Order of work
- Safety first. Old sheet vinyl, vinyl tile and their adhesive in houses built before the 1980s can contain asbestos: have them tested before you scrape or break them up. Cutting tile and cement board makes silica dust, so cut outdoors or wet and wear an N95 mask, safety glasses and hearing protection. Tiling a floor rarely needs a permit, but a bathroom remodel with plumbing work usually does; check with your building department.
- Check the floor. Tile needs a stiff, flat floor: most tile makers ask for no more than ⅛ in of variation over 10 ft (1/16 in over 2 ft for tile 15 in and larger). If the floor bounces, have the framing checked before tiling. Grind high spots and fill low ones with a patching compound.
- Lay the cement board on a wood subfloor: spread thin-set with a ¼ × ¼ in notch, set the sheets with their seams staggered and off the plywood seams, leave ⅛ in between sheets and ¼ in at the walls, and screw every 8 in. Fill the seams with thin-set and embed the mesh tape.
- Snap the start lines. Mark the center of the room both ways, dry-lay a row of tiles with spacers along each line, and shift by half a tile if the planner says so. The cut tiles at opposite walls should match.
- Set the tile one quadrant at a time, working toward the door. Comb the mortar in straight lines, back-butter large tiles, and lift a tile now and then to check the coverage. Keep the joints clean and let the mortar cure as the bag says, often 24 hours.
- Grout and seal. Pull the spacers, pack the grout in diagonally with a rubber float, and sponge off the haze. After the grout has cured (often 48–72 hours), brush on the sealer. Caulk, don’t grout, the gap at the walls and fit the transition strips and baseboard.
Tools you’ll need
- Tape measure, chalk line, carpenter’s square and a 4 ft level
- Notched trowels (sizes on the list), a margin trowel and a mixing paddle on a ½ in drill
- Manual tile cutter or wet saw, and a tile nipper or angle grinder with a diamond blade for notches
- Utility knife and straightedge for scoring cement board, and a drill/driver for the screws
- Rubber grout float, sponges and two buckets
- Knee pads, safety glasses, gloves, hearing protection and an N95 mask
About this planner
Tile is only part of what a tile floor costs. The same trip to the store needs thin-set mortar in the right amount for your trowel, grout in the right kind for your joint width, cement backer board with its own screws, mesh tape and mortar bed if the floor is wood, spacers, a sealer and a transition strip at each doorway. Most of those are sold in bags and jars whose coverage depends on the tile you picked.
This planner works all of it out from the size of your room and your tile, prices it with your local numbers, and draws the layout to scale. That shows what most people discover only once the first rows are down: how wide the cut tiles at the walls will be. It lays the tile out from the center of the room and picks the start that avoids thin slivers, so both walls get the same cut. It also tells you how much the floor will rise, which decides whether doors need trimming.
How to use it
- Measure the room’s length and width. For an L-shaped room, plan each rectangle separately and add up the lists.
- Enter the tile size, its thickness, the grout joint and the tiles per box from the label.
- Choose the subfloor. On plywood or OSB the planner adds cement board; on concrete the tile goes straight on. Leave the trowel on “pick by tile size” unless your mortar’s label says otherwise.
- Open Your local prices, enter what your store charges, and print the project sheet to shop from.
How the quantities are worked out
Tiles = area ÷ ((tile length + joint) × (tile width + joint)) × (1 + extra%), rounded up to boxes
Thin-set bags = area ÷ coverage for the trowel (+ area ÷ 85 sq ft under cement board)
Grout lb = (L + W) ÷ (L × W) × joint × tile thickness × area × 144 ÷ 1728 × 110 lb/cu ft × 1.1
Cement board = area × 1.1 ÷ 15 sq ft per sheet
Screws = area ÷ 15 × 54 per sheet (every 8 in)
Edge tile = half the room − ¼ in gap, less whole tiles + joints, from the center line
Thin-set coverage is the low end of Custom Building Products’ data sheets for a 50 lb bag: 85 sq ft with a ¼ × ¼ in square notch, 60 sq ft with ¼ × ⅜ in, and 42 sq ft with ½ × ½ in or a ¾ in U-notch. The trowel follows the tile’s longest side (up to 8 in, up to 15 in, larger). Grout is the volume of the joints at about 110 lb per cubic foot, which matches the published coverage of a 25 lb bag of sanded grout (348 sq ft of 12 × 12 in tile with ⅛ in joints). Cement board follows the Durock and HardieBacker floor instructions: ¼ in sheets over plywood, in a mortar bed, fastened every 8 in.
