Measuring three walls and a pan
Take each wall on its own. A common 36 by 60 inch alcove shower has a 60 inch back wall and two 36 inch end walls. Tiled to 84 inches that is 60 x 84 plus two lots of 36 x 84, which is 5,040 plus 6,048 square inches — 77 square feet.
The pan is width times depth: 36 x 60 is 15 square feet. Add the curb. A curb is three surfaces — the top, the outside face and the inside face — each about 60 inches long and 4 to 6 inches wide, so roughly 6 square feet in total.
That is 98 square feet before waste. At 15% — small cuts, lots of edges, usually a first attempt — you are ordering 113 square feet, and the wall tile and floor tile are two separate orders. Put the wall runs into the subway tile calculator to get the box count and the grout for the field, and run the pan separately because mosaic coverage is different.
| Shower size | Walls | Pan | Curb | Niche | Total + 15% |
|---|---|---|---|---|---|
| 32 x 32 in corner | 37 sq ft | 7 sq ft | 3 sq ft | 3 sq ft | 58 sq ft |
| 36 x 36 in corner | 42 sq ft | 9 sq ft | 4 sq ft | 3 sq ft | 67 sq ft |
| 48 x 36 in alcove | 70 sq ft | 12 sq ft | 5 sq ft | 3 sq ft | 104 sq ft |
| 60 x 32 in alcove | 72 sq ft | 13 sq ft | 6 sq ft | 3 sq ft | 109 sq ft |
| 60 x 36 in alcove | 77 sq ft | 15 sq ft | 6 sq ft | 3 sq ft | 116 sq ft |
Two notes on that table. The wall figure assumes tiling to 84 inches; going to the ceiling at 96 inches adds 14% to the wall number. And the pan figure is mosaic, which is bought and priced separately from the field tile — do not merge the two lines when you order.
The niche
A recessed niche is the detail that separates a considered shower from a builder-grade one, and it is where most DIY showers go wrong dimensionally.
Size the opening to whole tiles. If your field tile is 3 by 6 with a 1/16 inch joint, a niche 12 3/16 inches wide takes exactly four tiles across with no cut. Get this wrong and you have four slivers framing the most closely inspected 2 square feet of the bathroom.
Three more rules for niches:
- Put it on a dry wall — never on the wall with the plumbing, and never on an exterior wall in a cold climate, where the reduced insulation depth will cause condensation behind the tile.
- Slope the shelf so water runs out instead of sitting behind the shampoo. ANSI A108.01, as the Ceramic Tile Education Foundation quotes it, requires horizontal ledges to slope so that water on them flows toward the drain, without setting a figure, and the foundation counts niche shelves among them. This guide uses 1/8 inch of fall from the back of the shelf to the front: on a shelf up to 6 inches deep, that is at least the 1/4 inch per foot the plumbing code sets for the pan liner.
- Waterproof it completely before tiling. A niche is a hole in your waterproofing and it must be sealed as a five-sided box.
If you are fitting two niches, keep them on the same centre line so the grout lines run through both.
Curb and threshold
The curb takes more cuts per square foot than anything else in the room. Three faces, four corners, and the top should ideally be a single piece of stone or a full tile so there is no grout joint sitting in standing water.
Slope the top of the curb back into the shower by about 1/4 inch. A flat curb top holds water against the door seal; a curb sloped outward sends it onto the bathroom floor.
If you are using a glass door, ask the glass company for their tolerance before you tile. Most want the curb within 1/4 inch of level across its length, and a curb tiled to the wrong dimension is a $600 problem when the glass arrives. Ask them for the hinge positions too: drilling a hinge hole through a tile after it is set is possible but nobody enjoys it.
Waterproofing before tile
Tile is not waterproof. Grout is not waterproof. What keeps water out of your framing is the membrane behind the tile, and there are only three acceptable answers.
| System | What it is |
|---|---|
| Foam board | Kerdi-Board, Wedi and similar, sealed at the seams |
| Sheet membrane over backer | Cement board plus a bonded sheet membrane |
| Liquid membrane over backer | Cement board plus two coats of a rolled-on membrane |
What does not work: drywall, green board, cement board with nothing over it, and any of the above with an unsealed penetration for the mixing valve. Flood-test the pan before a single tile goes on. The plumbing code requires the liner to hold water at least 2 inches deep at the threshold for at least 15 minutes with no leakage (2021 IPC section 312.9; section 312.10 in the 2024 edition). This guide suggests leaving it 24 hours, which is longer than the code asks for. Finding a leak then costs an afternoon; finding it later costs the whole bathroom.
Do not mix systems. A liquid membrane rolled over a sheet membrane does not bond, and a foam board system sealed with the wrong brand of band voids the warranty on both. Pick one manufacturer's system and use its own corners, bands and sealant.
