Tiling a shower floor and tiling a shower wall are two different skills that happen to use the same materials. The wall is vertical, the tile is larger, and the cuts are around a shower head and a valve. The floor is horizontal and sloped, the tile must be small enough to follow the compound angle toward the drain, and the cuts are around a circular drain grate that sits at the lowest point of four converging planes. Doing both in the same project means switching between two different mindsets and two different sets of constraints while keeping the transition between them watertight and visually seamless.
The order of operations is not optional. Tile the walls first, leaving the bottom row of wall tile off. Tile the floor second, cutting the floor tile to fit under the bottom row of wall tile. Install the bottom row of wall tile last, overlapping the floor tile. This sequence, called walls before floor with a ledger board, ensures that water running down the wall drips onto the floor tile rather than into the joint between the floor and the wall. It also means you are not kneeling on freshly set floor tile while you finish the walls, which is how floor tile gets cracked, lippage gets introduced, and the entire floor has to be redone because a knee landed on a tile that was not fully set.
Tiling the Walls — Start Above the Bottom Row and Work Down
Screw a straight ledger board into the wall at a height equal to one full tile plus the width of a grout joint above the shower pan or the floor waterproofing. The ledger board supports the weight of the tile above it and keeps every row level. Use a level to draw a horizontal line at the top of the ledger board, and use a level to draw a vertical center line on each wall. The center line is where the layout begins. Starting from the center and working outward to the corners ensures the cuts at both ends of the wall are equal in width. A half-tile cut on the left and a half-tile cut on the right looks intentional. A full tile on the left and a two-inch sliver on the right looks like a mistake.
Spread thinset on the wall with the flat side of the trowel, then comb it with the notched side at a consistent forty-five-degree angle. Comb in one direction. Press each tile into the thinset with a slight twisting motion and check periodically by pulling a tile back off the wall. The back of the tile should be nearly completely covered with thinset, with the ridges flattened into a continuous bed. Spot-bonding, putting a dab of thinset in each corner and pressing the tile on, is how tiles fall off the wall a year later and how water collects in the air pockets behind the tile. In a wet area, coverage must be at least ninety-five percent.
Work row by row from the ledger board up. Set spacers between every tile, checking the alignment with a level after every row. A tile that is a sixteenth of an inch out of alignment at row three will be a quarter inch out by row eight, and the only fix is to pull off every tile back to the error. Small errors compound. Fix them immediately while the thinset is still wet. A tile that is crooked and has been on the wall for ten minutes costs thirty seconds to reset. A tile that is crooked and has been on the wall overnight costs an hour to remove, clean, and replace.
Cut the tile around the shower head and the shower valve as you reach them. The shower head cut is hidden by the escutcheon plate and does not need to be perfect. The shower valve cut is partially hidden by the trim plate, but the plate only covers about half an inch around the valve. Cut carefully. A jagged or oversized hole around the shower valve is the most visible mistake on any tiled shower wall. Use a diamond hole saw for the circular valve opening, and nibble the rest with tile nippers if the opening is not perfectly round.
When the walls above the ledger board are tiled and the thinset has cured for at least twenty-four hours, remove the ledger board. Fill the screw holes with waterproofing sealant. The bottom row of wall tile will be cut to fit and installed after the floor is tiled.
Tiling the Floor — Small Tiles, Compound Slopes, and the Drain
Shower floor tile must be small. A tile larger than four inches cannot follow the compound slope of a shower pan that drains to a center point. The floor slopes toward the drain from four directions, creating four triangular planes that meet at the drain. A rigid tile that spans across two of these planes will rock on the high point and leave a gap under the low point. Mosaic tile in sheets, with individual tiles no larger than two inches, conforms to the slope and provides the grip that smooth large-format tile cannot. The smaller the tile, the more grout joints, and the more grout joints, the more traction. A shower floor is not the place for large-format tile.
Dry-lay the mosaic sheets on the floor starting at the drain and working outward toward the walls. The goal is for the drain grate to sit as close to flush with the tile surface as possible, slightly below it, never above it. A drain grate that sits above the tile creates a lip that catches debris and pools water. The four tiles surrounding the drain will need to be cut to fit the circular grate. Mark the cuts with a pencil, cut the individual tiles with tile nippers or a wet saw, and dry-fit every piece before mixing thinset. The drain cuts are the most time-consuming part of the floor, and rushing them produces a grated area that looks like an afterthought.