Worked example
These are the planner’s starting values and the results they produce:
| Room length | 12 ft |
|---|---|
| Room width | 10 ft |
| Tile length (along the room length) | 12 in |
| Tile width | 12 in |
| Tile thickness | 0.375 in |
| Grout joint width | 0.125 in |
| Tiles per box | 15 |
| Extra for cuts and breakage | 10 % |
| Subfloor | Plywood or OSB (add cement board) |
| Trowel | Pick by tile size |
| Doorways | 1 |
| Doorway width | 3 ft |
| Tile, per sq ft | $3.00 |
| Thin-set mortar, 50 lb bag | $25.00 |
| Sanded grout, 25 lb bag | $25.00 |
| Unsanded grout, 10 lb bag | $20.00 |
| Cement board, 3 × 5 ft sheet | $15.00 |
| Backer board screws, jar of 200 | $15.00 |
| Mesh tape, 50 ft roll | $8.00 |
| Tile spacers, bag of 250 | $6.00 |
| Grout sealer, quart | $20.00 |
| Transition strip, each | $25.00 |
| Bought | Item | Buy | Cost |
|---|---|---|---|
| Floor tile130 tiles with 10% extra, 15 per box; 135 sq ft bought | 9 boxes | $405.00 | |
| Thin-set mortar, 50 lb60 sq ft per bag with a ¼ × ⅜ in square notch trowel, plus 85 sq ft per bag under the cement board (¼ × ¼ in notch); polymer-modified for most porcelain | 4 bags | $100.00 | |
| Sanded grout, 25 lb9.5 lb for ⅛ in joints ⅜ in deep, with 10% extra; sanded for joints ⅛ in and wider | 1 bag | $25.00 | |
| Cement board, ¼ in, 3 × 5 ft120 sq ft + 10% for cuts, 15 sq ft per sheet; seams staggered, never lined up with the plywood seams | 9 sheets | $135.00 | |
| Backer board screws, 1¼ inAbout 432 screws: every 8 in across each sheet, jars of 200 | 3 jars | $45.00 | |
| Alkali-resistant mesh tape, 2 inAbout 42 ft of board seams, 50 ft rolls; embedded in thin-set | 1 roll | $8.00 | |
| Tile spacers, ⅛ inAbout one per tile, bags of 250 | 1 bag | $6.00 | |
| Penetrating grout sealer, 1 quart bottleBrushed on the joints once the grout has cured, a quart per 200 sq ft; check the label | 1 bottle | $20.00 | |
| Transition strips, 6 ft1 per 3 ft doorway; a reducer if the tile ends higher than the next floor | 1 | $25.00 | |
| Estimated materials total | $769.00 | ||
Tips before you buy
- Mix tiles from several boxes as you go, and check that every box carries the same shade and lot number before you open any.
- Rectangular tile 18 in and longer can bow in the middle. Offset the rows by no more than a third of the tile length to keep the edges flush.
- Large tile needs a flatter floor and a leveling clip system; budget for the clips if your tile is 15 in or longer.
- Use a grout color close to the tile for a calm floor, or a contrasting one to show off the pattern. Grout cleanup is easier with sealed or glazed tile.
- Keep a few spare tiles, a little grout and the product names. A cracked tile is easy to replace if you have a match.
Frequently asked questions
What do I need to tile a 10×12 floor?
For a 12 × 10 ft room on a plywood subfloor with 12 × 12 in tile, ⅛ in joints and 15 tiles per box: 9 boxes of tile, 4 bags of thin-set, 1 bag of sanded grout, 9 sheets of cement board, 3 jars of backer board screws, a roll of mesh tape, a bag of spacers, a quart of grout sealer and a transition strip. At typical prices ($3 per sq ft for the tile) that comes to about $769, of which $405 is the tile.
How many bags of thinset do I need?
Divide the floor area by the coverage for your trowel: about 85 sq ft per 50 lb bag with a ¼ × ¼ in notch, 60 sq ft with ¼ × ⅜ in and 42 sq ft with ½ × ½ in. A 120 sq ft floor of 12 × 12 in tile takes 2 bags with a ¼ × ⅜ in trowel; with cement board underneath, add about 1.4 bags for its bed, so buy 4.
How much grout do I need for 12×12 tile?
About 7 lb per 100 sq ft for ⅜ in thick 12 × 12 tile with ⅛ in joints. For 120 sq ft that is 8.6 lb, or 9.5 lb with 10% extra, so one 25 lb bag of sanded grout. Narrower joints or bigger tile need less; ¼ in joints need twice as much.
How do I keep from ending with a thin sliver of tile at the wall?
Lay the tile out from the center of the room, not from a wall. In a 13 ft room with 12 in tile and ⅛ in joints, a joint on the center line leaves edge tiles under 5 in, but a tile centered on the line leaves 11 in tiles at both walls. The planner checks both starts and shows the better one.