Slanting a Ceramic Floor for a Drain

Clean the surface of your floor with a pH-neutral cleanser, using a mop to scrub away any dirt or debris. Rinse the floor with clean water after mopping it, and then allow it to dry for two to three hours.

Add a slight texture to the floor surface with a floor sander over wooden floors or a concrete grinder if subfloors are concrete. Run the machine over the floor once to create a slightly roughened surface for better adherence of the mud bed materials. Use a broom to sweep debris from the floor.

Use a hacksaw to cut a 3-inch length of PVC pipe of the same diameter as the drain. Place the pipe over the drain to protect it and mark its location.

Place a layer of roofing felt over the floor. Roll the felt out in rows, with the edge of each new row overlapping the previous row by four inches. Cut the felt paper to fit, using a utility knife. Use staples spaced every six inches across the felt to secure the felt to a wooden subfloor. Secure the felt to a concrete subfloor using asphalt mastic under the felt. Spread the mastic with a steel trowel. Cut the felt around the PVC drain marker, and work around the marker placement.

Place metal lath over the felt. Use a two-inch overlap between lath pieces, and cut the lath as needed, using tin snips. Staple the lath to wooden subfloors with six-inch spacing between the staples. Tie the overlapping edges together with wire ties over concrete subfloors, spacing the ties six inches apart. Cut the lath around the drain marker and work around it, maintaining its position.

Measure the distance from the drain to each wall the floor will touch. Make a horizontal line on each of the walls with a piece of chalk at the height of one-third inch for every five feet of distance from the drain to the wall, plus one-quarter inch. This marks the height of the sloped concrete surface at the wall. When you spread the concrete, build it up to this height at the wall, then slope the concrete toward the drain, where the finished height will be one-quarter inch.

Make marks along the floor at five-foot intervals from the drain to the wall, so you can check the height change of your sloping concrete at each point. The height change should be one-third inch for each five feet.

Create the mud bed mixture by mixing four parts masonry sand with one part Portland cement in a wheelbarrow. Use a spade to mix thoroughly. Add a latex additive to the mixture instead of water, and mix the additive into the sand and cement until the concrete is just wet enough to hold its shape when formed into a ball.

Use a trowel to place the mix over the floor. Press onto the concrete as you spread it into place to force the mix through the metal lath and onto the felt below. Begin at the outside edge of the floor, building up the mud to the maximum slope height and then sloping it downward steadily from there. Keep the slope as even as possible, checking at each five-foot mark to ensure that you're maintaining the proper slope.

Run a length of 2-by-4 plank over the mud floor to smooth it while maintaining the desired slope along the floor’s length. Hold the board with one end toward the wall and the other toward the drain, and press lightly. As you drag the board along it will level the slope, smoothing high spots and filling voids in your sloped surface. Watch the base of the board for any large spaces beneath it as you drag it along. You must use your trowel to fill in large voids with more of the concrete mix before continuing. Any large bumps noticeable below the board can be smoothed by slightly increasing the board's pressure.