Choosing between rectified and non-rectified tiles is one of those decisions that can make a real difference to the finished look of your floor or wall — yet many homeowners have never heard the terms before walking into a tile shop. Understanding the difference will help you pick the right product, budget correctly, and set realistic expectations for your tiler.
What Are Non-Rectified Tiles?
Non-rectified tiles (sometimes called calibrated or natural-edge tiles) are fired in a kiln and then sorted by size, but their edges are left in the natural state that comes out of the firing process. Because clay and other materials shift slightly during firing, individual tiles from the same batch can vary by a millimetre or two in their actual dimensions. This is completely normal and has been the standard for centuries.
To accommodate this natural variation, non-rectified tiles are traditionally laid with a wider grout joint — typically 3 mm or more — which allows the tiler to visually absorb size differences across the field. The slightly rounded or chamfered edges also help disguise minor lippage (where one tile sits fractionally higher than its neighbour).
What Are Rectified Tiles?
Rectified tiles go through an additional manufacturing step after firing: each tile is mechanically cut (or ground) on all four sides to achieve a very precise, consistent dimension. The result is a tile with sharp, square edges and almost no size variation between pieces.
Because every tile is essentially the same size, rectified tiles can be laid with very tight grout joints — often as narrow as 1.5–2 mm — giving a sleek, near-seamless appearance that is popular in contemporary NZ interiors. Large-format porcelain tiles (600 mm × 600 mm and above) are almost always rectified for this reason.
Key Differences at a Glance
| Feature | Non-Rectified | Rectified |
|---|---|---|
| Edge finish | Natural / chamfered | Mechanically cut, sharp |
| Size consistency | Minor variation (±1–2 mm typical) | Very precise, minimal variation |
| Minimum grout joint | 3 mm+ recommended | 1.5–2 mm possible |
| Typical formats | Small to medium (up to ~450 mm) | Medium to large format |
| Substrate prep required | Standard flat surface | Very flat — critical |
| Material cost | Generally lower | Generally higher |
| Labour cost | Standard | Can be higher (more prep needed) |
| Best look | Traditional, textured, rustic | Modern, minimal, seamless |
Grout Joint Width — Why It Matters
The grout joint is not just aesthetic. BRANZ research and industry best practice both confirm that grout joints allow for minor movement in the substrate and tile assembly, helping prevent cracking over time. Going too narrow with a non-rectified tile is a common DIY mistake — the size variation becomes visible as uneven joints, and the result looks unprofessional.
With rectified tiles, a narrow joint is achievable, but it places greater demands on the substrate. The floor or wall must be very flat and true — any high spots or hollows will cause lippage that is far more noticeable with a tight joint and sharp edges.
Substrate and Installation Considerations
For rectified tiles, your tiler will need to spend more time preparing the substrate. In NZ homes, concrete slabs, fibre-cement sheet (such as James Hardie products), and GIB Aqualine in wet areas all need to be checked for flatness — typically no more than 3 mm variation under a 3-metre straightedge, though tighter tolerances are preferred for large-format rectified tiles.
Wet areas (bathrooms, showers, laundries) must also comply with NZ Building Code clause E3 for internal moisture control. This means using an appropriate waterproof membrane system beneath the tiles regardless of tile type — your tiler should be familiar with compliant systems from suppliers like Ardex or Mapei.
Which Tile Is Right for Your Project?
Choose non-rectified tiles if you:
- Want a traditional, handmade, or rustic aesthetic
- Are tiling a smaller area with an existing substrate that is not perfectly flat
- Are working to a tighter budget
- Are using smaller mosaic or feature tiles
Choose rectified tiles if you:
- Want a modern, minimal look with tight grout lines
- Are using large-format tiles (600 mm or larger)
- Have — or are willing to invest in — a well-prepared, flat substrate
- Are tiling a high-visibility area like a main bathroom or open-plan living floor
Cost Expectations
As a rough guide, rectified tiles tend to cost more per square metre than comparable non-rectified options, and installation labour can also be higher due to the extra substrate preparation involved. Always get a detailed quote from your tiler that separates materials, prep work, and laying costs so you can compare accurately. Tile prices vary widely — browse ranges at Mitre 10 or Bunnings for a general sense, or visit a specialist tile supplier for a broader selection.
When to Call a Professional
While an experienced DIYer can lay non-rectified tiles in straightforward situations, rectified large-format tiles are best left to a qualified tiler. Getting the substrate flat enough, maintaining consistent narrow joints, and cutting sharp-edged porcelain without chipping all require professional tools and skill. Any tiling in a shower or wet area should also be done by someone who understands waterproofing compliance under the NZ Building Code — a botched wet-area job can lead to costly water damage and mould issues.
You can find qualified, local tilers on tradedirectory.co.nz — look for someone with experience in the tile format and finish you have in mind.