Slope and drain
The pan slopes to the drain at 1/4 inch per foot. In a 36 by 60 shower with a centre drain that is about 3/8 inch of fall from the wall to the drain — not much, but it must be consistent and it must be built into the mortar bed, not created with thinset under the tile.
Because the pan slopes and the walls do not, never start the wall tile off the pan. Screw a level ledger board one full tile height above the highest point of the pan, tile the field from there, then remove the ledger and cut the bottom row to follow the slope. That bottom row will be a tapered cut across the width of the shower, and that is correct.
Linear drains change this: they let the pan slope in one direction only, which means you can use large format tile on the floor instead of mosaic.
For the wall layout itself — where to put the centre line, how to balance the cuts at the corners — the method is the same as a floor and it is set out in how to lay out a tile floor. For choosing the tile body itself in a wet area, porcelain vs ceramic tile explains why absorption matters here more than anywhere else in the house.
Frequently asked questions
How much tile do I need for a standard shower?
A 3 by 5 foot shower tiled to 7 feet has 77 square feet of wall and 15 square feet of pan, plus the curb and the niche. With 15% waste that is about 116 square feet.
Do I tile the shower floor with the same tile?
Not with a centre drain. That pan needs small tile — 2 inch mosaic or smaller — so the grout joints provide grip and the sheet can follow the slope to the drain. Large tile cannot conform to the multiple sloped planes a centre drain creates. A linear drain slopes the floor in a single plane, which is why large format works with one and not with the other.
What goes behind shower tile?
A waterproof assembly: a foam board like Kerdi or Wedi, or cement board with a liquid membrane over it. Plain drywall, green board and cement board with no membrane all fail eventually.
How much thinset and grout does a shower take?
A 36 by 60 in alcove tiled to 84 inches is about 98 square feet of tile across the walls, the pan and the curb. At the 95 square feet a 50 lb bag covers with a 1/4 by 1/4 in trowel, which is the figure the calculators use, that is 2 bags of thinset, before any back-buttering. Grout follows the tile size more than the area: 3 by 6 tile at a 1/16 in joint takes about 5.2 lb of non-sanded grout on the walls, and 2 inch mosaic at 1/8 in about 3.9 lb of sanded on the pan, which is 15 of those square feet and 43% of the grout.
Sources
- International Plumbing Code 2021, section 421.5.2 — the 1/4 inch per foot fall on the pan: the liner under a shower floor is pitched one-fourth unit vertical in 12 units horizontal (2-percent slope) and sloped toward the drain. The 2018 and 2024 editions number the section the same; the 2012 and 2015 editions have it as section 417.5.2. The code your jurisdiction has adopted is the one that applies. International Code Council
- International Plumbing Code 2021, section 312.9 — the flood test of the liner: the drain plugged, the floor filled with water to a depth of not less than 2 inches measured at the threshold, and the water held for not less than 15 minutes with no evidence of leakage. The 2024 edition numbers the same test section 312.10. International Code Council
- Does Your Tile Slope to the Drain? — what the slope under the membrane is called — the pre-slope, or sloped fill — and the rule that every horizontal surface in a shower, curbs, seats and niche shelves included, slopes toward the drain. It quotes ANSI A108.01 section 3.6.4 and the note on the TCNA Handbook shower details. Ceramic Tile Education Foundation
- LATICRETE 253 Gold data sheet (DS-296-1026) — approximately 80 to 95 square feet per 50 lb bag with a 1/4 x 1/4 inch notched trowel, and back-buttering for tiles larger than 8 x 8 inches. The thinset figure in the questions below uses 95, as the calculators do. LATICRETE International
- Custom Building Products, Polyblend Plus Sanded Grout (TDS-360), coverage chart — square feet per 25 lb bag by tile size, tile thickness and joint width, for joints of 1/8 to 1/2 inch: 310 square feet for 12 x 24 x 3/8 inch tile at a 3/16 inch joint, 96 for 3 x 3 x 1/4 inch tile at the same joint. Custom Building Products
- Custom Building Products, Polyblend Plus Non-Sanded Grout (TDS-369), coverage chart — square feet per 10 lb box for joints up to 1/8 inch: 384 square feet for 12 x 24 x 3/8 inch tile at a 1/16 inch joint, 112 for 3 x 3 x 1/4 inch tile. Custom Building Products
The pan slope, the flood test the code asks for and the rule that ledges slope too come from the code and the foundation above; the thinset and grout in the questions are the calculators’ figures, from the LATICRETE and Custom Building Products documents. The areas are arithmetic on the dimensions given, with the walls as the subway tile calculator measures them, the niche taken as 3 square feet and the curb as 3 to 6 by shower size. Other figures are not from a published source, among them the 15% allowance, the 24 hours for the flood test, the 1/8 inch fall across the niche shelf, the 1/4 inch fall on the curb top, the glass-door tolerance and the $600 a curb tiled to the wrong dimension can cost when the glass arrives: check those with your merchant, your glass company and your inspector. Whatever your local code says beats everything on this page.