INFOTEHNIC
How do I choose adhesive and grout?
In short – which adhesive to choose, based on where you’re installing: for indoors and small-format tiles, a classic cement-based adhesive (C1/C2); for outdoors, wet areas, underfloor heating, or large tiles, an enhanced flexible adhesive (C2 S1/S2, e.g. Weber Marmo Plus); for marble and light-colored stone, a white adhesive; for special substrates (metal, wood, flexible surfaces), reactive-resin adhesives (R). If you’re unsure, ask your PIATRAONLINE advisor – full technical details are below.
1. Adhesives – types and codes
Under industry standards, the following adhesive types and codes are defined.
There are 3 types of adhesive:
- Mineral-binder based (C):
one-component – cement-based, with filler materials (e.g. sand), polymer resins, and additives; supplied as a powder and mixed on site
two-component – one powder component that’s cement-based, with fillers and organic additives, plus a liquid organic resin component, added on site, usually with no water added
Dispersion-based (D): a mix of organic binders as aqueous polymer dispersions, organic additives, and mineral fillers, ready to use
Reactive-resin based (R): a mix of synthetic resins, filler materials, and organic additives that undergo chemical reactions.
Standard codes: cement-based adhesives
C1: Mineral-binder adhesive with normal setting
C1E: Mineral-binder adhesive with normal setting and extended open time
C1F: Mineral-binder adhesive with fast setting
C1FT: Mineral-binder adhesive with fast setting and reduced slip
C2: Enhanced mineral-binder adhesive with additional properties
C2E: Enhanced mineral-binder adhesive with the additional property of extended open time
C2F: Enhanced mineral-binder adhesive with fast setting and additional properties
C2S1: Enhanced mineral-binder adhesive, deformable
C2S2: Enhanced mineral-binder adhesive, highly deformable
C2FT: Enhanced mineral-binder adhesive with fast setting, additional properties, and reduced slip
C2FTS1: Enhanced mineral-binder adhesive with fast setting, additional properties, flexibility, and reduced slip
2. Adhesive selection guide
Choosing an adhesive depends on the tile type and size, as well as where it’s being installed. In certain cases the substrate type also affects the choice.
Recommendations:
Low-porosity (low water-absorption) stone, installed indoors or outdoors (floor or wall), on a standard substrate: adhesive code C1T(E) or C2TE. For tiles up to 900 cm² (e.g. 30 x 30 cm, 30 x 15 cm, 40 x 20 cm), Weberset ST10 – C1T or Weberset Stone – C1T can be used; for tiles up to 1600 cm² (e.g. 40 x 40 cm), Weberset H₂O – C1TE is recommended; and for tiles up to 2500 cm² (e.g. 60 x 30 cm), Weberset EX25max² – C2TE is recommended.
High-porosity stone, sensitive to moisture and stains, installed indoors on a wall or floor: C2TE (possibly S1 for outdoor cladding and steps regardless of where they’re installed). Recommended: Weberset EX25Max², Weberset Portelanat Max² (tiles up to 6400 cm², e.g. 80×80 cm) – C2TES1, and Weberset Marmo Plus – C2TES1.
Stone in demanding environments (including flexible substrates, pools), Weberset Superflex max² – C2TES2 is recommended
3. Grout – types and codes
Based on joint type, grouts are divided into:
Rigid-joint grouts: supplied as a powder, mixed on site with water or with a liquid synthetic-resin component, designed for the joint size (small joints ≤2mm and large joints 2-15mm, even larger).
Flexible-joint grouts: flexible products, resistant to outdoor environmental factors, based on elastomers (silicone resins, polyurethane, etc.), supplied as pastes, in various colors.
Joint-depth adjustment products: plastic cord-shaped products, used to reduce excessive depth in some flexible joints
Based on the raw material used, grouts are divided into:
- Mineral-binder-based grout (CG)
Mineral-binder-based grouts are classified and labeled with the following codes:
CG1 – normal grout
CG2 – enhanced grout with additional properties
CG2W – enhanced grout with additional low-water-absorption properties
Reactive-resin-based grout (RG) = a mix of synthetic resins, aggregates, and inorganic and organic additives that set through a chemical reaction. Grouts are manufactured as single-component or multi-component products.
4. Grout selection guide
Stone cladding can be installed with or without joints, and joint sizes vary. Weber’s mineral-binder-based grouts are CG2W type (cement-based).
For joints of 1-6 mm (especially for indoor cladding), Webercolor Comfort is recommended – a flexible grout, resistant to water, mold, and discoloration.
For joints of 5-50 mm (especially for outdoor cladding), WeberColor Stone is recommended – a flexible grout, resistant to mechanical stress, abrasion, and environmental conditions.
For demanding environments (pools, areas with chemical cleaning), Weberepox Easy is recommended – a two-component epoxy grout, used indoors and outdoors, forming a chemical bond between components.
Grouting is not recommended for flexible slate cladding.
After grouting, residue can remain on the cladding. This is removed with specialized solutions, depending on the surface finish. Wiping the surface with a damp sponge is the best way to clean it, if done before the grout dries.
5. Calculating grout consumption
Per industry standards, grout consumption is calculated using the formula:
(A+B) x E x L x K / A x B (in mm) = kg/m²
Where K (a dimensionless coefficient) = 1.4 for WeberColor Comfort and 1.6 for Weberepox Easy
Example: for cladding a 23 m² floor with Travertino Classic Cross Cut Matte 61 x 40.6 x 1.2 cm, with a 0.5 cm joint, WeberColor Comfort grout consumption is calculated as follows:
A = 61 cm = 610 mm
B = 40.6 cm = 406 mm
E = 1.2 cm = 12 mm
L = 0.5 cm = 5 mm
K = 1.4
Per the standard formula, consumption per square meter is:
(610 + 406) x 12 x 5 x 1.4 / 610 x 406 = 85344/247660 = 0.344 kg/m²
For the whole surface, consumption is 0.344 kg/m² x 23 m² = 7.912 kg
WeberComfort grout is supplied in 2 kg and 20 kg bags.
In this example, the quantity to purchase is 4 x 2 kg bags.