Spread thinset on a small section of the floor, comb it in one direction, and press the mosaic sheets into it with a grout float or a flat piece of wood. Do not press with your fingers. Finger pressure sinks individual tiles deeper than their neighbors, producing a wavy surface. Align the seams between sheets so the gap between sheets matches the gap between tiles within the sheet. A seam that is wider or narrower than the internal gaps will be visible through the grout. Work from the drain outward, cutting the perimeter sheets to fit against the walls. The edges of the floor tile will be covered by the bottom row of wall tile, so the perimeter cuts do not need to be perfect.
Finishing the Walls, Grouting, and Sealing
After the floor tile has cured for at least twenty-four hours, cut and install the bottom row of wall tile. Measure each tile individually because the floor slopes and the distance from the floor to the bottom of the installed wall tile varies across the width of the wall. Cut each tile to fit with a gap of an eighth of an inch between the bottom of the wall tile and the floor tile. This gap allows for expansion and will be filled with silicone caulk, not grout.
Grout the walls and the floor in that order, using the appropriate grout for each surface. Wall grout joints are typically narrower and can be unsanded. Floor grout joints are typically wider and should be sanded for strength, unless the mosaic tiles have joints narrower than an eighth of an inch. Wait at least twenty-four hours after grouting the walls before grouting the floor if you are doing them on different days, or grout them together if the entire shower is ready. Protect the floor with a piece of cardboard or a drop cloth while grouting the walls to keep grout droppings off the fresh floor grout.
Seal the grout on both surfaces after it has cured for forty-eight to seventy-two hours. A penetrating sealer applied with a small foam brush keeps water and soap scum from soaking into the grout. Reapply sealer to the floor grout every year. Reapply to the wall grout every two to three years. A shower that is used daily puts more water on the floor grout in one week than the wall grout sees in a month. The floor needs more frequent sealing.
Apply silicone caulk, not grout, to every joint where two different surfaces meet. The joint between the floor and the walls, the joints in the corners where two walls meet, and the joint around the shower valve trim plate all get caulk. Grout in these joints will crack because the walls, floor, and fixtures expand and contract at different rates. A bead of color-matched silicone caulk costs ten dollars and replaces cracked grout in six months. Run the bead, smooth it with a wet finger, and let it cure for twenty-four hours before using the shower.
FAQ — Tiling a Shower Floor and Walls
Can I tile the floor first and then the walls, to avoid having to cut the bottom row?
You can, but you should not. Tiling the floor first means you must protect the finished floor while working on the walls for several days. A dropped tile, a dropped trowel, or a misstep on a knee will crack the floor tile. The thinset on the floor must cure completely before you can kneel on it, which adds a day to the project. Tiling the walls first with a ledger board, then tiling the floor, then cutting in the bottom row is the standard sequence for good reason. It protects the floor, it allows you to work on the walls without constraint, and the bottom row covers the edges of the floor tile for a clean transition.
Can I use the same tile on the walls and the floor?
If the tile is rated for floor use and is small enough to follow the shower pan slope, yes. A tile with a coefficient of friction rating suitable for wet floors, typically a DCOF of zero point four two or higher, is safe for the shower floor. Most wall tile is not rated for floor use and will be too slippery when wet. If you want the walls and floor to match, use a floor-rated tile in a smaller format for the floor than for the walls, in the same color or a coordinating color. A twelve-by-twenty-four wall tile with a two-inch mosaic floor tile in the same material and color looks intentional. The same large-format tile on the floor looks dangerous.
How do I waterproof the niche and the bench before tiling?
The niche and the bench must be waterproofed as part of the continuous waterproofing envelope before any tile is set. The inside corners of the niche are the most leak-prone joints in the entire shower. Apply waterproofing membrane to all six interior surfaces of the niche, including the top, bottom, back, and both sides. Embed waterproofing fabric or tape into the membrane at every inside corner. The bottom shelf of the niche must slope slightly forward so water drains out instead of pooling inside the niche. The bench must be waterproofed on the top, the front, and the sides, with the waterproofing extending at least six inches onto the surrounding walls. Tile the niche and the bench as you tile the walls, not as an afterthought. The cuts around the niche should align with the grout lines on the surrounding wall, which requires planning the niche position during the layout stage, not during the tiling stage.
