How to Regrout Tiles

Regrouting is one of the most transformative DIY jobs you can tackle in a weekend. Crumbling, discoloured grout makes even good-quality tiles look tired, replacing it freshens a bathroom or kitchen without touching the tiles themselves. Expect to spend £50–£150 on materials for a standard bathroom and a full day working methodically.

This guide covers the complete process: tools, preparation, grout removal, applying new grout, and finishing. Where a job warrants professional help, we say so plainly.

When Should You Regrout?

Not every grout problem needs a full regrout. Consider your options:

• Light mould or staining, try a grout restorer pen (£5–£12) or a bleach-based spray first.
• Cracked or crumbling lines, regrout, as cracked grout lets water behind tiles, eventually causing adhesive failure or damp.
• Missing grout in isolated patches, spot-fill with matching grout rather than a full regrout.
• Widespread discolouration that won’t clean, full regrout is the right call.

Check the grout lines with a screwdriver. If grout chips out easily in more than a few places, regrout everything.

Tools and Materials

For a 2 m² shower surround, allow one 2 kg bag of grout. For a full bathroom with floor and walls, budget 4–6 kg. Unsanded grout suits joints up to 3 mm wide; sanded grout handles anything wider.

Grout colour: standard grey or off-white is hardest to keep clean. Darker grey or anthracite shows less dirt long-term. Coloured grouts are available but match carefully to existing tiles, bring a tile photo to the builders’ merchant.

Step-by-Step: How to Regrout Tiles

1. Prepare the Area

Lay dust sheets on the floor, tape any adjacent surfaces you don’t want scratched, and turn off any extractor fans temporarily to stop spreading dust. Put on safety glasses and a dust mask, grout removal generates fine silica-containing dust.

2. Remove the Old Grout

An oscillating multi-tool with a carbide grout removal blade is the safest and most efficient option. Work along each joint at an angle, keeping the tool moving. You only need to remove 2–3 mm depth, you don’t have to reach the bottom of the joint.

Alternative: a manual grout rake (£8–£15) works on softer or already-crumbled grout but is slow and hard on wrists for large areas.

Avoid angle grinders near wall tiles, the risk of chipping tile faces is high.

Vacuum out all dust and loose debris from the joints before moving on. Wipe tiles with a damp cloth and allow to dry.

3. Mix or Prepare the Grout

Ready-mixed grout in tubs is convenient for small jobs. For most bathroom regrouts, powder mixed with water gives better control of consistency. Mix to a thick peanut-butter consistency, too runny and it slumps out; too stiff and it won’t press in.

Only mix what you can apply in 20–30 minutes.

4. Apply the Grout

Load your grout float and press grout diagonally across the tile joints, working in 0.5 m² sections. Push the float firmly across joints at 45° to pack grout in fully. Go back over the same area in the opposite diagonal direction to fill any voids.

Scrape excess off tile faces with the float held nearly flat.

5. Clean Off and Finish

After 10–20 minutes (check the manufacturer’s instructions, faster in warm dry conditions), wipe tiles with a barely damp sponge in circular motions. Rinse the sponge constantly. You’re aiming to remove surface grout without pulling from the joints.

Allow a further 30–60 minutes, then buff with a dry cloth to remove the haze that develops as grout cures.

Leave to cure for at least 24 hours before exposing to moisture. Most standard cement-based grouts reach full cure in 72 hours.

6. Seal the Grout

Apply a penetrating grout sealer once cured. This is especially important in shower enclosures. One coat is sufficient for most products, work along each joint with a small brush or applicator bottle, wipe excess off tiles immediately, and allow to dry per the manufacturer’s guidance.

Resealing every 2–3 years extends the life of light-coloured grout considerably.

Silicone vs Grout at Internal Corners

Never use rigid cement grout at internal corners (where walls meet each other, or where wall meets floor or bath). These joints move slightly with building movement and thermal expansion, grout will crack within months. Use silicone mastic instead: flexible, waterproof, and available in colours to match your grout. Remove old silicone with a Stanley knife and specialist silicone remover (£6–£10) before applying fresh.

Cost to Hire a Tiler

If the area is large, the tiles are delicate (cracked or thin), or you simply don’t want the dust, a tiler will charge:

Day rates for tilers run £200–£300 per day in London, £150–£220 outside the South East. Most bathroom regrouts take half a day to a full day.¹

Common Mistakes to Avoid

• Not removing enough old grout, applying new grout on top of unstable old grout means it cracks again quickly.
• Mixing too much at once, grout begins to set in the bucket; mixed-over grout becomes lumpy and hard to work.
• Letting the surface haze dry too long, grout haze left more than a few hours can be very difficult to remove without acid cleaner.
• Using the wrong grout width, always check tile joint width before buying; using sanded grout in a 2 mm joint can scratch polished tiles.
• Skipping the sealer, unsealed grout in wet areas stains and grows mould significantly faster.

Building Regulations

Regrouting is maintenance work and does not require Building Regulations approval or planning permission. However, if you are regrout tiles around an electric shower, ensure the shower unit itself complies with Part P, only a qualified electrician should touch electrical components near the shower.²

Regrouting is a satisfying job with a big visual payoff. Work methodically, don’t rush the cleaning stage, and the results will last a decade or more with basic maintenance.