How to Price Bathroom Re-Grouting and Re-Sealing

Summary

Re-grouting and re-sealing is one of the most underquoted jobs in the bathroom trade. A customer rings about "discoloured grout" and the tradesperson quotes £150 to "freshen it up." Two hours later they discover the bottom row of tiles around the bath is hollow (tile-to-substrate bond failure), the silicone seal is masking a leak through the bath flange, and the wall behind the shower screen is wet plasterboard. None of which were visible to the customer or quoted for.

The other underquote problem is failing to charge for the prep. Removing old grout cleanly (without chipping tile edges or scratching glaze) takes 50–70% of the total labour time on a re-grout. Silicone removal is even worse — old silicone bonds to glass, ceramic, and acrylic, and lifting it without scratching takes patience. Customers see new grout going in and think that's the job; they don't see the 4 hours of grout removal that preceded it.

This guide covers per-metre and per-m² pricing, scope-creep risks, material choice (cement vs epoxy grout, sanitary vs general silicone), and how to write a quote that protects you when the inevitable failing-tile turns up halfway through.

Key Facts

• Silicone linear pricing — £8–£18/m supplied and applied (sanitary-grade, anti-mould)
• Grout square-metre pricing — £25–£55/m² rake out and replace (cement grout)
• Epoxy grout square-metre pricing — £55–£120/m² (slower to apply, premium material)
• Plumber/tiler day rate — £280–£400/day regional, £350–£500/day London (2026)
• Half-day call-out — typically £180–£280 (minimum charge regardless of small scope)
• Standard bathroom silicone runs — bath perimeter (3–4m), shower tray/enclosure (3–5m), basin (1m), toilet base (1m), kitchen worktop (3–8m); total bathroom ≈ 8–12 linear metres
• Cement grout types — CG1 (general purpose) and CG2 (improved/water-resistant) per BS EN 13888
• Epoxy grout — R2 reaction resin per BS EN 13888; chemical-resistant, low porosity, doesn't stain
• Sanitary silicone — Type F (façade) per ISO 11600 with fungicide; anti-mould rated typically 5+ years
• Standard silicone (non-sanitary) — no fungicide; mould-stains within 12–18 months in wet rooms; do not use in bathrooms
• Bath/shower seal width — 6–10mm bead typical; never thinner than 4mm
• Grout joint width — 2–3mm for ceramic wall tile; 3–5mm for porcelain floor; 5–10mm for stone
• Tile substrate types — plasterboard (BS 5385 Pt 4 requires moisture-resistant green board), tile backer board (Hardiebacker, Marmox), waterproof tanking membrane
• VAT-rated — re-grouting and re-sealing is standard 20% VAT for VAT-registered traders; no reduced-rate exemption applies (it is not a primary energy efficiency measure)
• CDM Regulations — generally not notifiable for single-bathroom domestic work under 30 days

Quick Reference Table

Detailed Guidance

What to inspect before quoting

A 5-minute inspection saves a £400 dispute later. On every quote visit:

1. Tap-test tiles — fingertip-tap each tile around the perimeter and at low/wet zones (bath, shower, behind WC). Hollow sound = failing bond. If >10% of tiles tap hollow, this is not a re-grout, it's a re-tile.
2. Visual inspect grout colour change zones — black mould in grout is surface only and cleans off; black behind grout (visible at hairline cracks) means water penetration to substrate
3. Check silicone integrity — peel-test corner of each silicone bead. If it lifts cleanly, it's already failed and water is behind it; substrate may be wet
4. Press shower-tray edge — if it flexes more than 1mm, tray isn't fully bedded (see shower tray and waste installation); silicone alone won't fix it
5. Check for active leaks — water meter test (turn off all draw, watch meter for 10 min); if creeping, there's a leak somewhere
6. Inspect substrate — pull back ceiling access panel below if possible; brown staining on ceiling = historic or active leak
7. Photograph everything — at the quote stage; cover yourself if scope changes

Re-grout procedure (cement grout)

For a standard 12m² bathroom (walls + floor):

1. Mask edges — low-tack tape on tile edges to protect glaze
2. Rake out old grout — multi-tool with grout blade, or carbide grout saw by hand; remove 2–3mm depth minimum
3. Brush and vacuum joints — all dust and loose grout out
4. Mould-treat any black-stained areas — fungicidal spray, dwell 10 min, rinse
5. Dry the joints — ensure no standing water before grouting
6. Mix grout — to manufacturer's water ratio (usually ~25% water by weight); rest 5 min; remix
7. Apply grout with rubber float — diagonal pass, work into joints fully
8. Strike off excess — diagonal pass with float on edge
9. Wait initial set — 15–30 min (check by light touch; grout firm but not dry)
10. Sponge wipe — clean water, frequent sponge rinse, diagonal pass; remove haze without washing out joints
11. Polish off cement haze — once dry (4–6 hrs), dry cloth or grout-haze cleaner
12. Cure — 24 hrs no water before customer uses bath/shower
13. Optional: apply impregnating sealer — 24–48 hrs after grouting; £40–£80 extra material

Re-seal procedure (silicone)

For a standard 8m bathroom silicone run:

1. Cut out old silicone — Stanley knife both sides of bead, lift with fingers and pliers; difficult bits with silicone-remover gel (4 hrs dwell)
2. Scrape residue — plastic scraper or razor blade; avoid scratching acrylic baths
3. Solvent-wipe surfaces — IPA or methylated spirit to remove silicone oils (critical — new silicone won't adhere to old silicone residue)
4. Mask both sides of joint — low-tack tape, 4–8mm gap
5. Apply silicone — continuous bead, no breaks
6. Tool the bead — wet finger (washing-up liquid + water), silicone-tooling tool, or BS-shaped tool; one continuous pass
7. Remove masking tape immediately — while silicone wet
8. Cure — 24 hrs minimum before water exposure (some products 48 hrs)

Sanitary silicone ONLY in bathrooms — has fungicide additive (Tributyltin or similar). General-purpose silicone turns black with mould within 12–18 months in wet zones.

