is wood, lay the 1-by-2-by-48-inch lumber on any of the four lines representing the tile. Secure it to the floor with drywall screws. This is your starting edge; it will help you maintain a straight line while setting the first tiles.

  4. Mix the thin set mortar according to manufacturer instructions. Apply enough thin set mortar to lay four tiles with the mortar trowel. Place the tiles on the mortar against the one-by-two, inserting the spacers between the tiles. Once you reach the end of the one-by-two, start a second row adjoining the first. Lay as many tiles as the one-by-two will allow. Let this set overnight and begin in the opposite direction the next day.

  5. Cut the final pieces by measuring their size and shape and drawing it on a tile with the wax pencil. Make your cuts precise with the wet saw. Once the tile is cut and laid, allow the thin set mortar to dry overnight before applying the grout.

  6. Remove the spacers and clean out the grout lines if necessary. Mix the grout according to the manufacturer's instructions. Apply it with the grout trowel using a crisscross motion. This forces the grout into the grooves between the tile. Use a sponge and a bucket of water to clean excess grout from the tile, wringing the sponge often. A residue will show up as a haze after few minutes. Polish it off with a soft cloth.

  7. Allow the grout to set for 72 hours. Apply grout sealer with the applicator. Try not to get the sealer on the tile, as it will affect the sheen of the tile.

  8. Tip

    Always wear safety glasses. Work the tile into the wet saw blade slowly to prevent chipping. These principles work for any size or type of tile.


    Do not handle fresh cut edges with your fingers to avoid cuts.

    Do not apply any more mortar or grout than you can work with before it dries.

    Do not breathe the dust from cutting the tile.