Grouting is the final step that can make or break a tiling job. Get it right and your tiles look sharp, clean, and professional; get it wrong and you're left with smears, cracks, or mould down the track. Here's how to nail it every time.
Choose the Right Grout for the Job
Not all grouts are created equal. The two main types you'll find at Bunnings or Mitre 10 are:
| Grout Type | Best For | Key Benefit |
|---|---|---|
| Cement-based (sanded) | Joints wider than about 3 mm | Strong, economical, widely available |
| Cement-based (unsanded) | Narrow joints under 3 mm | Won't scratch polished or glass tiles |
| Epoxy grout | Wet areas, commercial kitchens | Highly stain- and water-resistant |
For wet areas like showers and bathrooms — which must comply with NZ Building Code clause E3 — choose a grout rated for wet area use. Epoxy grouts from brands like Mapei or Ardex offer excellent durability and are worth considering for high-moisture zones.
Colour matters too. Lighter grouts show dirt more easily; mid-tones tend to be more forgiving. Order a little extra — you'll want it for repairs later.
Gather Your Tools Before You Start
Having everything on hand before you mix saves time and prevents the grout from going off mid-job. You'll need:
- Rubber grout float — for pressing grout into joints
- Grout sponge — large, dense, and damp (not soaking wet)
- Bucket and clean water — change it often
- Mixing paddle and drill (for larger areas) or a margin trowel for small batches
- Grout sealer — for cement-based grouts
- Painter's tape — to protect silicone joints and edges
- Knee pads — your future self will thank you
Prepare the Surface Properly
Good grouting starts before you open the bag. Make sure:
- Tile adhesive is fully cured — check the adhesive manufacturer's instructions, but allow at least 24 hours (longer in cold or damp conditions).
- All tile spacers are removed from joints.
- Joints are clean and free of adhesive lumps — use a grout saw or Stanley knife to clear any high spots.
- The surface is dry — grouting over damp adhesive traps moisture and can cause problems.
Apply painter's tape along any silicone expansion joints (corners, wall-to-floor junctions, around fixtures). These joints must be filled with flexible silicone, not grout, to allow for movement and prevent cracking.
Mix the Grout to the Right Consistency
Follow the manufacturer's instructions closely — water ratios matter. The mixed grout should have a smooth, peanut butter-like consistency: firm enough to hold its shape but workable enough to press into joints.
- Mix only as much as you can use in 20–30 minutes (less in warm weather).
- Let the mix slake (rest) for 5–10 minutes after initial mixing, then briefly remix before use.
- Never add extra water to loosen grout that has started to stiffen — discard it and mix a fresh batch.
Apply the Grout Like a Pro
This is where technique makes the difference:
- Hold the float at roughly 45 degrees to the tile surface and work the grout diagonally across the joints. This pushes grout in firmly without dragging it back out.
- Work in manageable sections — around 1–2 square metres at a time for beginners.
- Pack joints fully — run the float over each area two or three times to ensure no voids or air pockets.
- Scrape off excess with the float held at a steeper angle, again working diagonally.
Clean Up at the Right Time
Timing the clean-up is critical. Wait until a light haze forms on the tile surface — usually 10–20 minutes depending on temperature and humidity — then begin cleaning.
- Use a damp (not wet) sponge in a circular motion to remove the bulk of the haze.
- Rinse the sponge frequently and change your water often — dirty water just redistributes grout across the tiles.
- After the first pass, do a second lighter pass with a clean, barely damp sponge.
- Once fully cured (usually 24 hours), buff off any remaining haze with a dry microfibre cloth.
Avoid washing excess grout down drains — it can set and cause blockages.
Seal the Grout for Long-Term Protection
Cement-based grouts are porous and will stain without sealing. Once the grout has cured fully (check the product datasheet — typically 48–72 hours minimum), apply a penetrating grout sealer. This is especially important in kitchens and bathrooms.
BRANZ research highlights moisture management as a key factor in tile installation longevity, particularly in NZ's varied climate conditions.
Reapply sealer every year or two, or whenever water stops beading on the grout surface.
Common Mistakes to Avoid
- Grouting too soon after laying tiles
- Mixing too much grout at once
- Using too much water when cleaning — it weakens the grout surface
- Forgetting silicone joints at movement points
- Skipping the sealer on cement-based grout
When to Call a Professional
While grouting itself is DIY-friendly, some aspects of tiling work are best left to the experts. If your tiling project involves waterproofing a shower or wet area, this is a critical step that must comply with NZ Building Code clause E3. Poor waterproofing is one of the most common and costly defects in NZ homes.
For large-format tiles, heated floors, or complex layouts, a qualified tiler will have the tools and experience to get the best result. You can find licensed local tilers on tradedirectory.co.nz.
If your tiling project involves moving or installing plumbing fixtures, that work must be carried out by a licensed plumber registered with the Plumbers, Gasfitters and Drainlayers Board. Similarly, any electrical work — such as installing in-floor heating thermostats — must be done by a registered electrician under the Electrical Workers Registration Board.