How to Lay Floor Tile for a Floor Drain When the Floor Slopes

Remove the drain strainer and stuff a rag down the open drain hole to keep any mortar from entering your pipes.

Remove any existing tile or flooring until the sloped underlying cement or floor mortar is exposed. Thoroughly clean the area, using a broom or vacuum to sweep up the larger debris and a damp rag to wipe up the leftover dust. Use a level to check the original slope of the clean floor.

Inspect the floor for damage such as cracks, large holes and extremely chipped spots or uneven areas. To repair the floor, mix a small batch of floor mortar and apply a thin, even layer with a trowel, ensuring you preserve the original slope by using your level as you go. Fill in any cracks or holes you pass over and apply the coat evenly. Allow the floor mortar to dry overnight.

Measure the thickness of the tile with a ruler. Reattach the drain strainer to the drain, adjusting it to allow for the thickness of your tile and 1/2 inch for the thinset mortar. For example, if your tile is 1/4 inch thick, add this amount to 1/2 inch, so you would adjust the drain strainer to 3/4 inch off the floor.

Draw a reference line on the walls surrounding the work area with a pencil, using a ruler to mark the line 3/4 inch off the floor. This will help to preserve your original slope as you lay down your tile.

Sketch reference lines in pencil, forming a grid on your floor, and dry-fit your tiles against the reference lines. Adjust your tiles as necessary to fit around the drain, the wall corners and any other obstacles.

Mix a batch of thinset mortar according to the manufacturer's directions. Apply the mortar evenly over the floor surface, using the notched edge of the trowel, working across the floor in small quadrants at a time. Use a soft rubber mallet to gently tap each tile into the mortar and place your spacers around the tile as needed. Place a small two-by-four board on top of several of the tiles you have laid down and use the rubber mallet to tap on the board to ensure the tiles are set into the mortar evenly.

Run your level as you lay down the tile to ensure you preserve the original slope. As you reach the walls, the top of your tile that touches the wall should be the same height as the reference lines you drew. Remove your spacers, using needle-nose pliers, and allow the mortar to dry overnight.

Make a batch of grout according to the manufacturer's directions. Spread the grout over your tile project, using a grout float and filling in all joints. Apply the grout in a figure-eight motion across the tiles.

Remove the excess grout with your float and wipe up the floor clean, using a damp sponge. Allow the grout to dry completely and spread the grout sealer over the grout lines, using a small sponge brush. Wipe up any excess sealer immediately

Apply some silicone caulk around the corners of the wall that touch the tile. Allow everything to dry before you use your drain.