How to Grout Tile: A Setter's Step-by-Step Method for Full, Clean Joints

To grout tile, wait until the setting mortar has cured, clean the joints, mix grout to a stiff peanut-butter consistency, pack it into the joints with a rubber float held at 45 degrees, strike off the excess diagonally, then wash with a barely damp sponge once the grout firms. Buff off the remaining haze within a few hours.

Readiness checks before you grout

Grout is the last wet trade on a tile job, and it locks in whatever is underneath it. Spend ten minutes confirming the installation is ready.

Is the mortar cured?

For standard modified thinset, most manufacturers call for about 24 hours at 70 deg F (21 deg C) before grouting. Rapid-setting mortars can be ready in 2 to 4 hours, while large-format tile over a thick bed, or any installation in a cool, damp room, may need 48 to 72 hours. Grouting over soft mortar traps moisture, can shift tiles under float pressure, and is a classic cause of dark blotches and shading in the finished joint. Our guide on when to grout after tiling covers the edge cases.

A quick check: press a fingernail into the mortar in an open joint. If it dents easily or looks dark and wet compared with an exposed edge, wait.

Are the joints clean and deep enough?

Industry guidance commonly calls for joints to be free of setting material to at least two-thirds of the tile thickness. Thinset that has squeezed up into the joint leaves a shallow bed of grout that cracks and pops out, and it often shows through as a different color. Remove it with a grout saw or a carbide scraper. Pull every spacer and wedge, and vacuum the joints rather than blowing them out, so dust does not settle back into them.

Are movement joints left open?

Inside corners, the joint where a wall meets a tub or floor, perimeter joints against walls, and any field movement joints should stay empty of grout. The caulk vs grout guide explains why TCNA EJ171 calls for sealant at every change of plane. Tape a strip of painter's tape or insert backer rod into these joints so grout cannot bridge them.

Is the room within the temperature range?

Most cement grout data sheets specify roughly 50 to 90 deg F (10 to 32 deg C) for both the air and the tile surface during installation and for the first few days. Below that range the grout stays workable far longer and can be damaged; above it, the working window shrinks quickly. See grouting in hot and cold weather before working in a garage, a sunroom, or an unheated addition.

Match the grout to the joint and the tile

Joint width and tile surface decide most of the choice. Location (shower, floor, countertop) narrows it further.

For a deeper comparison, see sanded vs unsanded grout and the grout joint width guide. This article describes cement grouts; epoxy grout application uses different tools and cleaning methods.

The grouting method, step by step

The sequence below assumes a polymer-modified or high-performance cement grout, which covers the large majority of residential work. Always defer to the timing and water ratios on your product's technical data sheet (TDS).

