- 1. Introduction
- 2. Classes (EN 13888 / ISO 13007-3)
- 3. When to choose
- 4. Selector database (0–6 mm joints only)
- 5. Joint rules of thumb
- 6. Field checklist
- Disclaimer
1. Introduction
Tile grouts fill and seal tile joints, prevent moisture ingress, and accommodate minor movement. Correct selection depends on joint width, exposure, tile type, and hygiene or chemical resistance needs. Grouts do not replace movement joints — use sealants there.
2. Classes (EN 13888 / ISO 13007-3)
- CG1 — Standard cementitious
- CG2 — Improved cementitious
- CG2WA — Hydrophobic, polymer‑modified
- RG — Reaction resin (epoxy/PU)
3. When to choose
- Dry interiors → CG1
- Wet rooms and outdoors → CG2WA
- Submerged or hygiene‑critical → RG
- Natural stone → White CG2 or RG
4. Selector database (0–6 mm joints only)
For joints > 6 mm, use sealant systems: No access.
Scenario | Joint (mm) | Grout Class | Binder | Notes |
Indoor dry | 2–4 | CG1 | Cementitious | Economical for low‑stress interiors |
Bathrooms / Kitchens / Balcony | 2–6 | CG2WA | Polymer‑Modified | Hydrophobic, better stain and water resistance |
Pools / Food areas | 3–6 | RG | Resin (Epoxy/PU) | Non‑porous, chemical resistant |
Natural stone / Marble | 2–6 | CG2 (white) or RG | Cementitious or Resin | White CG2 to avoid staining; RG where hygiene critical |
Outdoor terrace | 4–6 | CG2WA | Polymer‑Modified | Flexible for thermal movement and UV |
Industrial floor | 4–6 | RG | Resin (Epoxy/PU) | High compressive and chemical resistance |
5. Joint rules of thumb
- Tile ≤ 300 mm → 2 mm joints
- 300–600 mm → 3–5 mm joints
- ≥ 600 mm or high movement → 5–8 mm “rubber” joints
- Perimeter and movement joints every 4–6 m and at edges
- Depth ≈ width for even curing
6. Field checklist
- Clean, vacuum joints
- Mix per TDS, low RPM
- Pack fully with rubber float
- Initial clean after set
- Protect during cure
- Seal movement joints (don’t grout)
Failures → fixes
- Powdering/cracks → correct water ratio; upgrade to CG2/CG2WA
- Efflorescence → ensure waterproofing; consider RG
- Staining/variation → pre‑colored grout or RG; consistent cleaning
- Leakage → recut and regrout CG2WA/RG; full packing
- Mold/blackening → hydrophobic or epoxy grout; fix slopes/ventilation
Spec checks (minima)
- CG2 flexural ≥ 2.5 N/mm², compressive ≥ 15 N/mm²
- Water absorption ≤ 5 g / ≤ 10 g (prefer ≤ 2 g / ≤ 5 g for CG2WA)
- Slip ≤ 0.5 mm on walls
- RG: no deleterious change under chemicals
Consultant sidebar — quick pattern
- CG1 = dry interiors
- CG2WA = wet rooms and outdoors; choose white for light stones
- RG = submerged, food, labs, high chemical or hygiene need
- Movement joints: never grout. Use sealant systems from Joint Treatment Solutions
Disclaimer
Conix is an industry initiative & a neutral resource, compiled from industry references and best practices. It is not brand-specific. Always cross-check with project requirements and local codes before finalizing specifications.