Cement vs epoxy grout — when to choose epoxy

Cement grout (CG1/CG2) — 95% of jobs; cheap, easy to apply, can be re-coloured later, but porous and stains.

Epoxy grout (R2) — premium for high-spec wet rooms, commercial kitchens, swimming pools, areas with constant water exposure or chemical contact. Pros: non-porous, won't stain, no mould risk, lifetime 20+ years. Cons: 2–3× material cost, 2–3× harder to apply (sets fast, leaves haze that's hard to remove if missed), needs warm conditions (>15°C).

Recommend epoxy for: shower trays, wet room floors, kitchen worktop splashbacks. Recommend cement for: standard bathroom walls, splashbacks above sink.

Anti-mould silicone — the spec to insist on

Specify: "Sanitary-grade neutral-cure silicone with fungicide additive, complying with ISO 11600 Type F, minimum 5-year mould-free guarantee."

Examples (do not brand-name in quote, but for your own reference): Dow 785 Sanitary, Mapesil AC, Sika Sanisil, Geocel The Works Sanitary, CT1 Bathroom.

Avoid: general-purpose acetoxy silicone (smells of vinegar, no fungicide), construction silicone, frame sealants.

Scope creep — protect yourself in the quote

A re-grout/re-seal can flip into a much bigger job once work starts. Standard caveats to include in every quote:

• "Quote assumes existing tiles are sound. If hollow tiles (>10%) are found during work, a re-tile estimate will be provided separately."
• "Quote covers visible grout and silicone replacement only. If leak repair, plumbing alteration, or substrate replacement is required, this will be quoted as an extra."
• "Customer accepts colour-match cannot be guaranteed against existing grout in other rooms."
• "Quote excludes mould treatment behind tiles or substrate repair."
• "Curing time 24 hrs minimum; bath/shower not usable on day of work."

Pricing breakdown for a typical job

A typical "standard bathroom re-grout + re-seal" — 12m² of wall tiles + 4m² floor tiles + 10m of silicone runs:

Round to £780. Compare against £55/m² × 16m² = £880 — the per-m² rule is in the right zone. Add £150–£250 if customer wants epoxy grout instead of cement.

Frequently Asked Questions

How long does re-grouting last?

Cement grout in a properly ventilated bathroom: 8–15 years before significant staining/cracking. Epoxy grout: 20+ years. Silicone: 5–8 years before mould stain or peel. Lifespan is shortened by poor ventilation (no extract fan), excessive water exposure (badly fitted shower screen), and substrate movement (flexing floor under tile).

Should I always remove all the old silicone before applying new?

Yes — no exceptions. New silicone does not bond to cured silicone. Even a thin invisible residue will prevent adhesion and the new bead will lift within weeks. Always solvent-wipe with IPA or methylated spirit after physical removal.

Can I just paint over discoloured grout instead of re-grouting?

Grout colour pens and grout paints exist but they're a 6–12 month cosmetic fix only. The underlying grout is still aged, porous, and may be cracking. Recommend re-grout for any job where you want the result to look good in 2 years' time.

Does the customer have to be out of the bathroom for the cure?

No, but they cannot use the bath or shower for 24 hrs minimum (48 hrs is safer). Toilet and basin are fine immediately if their silicone is left untouched.

Why does mould keep coming back?

Three causes: (1) extract fan missing or inadequate (Approved Document F requires 15 L/s minimum in bathroom), (2) non-sanitary silicone with no fungicide, (3) hidden leak feeding moisture behind tile — re-sealing surface won't fix it. Always check ventilation before agreeing to re-seal a chronically mouldy room. See bathroom ventilation.

Regulations & Standards

• BS 5385-1:2018 — Wall and floor tiling — Code of practice for the design and installation of internal ceramic, natural stone and mosaic wall tiling

• BS 5385-3:2014 — Code of practice for the design and installation of internal and external ceramic and mosaic floor tiling

• BS 5385-4:2015 — Code of practice for tiling and mosaics in specific conditions (including wet areas)

• BS EN 13888-1:2022 — Grouts for tiles — requirements, evaluation of conformity, classification (CG1, CG2, R2)

• ISO 11600:2002+A1:2011 — Building construction — Jointing products — Classification and requirements for sealants

• BS EN 14411:2016 — Ceramic tiles classification and characteristics

• Building Regulations Part F — Ventilation (extract fan requirements in bathrooms)

• Building Regulations Part C — Site preparation and resistance to moisture (substrate suitability)

• Building Regulations Part G — Sanitation, hot water safety and water efficiency

• COSHH Regulations 2002 — silicone solvents, mould sprays, epoxy grout components

• BS 5385 family — Wall and floor tiling — BSI

• BS EN 13888 — Grouts for tiles — BSI

• Approved Document F: Ventilation — gov.uk

• The Tile Association (TTA) — technical guidance — industry body

• HSE COSHH guidance for trades — hse.gov.uk

• bathroom tiling pricing guide — pricing new tile installation

• bathroom waterproofing tanking — tanking substrate before re-tile

• bathroom ventilation — Part F extract fan requirements

• shower tray and waste installation — shower tray bedding (cause of failing silicone)

• waterproofing — wet room and tanking systems