Key points
- The first letter is the adhesive type: C cementitious, D dispersion (ready-mixed paste), R reaction resin (epoxy or polyurethane).
- The number: 1 normal, 2 improved (passes the same tests at higher levels). For cementitious C2 the adhesion threshold is 1 N/mm².
- T slip ≤ 0.5 mm on a wall, E extended open time ≥ 30 minutes, F fast-setting.
- S1 deformable (≥ 2.5 mm and < 5 mm), S2 highly deformable (≥ 5 mm) — important for large tiles and surfaces exposed to movement and heat.
Written for:OwnerContractorSupplier
Adhesive bags carry codes like C1T or C2TE S1. They come from the European standard EN 12004, now a worldwide reference for classifying tile adhesives, with the international equivalent ISO 13007. Understanding them lets you choose the right adhesive instead of relying on "the most expensive" or "what the shop says".
1) Adhesive type — the first letter
| Code | Type | Description |
|---|---|---|
| C | Cementitious | A mix of hydraulic binder (Portland cement), aggregates and organic additives such as polymers, mixed with water or a special liquid before use1. The most widely used. |
| D | Dispersion | Ready to use, made of organic binders as an aqueous polymer dispersion with fillers — i.e. the ready-mixed "paste"1. |
| R | Reaction resin | One or more synthetic resin components that harden by chemical reaction, such as epoxy and polyurethane1. |
2) Class — the number
- 1 = normal: passed the mandatory minimum tests for its type1.
- 2 = improved: passed the same tests at higher levels1.
For cementitious adhesive: the tensile adhesion threshold for class C2 is 1 N/mm² under EN 120042..
3) Additional properties — the letters
| Code | Meaning | Requirement in the standard | When you need it |
|---|---|---|---|
| T | Reduced slip (thixotropic) | Tile slip on a vertical wall ≤ 0.5 mm for C and D, and ≤ 5 mm for R1 | Wall tiling, especially top-down. |
| E | Extended open time | Achieves the required adhesion at least 30 minutes after spreading1. Not applicable to R. | Hot, dry weather and large areas, because the adhesive surface skins quickly. |
| F | Fast-setting | Meets the early-strength requirements for fast adhesives1. Not applicable to R. | Urgent work, commercial areas needing quick return to use. |
| S1 | Deformable | Deformation ≥ 2.5 mm and < 5 mm1 | Large tiles, facades, surfaces with temperature changes, tiling over old tile. |
| S2 | Highly deformable | Deformation ≥ 5 mm1 | More severe movement conditions, per designer and manufacturer. |
The S (deformability) property does not apply to dispersion (D) or resin (R) adhesives, and is written separately from the main class, e.g. C2FT S11.
4) Examples of reading the codes
| Code on the bag | Meaning |
|---|---|
C1 | Normal cementitious adhesive. |
C1T | Normal cementitious adhesive with reduced slip. |
C2TE | Improved cementitious adhesive, reduced slip, extended open time. |
C2TE S1 | As above, plus deformable. |
C2FT | Improved, fast-setting cementitious adhesive with reduced slip. |
D2TE | Improved ready-mixed paste, reduced slip, extended open time. |
R2 | Improved resin adhesive (e.g. epoxy). |
5) How to choose — a practical guide
| Situation | Common starting choice |
|---|---|
| Standard ceramic wall tile, interior | C1T |
| Medium-size interior porcelain floor | C2 or C2T/C2TE |
| Large-format porcelain, or porcelain on walls | C2TE, often C2TE S1 |
| Sun-exposed exterior areas, facades | C2TE S1 or S2 per the manufacturer |
| Chemical environments (food plants, labs) | R2 (epoxy) |
The key rule: read the technical data sheet of the product itself. Low-absorption tile (porcelain) doesn't "soak up" adhesive, so it needs a polymer-improved adhesive, and manufacturers specify the right adhesive for each tile and location. This table is indicative, not a substitute for the manufacturer's recommendation.
6) Common mistakes
- Exceeding the open time: if you touch the spread adhesive and nothing sticks to your finger, a skin has formed and it won't bond well; remove it and spread fresh adhesive.
- Adding extra water: weakens the adhesive and increases shrinkage; stick to the stated mixing ratio.
- Re-mixing adhesive with water after it starts to set: a common mistake that destroys its strength.
- Compensating for an uneven floor with adhesive thickness: every adhesive has a maximum thickness set by the manufacturer; level the floor first.
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.
- 1EN 12004 Classifications – TDS 137EN — LATICRETE International
- 2Assessment of Cementitious Ceramic Tile Adhesives in the Light of Repeatability and Reproducibility of the Tensile Adhesion Strength Measurements — Michalak & Ziomek — Materials (Basel) 16(12):4245, 2023-06-08
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This guide is for general information and planning, based on standards and technical guides. Standards are revised periodically; in Saudi Arabia the binding reference is the Saudi Building Code and the instructions of the competent authorities. For design and execution, use a licensed engineer or technician. Found an error? Tell us.