Key points
- ISO 13006 and the European EN 14411 classify tiles by forming method (A extruded, B dry-pressed) and water absorption (E).
- Technically, porcelain = tile with water absorption of 0.5% or less (group BIa for pressed tiles).
- The word 'porcelain' on the box is no guarantee; ask the supplier for the measured water absorption per ISO 10545-3 or ASTM C373.
- The lower the water absorption, the denser and more durable the tile, and the more resistant to frost and stains.
In a tile showroom you'll hear many names: ceramic, porcelain, granite porcelain, full body, matt, polished… Some are technical terms and some are marketing names. This guide explains the official classification used worldwide, so you know exactly what you're buying and can compare offers on a sound basis.
How are tiles classified internationally?
The European standard EN 14411 classifies ceramic tiles by two criteria1:
- Forming method:
- A — Extruded: formed from a plastic paste pushed through a die and cut to length.
- B — Dry-pressed: formed from fine granulated powder pressed at high pressure. Most modern floor and wall tiles on the market are this type.
- Water absorption (E): the increase in a tile's weight after saturation with water compared with its dry weight, measured per ISO 10545-31.
Water absorption groups
This is the most important table in the tile world. Every tile belongs to a group by its water absorption1:
| Group (dry-pressed) | Group (extruded) | Water absorption E | What it means in practice |
|---|---|---|---|
| BIa | AIa | E ≤ 0.5% | Very dense tile (porcelain). Suits interior and exterior floors and wet areas. |
| BIb | AIb | 0.5% < E ≤ 3% | Very low absorption, dense and durable. |
| BIIa | AIIa | 3% < E ≤ 6% | Medium absorption. |
| BIIb | AIIb | 6% < E ≤ 10% | Medium to high absorption. |
| BIII | AIII | E > 10% | High absorption; usually glazed interior wall tile. |
A note from the standard: group BIII applies mainly to glazed tiles, and groups AIIa and AIIb are each split into two parts with different requirements1.
What exactly is porcelain?
Porcelain isn't necessarily a different clay; it's tile fired to a high degree of vitrification (sintering) that makes its water absorption very low:
- In North America, ANSI A137.1 defines porcelain tile as tile with water absorption of 0.5% or less when tested per ASTM C3732.
- In the European/international classification it corresponds to group BIa (absorption ≤ 0.5%), described in manufacturers' technical guides as "highly sintered" tile1.
Porcelain types by colour and surface
| Type | Description | When to prefer it |
|---|---|---|
| Through-body (full body) porcelain | Unglazed, with no separate decorative surface or print; the colour runs through the full body of the tile3. | High-traffic areas, because a scratch or chipped edge doesn't reveal a different colour. |
| Colour-body porcelain | A glazed tile with a decorated surface and a body in a similar or complementary colour3. | A compromise between appearance and durability. |
| Glazed porcelain | A surface layer creates the visual; the body may or may not closely match it3. | Most residential uses, paying attention to the surface's PEI abrasion rating. |
And ceramic?
In market language, "ceramic" usually means higher-absorption tile (groups BIIa, BIIb and BIII), especially glazed wall tile. That doesn't make it poor: it's lighter, easier to cut and very suitable for interior walls. But:
- Avoid it outdoors in variable conditions and on high-traffic floors, unless its specifications allow it.
- High-absorption tile needs more care in choosing the adhesive and installation method; follow the manufacturer's instructions.
Other properties set by the standard
Besides water absorption, standards and manufacturers' technical guides specify important properties you'll find on the data sheet1:
- Fire behaviour: ceramic tile is classified A1 (non-combustible) per EN 13501-1.
- Thermal expansion: roughly 6×10⁻⁶ to 8×10⁻⁶ per °C; an 8 m floor can expand about 2.4 mm with a 50°C temperature difference, which is why large and exterior areas need movement joints. See tile problems.
- Colour fastness: glazed and unglazed tiles are colour-fast to light.
- Shade & calibre: their codes are printed on the box; only install boxes with the same codes in the same area.
Choosing indoor tiles step by step
| Question | Where to find the answer |
|---|---|
| Dry, wet or outdoor? (absorption group) | The water absorption groups section above |
| Walked on when wet? (slip resistance) | Tile specifications |
| How much surface wear? (PEI for glazed) | Tile specifications |
| Which adhesive? | Tile adhesive |
| Joints, installation, coverage | Tile installation, Grout |
| Maintenance and problems | Tile problems |
Practical summary before buying
- Ask for the absorption group (BIa, BIb…) or measured E value, not the trade name.
- For exterior floors, bathrooms and kitchens: prefer BIa/BIb.
- For glazed porcelain on floors: check the PEI and slip resistance ratings.
- Buy enough of the same shade and calibre code, with extra for waste and future repairs.
- Ask for the technical data sheet and keep it with your invoice.
Sources
The number next to a statement points to its source in this list. Sources back the general information; anything marked “practical advice” is editorial experience, not a quoted source. Anything that affects safety, structural design or electrical installations needs a licensed professional, and in Saudi Arabia the binding reference is the Saudi Building Code.
- 1Application Technique — Terms and Classifications according to DIN EN 14411 — AGROB BUCHTAL / Deutsche Steinzeug
- 2Porcelain in the Ceramic Tile Industry — Tile Council of North America (TCNA)
- 3The Real Scoop on Through-Body Porcelain Tile, Revisited — Crossville Tile — manufacturer blog, 2026-05-13