Dirty or cracked grout makes even good tiles look neglected — and failing grout in wet areas causes real damage. Here's what grout cleaning and repair costs in NZ in 2026 and how to decide whether to clean, seal, or regrout.
Grout Cleaning and Repair Cost NZ 2026
| Service | Typical cost |
|---|---|
| Professional grout cleaning (per m²) | $20–$50/m² |
| Bathroom grout clean + seal (5–10m²) | $200–$600 |
| Grout sealing only (per m²) | $8–$20/m² |
| Regrouting — remove and replace (per m²) | $60–$150/m² |
| Regrouting full bathroom (25m²) | $1,500–$4,000 |
| Grout colour change (staining/painting) | $15–$35/m² |
| Silicone replacement at corners (per lm) | $20–$50/lm |
| Single crack / chip repair | $80–$200 |
All prices GST inclusive. Auckland 15–20% above. Shower regrouting with waterproofing behind is significantly more complex — treat as partial shower renovation.
Grout Problems and Solutions
Discoloured / Dirty Grout
The most common complaint — grout goes grey, brown, or black from soap scum, mould, hard water deposits, and daily grime.
Cause: Grout is porous (especially cement-based grout without sealing) and absorbs stains over time. Dark, moist environments (showers) accelerate this.
Solution 1 — Professional cleaning: A tile and grout cleaning service uses high-pressure steam, alkaline cleaners, and rotary brushes to clean deep into grout lines. Removes staining that surface scrubbing can't reach.
Solution 2 — Grout staining/painting: A grout pen or grout paint covers discoloured grout with a new colour. Quick and inexpensive but not as permanent as regrouting — wears off over time.
Solution 3 — Regrouting: The definitive solution for grout that's too stained to clean — old grout is raked out and replaced with fresh grout. More expensive but lasts years.
Cracked or Crumbling Grout
Grout that cracks, chips, or crumbles out of joints is a maintenance and waterproofing issue.
Cause: Normal building movement (thermal expansion/contraction), insufficient flexible silicone at movement joints (corners), substrate movement, or old grout that's reached end of life.
Solution: Rake out cracked grout and regrout. For corners and junctions where different planes meet, use silicone (flexible) not grout — silicone accommodates movement, cement grout cracks.
The leak risk: Cracked grout in a shower allows water through to the substrate. If the waterproofing membrane behind the tiles is intact, the structure is protected but the wall stays wet and can develop mould. If the membrane is compromised, water reaches the framing — expensive to fix if left long.
Mouldy Grout (Shower / Bathroom)
Black or green mould in shower grout is extremely common in NZ's humid climate.
Surface mould: Scrub with a bleach-based bathroom cleaner and a stiff brush. For persistent mould, apply neat bleach gel, cover with clingfilm, leave 30 minutes, scrub and rinse.
Mould that keeps coming back: The grout may be very porous and mould is growing deep in the joint — professional cleaning with steam or rotary cleaning equipment may remove it better. After cleaning, seal all grout to reduce porosity.
If the mould is behind the grout (on the wall surface): This indicates a waterproofing failure — water is getting behind the tiles. This requires removing tiles to assess and repair, not just cleaning.
How to Decide: Clean, Seal, or Regrout?
| Grout condition | Recommended action |
|---|---|
| Dirty but structurally sound | Professional clean + seal |
| Minor staining, colour change wanted | Grout pen / paint |
| Cracked at corners | Replace silicone at movement joints |
| Widespread cracking or crumbling | Regrout |
| Mould that keeps returning | Clean, then seal; or regrout if persistent |
| Old grout + planning a tile refresh | Regrout (better long-term result) |
Regrouting Process
- Rake out old grout: An oscillating multi-tool with a grout removal blade removes old grout to a depth of 5–8mm (leaving the tiles intact)
- Clean joints: Vacuum and blow out dust
- Apply new grout: Mix and apply new grout, working it into joints with a rubber float
- Clean excess: Wipe diagonal to tiles with a damp sponge (multiple passes)
- Cure: Allow 24–48 hours before wetting
- Seal: Apply grout sealer to protect new grout
Total elapsed time: 1–2 days for a bathroom. Shower must not be used for 48 hours after regrouting.
Grout Sealing
Sealing grout after cleaning or regrouting dramatically extends its cleanliness and reduces mould growth.
Products in NZ: Aqua Mix Sealer's Choice, Mapei Ultracare Grout Protector, BAL Grout Protector. Available from tile suppliers and plumbing merchants.
How often to seal: Every 1–2 years for shower floor and bathroom floor grout. Wall grout in lower-moisture areas: every 3–5 years.
The water bead test: Drop water on a grout line. If it beads, the sealer is working. If it soaks in immediately, it's time to reseal.
DIY Grout Cleaning
For surface cleaning, DIY is very effective: - Baking soda + white vinegar: Sprinkle baking soda on grout, spray with vinegar, scrub with an old toothbrush. Good for surface soap scum. - Bleach gel (Domestos, Selleys): Apply to grout, leave 10–20 minutes, scrub. Effective for mould. - Steam cleaner: A home steam cleaner is very effective at cleaning grout without chemicals.
For sealing: DIY sealing after cleaning is straightforward — apply with a small brush along grout lines, wipe excess off tiles, allow to cure.
For regrouting: DIY regrouting is possible but the oscillating tool requires care to avoid scratching tiles. Professional regrouting is worth it for large areas or when tile damage is a concern.
Find tilers for grout work: Tilers NZ | Post Your Job Free
Frequently Asked Questions
How much does regrouting a bathroom cost in NZ? Regrouting (rake out and replace): $60–$150/m². A full bathroom (25m²): $1,500–$4,000 including labour and grout supply. Professional cleaning only: $20–$50/m².
How do I get rid of black mould in shower grout in NZ? Apply a bleach-based bathroom cleaner (neat bleach gel or Domestos) directly to the grout, cover with clingfilm to stop it drying out, leave 30–60 minutes, then scrub with a stiff brush and rinse. For persistent mould, professional steam cleaning reaches deeper into the porous grout. After cleaning, seal the grout to reduce future mould.
How long does regrouted shower grout last in NZ? Well-applied grout in a shower: 10–20 years before it needs replacing. Sealing after regrouting and annually thereafter extends this. Grout in a poorly ventilated bathroom or with structural movement cracks sooner.
Can I change the colour of my bathroom grout in NZ? Yes — grout pens and grout paint can change the colour without regrouting. These are cost-effective for surface discolouration but wear off over time (1–3 years in showers). Permanent colour change requires raking out and regrouting with new coloured grout.
Should shower corners be grout or silicone in NZ? Always silicone — never grout at internal corners where two tiled planes meet (floor-to-wall, wall-to-wall). Grout is rigid and cracks at movement joints from building movement and thermal expansion. Silicone is flexible and accommodates this movement. Cracked corner grout is a very common cause of shower leaks.
Related: Tiling Cost NZ | Shower Tiling Cost NZ | Bathroom Renovation Cost NZ