Adhesives for tiles. How do we choose them?

When deciding to install tiles in your home, it is important to be well-informed about the materials you are using. It is crucial to choose the right adhesive to ensure the durability of the project. With so many options on the market, it can be difficult to determine which adhesive to use, but with a little patience and attention to detail, you can choose the right one for your project.

Firstly, it is important to consider a number of aspects when selecting an adhesive. The correct choice of adhesive is closely related to the resistance and durability of the installation project, which prevents the tiles from coming loose, cracking, or allowing water infiltration. The adhesive for tiling is selected based on: the type of ceramic tiles (absorption grade, resistance to freezing, tile size, etc.), the surface of the substrate (cement, plaster, drywall), the location of use (interior or exterior, in a wet environment such as a bathroom, on a horizontal or vertical surface, in a high-traffic area, etc.).

There are two categories of ceramic tiles depending on the method of manufacturing: extruded (Class A) – obtained by deforming the material using a special device, resulting in a strip that is cut into tiles at predetermined lengths; they can be glazed or unglazed; dry pressed (Class B) – resulting from a fine mixture, ground and pressed in molds at high pressure; they can also be glazed or unglazed.

Adhesives Types

There are several types of adhesives on the market depending on the material they are made of. The most commonly used types of adhesives for ceramic tiles are those based on mineral binders (also known as cement-based adhesives). These have the letter “C” on the packaging.

Cement-based/Mineral-based adhesives (Type C) are divided into two main classes: normal adhesives (Class 1) and improved adhesives (Class 2). Normal adhesives (C1) are used in standard conditions when the substrate is standard (cement plaster, cement screed) to attach ceramic tiles inside (not in an environment exposed to moisture or with large temperature variations). Improved adhesives (C2) are used in difficult conditions such as wet environments, acidic environments, in the presence of underfloor heating systems, when installing over other ceramic tiles, etc.

1.Normal class C1 adhesives

C1 normal setting

C1E normal setting with extended open time

C1F rapid setting

C1FT rapid setting with reduced slip

2.Improved class C2 adhesives

C2 improved with additional characteristics

C2E improved with additional characteristics and extended open time

C2F improved with rapid setting

C2S1 improved and deformable

C2S2 highly improved and deformable

Examples of choosing the right adhesive: for porcelain tiles (absorption < 0.5%), a C2S1 adhesive should be used; for a bathroom, an improved C2 adhesive should be used; for exterior tiles, a C2 adhesive should be used; for large-sized tiles, a flexible adhesive (S1 or S2) is recommended; for wet areas, terraces, and underfloor heating, a C2S1 adhesive should be used.

Adhesives for interior and exterior

When choosing adhesives for exterior use, it is important to consider that they need to be suitable for wet spaces and for large temperature fluctuations. Waterproof adhesives, for example, are ideal for tiling bathrooms, as well as for terraces or verandas that are not entirely protected from the elements. Initially, waterproof adhesives were used for fountains and swimming pools. Their composition includes additives with strong bonding properties, as well as other substances that provide resistance to moisture and water. Although waterproof adhesives are suitable for bathrooms, some people prefer those with strong fixing properties for added safety, including in outdoor spaces. Universal adhesives are used in a wide range of exterior works, such as building facades, as well as interiors, such as tile flooring. However, it is important to note that this adhesive is not suitable for large tiles and cannot support heavy weights. Universal adhesive is suitable for standard sized ceramic and porcelain tiles. Generally, for one square meter, two to six kilograms of adhesive are needed, depending on the application and the space to be arranged.

Ceresit CM 9 (type CIT) vs CM 11 (type C1T) vs CM 17 (type C2TES1) – what are the differences between them

Ceresit CM 9 adhesive is ideal for standard tiling. Ceresit CM 9 adhesive for tile and ceramic installation can be used for any type of tile and ceramic with thicknesses between 5 and 15 mm. The adhesive can only be used for ceramic tiles with a water absorption greater than 3% (E>3%). CM 11 PLUS is an improved adhesive, with superior workability and adhesion, which allows for the installation of porcelain tiles only indoors. Ceresit CM 17 is a flexible gray adhesive for ceramic and natural stone tiling on critical surfaces indoors and outdoors in permanently wet environments. Ceresit CM 17 adhesive can be applied on load bearing, compact, clean, and dry surfaces without substances that could hinder adhesion (such as fats, bitumen, dust), such as concrete with a minimum age of three months, cement screeds (at least 28 days old). Areas of use include: ceramic and natural stone tiling; absorbent and non-absorbent substrates; bonding on deformable substrates such as gypsum boards, treated OSB, or chipboard; indoor, outdoor and permanently wet environments; application in residential, public or commercial buildings; mosaic tiles on concrete swimming pools; bonding on critical surfaces and on surfaces sealed with cement-based waterproofing; balconies and terraces; and water tank tiling. The adhesive mixture is obtained by adding clean water (approximately 6.5 liters of water to 25 kg of adhesive powder) in a clean container, then adding the adhesive from the bag and homogenizing it with a mixer. After a waiting time of 5 minutes, the homogenization process is resumed. Follow the manufacturer’s instructions regarding the mixture and dosages, to obtain a homogeneous paste, without lumps, that can be easily applied with a notched trowel, in a uniform layer.