Lippage — where one tile edge sits higher than its neighbour — is one of the most common tiling frustrations, and fixing it after the fact takes a bit of honest assessment. The good news is that minor lippage can often be corrected with the right tools and patience, while more severe cases may need tiles to be lifted and re-laid properly.
What Causes Lippage in the First Place?
Before you fix the problem, it helps to understand why it happened:
- Uneven substrate — a floor or wall that wasn't flat enough before tiling began
- Inconsistent adhesive coverage — hollow spots or ridges under tiles cause them to rock or sit unevenly
- Warped tiles — large-format tiles in particular can have a natural bow (known as warpage), which is covered under NZS ISO 10545 standards
- No tile levelling system used — clip-and-wedge levelling systems are now standard practice for large tiles
- Grout joints too narrow — very tight joints leave no room to absorb slight height differences
Industry guidance from BRANZ and the NZ Building Code generally expects finished tiled surfaces to be within acceptable flatness tolerances. For most residential floors, a maximum of 3 mm deviation under a 1.8 m straightedge is a common benchmark — check with your tile supplier or a licensed tiler for the specific tolerance relevant to your tile size and format.
Step 1 — Assess the Severity
Run your hand across the joints and use a straightedge to measure the height difference. As a rough guide:
| Lippage Level | Approximate Height Difference | Likely Fix |
|---|---|---|
| Minor | Up to ~1 mm | Grinding or feathering |
| Moderate | 1–3 mm | Re-lay affected tiles |
| Severe | 3 mm+ | Re-lay section or full area |
Be realistic — if a large area is affected, grinding is a temporary cosmetic fix at best.
Option 1 — Grinding Down High Edges (Minor Lippage)
For small height differences on floor tiles, an angle grinder fitted with a diamond cup wheel or a dedicated tile edge grinder can carefully shave down the raised edge.
How to do it:
- Protect surrounding tiles with masking tape.
- Work slowly at a low angle, grinding only the raised edge — not the tile face.
- Feather the ground area so there's no sharp step.
- Finish with a fine diamond hand pad to smooth the edge.
- Clean dust thoroughly before regrouting if needed.
Important safety note: Grinding ceramic and porcelain tiles produces fine silica dust, which is a serious respiratory hazard. Always wear a P2 respirator, safety glasses, and hearing protection. Work in a ventilated area and use wet grinding where possible. Refer to WorkSafe NZ for guidance on working safely with silica dust.
Grinding works best on unglazed porcelain or stone tiles. On glazed tiles, grinding through the glaze layer will leave a visible dull patch that's very difficult to disguise — weigh this up carefully before proceeding.
Option 2 — Re-Laying the Affected Tiles (Moderate to Severe Lippage)
If the lippage is more than about 1–2 mm, or if grinding would damage the tile surface, the most reliable fix is to lift and re-lay the problem tiles.
- Remove the grout around the affected tiles using an oscillating multi-tool with a grout removal blade or a manual grout rake.
- Lift the tiles carefully using a wide chisel and mallet, working from the grout joint inward. Take your time — rushing risks cracking adjacent tiles.
- Scrape off the old adhesive from both the substrate and the back of the tile (if the tile is undamaged and you want to reuse it).
- Check the substrate — if it's uneven, this is the time to fix it. Use a suitable floor levelling compound (products from Ardex or Mapei are widely used in NZ) and allow it to cure fully.
- Re-bed the tile using the correct notched trowel size for your tile format, ensuring full back-buttering for large tiles. Use a tile levelling system this time to prevent the problem recurring.
- Allow the adhesive to cure before regrouting.
Option 3 — Transition Strips or Trims (Localised Lippage at Joins)
If the lippage occurs at a transition between two tiled areas or between tile and another flooring material, a metal transition strip or reducer profile can bridge the height difference neatly. This is a practical solution when re-laying isn't feasible. These are available from Bunnings and Mitre 10.
Preventing Lippage Next Time
- Always check your substrate is flat before tiling — fix low spots with levelling compound
- Use a tile levelling system (clips and wedges) for tiles 300 mm or larger
- Back-butter large tiles in addition to applying adhesive to the substrate
- Choose grout joint widths appropriate for your tile's warpage tolerance
- Follow the adhesive manufacturer's open time and coverage recommendations
When to Call a Professional
If the lippage affects a large area, involves tiles in a wet area (shower, bathroom floor), or if lifting tiles risks damaging waterproofing membranes underneath, stop and call a licensed tiler. Wet area waterproofing is critical under the NZ Building Code (Clause E3) and must not be compromised. Attempting DIY repairs in these areas without understanding the waterproofing system beneath can lead to costly water damage.
You can find qualified, experienced local tilers on tradedirectory.co.nz who can assess the situation and advise on the best course of action.
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