How to tile a floor

By Ralph · Updated June 17, 2026

A tiled floor can last for decades — and most of the skill is in the prep and the layout, not the tiling itself. Get the substrate flat and solid, plan the layout so you're not left with thin slivers at the walls, and the rest is a steady rhythm of comb, set, space, repeat. Here's the whole process, start to finish — plus how much tile, thinset, and grout to buy.

Start with the substrate

Tile is rigid and unforgiving: if the floor under it flexes or isn't flat, the tile or grout cracks. So the surface has to be three things — stiff, flat, and clean:

• Stiff. The floor can't bounce. Over a wood subfloor that usually means adding cement backer board or an uncoupling membrane — never tile straight onto plywood or OSB. A concrete slab just needs to be sound.
• Flat. Aim for within about ¼″ over 10 ft (flatter still — ⅛″ — for large-format tile). Fill low spots with a self-leveling compound and grind down high ones.
• Clean. No dust, grease, paint, or old adhesive. Thinset needs bare, sound material to grip.

Plan your layout before you mix anything

Never start tiling against a wall — walls are rarely square, so the rows will drift and you'll end up with a tapered sliver on the far side. Instead:

• Snap two chalk lines through the center of the room to find the middle.
• Dry-lay a row of tiles (with spacers) in both directions to see where the cuts land at the walls.
• Shift your start point so the edge cuts are at least half a tile — balanced cuts on opposite walls look intentional; slivers look like a mistake.
• Plan to finish at a doorway or exit so you're not tiling yourself into a corner.

How much tile, thinset, and grout?

Three materials, three quick estimates:

• Tile — your floor area plus 10% waste (15–20% for diagonal layouts or large-format tile).
• Thinset — depends on your trowel notch and tile size; a 50 lb bag covers roughly 85–95 sq ft of small tile, far less for large.
• Grout — depends on tile size and joint width; smaller tiles and wider joints use much more.

What you'll need

• Tile (plus 10%+ for waste and future repairs), and cement backer board or uncoupling membrane if you're over wood
• Thinset mortar — modified for most jobs; check what your tile and any membrane call for
• Grout — unsanded for joints up to ⅛″, sanded for wider
• A notched trowel sized to your tile, plus a margin trowel and a mixing paddle
• Tile spacers and a level or straightedge to check for lippage
• A snap cutter for straight cuts, or a wet saw for big or hard tile; a hole saw for pipes
• Grout float, a couple of sponges, and two buckets
• Knee pads, gloves, and eye protection — plus grout sealer and matching silicone caulk

Step by step

1. Prepare the substrate. Make sure it's stiff, flat, and clean. Over wood, fasten backer board in a bed of thinset and tape the seams, or roll out an uncoupling membrane per its instructions.
2. Snap your layout lines. Find the center, dry-fit in both directions, and adjust so the perimeter cuts are at least half a tile. Mark your reference lines.
3. Mix the thinset. Add powder to water and mix to a peanut-butter consistency that holds a ridge. Let it slake for about 10 minutes, then remix — and only mix what you can use in 30–60 minutes.
4. Comb on the thinset. Spread with the flat side, then comb straight ridges with the notched edge, working a small section at a time. Use the trowel size your tile calls for, and back-butter tiles 15″ and larger.
5. Set the tiles. Press each tile in with a slight twist to collapse the ridges, add spacers, and check that neighbors sit flush (no lippage). Aim for full coverage — at least 80% of the tile backed by thinset, 95% in wet areas.
6. Cut the edge and obstacle tiles. Measure each perimeter and cut tile individually (walls wander), using the snap cutter or wet saw, and a hole saw for pipes and the toilet flange.
7. Let the thinset cure. Stay off the floor and wait at least 24 hours before grouting, so the mortar isn't still wet under the tile.
8. Grout the joints. Remove the spacers, mix the grout, and pack it in by sweeping the float diagonally across the tiles so the joints fill with no gaps.
9. Clean up and tool the joints. Wipe with a damp (not wet) sponge to shape the joints and remove the bulk, then come back as the haze appears and buff the tiles clean.
10. Seal and caulk. Once cured (48–72 hours), seal cement grout. Use flexible silicone caulk — not grout — where the floor meets walls, cabinets, and other changes of plane, since those joints move.

Mistakes to avoid

Related guides

• How much does it cost to tile a floor?
• How to measure a room for flooring