1. Stage the area and tools. Set out two buckets of clean, cool water (one for rinsing, one for the final wipe), a hydrophilic grout sponge, a rubber grout float, a margin trowel, microfiber cloths and a timer. Plan sections of about 10 to 25 sq ft (1 to 2.5 m2) so you can always wash grout at the right moment. The grout tools guide lists what each tool should be.
2. Dampen only if the TDS says so. Very absorbent tile edges or a hot, dry room can pull water out of the grout too quickly and cause powdery joints. Some data sheets allow lightly wiping the tile with a damp sponge first. Leave no standing water in the joints, which dilutes the grout at the bottom of the joint.
3. Mix the grout. Add powder to measured water, mix at low speed to a smooth, stiff paste, let it slake for the time on the bag (often 5 to 10 minutes), then remix briefly without adding water. Full detail is in how to mix grout. Mix only what you can place and clean in about 30 minutes until you know your pace.
4. Load and spread. Drop a few trowels of grout onto the tile. Hold the float at about 45 degrees to the tile face and push grout across the joints in short, diagonal strokes. Spreading diagonally keeps the float edge from dipping into a joint and dragging grout back out.
5. Pack the joints. Go back over the section with firm, overlapping passes in at least two directions. Packing forces grout to the bottom of the joint and drives out air. On wall tile, work from the bottom up so grout is supported as you go.
6. Strike off the excess. Raise the float nearly to 90 degrees and pull it diagonally across the joints to scrape off surplus grout. Leave as little on the tile face as possible: every gram left here is haze you will wash later.
7. Wait for initial set. Let the grout firm up until a light thumb press leaves a print without grout sticking to your skin. Depending on product, temperature and tile absorption, this takes roughly 10 to 30 minutes. Rapid-setting grouts can be ready in under 10 minutes.
8. Shape the joints. If you want a uniform profile, run a jointing tool or the rounded edge of a sponge lightly along the joints now. Joints should finish flush or very slightly below the tile edge. Deep, concave joints collect dirt and expose tile edges to chipping.
9. First wash. Wring the sponge until it is just damp. Wipe diagonally across the joints with light pressure and the flat face of the sponge, turning it to a clean face each pass and rinsing often. This pass removes surplus grout and levels the joints. Do not scrub.
10. Second wash. Change to clean water. Make slow, straight passes with a clean face of the sponge, then flip it. One face per pass, then rinse. This lifts most of the remaining film and leaves a smooth, even joint.
11. Buff the haze. After the surface dries to a light dull film, usually 30 minutes to a few hours, buff with a clean, dry microfiber cloth or cheesecloth. Removing haze at this stage takes minutes; letting it cure can take a chemical cleaner. See how to remove grout haze if it has already set.
12. Clear and caulk the movement joints. Remove tape or backer rod, clean the movement joints, and after the grout has cured enough to resist the caulking tools, fill them with a sealant color-matched to the grout.
13. Protect while it cures. Keep foot traffic off for at least the time on the TDS (often 24 hours for standard cement grout), and keep showers dry for the stated period, commonly 72 hours. The grout cure time guide breaks down each milestone.

Timing windows at a glance

Times below are typical for polymer-modified cement grout at around 70 deg F (21 deg C) and moderate humidity. Warm, dry conditions and absorbent tile shorten every window; cool, humid rooms and dense porcelain stretch them.

Why water control decides the result

Cement grout gets its strength from hydration, a chemical reaction between cement and a fairly specific amount of water. Extra water does not join that reaction. It evaporates and leaves microscopic pores behind, which makes the grout weaker, more absorbent and lighter in color. That is why blotchy, uneven grout color almost always traces back to water: a loose mix in one batch, a sopping sponge in one corner, or a section washed too soon.

Excess water also carries soluble salts to the surface, where they dry as white bloom. If a white film reappears after cleaning, it is likely efflorescence, a moisture problem, rather than haze, so do not just scrub harder.

Special cases that change the method

Natural stone

Many stones are porous and some are soft. Seal or pre-treat porous stone when the stone supplier recommends it, use unsanded or fine grout on polished surfaces, and avoid dark pigmented grout on light, absorbent stone until a test shows it will not stain. The natural stone grout guide goes into detail.

Glass and mosaic sheets

Glass shows every scratch and every void, and mosaic joints are narrow and numerous. Use a softer float, grout in smaller sections, and pay attention to the paper or mesh backing, which can leave the joints shallow. The glass tile grout guide covers product choice for both.

Walls vs floors

Wall grout must hold itself in a vertical joint, so it is mixed slightly stiffer, worked from the bottom up, and sectioned smaller because gravity pulls it out of joints during washing. The walls vs floors guide covers the differences in full.

Mistakes that cause callbacks

• Retempering. Adding water to grout that has started to stiffen weakens it and changes the color. Discard it and mix a fresh batch.
• Grouting sections too large. The far end overcures before you wash it, leaving hard haze and rough joints.
• Grouting into change-of-plane joints. These crack within months because they must move. Use sealant.
• Washing with a wet sponge. Pulls cement paste out of the joint, exposes sand and leaves pinholes that collect dirt.
• Ignoring the TDS maximum joint width. Exceeding it can cause shrinkage cracks.

More are collected in common grouting mistakes.