Yes — in most cases you can regrout existing tiles without pulling them off the wall or floor. As long as the tiles are firmly bonded, uncracked, and the substrate behind them is sound, regrouting is a straightforward DIY job that can make tired-looking tiles look almost new again. The key is removing the old grout thoroughly before applying the new.
Is Regrouting the Right Fix?
Before you reach for the grout rake, check that regrouting will actually solve your problem. Regrouting works well when:
- Grout is discoloured, stained, or mouldy but the tiles are solid
- Grout is crumbling or cracking in isolated areas
- You want to refresh the look of an older bathroom or kitchen
Regrouting is not the right fix if:
- Tiles are hollow-sounding when tapped (tap each tile gently — a dull thud suggests debonding)
- There is movement or flex in the tiles underfoot or when pressed
- You can see water damage, swelling, or mould behind the tiles — this points to a substrate problem that needs proper investigation
- Grout joints are wider than about 6 mm and cracking repeatedly, which may indicate structural movement
If tiles are loose or the substrate is compromised, regrouting is a temporary fix at best. In wet areas like showers, a failed substrate can lead to serious water damage — a concern taken seriously under NZ Building Code clause E3 (Internal Moisture).
What You'll Need
Tools:
- Grout rake or oscillating multi-tool with a grout removal blade
- Stiff brush and vacuum
- Grout float
- Sponge and two buckets
- Safety glasses and dust mask (P2 rated)
Materials:
- New grout (see below)
- Grout sealer (for cement-based grout)
- Painter's tape
- Silicone sealant for corners and junctions (do not grout these — more on this shortly)
Choosing the Right Grout
NZ hardware stores stock several grout types. The main ones are:
| Grout Type | Best For | Notes |
|---|---|---|
| Cement-based (unsanded) | Joints up to ~3 mm | Common, easy to work with, needs sealing |
| Cement-based (sanded) | Joints 3–12 mm | More durable for wider joints, needs sealing |
| Epoxy grout | Wet areas, high hygiene needs | Harder to apply, very durable, stain-resistant |
| Premixed acrylic | Light-duty, dry areas | Convenient but less durable in wet areas |
For bathrooms and kitchens, a quality cement-based or epoxy grout is recommended. Brands like Ardex and Mapei offer grout products widely available through NZ tile and building suppliers. Sika also produces grout and tile products suited to NZ conditions.
Step-by-Step: How to Regrout
1. Remove the Old Grout
This is the most important step. Use a grout rake or oscillating tool to remove grout to a depth of at least 5–6 mm. Work carefully to avoid chipping tile edges. Wear safety glasses — old grout chips fly. Vacuum out all dust and debris.
2. Clean the Joints
Wipe joints with a damp cloth and allow to dry fully. Any residue or dust will prevent the new grout bonding properly.
3. Mix and Apply New Grout
Mix grout to a peanut-butter consistency (follow the manufacturer's instructions exactly). Using a grout float, press grout firmly into the joints at a diagonal angle, working in small sections. Remove excess grout from tile faces with the edge of the float.
4. Clean Up
After 10–20 minutes (check your product's instructions), wipe tiles with a damp sponge using a circular motion. Rinse the sponge frequently. Repeat until the haze is gone. Avoid flooding joints with water.
5. Seal the Grout
Once fully cured (typically 48–72 hours, but check the product datasheet), apply a penetrating grout sealer to cement-based grout. This is especially important in wet areas to resist mould and staining.
6. Silicone at Movement Joints
Corners, junctions between walls and floors, and around fixtures like baths and shower trays should never be filled with grout. These are movement joints — always use a flexible, mould-resistant silicone sealant here. This is standard practice per BRANZ guidelines and helps prevent cracking and water ingress.
Safety Note
If your home was built before the 1990s, older tile adhesives or grout may contain asbestos. Do not dry-grind or aggressively rake old grout without checking first. If in doubt, contact a licensed asbestos assessor before disturbing any materials. WorkSafe NZ has guidance on identifying and managing asbestos safely.
When to Call a Professional
Call a qualified tiler if:
- Multiple tiles are loose, cracked, or hollow-sounding
- There is evidence of water damage behind tiles (especially in showers)
- You're dealing with a large area or complex layout
- The job involves removing and relaying tiles, which requires skill to match existing tiles and ensure a waterproof result in wet areas
- You're unsure whether the substrate is sound
In wet areas, poor tiling and waterproofing can lead to costly damage. A licensed tiler will ensure the work meets the NZ Building Code. You can find qualified local tilers on tradedirectory.co.nz.
Note: Tiling work itself is generally not restricted work under NZ law, but associated plumbing or drainage work must be carried out by a licensed tradesperson registered with the Plumbers, Gasfitters and Drainlayers Board.
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