How to Grout Tiles (and Get Clean, Even Lines)

Learning how to grout tiles is the step that decides whether a tiling job looks professional or homemade. The tiles do a lot of the work, but it is the grout lines, straight, evenly filled and cleanly finished, that your eye lands on every time you walk into the room. The good news is that grouting is one of the more forgiving parts of tiling. Get the timing, mix and technique right and you can grout a bathroom wall in an afternoon with no specialist skill.

This guide walks through the whole process: when to start, which grout to buy, how to mix and apply it, and how to get sharp, even joints without the haze that ruins so many DIY finishes. For anything beyond a straightforward wall or floor, our team of Bromley tilers can take the job on, but most homeowners can handle grouting themselves.

When to grout after tiling

Do not rush this. The tile adhesive underneath needs to cure before you grout, or the moisture trapped behind the tiles can weaken the bond and your tiles may come loose. As a rule, wait at least 24 hours after fixing the tiles, and ideally 48 to 72 hours if the room is cold or humid, or if you have used a standard (non-rapid) adhesive.

Rapid-set adhesives cure faster, sometimes ready to grout in three to six hours, but always check the bag: the manufacturer’s stated time is the one that matters, not a rule of thumb. Before you start, run a blade or grout rake through the joints to clear any adhesive that has squeezed up between the tiles. Grout needs room to sit, and lumps of dried adhesive near the surface will show through.

Choosing the right grout

Grout is not just filler, and the type you pick affects how the finish wears. The two main families are:

Cement-based grout is the standard choice for most walls and floors. It is easy to mix, easy to apply and comes in a wide range of colours. Modern flexible cement grouts cope well with the small amounts of movement in a typical home.
Epoxy grout is made from resin and hardener. It is waterproof, stain-resistant and extremely tough, which makes it the better option for wet rooms, kitchen splashbacks and anywhere hygiene matters. It is harder to work with and sets fast, so it suits smaller areas unless you are confident.

Match the joint width to the grout, too. Narrow joints under 3mm usually want a fine, unsanded grout; wider joints take a sanded grout that resists shrinkage and cracking. Buy the grout and, if it is not built in, a suitable sealer at the same time so the colours are from one batch. For wet rooms and larger tiles it is worth checking current best practice, and industry guidance from The Tile Association covers grout and adhesive selection for different settings.

Tools you need to grout tiles

You do not need much, but the right kit makes the job far easier:

A rubber grout float (the flat, soft-faced tool that spreads and packs the grout)
A grout mixing bucket and a second bucket of clean water
A large tiling sponge with rounded edges
A grout finishing tool or a clean, rounded stick for shaping the joints
Microfibre or lint-free cloths for the final polish
A margin trowel or paddle mixer if you are mixing powder grout
Rubber gloves and knee pads for floors

How to mix and apply grout step by step

If you are using powdered grout, add the powder to the water rather than the other way round, and mix to a smooth, toothpaste-like consistency with no dry lumps. Let it stand (slake) for the few minutes the bag specifies, then stir again. Ready-mixed and epoxy grouts skip this step. Only mix as much as you can use in about 20 to 30 minutes.

Load the float and spread the grout diagonally across the tiles, holding the float at roughly a 45-degree angle. Working diagonally, rather than along the joints, packs grout fully into each gap without dragging it back out. Press firmly so the joints fill completely with no air pockets, then scrape off the excess by drawing the float diagonally across the surface again, almost on its edge. Work in sections of about one square metre so the grout does not dry before you can clean it.

Shaping and cleaning the joints

Once a section has firmed up for the 10 to 15 minutes the manufacturer suggests (it should be touch-dry but not hard), it is time to clean and shape. Wring your sponge until it is just damp, never wet, and wipe gently across the tiles in a circular motion to lift the film of grout off the surface. Rinse the sponge often and change the water regularly, because dirty water simply smears haze back on.

Run a finishing tool or a rounded stick along each joint to compact the grout and leave a neat, slightly concave line. Do not overwork it, and resist the urge to keep wiping with a soaking sponge: pulling water out of fresh grout weakens it and washes out the colour, leaving pale, patchy lines. A couple of careful passes is enough.

Dealing with grout haze

As the grout dries you will see a light, cloudy film settle over the tiles. This is grout haze, and it is normal. Leave it until the grout has firmed up, then buff it off with a dry microfibre cloth. If a stubborn haze remains after a day, a dedicated grout haze remover will shift it, but always test it on a spare tile first, especially on natural stone, which can be sensitive to acidic cleaners.

Curing and sealing your grout

Grout dries to the touch within 24 to 48 hours but takes around 7 to 14 days to fully cure and reach its strength. During that first period keep the area dry: no showers on a freshly grouted enclosure, and go easy on a new floor. Ventilate the room to help it cure evenly.

Cement-based grout is porous, so once it has fully cured, sealing it makes a real difference in bathrooms and kitchens. A grout sealer repels water and staining and makes the joints far easier to keep clean. Epoxy grout does not need sealing because it is already waterproof. Finish the job by running a bead of silicone, not grout, into the internal corners and where tiles meet the bath, tray or worktop. These junctions move slightly, and rigid grout there will crack, whereas flexible silicone will not.

Frequently asked questions

How long should you leave tiles before grouting?

Wait at least 24 hours after fixing the tiles, and 48 to 72 hours if the room is cold or damp or you used a standard adhesive. Rapid-set adhesives can be ready in a few hours, but always follow the time printed on the adhesive bag rather than a general rule.

What angle should you hold a grout float at?

Hold the float at about 45 degrees to the tiles and spread the grout diagonally across the joints. This packs the gaps fully and stops you dragging grout back out. To remove the excess, tilt the float almost onto its edge and scrape diagonally.

Why does my grout look patchy or pale?

Patchy, pale grout is usually caused by too much water. Wiping fresh grout with a soaking sponge pulls the water and colour out of the joints and leaves an uneven finish. Use a barely damp sponge, rinse it often and make only a couple of light passes.

Do you need to seal grout?

Cement-based grout is porous and benefits from sealing in wet areas once it has fully cured, which takes up to two weeks. Sealing repels water and stains and keeps the joints cleaner. Epoxy grout is already waterproof and does not need a sealer.

Can you grout over old grout?

You can grout over existing grout only if you first rake out the old grout to a depth of at least 2mm so the new grout has something to key into. Applying a thin skim over sound, full joints rarely lasts and tends to flake away. For crumbling or cracked joints, rake them out fully and re-grout.

How soon can you use the shower after grouting?

Keep a newly grouted shower dry for at least 24 to 48 hours, and ideally longer, so the grout can begin to cure properly. Full curing takes up to two weeks, so avoid heavy or prolonged water exposure in that window and make sure any silicone in the corners has fully set before use.

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